Progress Energy (PREX) 10-K 28 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 31, 2019	Jun. 30, 2018
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Entity Registrant Name	Duke Energy Corporation
Entity Central Index Key	1,326,160
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		727,010,882
Entity Public Float			$ 56,283,598,357
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	DUK
Duke Energy Carolinas [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Carolinas, LLC
Entity Central Index Key	30,371
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Progress Energy [Member]
Document Information [Line Items]
Entity Registrant Name	Progress Energy, Inc.
Entity Central Index Key	1,094,093
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Duke Energy Progress [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Progress, LLC
Entity Central Index Key	17,797
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Duke Energy Florida [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Florida, LLC
Entity Central Index Key	37,637
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Duke Energy Ohio [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Ohio, Inc.
Entity Central Index Key	20,290
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Duke Energy Indiana [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Indiana, LLC
Entity Central Index Key	81,020
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Piedmont Natural Gas [Member]
Document Information [Line Items]
Entity Registrant Name	Piedmont Natural Gas Company, Inc.
Entity Central Index Key	78,460
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016		Oct. 31, 2016
Operating Revenues
Regulated electric		$ 22,097	$ 21,177	$ 21,221
Regulated natural gas		1,773	1,734	863
Nonregulated electric and other		651	654	659
Total operating revenues		24,521	23,565	22,743
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas		6,831	6,350	6,625
Cost of natural gas		697	632	265
Operation, maintenance and other		6,463	5,944	6,224
Depreciation and amortization		4,074	3,527	3,294
Property and other taxes		1,280	1,233	1,142
Impairment charges		402	282	18
Total operating expenses		19,747	17,968	17,568
(Losses) Gains on Sales of Other Assets and Other, net		(89)	28	27
Operating Income		4,685	5,625	5,202
Other Income and Expenses
Equity in earnings (losses) of unconsolidated affiliates		83	119	(15)
Other income and expenses, net		399	508	463
Total other income and expenses		482	627	448
Interest Expense		2,094	1,986	1,916
Income From Continuing Operations Before Income Taxes		3,073	4,266	3,734
Income Tax Expense From Continuing Operations		448	1,196	1,156
Income From Continuing Operations		2,625	3,070	2,578
Income (Loss) From Discontinued Operations, net of tax		19	(6)	(408)
Net Income		2,644	3,064	2,170
Less: Net (Loss) Income Attributable to Noncontrolling Interests		(22)	5	18
Net Income Attributable to Parent		2,666	3,059	2,152
Other Comprehensive (Loss) Income, net of tax
Pension and OPEB adjustments		(6)	3	(11)
Net unrealized (losses) gains on cash flow hedges		(10)	2	17
Reclassification into earnings from cash flow hedges		6	8	13
Unrealized gains on available for sale securities		(3)	13	2
Other Comprehensive (Loss) Income, net of tax		(13)	26	715	[1]
Comprehensive Income		2,631	3,090	2,885
Less: Comprehensive (Loss) Income Attributable to Noncontrolling Interests		(22)	5	20
Comprehensive (Loss) Income Attributable to Parent		$ 2,653	$ 3,085	$ 2,865
Income from continuing operations attributable to Duke Energy Corporation common stockholders
Basic (in usd per share)		$ 3.73	$ 4.37	$ 3.71
Diluted (in usd per share)		3.73	4.37	3.71
Income (Loss) from discontinued operations attributable to Duke Energy Corporation common stockholders
Basic (in usd per share)		0.03	(0.01)	(0.60)
Diluted (in usd per share)		0.03	(0.01)	(0.60)
Net income attributable to Duke Energy Corporation common stockholders
Basic (in usd per share)		3.76	4.36	3.11
Diluted (in usd per share)		$ 3.76	$ 4.36	$ 3.11
Weighted average shares outstanding
Basic (in shares)		708	700	691
Diluted (in shares)		708	700	691
Duke Energy Carolinas [Member]
Operating Revenues
Total operating revenues		$ 7,300	$ 7,302	$ 7,322
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas		1,821	1,822	1,797
Operation, maintenance and other		2,130	2,021	2,158
Depreciation and amortization		1,201	1,090	1,075
Property and other taxes		295	281	276
Impairment charges		192		1
Total operating expenses		5,639	5,214	5,307
(Losses) Gains on Sales of Other Assets and Other, net		(1)	1	(5)
Operating Income		1,660	2,089	2,010
Other Income and Expenses
Other income and expenses, net		153	199	214
Total other income and expenses		153	199	214
Interest Expense		439	422	424
Income From Continuing Operations Before Income Taxes		1,374	1,866	1,800
Income Tax Expense From Continuing Operations		303	652	634
Net Income Attributable to Parent		1,071	1,214	1,166
Other Comprehensive (Loss) Income, net of tax
Reclassification into earnings from cash flow hedges		1	2	2
Other Comprehensive (Loss) Income, net of tax		1	2	2
Comprehensive (Loss) Income Attributable to Parent		1,072	1,216	1,168
Progress Energy [Member]
Operating Revenues
Total operating revenues		10,728	9,783	9,853
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas		3,976	3,417	3,644
Operation, maintenance and other		2,613	2,301	2,458
Depreciation and amortization		1,619	1,285	1,213
Property and other taxes		529	503	487
Impairment charges		87	156	7
Total operating expenses		8,824	7,662	7,809
(Losses) Gains on Sales of Other Assets and Other, net		24	26	25
Operating Income		1,928	2,147	2,069
Other Income and Expenses
Other income and expenses, net		165	209	186
Total other income and expenses		165	209	186
Interest Expense		842	824	689
Income From Continuing Operations Before Income Taxes		1,251	1,532	1,566
Income Tax Expense From Continuing Operations		218	264	527
Income From Continuing Operations		1,033	1,268	1,039
Income (Loss) From Discontinued Operations, net of tax				2
Net Income		1,033	1,268	1,041
Less: Net (Loss) Income Attributable to Noncontrolling Interests		6	10	10
Net Income Attributable to Parent		1,027	1,258	1,031
Other Comprehensive (Loss) Income, net of tax
Pension and OPEB adjustments		5	4	1
Net unrealized (losses) gains on cash flow hedges		6	5
Reclassification into earnings from cash flow hedges		0	0	8
Unrealized gains on available for sale securities		(1)	4	1
Other Comprehensive (Loss) Income, net of tax		10	13	10
Comprehensive Income		1,043	1,281	1,051
Less: Comprehensive (Loss) Income Attributable to Noncontrolling Interests		6	10	10
Comprehensive (Loss) Income Attributable to Parent		1,037	1,271	1,041
Duke Energy Progress [Member]
Operating Revenues
Total operating revenues		5,699	5,129	5,277
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas		1,892	1,609	1,830
Operation, maintenance and other		1,578	1,439	1,565
Depreciation and amortization		991	725	703
Property and other taxes		155	156	156
Impairment charges		33	19	1
Total operating expenses		4,649	3,948	4,255
(Losses) Gains on Sales of Other Assets and Other, net		9	4	3
Operating Income		1,059	1,185	1,025
Other Income and Expenses
Other income and expenses, net		87	115	132
Total other income and expenses		87	115	132
Interest Expense		319	293	257
Income From Continuing Operations Before Income Taxes		827	1,007	900
Income Tax Expense From Continuing Operations		160	292	301
Net Income Attributable to Parent		667	715	599
Other Comprehensive (Loss) Income, net of tax
Comprehensive (Loss) Income Attributable to Parent		667	715	599
Duke Energy Florida [Member]
Operating Revenues
Total operating revenues		5,021	4,646	4,568
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas		2,085	1,808	1,814
Operation, maintenance and other		1,025	853	884
Depreciation and amortization		628	560	509
Property and other taxes		374	347	333
Impairment charges		54	138	6
Total operating expenses		4,166	3,706	3,546
(Losses) Gains on Sales of Other Assets and Other, net		1	1
Operating Income		856	941	1,022
Other Income and Expenses
Other income and expenses, net		86	96	63
Total other income and expenses		86	96	63
Interest Expense		287	279	212
Income From Continuing Operations Before Income Taxes		655	758	873
Income Tax Expense From Continuing Operations		101	46	322
Net Income Attributable to Parent		554	712	551
Other Comprehensive (Loss) Income, net of tax
Unrealized gains on available for sale securities		(1)	3	1
Other Comprehensive (Loss) Income, net of tax		(1)	3	1
Comprehensive (Loss) Income Attributable to Parent		553	715	552
Duke Energy Ohio [Member]
Operating Revenues
Regulated electric		1,450	1,373	1,410
Regulated natural gas		506	508	503
Nonregulated electric and other		1	42	31
Total operating revenues		1,957	1,923	1,944
Operating Expenses
Cost of natural gas		113	107	103
Operation, maintenance and other		480	530	514
Depreciation and amortization		268	261	233
Property and other taxes		290	278	258
Impairment charges			1
Total operating expenses		1,563	1,604	1,601
(Losses) Gains on Sales of Other Assets and Other, net		(106)	1	2
Operating Income		288	320	345
Other Income and Expenses
Other income and expenses, net		23	23	11
Total other income and expenses		23	23	11
Interest Expense		92	91	86
Income From Continuing Operations Before Income Taxes		219	252	270
Income Tax Expense From Continuing Operations		43	59	78
Income From Continuing Operations		176	193	192
Income (Loss) From Discontinued Operations, net of tax			(1)	36
Net Income Attributable to Parent		176	192	228
Other Comprehensive (Loss) Income, net of tax
Comprehensive (Loss) Income Attributable to Parent		176	192	228
Duke Energy Indiana [Member]
Operating Revenues
Total operating revenues		3,059	3,047	2,958
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas		1,000	966	909
Operation, maintenance and other		788	743	727
Depreciation and amortization		520	458	496
Property and other taxes		78	76	58
Impairment charges		30	18	8
Total operating expenses		2,416	2,261	2,198
(Losses) Gains on Sales of Other Assets and Other, net				1
Operating Income		643	786	761
Other Income and Expenses
Other income and expenses, net		45	47	26
Total other income and expenses		45	47	26
Interest Expense		167	178	181
Income From Continuing Operations Before Income Taxes		521	655	606
Income Tax Expense From Continuing Operations		128	301	225
Net Income Attributable to Parent		393	354	381
Other Comprehensive (Loss) Income, net of tax
Reclassification into earnings from cash flow hedges				(1)
Other Comprehensive (Loss) Income, net of tax				(1)
Comprehensive (Loss) Income Attributable to Parent		393	354	380
Piedmont Natural Gas [Member]
Operating Revenues
Regulated natural gas	$ 320	1,365	1,319			$ 1,139
Nonregulated electric and other	2	10	9			10
Total operating revenues	322	1,375	1,328			1,149
Operating Expenses
Cost of natural gas	144	584	524			391
Operation, maintenance and other	50	357	304			353
Depreciation and amortization	23	159	148			137
Property and other taxes	7	49	48			43
Impairment charges			7
Total operating expenses	224	1,149	1,031			924
Operating Income	98	226	297			225
Other Income and Expenses
Equity in earnings (losses) of unconsolidated affiliates	2	7	(6)			29
Gain on sale of unconsolidated affiliates						133
Other income and expenses, net	(2)	14	(11)			(1)
Total other income and expenses		21	(17)			161
Interest Expense	12	81	79			69
Income From Continuing Operations Before Income Taxes	86	166	201			317
Income Tax Expense From Continuing Operations	32	37	62			124
Net Income Attributable to Parent	54	129	139			193
Other Comprehensive (Loss) Income, net of tax
Net unrealized (losses) gains on cash flow hedges						(3)
Reclassification into earnings from cash flow hedges						4
Other Comprehensive (Loss) Income, net of tax						1
Comprehensive (Loss) Income Attributable to Parent	$ 54	129	139			$ 194
Electricity, US Regulated [Member] | Duke Energy Ohio [Member]
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas		$ 412	369	442
Electricity, Nonregulated [Member] | Duke Energy Ohio [Member]
Operating Expenses
Fuel used in electric generation and purchased power/Cost of natural gas			$ 58	$ 51
[1]	Foreign Currency Translation Adjustments amount includes $620 million of cumulative adjustment realized as a result of the sale of the Latin American generation business. See Note 2 to the Consolidated Financial Statements.

Consolidated Statements of Op_2

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 2,653	$ 3,085	$ 2,865
Duke Energy Progress [Member]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	667	715	599
Duke Energy Ohio [Member]
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 176	$ 192	$ 228

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 2,644	$ 3,064	$ 2,170
Other Comprehensive (Loss) Income, net of tax
Foreign currency translation adjustments	0	0	694
Pension and OPEB adjustments	(6)	3	(11)
Net unrealized (losses) gains on cash flow hedges	(10)	2	17
Reclassification into earnings from cash flow hedges	6	8	13
Unrealized (losses) gains on available-for-sale securities	(3)	13	2
Other Comprehensive (Loss) Income, net of tax	(13)	26	715	[1]
Comprehensive Income	2,631	3,090	2,885
Less: Comprehensive (Loss) Income Attributable to Noncontrolling Interests	(22)	5	20
Comprehensive (Loss) Income Attributable to Parent	$ 2,653	$ 3,085	$ 2,865
[1]	Foreign Currency Translation Adjustments amount includes $620 million of cumulative adjustment realized as a result of the sale of the Latin American generation business. See Note 2 to the Consolidated Financial Statements.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 442	$ 358
Receivables (net of allowance for doubtful accounts)	962	779
Receivables of VIEs (net of allowance for doubtful accounts)	2,172	1,995
Inventory	3,084	3,250
Regulatory assets (includes amounts related to VIEs)	2,005	1,437
Other (including amounts related to VIEs)	1,049	634
Total current assets	9,714	8,453
Property, Plant and Equipment
Cost	134,458	127,507
Accumulated depreciation and amortization	(43,126)	(41,537)
Generation facilities to be retired, net	362	421
Net property, plant and equipment	91,694	86,391
Other Noncurrent Assets
Goodwill	19,303	19,396
Regulatory assets (includes amounts related to VIEs)	13,617	12,442
Nuclear decommissioning trust funds	6,720	7,097
Investments in equity method unconsolidated affiliates	1,409	1,175
Other	2,935	2,960
Total other noncurrent assets	43,984	43,070
Total Assets	145,392	137,914
Current Liabilities
Accounts payable	3,487	3,043
Notes payable and commercial paper	3,410	2,163
Taxes accrued	577	551
Interest accrued	559	525
Current maturities of long-term debt (includes amounts related to VIEs)	3,406	3,244
Asset retirement obligations	919	689
Regulatory liabilities	598	402
Other	2,085	1,865
Total current liabilities	15,041	12,482
Long-Term Debt (includes amounts related to VIEs)	51,123	49,035
Other Noncurrent Liabilities
Deferred income taxes	7,806	6,621
Asset retirement obligations	9,548	9,486
Regulatory liabilities	14,834	15,330
Accrued pension and other post-retirement benefit costs	988	1,103
Investment tax credits	568	539
Other (includes amounts related to VIEs)	1,650	1,581
Total other noncurrent liabilities	35,394	34,660
Equity
Common stock	1	1
Additional paid-in capital	40,795	38,792
Retained earnings	3,113	3,013
Accumulated other comprehensive (loss) income	(92)	(67)
Total Parent stockholders' equity	43,817	41,739
Noncontrolling interests	17	(2)
Total equity	43,834	41,737
Total Liabilities and Equity	145,392	137,914
Duke Energy Carolinas [Member]
Current Assets
Cash and cash equivalents	33	16
Receivables (net of allowance for doubtful accounts)	219	200
Receivables of VIEs (net of allowance for doubtful accounts)	699	640
Receivables from affiliated companies	182	95
Inventory	948	971
Regulatory assets (includes amounts related to VIEs)	520	299
Other (including amounts related to VIEs)	72	19
Total current assets	2,673	2,240
Property, Plant and Equipment
Cost	44,741	42,939
Accumulated depreciation and amortization	(15,496)	(15,063)
Net property, plant and equipment	29,245	27,876
Other Noncurrent Assets
Regulatory assets (includes amounts related to VIEs)	3,457	2,853
Nuclear decommissioning trust funds	3,558	3,772
Other	1,027	979
Total other noncurrent assets	8,042	7,604
Total Assets	39,960	37,720
Current Liabilities
Accounts payable	988	842
Accounts payable to affiliated companies	230	209
Notes payable to affiliated companies	439	104
Taxes accrued	171	234
Interest accrued	102	108
Current maturities of long-term debt (includes amounts related to VIEs)	6	1,205
Asset retirement obligations	290	337
Regulatory liabilities	199	126
Other	571	486
Total current liabilities	2,996	3,651
Long-Term Debt (includes amounts related to VIEs)	10,633	8,598
Long-Term Debt Payable to Affiliated Companies	300	300
Other Noncurrent Liabilities
Deferred income taxes	3,689	3,413
Asset retirement obligations	3,659	3,273
Regulatory liabilities	5,999	6,231
Accrued pension and other post-retirement benefit costs	99	95
Investment tax credits	231	232
Other (includes amounts related to VIEs)	671	566
Total other noncurrent liabilities	14,348	13,810
Commitments and Contingencies
Equity
Member's equity	11,689	11,368
Accumulated other comprehensive (loss) income	(6)	(7)
Total member's equity	11,683	11,361
Total Liabilities and Equity	39,960	37,720
Progress Energy [Member]
Current Assets
Cash and cash equivalents	67	40
Receivables (net of allowance for doubtful accounts)	220	123
Receivables of VIEs (net of allowance for doubtful accounts)	909	780
Receivables from affiliated companies	168	31
Notes receivable from affiliated companies		240
Inventory	1,459	1,592
Regulatory assets (includes amounts related to VIEs)	1,137	741
Other (including amounts related to VIEs)	125	334
Total current assets	4,085	3,881
Property, Plant and Equipment
Cost	50,260	47,323
Accumulated depreciation and amortization	(16,398)	(15,857)
Generation facilities to be retired, net	362	421
Net property, plant and equipment	34,224	31,887
Other Noncurrent Assets
Goodwill	3,655	3,655
Regulatory assets (includes amounts related to VIEs)	6,564	6,010
Nuclear decommissioning trust funds	3,162	3,324
Other	974	931
Total other noncurrent assets	14,355	13,920
Total Assets	52,664	49,688
Current Liabilities
Accounts payable	1,172	1,006
Accounts payable to affiliated companies	360	251
Notes payable to affiliated companies	1,235	805
Taxes accrued	109	101
Interest accrued	246	212
Current maturities of long-term debt (includes amounts related to VIEs)	1,672	771
Asset retirement obligations	514	295
Regulatory liabilities	280	213
Other	821	729
Total current liabilities	6,409	4,383
Long-Term Debt (includes amounts related to VIEs)	17,089	16,916
Long-Term Debt Payable to Affiliated Companies	150	150
Other Noncurrent Liabilities
Deferred income taxes	3,941	3,502
Asset retirement obligations	4,897	5,119
Regulatory liabilities	5,049	5,306
Accrued pension and other post-retirement benefit costs	521	545
Other (includes amounts related to VIEs)	351	302
Total other noncurrent liabilities	14,759	14,774
Commitments and Contingencies
Equity
Additional paid-in capital	9,143	9,143
Retained earnings	5,131	4,350
Accumulated other comprehensive (loss) income	(20)	(25)
Total Parent stockholders' equity	14,254	13,468
Noncontrolling interests	3	(3)
Total equity	14,257	13,465
Total Liabilities and Equity	52,664	49,688
Duke Energy Progress [Member]
Current Assets
Cash and cash equivalents	23	20
Receivables (net of allowance for doubtful accounts)	75	56
Receivables of VIEs (net of allowance for doubtful accounts)	547	459
Receivables from affiliated companies	23	3
Inventory	954	1,017
Regulatory assets (includes amounts related to VIEs)	703	352
Other (including amounts related to VIEs)	62	97
Total current assets	2,387	2,004
Property, Plant and Equipment
Cost	31,459	29,583
Accumulated depreciation and amortization	(11,423)	(10,903)
Generation facilities to be retired, net	362	421
Net property, plant and equipment	20,398	19,101
Other Noncurrent Assets
Regulatory assets (includes amounts related to VIEs)	4,111	3,507
Nuclear decommissioning trust funds	2,503	2,588
Other	612	599
Total other noncurrent assets	7,226	6,694
Total Assets	30,011	27,799
Current Liabilities
Accounts payable	660	402
Accounts payable to affiliated companies	278	179
Notes payable to affiliated companies	294	240
Taxes accrued	53	64
Interest accrued	116	102
Current maturities of long-term debt (includes amounts related to VIEs)	603	3
Asset retirement obligations	509	295
Regulatory liabilities	178	139
Other	408	376
Total current liabilities	3,099	1,800
Long-Term Debt (includes amounts related to VIEs)	7,451	7,204
Long-Term Debt Payable to Affiliated Companies	150	150
Other Noncurrent Liabilities
Deferred income taxes	2,119	1,883
Asset retirement obligations	4,311	4,378
Regulatory liabilities	3,955	3,999
Accrued pension and other post-retirement benefit costs	237	248
Investment tax credits	142	143
Other (includes amounts related to VIEs)	106	45
Total other noncurrent liabilities	10,870	10,696
Equity
Total member's equity	8,441	7,949
Total Liabilities and Equity	30,011	27,799
Duke Energy Florida [Member]
Current Assets
Cash and cash equivalents	36	13
Receivables (net of allowance for doubtful accounts)	143	65
Receivables of VIEs (net of allowance for doubtful accounts)	362	321
Receivables from affiliated companies	28	2
Notes receivable from affiliated companies		313
Inventory	504	574
Regulatory assets (includes amounts related to VIEs)	434	389
Other (including amounts related to VIEs)	46	86
Total current assets	1,553	1,763
Property, Plant and Equipment
Cost	18,792	17,730
Accumulated depreciation and amortization	(4,968)	(4,947)
Net property, plant and equipment	13,824	12,783
Other Noncurrent Assets
Regulatory assets (includes amounts related to VIEs)	2,454	2,503
Nuclear decommissioning trust funds	659	736
Other	311	284
Total other noncurrent assets	3,424	3,523
Total Assets	18,801	18,069
Current Liabilities
Accounts payable	511	602
Accounts payable to affiliated companies	91	74
Notes payable to affiliated companies	108
Taxes accrued	74	34
Interest accrued	75	56
Current maturities of long-term debt (includes amounts related to VIEs)	270	768
Asset retirement obligations	5
Regulatory liabilities	102	74
Other	406	334
Total current liabilities	1,642	1,942
Long-Term Debt (includes amounts related to VIEs)	7,051	6,327
Other Noncurrent Liabilities
Deferred income taxes	1,986	1,761
Asset retirement obligations	586	742
Regulatory liabilities	1,094	1,307
Accrued pension and other post-retirement benefit costs	254	264
Other (includes amounts related to VIEs)	93	108
Total other noncurrent liabilities	4,013	4,182
Equity
Member's equity	6,097	5,614
Accumulated other comprehensive (loss) income	(2)	4
Total member's equity	6,095	5,618
Total Liabilities and Equity	18,801	18,069
Duke Energy Ohio [Member]
Current Assets
Cash and cash equivalents	21	12
Receivables (net of allowance for doubtful accounts)	102	68
Receivables from affiliated companies	114	133
Notes receivable from affiliated companies		14
Inventory	126	133
Regulatory assets (includes amounts related to VIEs)	33	49
Other (including amounts related to VIEs)	24	39
Total current assets	420	448
Property, Plant and Equipment
Cost	9,360	8,732
Accumulated depreciation and amortization	(2,717)	(2,691)
Net property, plant and equipment	6,643	6,041
Other Noncurrent Assets
Goodwill	920	920
Regulatory assets (includes amounts related to VIEs)	531	445
Other	41	21
Total other noncurrent assets	1,492	1,386
Total Assets	8,555	7,875
Current Liabilities
Accounts payable	316	313
Accounts payable to affiliated companies	78	62
Notes payable to affiliated companies	274	29
Taxes accrued	202	190
Interest accrued	22	21
Current maturities of long-term debt (includes amounts related to VIEs)	551	3
Asset retirement obligations	6	3
Regulatory liabilities	57	36
Other	74	71
Total current liabilities	1,580	728
Long-Term Debt (includes amounts related to VIEs)	1,589	2,039
Long-Term Debt Payable to Affiliated Companies	25	25
Other Noncurrent Liabilities
Deferred income taxes	817	781
Asset retirement obligations	87	81
Regulatory liabilities	840	891
Accrued pension and other post-retirement benefit costs	79	59
Other (includes amounts related to VIEs)	93	108
Total other noncurrent liabilities	1,916	1,920
Equity
Common stock	762	762
Additional paid-in capital	2,776	2,670
Retained earnings	(93)	(269)
Total Parent stockholders' equity	3,445	3,163
Total Liabilities and Equity	8,555	7,875
Duke Energy Indiana [Member]
Current Assets
Cash and cash equivalents	24	9
Receivables (net of allowance for doubtful accounts)	52	57
Receivables from affiliated companies	122	125
Inventory	422	450
Regulatory assets (includes amounts related to VIEs)	175	165
Other (including amounts related to VIEs)	35	30
Total current assets	830	836
Property, Plant and Equipment
Cost	15,443	14,948
Accumulated depreciation and amortization	(4,914)	(4,662)
Net property, plant and equipment	10,529	10,286
Other Noncurrent Assets
Regulatory assets (includes amounts related to VIEs)	982	978
Other	194	189
Total other noncurrent assets	1,176	1,167
Total Assets	12,535	12,289
Current Liabilities
Accounts payable	200	196
Accounts payable to affiliated companies	83	78
Notes payable to affiliated companies	167	161
Taxes accrued	43	95
Interest accrued	58	57
Current maturities of long-term debt (includes amounts related to VIEs)	63	3
Asset retirement obligations	109	54
Regulatory liabilities	25	24
Other	107	104
Total current liabilities	855	772
Long-Term Debt (includes amounts related to VIEs)	3,569	3,630
Long-Term Debt Payable to Affiliated Companies	150	150
Other Noncurrent Liabilities
Deferred income taxes	1,009	925
Asset retirement obligations	613	727
Regulatory liabilities	1,722	1,723
Accrued pension and other post-retirement benefit costs	115	76
Investment tax credits	147	147
Other (includes amounts related to VIEs)	16	18
Total other noncurrent liabilities	3,622	3,616
Equity
Total member's equity	4,339	4,121
Total Liabilities and Equity	12,535	12,289
Piedmont Natural Gas [Member]
Current Assets
Cash and cash equivalents	0	19
Receivables (net of allowance for doubtful accounts)	266	275
Receivables from affiliated companies	22	7
Inventory	70	66
Regulatory assets (includes amounts related to VIEs)	54	95
Other (including amounts related to VIEs)	19	52
Total current assets	431	514
Property, Plant and Equipment
Cost	7,486	6,725
Accumulated depreciation and amortization	(1,575)	(1,479)
Net property, plant and equipment	5,911	5,246
Other Noncurrent Assets
Goodwill	49	49
Regulatory assets (includes amounts related to VIEs)	303	283
Investments in equity method unconsolidated affiliates	64	61
Other	52	65
Total other noncurrent assets	468	458
Total Assets	6,810	6,218
Current Liabilities
Accounts payable	203	125
Accounts payable to affiliated companies	38	13
Notes payable to affiliated companies	198	364
Taxes accrued	84	19
Interest accrued	31	31
Current maturities of long-term debt (includes amounts related to VIEs)	350	250
Regulatory liabilities	37	3
Other	58	69
Total current liabilities	999	874
Long-Term Debt (includes amounts related to VIEs)	1,788	1,787
Other Noncurrent Liabilities
Deferred income taxes	551	564
Asset retirement obligations	19	15
Regulatory liabilities	1,181	1,141
Accrued pension and other post-retirement benefit costs	4	5
Other (includes amounts related to VIEs)	177	170
Total other noncurrent liabilities	1,932	1,895
Equity
Common stock	1,160	860
Retained earnings	931	802
Total Parent stockholders' equity	2,091	1,662
Total Liabilities and Equity	$ 6,810	$ 6,218

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts - receivables	$ 16	$ 14
Regulatory assets	2,005	1,437
Regulatory assets, noncurrent	13,617	12,442
Other (including amounts related to VIEs)	1,049	634
Current maturities of long-term debt	3,406	3,244
Long-Term Debt	$ 51,123	$ 49,035
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	2,000,000,000	2,000,000,000
Common stock, shares outstanding	727,000,000	700,000,000
Other (includes amounts related to VIEs)	$ 1,650	$ 1,581
Variable Interest Entity [Member]
Allowance for doubtful accounts - receivables of VIEs	55	54
Regulatory assets	52	51
Regulatory assets, noncurrent	1,041	1,091
Other (including amounts related to VIEs)	162	214
Current maturities of long-term debt	227	225
Long-Term Debt	3,998	4,306
Other (includes amounts related to VIEs)	212	241
Duke Energy Carolinas [Member]
Allowance for doubtful accounts - receivables	2	2
Regulatory assets	520	299
Regulatory assets, noncurrent	3,457	2,853
Other (including amounts related to VIEs)	72	19
Current maturities of long-term debt	6	1,205
Long-Term Debt	10,633	8,598
Other (includes amounts related to VIEs)	671	566
Duke Energy Carolinas [Member] | Variable Interest Entity [Member]
Allowance for doubtful accounts - receivables of VIEs	7	7
Progress Energy [Member]
Allowance for doubtful accounts - receivables	5	4
Regulatory assets	1,137	741
Regulatory assets, noncurrent	6,564	6,010
Other (including amounts related to VIEs)	125	334
Current maturities of long-term debt	1,672	771
Long-Term Debt	$ 17,089	$ 16,916
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100	100
Common stock, shares outstanding	100	100
Other (includes amounts related to VIEs)	$ 351	$ 302
Progress Energy [Member] | Variable Interest Entity [Member]
Allowance for doubtful accounts - receivables of VIEs	8	7
Regulatory assets	52	51
Regulatory assets, noncurrent	1,041	1,091
Other (including amounts related to VIEs)	39	44
Current maturities of long-term debt	53	53
Long-Term Debt	1,636	1,689
Duke Energy Progress [Member]
Allowance for doubtful accounts - receivables	2	1
Regulatory assets	703	352
Regulatory assets, noncurrent	4,111	3,507
Other (including amounts related to VIEs)	62	97
Current maturities of long-term debt	603	3
Long-Term Debt	7,451	7,204
Other (includes amounts related to VIEs)	106	45
Duke Energy Progress [Member] | Variable Interest Entity [Member]
Allowance for doubtful accounts - receivables of VIEs	5	5
Duke Energy Florida [Member]
Allowance for doubtful accounts - receivables	3	3
Regulatory assets	434	389
Regulatory assets, noncurrent	2,454	2,503
Other (including amounts related to VIEs)	46	86
Current maturities of long-term debt	270	768
Long-Term Debt	7,051	6,327
Other (includes amounts related to VIEs)	93	108
Duke Energy Florida [Member] | Variable Interest Entity [Member]
Allowance for doubtful accounts - receivables of VIEs	3	2
Regulatory assets	52	51
Regulatory assets, noncurrent	1,041	1,091
Other (including amounts related to VIEs)	39	40
Current maturities of long-term debt	53	53
Long-Term Debt	1,336	1,389
Duke Energy Ohio [Member]
Allowance for doubtful accounts - receivables	2	3
Regulatory assets	33	49
Regulatory assets, noncurrent	531	445
Other (including amounts related to VIEs)	24	39
Current maturities of long-term debt	551	3
Long-Term Debt	$ 1,589	$ 2,039
Common stock, par value	$ 8.50	$ 8.50
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares outstanding	90,000,000	90,000,000
Other (includes amounts related to VIEs)	$ 93	$ 108
Duke Energy Indiana [Member]
Allowance for doubtful accounts - receivables	2	2
Regulatory assets	175	165
Regulatory assets, noncurrent	982	978
Other (including amounts related to VIEs)	35	30
Current maturities of long-term debt	63	3
Long-Term Debt	3,569	3,630
Other (includes amounts related to VIEs)	16	18
Piedmont Natural Gas [Member]
Allowance for doubtful accounts - receivables	2	2
Regulatory assets	54	95
Regulatory assets, noncurrent	303	283
Other (including amounts related to VIEs)	19	52
Current maturities of long-term debt	350	250
Long-Term Debt	$ 1,788	$ 1,787
Common stock, shares authorized	100	100
Common stock, shares outstanding	100	100
Other (includes amounts related to VIEs)	$ 177	$ 170

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	2 Months Ended	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income		$ 454	$ 622	$ 703	$ 717	$ 2,644	$ 3,064	$ 2,170
Net Income Attributable to Parent		464	620	703	716	2,666	3,059	2,152
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)						4,696	4,046	3,880
Equity component of AFUDC						(221)	(237)	(200)
Losses (Gains) on sales of other assets						88	(33)	477
Impairment charges						402	282	212
Deferred income taxes						1,079	1,433	900
Equity in (earnings) losses of unconsolidated affiliates						(83)	(119)	15
Accrued pension and other post-retirement benefit costs						61	8	21
Contributions to qualified pension plans						(141)	(19)	(155)
Payments for asset retirement obligations						(533)	(571)	(608)
Payment for the disposal of other assets						(105)
Other rate case adjustments						37
Provision for rate refunds						425
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions						22	18	34
Receivables						(345)	(83)	(372)
Inventory						156	268	272
Other current assets						(721)	(400)	(174)
Increase (decrease) in
Accounts payable						479	(204)	296
Taxes accrued						23	149	236
Other current liabilities						270	(482)	182
Other assets						(1,008)	(436)	(186)
Other liabilities						(39)	(60)	(137)
Net cash provided by (used in) operating activities						7,186	6,624	6,863
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures						(9,389)	(8,052)	(7,901)
Contributions to equity method investments						(416)	(414)	(307)
Acquisitions, net of cash acquired							(13)	(4,778)
Return of investment capital						137	281	1
Purchases of debt and equity securities						(3,762)	(4,071)	(5,153)
Proceeds from sales and maturities of debt and equity securities						3,747	4,098	5,236
Proceeds from the sales of discontinued operations and other assets, net of cash divested						41		1,418
Other						(418)	(271)	(44)
Net cash used in investing activities						(10,060)	(8,442)	(11,528)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt						5,299	6,909	9,238
Proceeds from Issuance of Common Stock						1,838		731
Payments for the redemption of long-term debt						(2,906)	(2,316)	(1,923)
Proceeds from the issuance of short-term debt with original maturities greater than 90 days						472	319	2,081
Payments for the redemption of short-term debt with original maturities greater than 90 days						(282)	(272)	(2,166)
Notes payable and commercial paper						981	(409)	(1,362)
Dividends paid						(2,471)	(2,450)	(2,332)
Other						29	1	(16)
Net cash provided by financing activities						2,960	1,782	4,251
Changes in cash and cash equivalents included in assets held for sale								474
Net increase (decrease) in cash, cash equivalents, and restricted cash						86	(36)	60
Cash, cash equivalents, and restricted cash at beginning of period			505		541	505	541	481
Cash, cash equivalents, and restricted cash at end of period	$ 541	591		505		591	505	541
Cash and cash equivalents at beginning of period			358			358
Cash and cash equivalents at end of period		442		358		442	358
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized						2,086	1,963	1,794
Cash (received from) paid for income taxes						(266)	4	229
Significant non-cash transactions:
Accrued capital expenditures						1,112	1,032	1,000
Non-cash dividends						107
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income Attributable to Parent		135	323	205	270	1,071	1,214	1,166
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)						1,487	1,409	1,382
Equity component of AFUDC						(73)	(106)	(102)
Losses (Gains) on sales of other assets						1	(1)	5
Impairment charges						192		1
Deferred income taxes						305	410	470
Accrued pension and other post-retirement benefit costs						4	(4)	4
Contributions to qualified pension plans						(46)		(43)
Payments for asset retirement obligations						(230)	(271)	(287)
Provision for rate refunds						182
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions						2	9	5
Receivables						(86)	(9)	(76)
Receivables from affiliated companies						(87)	68	(56)
Inventory						25	78	215
Other current assets						(161)	7	67
Increase (decrease) in
Accounts payable						168	23	(69)
Accounts payable to affiliated companies						21	(38)	18
Taxes accrued						(65)	86	187
Other current liabilities						89	(161)	63
Other assets						(179)	(49)	20
Other liabilities						(90)	(31)	6
Net cash provided by (used in) operating activities						2,530	2,634	2,976
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures						(2,706)	(2,524)	(2,220)
Purchases of debt and equity securities						(1,810)	(2,124)	(2,832)
Proceeds from sales and maturities of debt and equity securities						1,810	2,128	2,832
Notes receivable from affiliated companies							66	97
Other						(147)	(109)	(83)
Net cash used in investing activities						(2,853)	(2,563)	(2,206)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt						1,983	569	1,587
Payments for the redemption of long-term debt						(1,205)	(116)	(356)
Notes payable to affiliated companies						335	104
Distributions to parent						(750)	(625)	(2,000)
Other						(23)	(1)
Net cash provided by financing activities						340	(69)	(769)
Net increase in cash and cash equivalents						17	2	1
Cash and cash equivalents at beginning of period			16		14	16	14	13
Cash and cash equivalents at end of period	14	33		16		33	16	14
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized						452	398	393
Cash (received from) paid for income taxes						89	193	(60)
Significant non-cash transactions:
Accrued capital expenditures						302	315	347
Progress Energy [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income		123	237	447	201	1,033	1,268	1,041
Net Income Attributable to Parent		123	235	444	199	1,027	1,258	1,031
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)						1,987	1,516	1,435
Equity component of AFUDC						(104)	(92)	(76)
Losses (Gains) on sales of other assets						(24)	(28)	(34)
Impairment charges						87	156	7
Deferred income taxes						358	703	532
Accrued pension and other post-retirement benefit costs						24	(28)	(24)
Contributions to qualified pension plans						(45)		(43)
Payments for asset retirement obligations						(230)	(248)	(270)
Other rate case adjustments						37
Provision for rate refunds						122
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions						18		42
Receivables						(207)	(89)	7
Receivables from affiliated companies						(137)	71	211
Inventory						121	125	35
Other current assets						(12)	(397)	50
Increase (decrease) in
Accounts payable						217	(260)	252
Accounts payable to affiliated companies						109	(97)	37
Taxes accrued						8	17	15
Other current liabilities						129	(166)	(42)
Other assets						(913)	(300)	(248)
Other liabilities						(34)	(98)	(36)
Net cash provided by (used in) operating activities						2,544	2,053	2,891
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures						(3,854)	(3,152)	(3,306)
Asset acquisitions								(10)
Proceeds from the sales of other assets						20
Purchases of debt and equity securities						(1,753)	(1,806)	(2,143)
Proceeds from sales and maturities of debt and equity securities						1,769	1,824	2,187
Proceeds from insurance							7	58
Proceeds from the sale of nuclear fuel							20	20
Notes receivable from affiliated companies						240	(160)	(80)
Other						(182)	(86)	47
Net cash used in investing activities						(3,760)	(3,353)	(3,227)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt						1,833	2,118	2,375
Payments for the redemption of long-term debt						(771)	(813)	(327)
Notes payable to affiliated companies						430	100	444
Dividends to parent						(250)	(124)	(2,098)
Other						(1)	(4)	(3)
Net cash provided by financing activities						1,241	1,277	391
Net increase (decrease) in cash, cash equivalents, and restricted cash						25	(23)	55
Cash, cash equivalents, and restricted cash at beginning of period			87		110	87	110	55
Cash, cash equivalents, and restricted cash at end of period	110	112		87		112	87	110
Cash and cash equivalents at beginning of period			40			40
Cash and cash equivalents at end of period		67		40		67	40
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized						798	773	673
Cash (received from) paid for income taxes						(348)	(146)	(187)
Significant non-cash transactions:
Accrued capital expenditures						478	391	317
Equitization of certain notes payable to affiliates							1,047
Dividend to parent related to a legal entity restructuring							547
Duke Energy Progress [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income Attributable to Parent		135	177	168	147	667	715	599
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)						1,183	936	907
Equity component of AFUDC						(57)	(47)	(50)
Losses (Gains) on sales of other assets						(9)	(5)	(6)
Impairment charges						33	19	1
Deferred income taxes						236	384	384
Accrued pension and other post-retirement benefit costs						15	(20)	(32)
Contributions to qualified pension plans						(25)		(24)
Payments for asset retirement obligations						(195)	(192)	(212)
Other rate case adjustments						37
Provision for rate refunds						122
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions						5	(4)	4
Receivables						(107)	(58)	(17)
Receivables from affiliated companies						(20)	2	11
Inventory						63	59	12
Other current assets						(201)	(75)	84
Increase (decrease) in
Accounts payable						219	(230)	181
Accounts payable to affiliated companies						99	(48)	37
Taxes accrued						(11)	(39)	90
Other current liabilities						46	(131)	114
Other assets						(484)	(53)	(163)
Other liabilities						12	(18)	12
Net cash provided by (used in) operating activities						1,628	1,195	1,932
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures						(2,220)	(1,715)	(1,733)
Proceeds from the sales of other assets						20
Purchases of debt and equity securities						(1,236)	(1,249)	(1,658)
Proceeds from sales and maturities of debt and equity securities						1,206	1,207	1,615
Proceeds from insurance							4
Notes receivable from affiliated companies							165	(165)
Other						(115)	(55)	26
Net cash used in investing activities						(2,345)	(1,643)	(1,915)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt						845	812	505
Payments for the redemption of long-term debt						(3)	(470)	(15)
Notes payable to affiliated companies						54	240	(209)
Distributions to parent						(175)	(124)	(300)
Other						(1)	(1)	(2)
Net cash provided by financing activities						720	457	(21)
Net increase in cash and cash equivalents						3	9	(4)
Cash and cash equivalents at beginning of period			20		11	20	11	15
Cash and cash equivalents at end of period	11	23		20		23	20	11
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized						303	291	248
Cash (received from) paid for income taxes						(112)	59	(287)
Significant non-cash transactions:
Accrued capital expenditures						220	191	147
Duke Energy Florida [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income Attributable to Parent		40	103	344	90	554	712	551
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)						793	570	516
Equity component of AFUDC						(47)	(45)	(26)
Losses (Gains) on sales of other assets						(1)	(1)
Impairment charges						54	138	6
Deferred income taxes						159	245	224
Accrued pension and other post-retirement benefit costs						5	(13)	2
Contributions to qualified pension plans						(20)		(20)
Payments for asset retirement obligations						(35)	(56)	(58)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions						7	5	38
Receivables						(100)	(38)	23
Receivables from affiliated companies						(26)		21
Inventory						58	66	23
Other current assets						59	(138)	(86)
Increase (decrease) in
Accounts payable						(1)	(32)	71
Accounts payable to affiliated companies						17	(51)	9
Taxes accrued						40	1	(117)
Other current liabilities						82	(37)	(149)
Other assets						(428)	(229)	(84)
Other liabilities						(61)	(82)	(53)
Net cash provided by (used in) operating activities						1,109	1,015	891
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures						(1,634)	(1,437)	(1,583)
Purchases of debt and equity securities						(517)	(557)	(485)
Proceeds from sales and maturities of debt and equity securities						563	617	572
Proceeds from insurance							4	58
Proceeds from the sale of nuclear fuel							20	20
Notes receivable from affiliated companies						313	(313)
Other						(65)	(31)	21
Net cash used in investing activities						(1,340)	(1,697)	(1,397)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt						988	1,306	1,870
Payments for the redemption of long-term debt						(769)	(342)	(12)
Notes payable to affiliated companies						108	(297)	(516)
Distributions to parent						(75)		(775)
Other						1	(1)
Net cash provided by financing activities						253	666	567
Net increase (decrease) in cash, cash equivalents, and restricted cash						22	(16)	61
Cash, cash equivalents, and restricted cash at beginning of period			53		69	53	69	8
Cash, cash equivalents, and restricted cash at end of period	69	75		53		75	53	69
Cash and cash equivalents at beginning of period			13			13
Cash and cash equivalents at end of period		36		13		36	13
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized						270	274	208
Cash (received from) paid for income taxes						(120)	(197)	216
Significant non-cash transactions:
Accrued capital expenditures						258	199	170
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income Attributable to Parent		55	(25)	65	42	176	192	228
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)						271	265	237
Equity component of AFUDC						(11)	(11)	(6)
Losses (Gains) on sales of other assets						106	(1)	(2)
Impairment charges							1
Deferred income taxes						25	90	55
Accrued pension and other post-retirement benefit costs						3	2	6
Contributions to qualified pension plans							(4)	(5)
Payments for asset retirement obligations						(3)	(7)	(5)
Provision for rate refunds						24
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions								(2)
Receivables						(33)	2	(4)
Receivables from affiliated companies						19	(4)	(36)
Inventory						7	6	(32)
Other current assets						16	(22)	79
Increase (decrease) in
Accounts payable						(19)	12	19
Accounts payable to affiliated companies						16	(1)	10
Taxes accrued						12	11	3
Other current liabilities						14	(19)	(54)
Other assets						(26)	(28)	(35)
Other liabilities						(27)	(5)	(31)
Net cash provided by (used in) operating activities						570	479	425
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures						(827)	(686)	(476)
Notes receivable from affiliated companies						14	80	(94)
Other						(89)	(41)	(30)
Net cash used in investing activities						(902)	(647)	(600)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt						99	182	341
Payments for the redemption of long-term debt						(3)	(2)	(53)
Notes payable to affiliated companies						245	13	(87)
Capital contribution from parent						106
Dividends to parent							(25)	(25)
Other							(1)	(2)
Net cash provided by financing activities						341	167	174
Net increase in cash and cash equivalents						9	(1)	(1)
Cash and cash equivalents at beginning of period			12		13	12	13	14
Cash and cash equivalents at end of period	13	21		12		21	12	13
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized						87	85	81
Cash (received from) paid for income taxes						(6)	(8)	(46)
Significant non-cash transactions:
Accrued capital expenditures						95	82	83
Transfer of ownership interest of certain equity method investees to parent						106
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income Attributable to Parent		76	100	36	91	393	354	381
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)						524	462	499
Equity component of AFUDC						(32)	(28)	(16)
Impairment charges						30	18	8
Deferred income taxes						95	152	213
Accrued pension and other post-retirement benefit costs						7	2	8
Contributions to qualified pension plans						(8)		(9)
Payments for asset retirement obligations						(69)	(45)	(46)
Provision for rate refunds						53
(Increase) decrease in
Receivables						7	59	(2)
Receivables from affiliated companies						3	(11)	(43)
Inventory						28	54	66
Other current assets						(25)	28	(67)
Increase (decrease) in
Accounts payable						37	(86)	8
Accounts payable to affiliated companies						5	4	(9)
Taxes accrued						(52)	64	(4)
Other current liabilities						14	(10)	(81)
Other assets						29	(28)	(27)
Other liabilities						(33)	(20)	(8)
Net cash provided by (used in) operating activities						1,006	969	871
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures						(832)	(840)	(755)
Purchases of debt and equity securities						(48)	(20)	(14)
Proceeds from sales and maturities of debt and equity securities						44	7	11
Proceeds from the sales of discontinued operations and other assets, net of cash divested						15
Notes receivable from affiliated companies							86	(3)
Other						3	(65)	32
Net cash used in investing activities						(818)	(832)	(729)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt								494
Payments for the redemption of long-term debt						(3)	(5)	(478)
Notes payable to affiliated companies						6	161
Distributions to parent						(175)	(300)	(149)
Other						(1)	(1)	(1)
Net cash provided by financing activities						(173)	(145)	(134)
Net increase in cash and cash equivalents						15	(8)	8
Cash and cash equivalents at beginning of period			9		17	9	17	9
Cash and cash equivalents at end of period	17	24		9		24	9	17
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized						162	179	171
Cash (received from) paid for income taxes						75	117	(7)
Significant non-cash transactions:
Accrued capital expenditures						88	125	99
Piedmont Natural Gas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net Income Attributable to Parent	54	48	110	63	95	129	139		$ 193
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	25					161	151		148
Losses (Gains) on sales of other assets									(133)
Impairment charges							7
Deferred income taxes	26					(31)	154		74
Equity in (earnings) losses of unconsolidated affiliates	(2)					(7)	6		(29)
Accrued pension and other post-retirement benefit costs	5					(4)	23		3
Contributions to qualified pension plans	(10)						(11)		(14)
Payments for asset retirement obligations	(1)								(6)
Provision for rate refunds						43
(Increase) decrease in
Receivables	(157)					7	(40)		12
Receivables from affiliated companies						(15)			(7)
Inventory	(11)					(4)			14
Other current assets	8					71	(20)		(98)
Increase (decrease) in
Accounts payable	35					15	(13)		6
Accounts payable to affiliated companies	4					25	5		6
Taxes accrued	(2)					65	(48)		38
Other current liabilities	2					21	(9)		28
Other assets	(7)					6	7		(91)
Other liabilities	5					(4)	(2)		180
Net cash provided by (used in) operating activities	(26)					478	349		324
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(113)					(721)	(585)		(522)
Contributions to equity method investments	(12)						(12)		(47)
Proceeds from the sales of other assets									175
Return of investment capital	1					3	2		18
Other	1					(10)	(6)		5
Net cash used in investing activities	(124)					(731)	(603)		(389)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt						100	250		295
Proceeds from Issuance of Common Stock									122
Payments for the redemption of long-term debt							(35)		(40)
Notes payable and commercial paper	185						(330)		(195)
Notes payable to affiliated companies						(166)	364
Capital contribution from parent						300
Dividends to parent	(27)
Dividends paid									(114)
Other							(1)
Net cash provided by financing activities	158					234	248		68
Net increase in cash and cash equivalents	8					(19)	(6)		3
Cash and cash equivalents at beginning of period	17		$ 19		$ 25	19	25		14
Cash and cash equivalents at end of period	25	$ 0		$ 19		0	19	$ 25	17
Supplemental Disclosures:
Cash paid for interest, net of amount capitalized	11					79	78		81
Cash (received from) paid for income taxes						(16)	(12)		(25)
Significant non-cash transactions:
Accrued capital expenditures	$ 48					$ 96	34		$ 63
Transfer of ownership interest of certain equity method investees to parent							$ 149

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Total		Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]		Foreign Currency Translation Adjustments [Member]		Net Gains (Losses) on Cash Flow Hedges [Member]	Net Gains (Losses) on Cash Flow Hedges [Member]		Net Unrealized Gains (Losses) on Available-for-Sale Securities [Member]		Pension And OPEB Adjustments [Member]		Common Stockholders' Equity [Member]		Noncontrolling Interest [Member]		Duke Energy Carolinas [Member]	Duke Energy Carolinas [Member]Members Equity [Member]	Duke Energy Carolinas [Member]Net Gains (Losses) on Cash Flow Hedges [Member]	Duke Energy Carolinas [Member]Net Gains (Losses) on Cash Flow Hedges [Member]	Progress Energy [Member]		Progress Energy [Member]Additional Paid In Capital [Member]	Progress Energy [Member]Retained Earnings [Member]		Progress Energy [Member]Net Gains (Losses) on Cash Flow Hedges [Member]	Progress Energy [Member]Net Gains (Losses) on Cash Flow Hedges [Member]	Progress Energy [Member]Net Unrealized Gains (Losses) on Available-for-Sale Securities [Member]		Progress Energy [Member]Pension And OPEB Adjustments [Member]	Progress Energy [Member]Common Stockholders' Equity [Member]		Progress Energy [Member]Noncontrolling Interest [Member]		Duke Energy Progress [Member]	Duke Energy Progress [Member]Members Equity [Member]	Duke Energy Florida [Member]		Duke Energy Florida [Member]Members Equity [Member]		Duke Energy Florida [Member]Net Unrealized Gains (Losses) on Available-for-Sale Securities [Member]		Duke Energy Ohio [Member]	Duke Energy Ohio [Member]Common Stock [Member]	Duke Energy Ohio [Member]Additional Paid In Capital [Member]	Duke Energy Ohio [Member]Retained Earnings [Member]	Duke Energy Indiana [Member]	Duke Energy Indiana [Member]Common Stock [Member]	Duke Energy Indiana [Member]Additional Paid In Capital [Member]	Duke Energy Indiana [Member]Retained Earnings [Member]	Duke Energy Indiana [Member]Members Equity [Member]	Duke Energy Indiana [Member]Net Gains (Losses) on Cash Flow Hedges [Member]	Piedmont Natural Gas [Member]	Piedmont Natural Gas [Member]Common Stock [Member]	Piedmont Natural Gas [Member]Retained Earnings [Member]	Piedmont Natural Gas [Member]Net Gains (Losses) on Cash Flow Hedges [Member]
Beginning Balance (Attributable to Parent) at Oct. 31, 2015	$ (1)																																																							$ 1,426	$ 721	$ 706
Net Income Attributable to Parent																																																								193		193
Other comprehensive income (loss), net of tax																																																								1			$ 1
Common stock issuances, including dividend reinvestment and employee benefits																																																								139	139
Distributions/Dividends to parent																																																								(114)		(114)
Ending Balance (Attributable to Parent) at Oct. 31, 2016																																																								1,645	860	785
Beginning Balance (parent) at Dec. 31, 2015	39,771		$ 1	$ 37,968	$ 2,564		$ (692)			$ (50)		$ (3)		$ (61)		$ 39,727		$ 44						$ 12,853		$ 8,092	$ 4,831			$ (31)			$ (17)	$ 12,875		$ (22)
Beginning Members' Equity at Dec. 31, 2015																				$ 11,606	$ 11,617		$ (11)																$ 7,059
Beginning Balance (Attributable to Parent) at Dec. 31, 2015																																								$ 5,121		$ 5,121				$ 2,784	$ 762	$ 2,720	$ (698)	$ 3,836	$ 1	$ 1,384	$ 2,450		$ 1
Balance (in shares) at Dec. 31, 2015			688,000,000
Net income	2,170				2,152											2,152		18						1,041			1,031							1,031		10
Net Income Attributable to Parent	2,152																			1,166	1,166			1,031														$ 599	599	551		551				228			228	381				$ 381
Other comprehensive income (loss), net of tax	715	[1]					$ 692	[2]		30	[1]	2	[1]	(11)	[1]	713	[1]	2	[1]	2			2	10						8	$ 1		1	10						1				$ 1						(1)					$ (1)
Common stock issuances, including dividend reinvestment and employee benefits (in shares)			12,000,000
Common stock issuances, including dividend reinvestment and employee benefits	773			773												773
Distributions/Dividends to parent	(2,332)				(2,332)											(2,332)				(2,000)	(2,000)			(2,098)			(2,098)							(2,098)					(300)	(775)		(775)				(25)		(25)		(149)				(149)
Distributions to noncontrolling interest in subsidiaries	(6)																	(6)						(1)												(1)
Other	(50)	[3]																(50)	[3]	(2)	(2)			2		2								2						2		2				9			9		$ (1)	$ (1,384)	$ (2,450)	3,835
Balance (in shares) at Dec. 31, 2016			700,000,000
Ending Balance (parent) at Dec. 31, 2016	41,041		$ 1	38,741	2,384					(20)		(1)		(72)		41,033		8						11,807		8,094	3,764			(23)	1		(16)	11,820		(13)
Ending member's equity at Dec. 31, 2016																				10,772	10,781		(9)																7,358	4,900		4,899		1
Ending Balance (Attributable to Parent) at Dec. 31, 2016																																														2,996	762	2,695	(461)	4,067				4,067		1,672	860	812
Beginning Balance (Attributable to Parent) at Oct. 31, 2016																																																								1,645	860	785
Net Income Attributable to Parent																																																								54		54
Distributions/Dividends to parent																																																								(27)		(27)
Balance (in shares) at Dec. 31, 2016			700,000,000
Ending Balance (parent) at Dec. 31, 2016	41,041		$ 1	38,741	2,384					(20)		(1)		(72)		41,033		8						11,807		8,094	3,764			(23)	1		(16)	11,820		(13)
Ending member's equity at Dec. 31, 2016																				10,772	10,781		(9)																7,358	4,900		4,899		1
Ending Balance (Attributable to Parent) at Dec. 31, 2016																																														2,996	762	2,695	(461)	4,067				4,067		1,672	860	812
Net income	3,064				3,059											3,059		5						1,268			1,258							1,258		10
Net Income Attributable to Parent	3,059																			1,214	1,214			1,258														715	715	712		712				192			192	354				354		139		139
Other comprehensive income (loss), net of tax	26									$ 10		13		3		26				2			$ 2	13						$ 5	4		4	13						3				3
Common stock issuances, including dividend reinvestment and employee benefits	51			51												51
Distributions/Dividends to parent	(2,450)				(2,450)											(2,450)				(625)	(625)			(672)	[2]		(672)	[2]						(672)	[2]				(124)							$ (25)		(25)		(300)				(300)
Distributions to noncontrolling interest in subsidiaries	(2)																	(2)
Equitization of certain notes payable to affiliates																								1,047		1,047								1,047
Other	$ 7	[4]			20	[4]										20	[4]	(13)	[4]	(2)	(2)			$ 2		2								2						3		3														$ 149		149
Balance (in shares) at Dec. 31, 2017	700,000,000		700,000,000																					100																						90,000,000										100
Ending Balance (parent) at Dec. 31, 2017	$ 41,737		$ 1	38,792	3,013				$ (10)			12		(69)		41,739		(2)						$ 13,465		9,143	4,350		$ (18)		5		(12)	13,468		(3)
Ending member's equity at Dec. 31, 2017																				11,361	11,368	$ (7)																7,949	7,949	5,618		5,614		4						4,121				4,121
Ending Balance (Attributable to Parent) at Dec. 31, 2017	41,739																							13,468																						$ 3,163	762	2,670	(269)							$ 1,662	860	802
Net income	2,644				2,666											2,666		(22)						1,033			1,027							1,027		6
Net Income Attributable to Parent	2,666																			1,071	1,071			1,027														667	667	554		554				176			176	393				393		129
Other comprehensive income (loss), net of tax	(13)								(4)			(3)		(6)		(13)				1				10					6		(1)		5	10						(1)				(1)
Common stock issuances, including dividend reinvestment and employee benefits (in shares)			27,000,000
Common stock issuances, including dividend reinvestment and employee benefits	2,003			2,003												2,003
Distributions/Dividends to parent	(2,578)				(2,578)											(2,578)				(750)	(750)			(250)			(250)							(250)					(175)	(75)		(75)								(175)				(175)
Distributions to noncontrolling interest in subsidiaries	(1)																	(1)						$ (1)												(1)
Capital contribution from parent																																														$ 106		106								300
Other	$ 42	[5]			12	[5]						(12)	[5]					42	[5]								4	[6]			(5)	[6]		(1)	[6]	1	[6]			(1)	[7]	(4)	[7]	5	[7]											$ 300	300
Balance (in shares) at Dec. 31, 2018	727,000,000		727,000,000																					100																						90,000,000										100
Ending Balance (parent) at Dec. 31, 2018	$ 43,834		$ 1	$ 40,795	$ 3,113				$ (14)			$ (3)		$ (75)		$ 43,817		$ 17						$ 14,257		$ 9,143	$ 5,131		$ (12)		$ (1)		$ (7)	$ 14,254		$ 3
Ending member's equity at Dec. 31, 2018																				$ 11,683	$ 11,689	$ (6)																$ 8,441	$ 8,441	$ 6,095		$ 6,097		$ (2)						$ 4,339				$ 4,339
Ending Balance (Attributable to Parent) at Dec. 31, 2018	$ 43,817																							$ 14,254																						$ 3,445	$ 762	$ 2,776	$ (93)							$ 2,091	$ 1,160	$ 931
[1]	Foreign Currency Translation Adjustments amount includes $620 million of cumulative adjustment realized as a result of the sale of the Latin American generation business. See Note 2 to the Consolidated Financial Statements.
[2]	Includes a $547 million non-cash dividend related to a legal entity restructuring.
[3]	Noncontrolling Interests amount is primarily related to the sale of the Latin American generation business. See Note 2 to the Consolidated Financial Statements.
[4]	Retained Earnings relates to a cumulative-effect adjustment due to implementation of a new accounting standard related to stock-based compensation and the associated income taxes. See Note 1 to the Consolidated Financial Statements for additional information. Noncontrolling Interests relates to the purchase of remaining interest in REC Solar.
[5]	Amounts in Retained Earnings and Accumulated Other Comprehensive Loss represent a cumulative-effect adjustment due to implementation of a new accounting standard related to Financial Instruments Classification and Measurement. See Note 1 for more information. Amount in Noncontrolling Interests primarily relates to tax equity financing activity in the Commercial Renewables segment.
[6]	Amounts in Retained Earnings and Accumulated Other Comprehensive Loss represent a cumulative-effect adjustment due to implementation of a new accounting standard related to Financial Instruments Classification and Measurement. See Note 1 for more information.
[7]	Amounts represent a cumulative-effect adjustment due to implementation of a new accounting standard related to Financial Instruments Classification and Measurement. See Note 1 for more information.

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Parentheticals) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Progress Energy [Member]
Non-cash dividend	$ 547

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Index to Combined Notes To Consolidated Financial Statements The notes to the consolidated financial statements are a combined presentation. The following table indicates the registrants to which the notes apply. Applicable Notes Registrant 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Duke Energy • • • • • • • • • • • • • • • • • • • • • • • • • Duke Energy Carolinas • • • • • • • • • • • • • • • • • • • • • • • Progress Energy • • • • • • • • • • • • • • • • • • • • • • Duke Energy Progress • • • • • • • • • • • • • • • • • • • • • Duke Energy Florida • • • • • • • • • • • • • • • • • • • • • Duke Energy Ohio • • • • • • • • • • • • • • • • • • • • • Duke Energy Indiana • • • • • • • • • • • • • • • • • • • • • • Piedmont • • • • • • • • • • • • • • • • • • • • • Tables within the notes may not sum across due to (i) Progress Energy's consolidation of Duke Energy Progress, Duke Energy Florida and other subsidiaries that are not registrants and (ii) subsidiaries that are not registrants but included in the consolidated Duke Energy balances. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Nature of Operations and Basis of Consolidation Duke Energy is an energy company headquartered in Charlotte, North Carolina, subject to regulation by the FERC and other regulatory agencies listed below. Duke Energy operates in the U.S. primarily through its direct and indirect subsidiaries. Certain Duke Energy subsidiaries are also subsidiary registrants, including Duke Energy Carolinas; Progress Energy; Duke Energy Progress; Duke Energy Florida; Duke Energy Ohio; Duke Energy Indiana and Piedmont. When discussing Duke Energy’s consolidated financial information, it necessarily includes the results of its separate Subsidiary Registrants, which along with Duke Energy, are collectively referred to as the Duke Energy Registrants. In October 2016, Duke Energy completed the acquisition of Piedmont. Duke Energy's consolidated financial statements include Piedmont's results of operations and cash flows activity subsequent to the acquisition date. Effective November 1, 2016, Piedmont's fiscal year-end was changed from October 31 to December 31, the year-end of Duke Energy. A transition report was filed on Form 10-Q (Form 10-QT) for the transition period from November 1, 2016, to December 31, 2016. See Note 2 for additional information regarding the acquisition. In December 2016, Duke Energy completed an exit of the Latin American market to focus on its domestic regulated business, which was further bolstered by the acquisition of Piedmont. The sale of the International Energy business segment, excluding an equity method investment in NMC, was completed through two transactions including a sale of assets in Brazil to CTG and a sale of Duke Energy's remaining Latin American assets in Peru, Chile, Ecuador, Guatemala, El Salvador and Argentina to I Squared (collectively, the International Disposal Group). See Note 2 for additional information on the sale of International Energy. The information in these combined notes relates to each of the Duke Energy Registrants as noted in the Index to Combined Notes to Consolidated Financial Statements. However, none of the Subsidiary Registrants make any representation as to information related solely to Duke Energy or the Subsidiary Registrants of Duke Energy other than itself. These Consolidated Financial Statements include, after eliminating intercompany transactions and balances, the accounts of the Duke Energy Registrants and subsidiaries or VIEs where the respective Duke Energy Registrants have control. See Note 17 for additional information on VIEs. These Consolidated Financial Statements also reflect the Duke Energy Registrants’ proportionate share of certain jointly owned generation and transmission facilities. See Note 8 for additional information on joint ownership. Substantially all of the Subsidiary Registrants' operations qualify for regulatory accounting. Duke Energy Carolinas is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of North Carolina and South Carolina. Duke Energy Carolinas is subject to the regulatory provisions of the NCUC, PSCSC, NRC and FERC. Progress Energy is a public utility holding company, which conducts operations through its wholly owned subsidiaries, Duke Energy Progress and Duke Energy Florida. Progress Energy is subject to regulation by FERC and other regulatory agencies listed below. Duke Energy Progress is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of North Carolina and South Carolina. Duke Energy Progress is subject to the regulatory provisions of the NCUC, PSCSC, NRC and FERC. Duke Energy Florida is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of Florida. Duke Energy Florida is subject to the regulatory provisions of the FPSC, NRC and FERC. Duke Energy Ohio is a regulated public utility primarily engaged in the transmission and distribution of electricity in portions of Ohio and Kentucky, the generation and sale of electricity in portions of Kentucky and the transportation and sale of natural gas in portions of Ohio and Kentucky. Duke Energy Ohio conducts competitive auctions for retail electricity supply in Ohio whereby the energy price is recovered from retail customers and recorded in Operating Revenues on the Consolidated Statements of Operations and Comprehensive Income. Operations in Kentucky are conducted through its wholly owned subsidiary, Duke Energy Kentucky. References herein to Duke Energy Ohio collectively include Duke Energy Ohio and its subsidiaries, unless otherwise noted. Duke Energy Ohio is subject to the regulatory provisions of the PUCO, KPSC and FERC. Duke Energy Indiana is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of Indiana. Duke Energy Indiana is subject to the regulatory provisions of the IURC and FERC. Piedmont is a regulated public utility primarily engaged in the distribution of natural gas in portions of North Carolina, South Carolina and Tennessee. Piedmont is subject to the regulatory provisions of the NCUC, PSCSC, TPUC and FERC. Certain prior year amounts have been reclassified to conform to the current year presentation. Other Current Assets and Liabilities The following table provides a description of amounts included in Other within Current Assets or Current Liabilities that exceed 5 percent of total Current Assets or Current Liabilities on the Duke Energy Registrants' Consolidated Balance Sheets at either December 31, 2018 , or 2017 . December 31, (in millions) Location 2018 2017 Duke Energy Income taxes receivable Current Assets $ 729 $ 330 Accrued compensation Current Liabilities 793 757 Duke Energy Carolinas Accrued compensation Current Liabilities $ 251 $ 252 Progress Energy Income taxes receivable Current Assets $ 66 $ 278 Customer deposits Current Liabilities 345 338 Duke Energy Progress Customer deposits Current Liabilities $ 137 $ 129 Accrued compensation Current Liabilities 130 132 Duke Energy Florida Customer deposits Current Liabilities $ 208 $ 208 Other accrued liabilities Current Liabilities 85 16 Duke Energy Ohio Income taxes receivable Current Assets $ 13 $ 36 Customer deposits Current Liabilities 44 46 Duke Energy Indiana Customer deposits Current Liabilities $ 47 $ 45 Piedmont Income taxes receivable Current Assets $ 11 $ 43 Discontinued Operations The results of operations of the International Disposal Group have been classified as Discontinued Operations on Duke Energy's Consolidated Statements of Operations. Duke Energy has elected to present cash flows of discontinued operations combined with cash flows of continuing operations. Unless otherwise noted, the notes to these consolidated financial statements exclude amounts related to discontinued operations for all periods presented. See Note 2 for additional information. Amounts Attributable to Controlling Interests For the years ended December 31, 2018 , and 2017 , the Income (Loss) From Discontinued Operations, net of tax on Duke Energy's Consolidated Statements of Operations is entirely attributable to controlling interest. For the year ended December 31, 2016, $18 million of net income is attributable to noncontrolling interests, which consisted of $7 million included in Income from Continuing Operations and $11 million included in Income (Loss) From Discontinued Operations, net of tax on Duke Energy's Consolidated Statement of Operations. Significant Accounting Policies Use of Estimates In preparing financial statements that conform to GAAP, the Duke Energy Registrants must make estimates and assumptions that affect the reported amounts of assets and liabilities, the reported amounts of revenues and expenses and the disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. Regulatory Accounting The majority of the Duke Energy Registrants’ operations are subject to price regulation for the sale of electricity and natural gas by state utility commissions or FERC. When prices are set on the basis of specific costs of the regulated operations and an effective franchise is in place such that sufficient natural gas or electric services can be sold to recover those costs, the Duke Energy Registrants apply regulatory accounting. Regulatory accounting changes the timing of the recognition of costs or revenues relative to a company that does not apply regulatory accounting. As a result, regulatory assets and regulatory liabilities are recognized on the Consolidated Balance Sheets. Regulatory assets and liabilities are amortized consistent with the treatment of the related cost in the ratemaking process. See Note 4 for further information. Regulatory accounting rules also require recognition of a disallowance (also called "impairment") loss if it becomes probable that part of the cost of a plant under construction (or a recently completed plant or an abandoned plant) will be disallowed for ratemaking purposes and a reasonable estimate of the amount of the disallowance can be made. For example, if a cost cap is set for a plant still under construction, the amount of the disallowance is a result of a judgment as to the ultimate cost of the plant. These disallowances can require judgments on allowed future rate recovery. When it becomes probable that regulated generation, transmission or distribution assets will be abandoned, the cost of the asset is removed from plant in service. The value that may be retained as a regulatory asset on the balance sheet for the abandoned property is dependent upon amounts that may be recovered through regulated rates, including any return. As such, an impairment charge could be partially or fully offset by the establishment of a regulatory asset if rate recovery is probable. The impairment charge for a disallowance of costs for regulated plants under construction, recently completed or abandoned is based on discounted cash flows. The Duke Energy Registrants utilize cost-tracking mechanisms, commonly referred to as fuel adjustment clauses or PGA clauses. These clauses allow for the recovery of fuel and fuel-related costs, portions of purchased power, natural gas costs and hedging costs through surcharges on customer rates. The difference between the costs incurred and the surcharge revenues is recorded either as an adjustment to Operating Revenues, Operating Expenses – Fuel used in electric generation or Operating Expenses – Cost of natural gas on the Consolidated Statements of Operations, with an off-setting impact on regulatory assets or liabilities. Cash, Cash Equivalents and Restricted Cash All highly liquid investments with maturities of three months or less at the date of acquisition are considered cash equivalents. Duke Energy, Progress Energy and Duke Energy Florida have restricted cash balances related primarily to collateral assets, escrow deposits and VIEs. See Note 17 for additional information. Restricted cash amounts are included in Other within Current Assets and Other Noncurrent Assets on the Consolidated Balance Sheets. The following table presents the components of cash, cash equivalents and restricted cash included in the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 Duke Duke Duke Progress Energy Duke Progress Energy Energy Energy Florida Energy Energy Florida Current Assets Cash and cash equivalents $ 442 $ 67 $ 36 $ 358 $ 40 $ 13 Other 141 39 39 138 40 40 Other Noncurrent Assets Other 8 6 — 9 7 — Total cash, cash equivalents and restricted cash $ 591 $ 112 $ 75 $ 505 $ 87 $ 53 Inventory Inventory is used for operations and is recorded primarily using the average cost method. Inventory related to regulated operations is valued at historical cost. Inventory related to nonregulated operations is valued at the lower of cost or market. Materials and supplies are recorded as inventory when purchased and subsequently charged to expense or capitalized to property, plant and equipment when installed. Inventory, including excess or obsolete inventory, is written-down to the lower of cost or market value. Once inventory has been written-down, it creates a new cost basis for the inventory that is not subsequently written-up. Provisions for inventory write-offs were not material at December 31, 2018 , and 2017 . The components of inventory are presented in the tables below. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Materials and supplies $ 2,238 $ 731 $ 1,049 $ 734 $ 315 $ 84 $ 312 $ 2 Coal 491 175 192 106 86 14 109 — Natural gas, oil and other 355 42 218 114 103 28 1 68 Total inventory $ 3,084 $ 948 $ 1,459 $ 954 $ 504 $ 126 $ 422 $ 70 December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Materials and supplies $ 2,293 $ 744 $ 1,118 $ 774 $ 343 $ 82 $ 309 $ 2 Coal 603 192 255 139 116 17 139 — Natural gas, oil and other 354 35 219 104 115 34 2 64 Total inventory $ 3,250 $ 971 $ 1,592 $ 1,017 $ 574 $ 133 $ 450 $ 66 Investments in Debt and Equity Securities The Duke Energy Registrants classify investments in equity securities as FV-NI and investments in debt securities as AFS. Both categories are recorded at fair value on the Consolidated Balance Sheets. Realized and unrealized gains and losses on securities classified as FV-NI are reported through net income. Unrealized gains and losses for debt securities classified as AFS are included in AOCI until realized, except OTTIs that are included in earnings immediately. At the time gains and losses for debt securities are realized, they are reported through net income. For certain investments of regulated operations, such as substantially all of the NDTF, realized and unrealized gains and losses (including any OTTIs) on debt securities are recorded as a regulatory asset or liability. The credit loss portion of debt securities of nonregulated operations are included in earnings. Investments in debt and equity securities are classified as either current or noncurrent based on management’s intent and ability to sell these securities, taking into consideration current market liquidity. See Note 15 for further information. Goodwill and Intangible Assets Goodwill Duke Energy, Progress Energy, Duke Energy Ohio and Piedmont perform annual goodwill impairment tests as of August 31 each year at the reporting unit level, which is determined to be a business segment or one level below. Duke Energy, Progress Energy, Duke Energy Ohio and Piedmont update these tests between annual tests if events or circumstances occur that would more likely than not reduce the fair value of a reporting unit below its carrying value. See Note 11 for further information. Intangible Assets Intangible assets are included in Other in Other Noncurrent Assets on the Consolidated Balance Sheets. Generally, intangible assets are amortized using an amortization method that reflects the pattern in which the economic benefits of the intangible asset are consumed or on a straight-line basis if that pattern is not readily determinable. Amortization of intangibles is reflected in Depreciation and amortization on the Consolidated Statements of Operations. Intangible assets are subject to impairment testing and if impaired, the carrying value is accordingly reduced. Emission allowances permit the holder of the allowance to emit certain gaseous byproducts of fossil fuel combustion, including SO 2 and NO X . Allowances are issued by the EPA at zero cost and may also be bought and sold via third-party transactions. Allowances allocated to or acquired by the Duke Energy Registrants are held primarily for consumption. Carrying amounts for emission allowances are based on the cost to acquire the allowances or, in the case of a business combination, on the fair value assigned in the allocation of the purchase price of the acquired business. Emission allowances are expensed to Fuel used in electric generation and purchased power on the Consolidated Statements of Operations. RECs are used to measure compliance with renewable energy standards and are held primarily for consumption. See Note 11 for further information. Long-Lived Asset Impairments The Duke Energy Registrants evaluate long-lived assets, excluding goodwill, for impairment when circumstances indicate the carrying value of those assets may not be recoverable. An impairment exists when a long-lived asset’s carrying value exceeds the estimated undiscounted cash flows expected to result from the use and eventual disposition of the asset. The estimated cash flows may be based on alternative expected outcomes that are probability weighted. If the carrying value of the long-lived asset is not recoverable based on these estimated future undiscounted cash flows, the carrying value of the asset is written-down to its then-current estimated fair value and an impairment charge is recognized. The Duke Energy Registrants assess fair value of long-lived assets using various methods, including recent comparable third-party sales, internally developed discounted cash flow analysis and analysis from outside advisors. Triggering events to reassess cash flows may include, but are not limited to, significant changes in commodity prices, the condition of an asset or management’s interest in selling the asset. Equity Method Investment Impairments Investments in affiliates that are not controlled by Duke Energy, but over which it has significant influence, are accounted for using the equity method. Equity method investments are assessed for impairment whenever events or changes in circumstances indicate that the carrying amount of the investment may not be recoverable. If the decline in value is considered to be other than temporary, the investment is written down to its estimated fair value, which establishes a new cost basis in the investment. Impairment assessments use a discounted cash flow income approach and include consideration of the severity and duration of any decline in the fair value of the investments. The estimated cash flows may be based on alternative expected outcomes that are probability weighted. Key inputs that involve estimates and significant management judgment include cash flow projections, selection of a discount rate, probability weighting of potential outcomes, and whether any decline in value is considered temporary. Property, Plant and Equipment Property, plant and equipment are stated at the lower of depreciated historical cost net of any disallowances or fair value, if impaired. The Duke Energy Registrants capitalize all construction-related direct labor and material costs, as well as indirect construction costs such as general engineering, taxes and financing costs. See “Allowance for Funds Used During Construction and Interest Capitalized” for information on capitalized financing costs. Costs of renewals and betterments that extend the useful life of property, plant and equipment are also capitalized. The cost of repairs, replacements and major maintenance projects, which do not extend the useful life or increase the expected output of the asset, are expensed as incurred. Depreciation is generally computed over the estimated useful life of the asset using the composite straight-line method. Depreciation studies are conducted periodically to update composite rates and are approved by state utility commissions and/or the FERC when required. The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows. Years Ended December 31, 2018 2017 2016 Duke Energy 3.0 % 2.8 % 2.8 % Duke Energy Carolinas 2.8 % 2.8 % 2.8 % Progress Energy 2.9 % 2.6 % 2.7 % Duke Energy Progress 2.9 % 2.6 % 2.6 % Duke Energy Florida 3.0 % 2.8 % 2.8 % Duke Energy Ohio 2.8 % 2.8 % 2.6 % Duke Energy Indiana 3.3 % 3.0 % 3.1 % Piedmont (a) 2.5 % 2.3 % (a) Piedmont's weighted average depreciation rate was 2.4 percent for the annualized two months ended December 31, 2016, and for the year ended October 31, 2016. In general, when the Duke Energy Registrants retire regulated property, plant and equipment, the original cost plus the cost of retirement, less salvage value and any depreciation already recognized, is charged to accumulated depreciation. However, when it becomes probable the asset will be retired substantially in advance of its original expected useful life or is abandoned, the cost of the asset and the corresponding accumulated depreciation is recognized as a separate asset. If the asset is still in operation, the net amount is classified as Generation facilities to be retired, net on the Consolidated Balance Sheets. If the asset is no longer operating, the net amount is classified in Regulatory assets on the Consolidated Balance Sheets if deemed recoverable (see discussion of long-lived asset impairments above). When it becomes probable an asset will be abandoned, the cost of the asset and accumulated depreciation is reclassified to Regulatory assets on the Consolidated Balance Sheets for amounts recoverable in rates. The carrying value of the asset is based on historical cost if the Duke Energy Registrants are allowed to recover the remaining net book value and a return equal to at least the incremental borrowing rate. If not, an impairment is recognized to the extent the net book value of the asset exceeds the present value of future revenues discounted at the incremental borrowing rate. When the Duke Energy Registrants sell entire regulated operating units, or retire or sell nonregulated properties, the original cost and accumulated depreciation and amortization balances are removed from Property, Plant and Equipment on the Consolidated Balance Sheets. Any gain or loss is recorded in earnings, unless otherwise required by the applicable regulatory body. See Note 10 for additional information. Nuclear Fuel Nuclear fuel is classified as Property, Plant and Equipment on the Consolidated Balance Sheets. Nuclear fuel in the front-end fuel processing phase is considered work in progress and not amortized until placed in service. Amortization of nuclear fuel is included within Fuel used in electric generation and purchased power on the Consolidated Statements of Operations. Amortization is recorded using the units-of-production method. Allowance for Funds Used During Construction and Interest Capitalized For regulated operations, the debt and equity costs of financing the construction of property, plant and equipment are reflected as AFUDC and capitalized as a component of the cost of property, plant and equipment. AFUDC equity is reported on the Consolidated Statements of Operations as non-cash income in Other income and expenses, net. AFUDC debt is reported as a non-cash offset to Interest Expense. After construction is completed, the Duke Energy Registrants are permitted to recover these costs through their inclusion in rate base and the corresponding subsequent depreciation or amortization of those regulated assets. AFUDC equity, a permanent difference for income taxes, reduces the ETR when capitalized and increases the ETR when depreciated or amortized. See Note 23 for additional information. For nonregulated operations, interest is capitalized during the construction phase with an offsetting non-cash credit to Interest Expense on the Consolidated Statements of Operations. Asset Retirement Obligations AROs are recognized for legal obligations associated with the retirement of property, plant and equipment. Substantially all AROs are related to regulated operations. When recording an ARO, the present value of the projected liability is recognized in the period in which it is incurred, if a reasonable estimate of fair value can be made. The liability is accreted over time. For operating plants, the present value of the liability is added to the cost of the associated asset and depreciated over the remaining life of the asset. For retired plants, the present value of the liability is recorded as a regulatory asset unless determined not to be probable of recovery. The present value of the initial obligation and subsequent updates are based on discounted cash flows, which include estimates regarding timing of future cash flows, selection of discount rates and cost escalation rates, among other factors. These estimates are subject to change. Depreciation expense is adjusted prospectively for any changes to the carrying amount of the associated asset. The Duke Energy Registrants receive amounts to fund the cost of the ARO for regulated operations through a combination of regulated revenues and earnings on the NDTF. As a result, amounts recovered in regulated revenues, earnings on the NDTF, accretion expense and depreciation of the associated asset are netted and deferred as a regulatory asset or liability. Obligations for nuclear decommissioning are based on site-specific cost studies. Duke Energy Carolinas and Duke Energy Progress assume prompt dismantlement of the nuclear facilities after operations are ceased. Duke Energy Florida assumes Crystal River Unit 3 will be placed into a safe storage configuration until eventual dismantlement is completed by 2074. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida also assume that spent fuel will be stored on-site until such time that it can be transferred to a yet to be built DOE facility. Obligations for closure of ash basins are based upon discounted cash flows of estimated costs for site-specific plans, if known, or probability weightings of the potential closure methods if the closure plans are under development and multiple closure options are being considered and evaluated on a site-by-site basis. See Note 9 for additional information. Revenue Recognition Duke Energy recognizes revenue as customers obtain control of promised goods and services in an amount that reflects consideration expected in exchange for those goods or services. Generally, the delivery of electricity and natural gas results in the transfer of control to customers at the time the commodity is delivered and the amount of revenue recognized is equal to the amount billed to each customer, including estimated volumes delivered when billings have not yet occurred. See Note 18 for further information. Derivatives and Hedging Derivative and non-derivative instruments may be used in connection with commodity price and interest rate activities, including swaps, futures, forwards and options. All derivative instruments, except those that qualify for the NPNS exception, are recorded on the Consolidated Balance Sheets at fair value. Qualifying derivative instruments may be designated as either cash flow hedges or fair value hedges. Other derivative instruments (undesignated contracts) either have not been designated or do not qualify as hedges. The effective portion of the change in the fair value of cash flow hedges is recorded in AOCI. The effective portion of the change in the fair value of a fair value hedge is offset in net income by changes in the hedged item. For activity subject to regulatory accounting, gains and losses on derivative contracts are reflected as regulatory assets or liabilities and not as other comprehensive income or current period income. As a result, changes in fair value of these derivatives have no immediate earnings impact. Formal documentation, including transaction type and risk management strategy, is maintained for all contracts accounted for as a hedge. At inception and at least every three months thereafter, the hedge contract is assessed to see if it is highly effective in offsetting changes in cash flows or fair values of hedged items. See Note 14 for further information. Captive Insurance Reserves Duke Energy has captive insurance subsidiaries that provide coverage, on an indemnity basis, to the Subsidiary Registrants as well as certain third parties, on a limited basis, for financial losses, primarily related to property, workers’ compensation and general liability. Liabilities include provisions for estimated losses IBNR, as well as estimated provisions for known claims. IBNR reserve estimates are primarily based upon historical loss experience, industry data and other actuarial assumptions. Reserve estimates are adjusted in future periods as actual losses differ from experience. Duke Energy, through its captive insurance entities, also has reinsurance coverage with third parties for certain losses above a per occurrence and/or aggregate retention. Receivables for reinsurance coverage are recognized when realization is deemed probable. Unamortized Debt Premium, Discount and Expense Premiums, discounts and expenses incurred with the issuance of outstanding long-term debt are amortized over the term of the debt issue. The gain or loss on extinguishment associated with refinancing higher-cost debt obligations in the regulated operations is amortized. Amortization expense is recorded as Interest Expense in the Consolidated Statements of Operations and is reflected as Depreciation, amortization and accretion within Net cash provided by operating activities on the Consolidated Statements of Cash Flows. Premiums, discounts and expenses are presented as an adjustment to the carrying value of the debt amount and included in Long-Term Debt on the Consolidated Balance Sheets presented. Loss Contingencies and Environmental Liabilities Contingent losses are recorded when it is probable a loss has occurred and can be reasonably estimated. When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, the minimum amount in the range is recorded. Unless otherwise required by GAAP, legal fees are expensed as incurred. Environmental liabilities are recorded on an undiscounted basis when environmental remediation or other liabilities become probable and can be reasonably estimated. Environmental expenditures related to past operations that do not generate current or future revenues are expensed. Environmental expenditures related to operations that generate current or future revenues are expensed or capitalized, as appropriate. Certain environmental expenditures receive regulatory accounting treatment and are recorded as regulatory assets. See Notes 4 and 5 for further information. Pension and Other Post-Retirement Benefit Plans Duke Energy maintains qualified, non-qualified and other post-retirement benefit plans. Eligible employees of the Subsidiary Registrants participate in the respective qualified, non-qualified and other post-retirement benefit plans and the Subsidiary Registrants are allocated their proportionate share of benefit costs. See Note 22 for further information, including significant accounting policies associated with these plans. Severance and Special Termination Benefits Duke Energy has severance plans under which in general, the longer a terminated employee worked prior to termination the greater the amount of severance benefits. A liability for involuntary severance is recorded once an involuntary severance plan is committed to by management if involuntary severances are probable and can be reasonably estimated. For involuntary severance benefits incremental to its ongoing severance plan benefits, the fair value of the obligation is expensed at the communication d

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions and Dispositions	ACQUISITIONS AND DISPOSITIONS ACQUISITIONS The Duke Energy Registrants consolidate assets and liabilities from acquisitions as of the purchase date and include earnings from acquisitions in consolidated earnings after the purchase date. 2016 Acquisition of Piedmont Natural Gas On October 3, 2016, Duke Energy acquired all outstanding common stock of Piedmont for a total cash purchase price of $5.0 billion and assumed Piedmont's existing long-term debt, which had a fair value of approximately $2.0 billion at the time of the acquisition. The acquisition provides a foundation for Duke Energy to establish a broader, long-term strategic natural gas infrastructure platform to complement its existing natural gas pipeline investments and regulated natural gas business in the Midwest. In connection with the closing of the acquisition, Piedmont became a wholly owned subsidiary of Duke Energy. Accounting Charges Related to the Acquisition Duke Energy incurred pretax transaction and integration costs associated with the acquisition of $84 million , $103 million and $439 million for the years ended December 31, 2018, 2017 and 2016, respectively. Amounts recorded on the Consolidated Statements of Operations in 2018 and 2017 were primarily system integration costs of $78 million and $71 million , respectively, related to combining the various operational and financial systems of Duke Energy and Piedmont, including a one-time software impairment resulting from planned accounting system and process integration in 2017. A $7 million charge was recorded within Impairment Charges, with the remaining $64 million recorded within Operation, maintenance and other in 2017. Amounts recorded in 2016 include: • Interest expense of $234 million related to the acquisition financing, including realized losses on forward-starting interest rate swaps of $190 million . See Note 14 for additional information on the swaps. • Charges of $104 million related to commitments made in conjunction with the transaction, including charitable contributions and a one-time bill credit to Piedmont customers. $10 million was recorded as a reduction in Operating Revenues, with the remaining $94 million recorded within Operation, maintenance and other. • Other transaction and integration costs of $101 million recorded to Operation, maintenance and other, including professional fees and severance charges. The majority of transition and integration activities were completed by the end of 2018. Pro Forma Financial Information The following unaudited pro forma financial information reflects the combined results of operations of Duke Energy and Piedmont as if the merger had occurred as of January 1, 2015. The pro forma financial information does not include potential cost savings, intercompany revenues, Piedmont’s earnings from a certain equity method investment sold immediately prior to the merger or non-recurring transaction and integration costs incurred by Duke Energy and Piedmont. The after-tax transaction and integration costs incurred by Duke Energy and Piedmont were $279 million for the year ended December 31, 2016. This information has been presented for illustrative purposes only and is not necessarily indicative of the consolidated results of operations that would have been achieved or the future consolidated results of operations of Duke Energy. Year Ended December 31, (in millions) 2016 Operating Revenues $ 23,504 Net Income Attributable to Duke Energy Corporation 2,442 Piedmont's Earnings Piedmont's revenues and net income included in Duke Energy's Consolidated Statements of Operations for the year ended December 31, 2016, were $367 million and $20 million , respectively. Piedmont's revenues and net income for the year ended December 31, 2016, include the impact of non-recurring transaction costs of $10 million and $46 million , respectively. DISPOSITIONS For the years ended December 31, 2018, and 2017, the Income (Loss) from Discontinued Operations, net of tax, was immaterial. The following table summarizes the Loss from Discontinued Operations, net of tax recorded on Duke Energy's Consolidated Statements of Operations for the year ended December 31, 2016: Year Ended December 31, (in millions) 2016 International Disposal Group $ (534 ) Other (a) 126 Loss from Discontinued Operations, net of tax $ (408 ) (a) Amount represents an income tax benefit resulting from immaterial out of period deferred tax liability adjustments for previously sold businesses not related to the International Disposal Group. 2016 Sale of International Energy In February 2016, Duke Energy announced it had initiated a process to divest the International Disposal Group, and in October 2016, announced it had entered into two separate purchase and sale agreements to execute the divestiture. Both sales closed in December of 2016, resulting in available cash proceeds of $1.9 billion , excluding transaction costs. Proceeds were primarily used to reduce the Parent debt. Existing favorable tax attributes result in no immediate U.S. federal-level cash tax impacts. Details of each transaction are as follows: • On December 20, 2016, Duke Energy closed on the sale of its ownership interests in businesses in Argentina, Chile, Ecuador, El Salvador, Guatemala and Peru to I Squared Capital. The assets sold included approximately 2,230 MW of hydroelectric and natural gas generation capacity, transmission infrastructure and natural gas processing facilities. I Squared Capital purchased the businesses for an enterprise value of $1.2 billion . • On December 29, 2016, Duke Energy closed on the sale of its Brazilian business, which included approximately 2,090 MW of hydroelectric generation capacity, to CTG for an enterprise value of $1.2 billion . With the closing of the CTG deal, Duke Energy finalized its exit from the Latin American market. Assets Held For Sale and Discontinued Operations As a result of the transactions, the International Disposal Group was classified as held for sale and as discontinued operations in the fourth quarter of 2016. Interest expense directly associated with the International Disposal Group was allocated to discontinued operations. No interest from corporate level debt was allocated to discontinued operations. The following table presents the results of the International Disposal Group for the year ended December 31, 2016, which are included in Loss from Discontinued Operations, net of tax in Duke Energy's Consolidated Statements of Operations. Year Ended December 31, (in millions) 2016 Operating Revenues $ 988 Fuel used in electric generation and purchased power 227 Cost of natural gas 43 Operation, maintenance and other 341 Depreciation and amortization (a) 62 Property and other taxes 15 Impairment charges (b) 194 (Losses) Gains on Sales of Other Assets and Other, net (3 ) Other Income and Expenses, net 58 Interest Expense 82 Pretax loss on disposal (c) (514 ) Loss before income taxes (d) (435 ) Income tax expense (e)(f) 99 Loss from discontinued operations of the International Disposal Group $ (534 ) (a) Upon meeting the criteria for assets held for sale, beginning in the fourth quarter of 2016 depreciation expense ceased. (b) In conjunction with the advancements of marketing efforts during 2016, Duke Energy performed recoverability tests of the long-lived asset groups of International Energy. As a result, Duke Energy determined the carrying value of certain assets in Central America was not fully recoverable and recorded a pretax impairment charge of $194 million . The charge represents the excess of carrying value over the estimated fair value of the assets, which was based on a Level 3 Fair Value measurement that was primarily determined from the income approach using discounted cash flows but also considered market information obtained in 2016. (c) The pretax loss on disposal includes the recognition of cumulative foreign currency translation losses of $620 million as of the disposal date. See the Consolidated Statements of Changes in Equity for additional information. (d) Pretax Loss attributable to Duke Energy Corporation was $(445) million for the year ended December 31, 2016. (e) Amount includes $126 million of income tax expense on the disposal, which primarily reflects in-country taxes incurred as a result of the sale. The after-tax loss on disposal was $640 million . (f) Amount includes an income tax benefit of $95 million . See Note 23 , "Income Taxes," for additional information. Duke Energy has elected not to separately disclose discontinued operations on the Consolidated Statements of Cash Flows. The following table summarizes Duke Energy's cash flows from discontinued operations related to the International Disposal Group. Year Ended December 31, (in millions) 2016 Cash flows provided by (used in): Operating activities $ 204 Investing activities (434 ) Other Sale Related Matters During 2017, Duke Energy provided certain transition services to CTG and I Squared Capital. Cash flows related to providing the transition services were not material as of December 31, 2017. All transition services related to the International Disposal Group ended in 2017. Additionally, Duke Energy will reimburse CTG and I Squared Capital for all tax obligations arising from the period preceding consummation on the transactions, and recorded a liability of $54 million and $78 million as of December 31, 2018 , and 2017 , respectively. Duke Energy has not recorded any other liabilities, contingent liabilities or indemnifications related to the International Disposal Group.

Business Segments

Business Segments	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS Reportable segments are determined based on information used by the chief operating decision-maker in deciding how to allocate resources and evaluate the performance of the business. Duke Energy evaluates segment performance based on segment income. Segment income is defined as income from continuing operations net of income attributable to noncontrolling interests. Segment income, as discussed below, includes intercompany revenues and expenses that are eliminated on the Consolidated Financial Statements. Certain governance costs are allocated to each segment. In addition, direct interest expense and income taxes are included in segment income. Products and services are sold between affiliate companies and reportable segments of Duke Energy at cost. Segment assets as presented in the tables that follow exclude all intercompany assets. Duke Energy Duke Energy's segment structure includes the following segments: Electric Utilities and Infrastructure, Gas Utilities and Infrastructure and Commercial Renewables. The Electric Utilities and Infrastructure segment includes Duke Energy's regulated electric utilities in the Carolinas, Florida and the Midwest. The regulated electric utilities conduct operations through the Subsidiary Registrants that are substantially all regulated and, accordingly, qualify for regulatory accounting treatment. Electric Utilities and Infrastructure also includes Duke Energy's commercial electric transmission infrastructure investments. The Gas Utilities and Infrastructure segment includes Piedmont, Duke Energy's natural gas local distribution companies in Ohio and Kentucky, and Duke Energy's natural gas storage and midstream pipeline investments. Gas Utilities and Infrastructure's operations are substantially all regulated and, accordingly, qualify for regulatory accounting treatment. The Commercial Renewables segment is primarily comprised of nonregulated utility scale wind and solar generation assets located throughout the U.S. The remainder of Duke Energy’s operations is presented as Other, which is primarily comprised of interest expense on holding company debt, unallocated corporate costs and Duke Energy’s wholly owned captive insurance company, Bison. Other also includes Duke Energy's interest in NMC. See Note 12 for additional information on the investment in NMC. Business segment information is presented in the following tables. Segment assets presented exclude intercompany assets. Year Ended December 31, 2018 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Total Unaffiliated Revenues $ 22,242 $ 1,783 $ 477 $ 24,502 $ 19 $ — $ 24,521 Intersegment Revenues 31 98 — 129 70 (199 ) — Total Revenues $ 22,273 $ 1,881 $ 477 $ 24,631 $ 89 $ (199 ) $ 24,521 Interest Expense $ 1,288 $ 106 $ 88 $ 1,482 $ 657 $ (45 ) $ 2,094 Depreciation and amortization 3,523 245 155 3,923 152 (1 ) 4,074 Equity in earnings (losses) of unconsolidated affiliates 5 27 (1 ) 31 52 — 83 Income tax expense (benefit) (a) 799 78 (147 ) 730 (282 ) — 448 Segment income (loss) (b)(c)(d)(e) 3,058 274 9 3,341 (694 ) — 2,647 Add back noncontrolling interest component (22 ) Income from discontinued operations, net of tax 19 Net income $ 2,644 Capital investments expenditures and acquisitions $ 8,086 $ 1,133 $ 193 $ 9,412 $ 256 $ — $ 9,668 Segment assets 125,364 12,361 4,204 141,929 3,275 188 145,392 (a) All segments include adjustments to the December 31, 2017 estimate of the income tax effects of the Tax Act. Electric Utilities and Infrastructure includes a $24 million expense, Gas Utilities and Infrastructure includes a $1 million expense, Commercial Renewables includes a $3 million benefit and Other includes a $2 million benefit. See Note 23 for additional information. (b) Electric Utilities and Infrastructure includes after-tax regulatory and legislative impairment charges of $202 million related to rate case orders, settlements or other actions of regulators or legislative bodies and an after-tax impairment charge of $46 million related to the Citrus County CC at Duke Energy Florida. See Note 4 for additional information. (c) Gas Utilities and Infrastructure includes an after-tax impairment charge of $42 million for the investment in Constitution. See Note 12 for additional information. (d) Commercial Renewables includes an impairment charge of $91 million , net of $2 million Noncontrolling interests, related to goodwill. See Note 11 for additional information. (e) Other includes $65 million of after-tax costs to achieve the Piedmont merger, $144 million of after-tax severance charges related to a companywide initiative and an $82 million after-tax loss on the sale of the retired Beckjord Generating Station described below. For additional information, see Note 2 for the Piedmont Merger and Note 20 for severance charges. In February 2018, Duke Energy sold Beckjord, a nonregulated facility retired during 2014, and recorded a pretax loss of $106 million within (Losses) Gains on Sales of Other Assets and Other, net and $1 million within Operation, maintenance and other on Duke Energy's Consolidated Statements of Operations for the year ended December 31, 2018. The sale included the transfer of coal ash basins and other real property and indemnification from any and all potential future claims related to the property, whether arising under environmental laws or otherwise. Year Ended December 31, 2017 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Total Unaffiliated Revenues $ 21,300 $ 1,743 $ 460 $ 23,503 $ 62 $ — $ 23,565 Intersegment Revenues 31 93 — 124 76 (200 ) — Total Revenues $ 21,331 $ 1,836 $ 460 $ 23,627 $ 138 $ (200 ) $ 23,565 Interest Expense $ 1,240 $ 105 $ 87 $ 1,432 $ 574 $ (20 ) $ 1,986 Depreciation and amortization 3,010 231 155 3,396 131 — 3,527 Equity in earnings (losses) of unconsolidated affiliates 5 62 (5 ) 62 57 — 119 Income tax expense (benefit) (a) 1,355 116 (628 ) 843 353 — 1,196 Segment income (loss) (b)(c)(d) 3,210 319 441 3,970 (905 ) — 3,065 Add back noncontrolling interest component 5 Loss from discontinued operations, net of tax (6 ) Net income $ 3,064 Capital investments expenditures and acquisitions $ 7,024 $ 907 $ 92 $ 8,023 $ 175 $ — $ 8,198 Segment assets 119,423 11,462 4,156 135,041 2,685 188 137,914 (a) All segments include impacts of the Tax Act. Electric Utilities and Infrastructure includes a $231 million benefit, Gas Utilities and Infrastructure includes a $26 million benefit, Commercial Renewables includes a $442 million benefit and Other includes charges of $597 million . (b) Electric Utilities and Infrastructure includes after-tax regulatory settlement charges of $98 million . See Note 4 for additional information. (c) Commercial Renewables includes after-tax impairment charges of $74 million related to certain wind projects and the Energy Management Solutions reporting unit. See Notes 10 and 11 for additional information. (d) Other includes $64 million of after-tax costs to achieve the Piedmont merger. See Note 2 for additional information. Year Ended December 31, 2016 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Total Unaffiliated Revenues $ 21,336 $ 875 $ 484 $ 22,695 $ 48 $ — $ 22,743 Intersegment Revenues 30 26 — 56 69 (125 ) — Total Revenues $ 21,366 $ 901 $ 484 $ 22,751 $ 117 $ (125 ) $ 22,743 Interest Expense $ 1,136 $ 46 $ 53 $ 1,235 $ 693 $ (12 ) $ 1,916 Depreciation and amortization 2,897 115 130 3,142 152 — 3,294 Equity in earnings (losses) of unconsolidated affiliates (a) 5 19 (82 ) (58 ) 43 — (15 ) Income tax expense (benefit) 1,672 90 (160 ) 1,602 (446 ) — 1,156 Segment income (loss) (b)(c) 3,040 152 23 3,215 (645 ) 1 2,571 Add back noncontrolling interest component 7 Loss from discontinued operations, net of tax (d) (408 ) Net income $ 2,170 Capital investments expenditures and acquisitions (e) $ 6,649 $ 5,519 $ 857 $ 13,025 $ 190 $ — $ 13,215 Segment assets 114,993 10,760 4,377 130,130 2,443 188 132,761 (a) Commercial Renewables includes a pretax impairment charge of $71 million . See Note 12 for additional information. (b) Other includes $329 million of after-tax costs to achieve mergers. See Note 2 for additional information on costs related to the Piedmont merger. (c) Other includes after-tax charges of $57 million related to cost savings initiatives. See Note 20 for further information. (d) Includes a loss on sale of the International Disposal Group. Refer to Note 2 for further information. (e) Other includes $26 million of capital investment expenditures related to the International Disposal Group. Gas Utilities and Infrastructure includes the Piedmont acquisition of $5 billion . See Note 2 for more information on the Piedmont acquisition. Geographical Information All assets and revenues from continuing operations are within the U.S. Major Customers For the year ended December 31, 2018, revenues from one customer of Duke Energy Progress are $633 million . Duke Energy Progress has one reportable segment, Electric Utilities and Infrastructure. No other Subsidiary Registrant has an individual customer representing more than 10 percent of its revenues. Products and Services The following table summarizes revenues of the reportable segments by type. Retail Wholesale Retail Total (in millions) Electric Electric Natural Gas Other Revenues 2018 Electric Utilities and Infrastructure $ 19,013 $ 2,345 $ — $ 915 $ 22,273 Gas Utilities and Infrastructure — — 1,817 64 1,881 Commercial Renewables — 375 — 102 477 Total Reportable Segments $ 19,013 $ 2,720 $ 1,817 $ 1,081 $ 24,631 2017 Electric Utilities and Infrastructure $ 18,177 $ 2,104 $ — $ 1,050 $ 21,331 Gas Utilities and Infrastructure — — 1,732 104 1,836 Commercial Renewables — 375 — 85 460 Total Reportable Segments $ 18,177 $ 2,479 $ 1,732 $ 1,239 $ 23,627 2016 Electric Utilities and Infrastructure $ 18,338 $ 2,095 $ — $ 933 $ 21,366 Gas Utilities and Infrastructure — — 871 30 901 Commercial Renewables — 303 — 181 484 Total Reportable Segments $ 18,338 $ 2,398 $ 871 $ 1,144 $ 22,751 Duke Energy Ohio Duke Energy Ohio has two reportable segments, Electric Utilities and Infrastructure and Gas Utilities and Infrastructure. Electric Utilities and Infrastructure transmits and distributes electricity in portions of Ohio and generates, distributes and sells electricity in portions of Northern Kentucky. Gas Utilities and Infrastructure transports and sells natural gas in portions of Ohio and Northern Kentucky. Both reportable segments conduct operations primarily through Duke Energy Ohio and its wholly owned subsidiary, Duke Energy Kentucky. The remainder of Duke Energy Ohio's operations is presented as Other. In December 2018, the PUCO approved an order which allows the recovery or credit of revenues and expenses related to Duke Energy Ohio's contractual arrangement to buy power from OVEC power plants. Due to the change in regulatory treatment of these amounts, OVEC revenues and expenses are now reflected in the Electric Utilities and Infrastructure segment. Previously, OVEC revenues and expense were included in Other. These amounts are deemed immaterial for Duke Energy Ohio. Therefore, no prior period amounts were restated. See Note 4 for additional information on the PUCO order. All Duke Energy Ohio assets and revenues from continuing operations are within the U.S. Year Ended December 31, 2018 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Total Total revenues $ 1,450 $ 506 $ 1,956 $ 1 $ 1,957 Interest expense $ 67 $ 24 $ 91 $ 1 $ 92 Depreciation and amortization 183 85 268 — 268 Income tax expense (benefit) 47 24 71 (28 ) 43 Segment income (loss)/Net income (a) 186 93 279 (103 ) 176 Capital expenditures $ 655 $ 172 $ 827 $ — $ 827 Segment assets 5,643 2,874 8,517 38 8,555 (a) Other includes the loss on the sale of Beckjord, see discussion above. Year Ended December 31, 2017 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Total Total revenues $ 1,373 $ 508 $ 1,881 $ 42 $ — $ 1,923 Interest expense $ 62 $ 28 $ 90 $ 1 $ — $ 91 Depreciation and amortization 178 83 261 — — 261 Income tax expense (benefit) 40 39 79 (20 ) — 59 Segment income (loss) 138 85 223 (30 ) — 193 Loss from discontinued operations, net of tax (1 ) Net income $ 192 Capital expenditures $ 491 $ 195 $ 686 $ — $ — $ 686 Segment assets 5,066 2,758 7,824 66 (15 ) 7,875 Year Ended December 31, 2016 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Total Total revenues $ 1,410 $ 503 $ 1,913 $ 31 $ — $ 1,944 Interest expense $ 58 $ 27 $ 85 $ 1 $ — $ 86 Depreciation and amortization 151 80 231 2 — 233 Income tax expense (benefit) 55 44 99 (21 ) — 78 Segment income (loss) 154 77 231 (39 ) — 192 Income from discontinued operations, net of tax 36 Net income $ 228 Capital expenditures $ 322 $ 154 $ 476 $ — $ — $ 476 Segment assets 4,782 2,696 7,478 62 (12 ) 7,528

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2018
Regulated Operations [Abstract]
Regulatory Matters	REGULATORY MATTERS REGULATORY ASSETS AND LIABILITIES The Duke Energy Registrants record regulatory assets and liabilities that result from the ratemaking process. See Note 1 for further information. The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant. Duke Energy Progress Energy December 31, December 31, (in millions) 2018 2017 2018 2017 Regulatory Assets AROs – coal ash $ 4,255 $ 4,025 $ 2,061 $ 1,984 AROs – nuclear and other 772 852 601 655 Accrued pension and OPEB 2,654 2,249 1,074 906 Retired generation facilities 445 480 367 386 Debt fair value adjustment 1,099 1,197 — — Deferred asset – Lee COLA 383 — — — Storm cost deferrals 1,117 531 953 526 Nuclear asset securitized balance, net 1,093 1,142 1,093 1,142 Hedge costs deferrals 204 234 74 94 Derivatives – natural gas supply contracts 141 142 — — Demand side management (DSM)/Energy efficiency (EE) 449 530 256 281 Grid modernization 31 39 — — Vacation accrual 213 213 41 42 Deferred fuel and purchased power 838 507 600 349 Nuclear deferral 133 119 46 35 Post-in-service carrying costs (PISCC) and deferred operating expenses 320 366 36 38 Transmission expansion obligation 39 46 — — Manufactured gas plant (MGP) 99 91 — — Advanced metering infrastructure (AMI) 367 362 127 150 NCEMPA deferrals 50 53 50 53 East Bend deferrals 47 45 — — Deferred pipeline integrity costs 65 54 — — Amounts due from customers 24 64 — — Other 784 538 322 110 Total regulatory assets 15,622 13,879 7,701 6,751 Less: current portion 2,005 1,437 1,137 741 Total noncurrent regulatory assets $ 13,617 $ 12,442 $ 6,564 $ 6,010 Regulatory Liabilities Costs of removal $ 5,421 $ 5,968 $ 2,135 $ 2,537 AROs – nuclear and other 538 806 — — Net regulatory liability related to income taxes 8,058 8,113 2,710 2,802 Amounts to be refunded to customers 34 10 — — Storm reserve — 20 — — Accrued pension and OPEB 301 146 149 — Deferred fuel and purchased power 16 47 16 1 Other 1,064 622 319 179 Total regulatory liabilities 15,432 15,732 5,329 5,519 Less: current portion 598 402 280 213 Total noncurrent regulatory liabilities $ 14,834 $ 15,330 $ 5,049 $ 5,306 Descriptions of regulatory assets and liabilities summarized in the tables above and below follow. See tables below for recovery and amortization periods at the separate registrants. AROs – coal ash. Represents deferred depreciation and accretion related to the legal obligation to close ash basins. The costs are deferred until recovery treatment has been determined. See Notes 1 and 9 for additional information. AROs – nuclear and other. Represents regulatory assets or liabilities, including deferred depreciation and accretion, related to legal obligations associated with the future retirement of property, plant and equipment, excluding amounts related to coal ash. The AROs relate primarily to decommissioning nuclear power facilities. The amounts also include certain deferred gains and losses on NDTF investments. See Notes 1 and 9 for additional information. Accrued pension and OPEB. Accrued pension and OPEB represent regulatory assets and liabilities related to each of the Duke Energy Registrants’ respective shares of unrecognized actuarial gains and losses and unrecognized prior service cost and credit attributable to Duke Energy’s pension plans and OPEB plans. The regulatory asset or liability is amortized with the recognition of actuarial gains and losses and prior service cost and credit to net periodic benefit costs for pension and OPEB plans. The accrued pension and OPEB regulatory asset is expected to be recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail. Retired generation facilities. Represents amounts to be recovered for facilities that have been retired and are probable of recovery. Debt fair value adjustment. Purchase accounting adjustments recorded to state the carrying value of Progress Energy and Piedmont at fair value in connection with the 2012 and 2016 mergers, respectively. Amount is amortized over the life of the related debt. Net regulatory asset or liability related to income taxes. Amounts for all registrants include regulatory liabilities related primarily to impacts from the Tax Act. See Note 23 for additional information. Amounts have no immediate impact on rate base as regulatory assets are offset by deferred tax liabilities. Deferred asset – Lee COLA. Represents deferred costs incurred for the canceled Lee nuclear project. Storm cost deferrals. Represents deferred incremental costs incurred related to extraordinary weather-related events. Nuclear asset securitized balance, net. Represents the balance associated with Crystal River Unit 3 retirement approved for recovery by the FPSC on September 15, 2015, and the upfront financing costs securitized in 2016 with issuance of the associated bonds. The regulatory asset balance is net of the AFUDC equity portion. Hedge costs and other deferrals. Amounts relate to unrealized gains and losses on derivatives recorded as a regulatory asset or liability, respectively, until the contracts are settled. Derivatives – natural gas supply contracts . Represents costs for certain long-dated, fixed quantity forward gas supply contracts, which are recoverable through PGA clauses. DSM/EE. Deferred costs related to various DSM and EE programs recoverable through various mechanisms. Grid modernization. Amounts represent deferred depreciation and operating expenses as well as carrying costs on the portion of capital expenditures placed in service but not yet reflected in retail rates as plant in service. Vacation accrual. Represents.vacation entitlement, which is generally recovered in the following year. Deferred fuel and purchased power. Represents certain energy-related costs that are recoverable or refundable as approved by the applicable regulatory body. Nuclear deferral. Includes amounts related to levelizing nuclear plant outage costs, which allows for the recognition of nuclear outage expenses over the refueling cycle rather than when the outage occurs, resulting in the deferral of operations and maintenance costs associated with refueling. Post-in-service carrying costs and deferred operating expenses. Represents deferred depreciation and operating expenses as well as carrying costs on the portion of capital expenditures placed in service but not yet reflected in retail rates as plant in service. Transmission expansion obligation. Represents transmission expansion obligations related to Duke Energy Ohio’s withdrawal from Midcontinent Independent System Operator, Inc. (MISO). MGP. Represents remediation costs incurred at former MGP sites and the deferral of costs to be incurred at Duke Energy Ohio's East End and West End sites. AMI. Represents deferred costs related to the installation of AMI meters and remaining net book value of non-AMI meters to be replaced at Duke Energy Carolinas, net book value of existing meters at Duke Energy Florida , Duke Energy Progress and Duke Energy Ohio and expected future recovery of net book value of electromechanical meters that have been replaced with AMI meters at Duke Energy Indiana. NCEMPA deferrals. Represents retail allocated cost deferrals and returns associated with the additional ownership interest in assets acquired from NCEMPA in 2015. East Bend deferrals. Represents both deferred operating expenses and deferred depreciation as well as carrying costs on the portion of East Bend that was acquired from Dayton Power and Light and that had been previously operated as a jointly owned facility. Deferred pipeline integrity costs. Represents pipeline integrity management costs in compliance with federal regulations recovered through a rider mechanism. Amounts due from customers. Relates primarily to margin decoupling and IMR recovery mechanisms. Costs of removal. Represents funds received from customers to cover the future removal of property, plant and equipment from retired or abandoned sites as property is retired. Also includes certain deferred gains on NDTF investments. Amounts to be refunded to customers. Represents required rate reductions to retail customers by the applicable regulatory body. Storm reserve. Amounts are used to offset future incurred costs for named storms as approved by regulatory commissions. RESTRICTIONS ON THE ABILITY OF CERTAIN SUBSIDIARIES TO MAKE DIVIDENDS, ADVANCES AND LOANS TO DUKE ENERGY As a condition to the approval of merger transactions, the NCUC, PSCSC, PUCO, KPSC and IURC imposed conditions on the ability of Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio, Duke Energy Kentucky, Duke Energy Indiana and Piedmont to transfer funds to Duke Energy through loans or advances, as well as restricted amounts available to pay dividends to Duke Energy. Certain subsidiaries may transfer funds to the parent by obtaining approval of the respective state regulatory commissions. These conditions imposed restrictions on the ability of the public utility subsidiaries to pay cash dividends as discussed below. Duke Energy Progress and Duke Energy Florida also have restrictions imposed by their first mortgage bond indentures, which in certain circumstances, limit their ability to make cash dividends or distributions on common stock. Amounts restricted as a result of these provisions were not material at December 31, 2018 . Additionally, certain other subsidiaries of Duke Energy have restrictions on their ability to dividend, loan or advance funds to Duke Energy due to specific legal or regulatory restrictions, including, but not limited to, minimum working capital and tangible net worth requirements. The restrictions discussed below were not a material amount of Duke Energy's and Progress Energy's net assets at December 31, 2018 . Duke Energy Carolinas Duke Energy Carolinas must limit cumulative distributions subsequent to mergers to (i) the amount of retained earnings on the day prior to the closing of the mergers, plus (ii) any future earnings recorded. Duke Energy Progress Duke Energy Progress must limit cumulative distributions subsequent to the mergers between Duke Energy and Progress Energy and Duke Energy and Piedmont to (i) the amount of retained earnings on the day prior to the closing of the respective mergers, plus (ii) any future earnings recorded. Duke Energy Ohio Duke Energy Ohio will not declare and pay dividends out of capital or unearned surplus without the prior authorization of the PUCO. Duke Energy Ohio received FERC and PUCO approval to pay dividends from its equity accounts that are reflective of the amount that it would have in its retained earnings account had push-down accounting for the Cinergy merger not been applied to Duke Energy Ohio’s balance sheet. The conditions include a commitment from Duke Energy Ohio that equity, adjusted to remove the impacts of push-down accounting, will not fall below 30 percent of total capital. Duke Energy Kentucky is required to pay dividends solely out of retained earnings and to maintain a minimum of 35 percent equity in its capital structure. Duke Energy Indiana Duke Energy Indiana must limit cumulative distributions subsequent to the merger between Duke Energy and Cinergy to (i) the amount of retained earnings on the day prior to the closing of the merger, plus (ii) any future earnings recorded. In addition, Duke Energy Indiana will not declare and pay dividends out of capital or unearned surplus without prior authorization of the IURC. Piedmont Piedmont must limit cumulative distributions subsequent to the acquisition of Piedmont by Duke Energy to (i) the amount of retained earnings on the day prior to the closing of the merger, plus (ii) any future earnings recorded. RATE-RELATED INFORMATION The NCUC, PSCSC, FPSC, IURC, PUCO, TPUC and KPSC approve rates for retail electric and natural gas services within their states. The FERC approves rates for electric sales to wholesale customers served under cost-based rates (excluding Ohio and Indiana), as well as sales of transmission service. The FERC also regulates certification and siting of new interstate natural gas pipeline projects. Duke Energy Carolinas and Duke Energy Progress Grid Improvement – South Carolina On June 22, 2018, Duke Energy Carolinas and Duke Energy Progress filed a joint petition with the PSCSC seeking an accounting order authorizing deferral of certain costs incurred in connection with grid reliability, resiliency and modernization work that is being performed under the companies’ grid improvement initiative. On October 3, 2018, the PSCSC granted Duke Energy Carolinas' and Duke Energy Progress' joint petition, which authorizes the deferral of these costs until the rate effective dates of each Company’s next general rate case. Hurricane Florence, Hurricane Michael and Winter Storm Diego In September 2018, Hurricane Florence made landfall and inflicted severe damage to the Duke Energy Carolinas and Duke Energy Progress territories in North Carolina and South Carolina. Approximately 2 million customers were impacted. The companies incurred approximately $500 million in incremental operation and maintenance expenses ( $70 million and $430 million for Duke Energy Carolinas and Duke Energy Progress, respectively,) and approximately $90 million in capital costs ( $5 million and $85 million for Duke Energy Carolinas and Duke Energy Progress, respectively,) which are included in Net property, plant and equipment on the Consolidated Balance Sheets as of December 31, 2018, resulting from the hurricane restoration efforts. Most of the operation and maintenance expenses are deferred in Regulatory assets within Other Noncurrent Assets on the Consolidated Balance Sheets as of December 31, 2018. The balance of operation and maintenance expenses are included in Operation, maintenance and other on the Consolidated Statements of Operations for the year ended December 31, 2018. In October 2018, the remnants of Hurricane Michael inflicted severe damage to the Duke Energy Carolinas and Duke Energy Progress territories in North Carolina and South Carolina. Approximately 1 million customers were impacted. The companies incurred approximately $100 million in incremental operation and maintenance expenses ( $75 million and $25 million for Duke Energy Carolinas and Duke Energy Progress, respectively,) and approximately $21 million in capital costs ( $12 million and $9 million for Duke Energy Carolinas and Duke Energy Progress, respectively,) which are included in Net property, plant and equipment on the Consolidated Balance Sheets as of December 31, 2018, resulting from the hurricane restoration efforts. Most of the operation and maintenance expenses are deferred in Regulatory assets within Other Noncurrent Assets on the Consolidated Balance Sheets as of December 31, 2018. The balance of operation and maintenance expenses are included in Operation, maintenance and other on the Consolidated Statements of Operations for the year ended December 31, 2018. In December 2018, Winter Storm Diego inflicted severe damage to the Duke Energy Carolinas and Duke Energy Progress territories in North Carolina and South Carolina. Approximately 800,000 customers were impacted. The companies incurred approximately $85 million in incremental operation and maintenance expenses ( $60 million and $25 million for Duke Energy Carolinas and Duke Energy Progress, respectively,) and approximately $9 million in capital costs ( $7 million and $2 million for Duke Energy Carolinas and Duke Energy Progress, respectively,) which are included in Net property, plant and equipment on the Consolidated Balance Sheets as of December 31, 2018, resulting from the winter storm restoration efforts. Most of the operation and maintenance expenses are deferred in Regulatory assets within Other Noncurrent Assets on the Consolidated Balance Sheets as of December 31, 2018. The balance of operation and maintenance expenses are included in Operation, maintenance and other on the Consolidated Statements of Operations for the year ended December 31, 2018. On December 21, 2018, Duke Energy Carolinas and Duke Energy Progress filed with the NCUC petitions for approval to defer the incremental costs incurred to a regulatory asset for recovery in the next base rate case. The NCUC issued an order requesting comments on the deferral positions. Duke Energy Carolinas and Duke Energy Progress cannot predict the outcome of this matter. Duke Energy Progress filed a similar request with the PSCSC on January 11, 2019, which also included a request for the continuation of prior deferrals requested for ice storms and Hurricane Matthew, and on January 30, 2019, the PSCSC issued a directive approving the deferral request. North Carolina State Corporate Income Tax On December 12, 2018, Duke Energy Carolinas and Duke Energy Progress filed requests to reduce their rates effective January 1, 2019, based on a reduction in North Carolina’s corporate income tax rate from 3 to 2.5 percent, as enacted by the General Assembly in Session Law 2017-57, which became law on June 28, 2017, with an effective date of January 1, 2019. On December 17, 2018, the NCUC issued orders approving the Duke Energy Carolinas and Duke Energy Progress rate decrements. Duke Energy Carolinas Regulatory Assets and Liabilities The following tables present the regulatory assets and liabilities recorded on Duke Energy Carolinas' Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 1,725 $ 1,645 (i) (b) Accrued pension and OPEB 581 410 (j) Retired generation facilities (c) 21 29 X 2023 Deferred Asset – Lee COLA 383 — (b) Storm cost deferrals 160 — X (b) Hedge costs deferrals (c) 101 109 X 2041 DSM/EE 169 210 (h) (h) Vacation accrual 78 83 (e) 2019 Deferred fuel and purchased power 196 140 (f) 2020 Nuclear deferral 87 84 2020 PISCC (c) 34 35 X (b) AMI 176 185 X (b) Other 266 222 (b) Total regulatory assets 3,977 3,152 Less: current portion 520 299 Total noncurrent regulatory assets $ 3,457 $ 2,853 Regulatory Liabilities (a) Costs of removal (c) $ 1,968 $ 2,054 X (g) ARO – nuclear and other 538 806 (b) Net regulatory liability related to income taxes (d) 3,082 3,028 (b) Storm reserve (c) — 20 (b) Accrued pension and OPEB 38 44 (j) Deferred fuel and purchased power — 46 (f) 2020 Other 572 359 (b) Total regulatory liabilities 6,198 6,357 Less: current portion 199 126 Total noncurrent regulatory liabilities $ 5,999 $ 6,231 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Includes regulatory liabilities related to the change in the federal tax rate as a result of the Tax Act and the change in the North Carolina tax rate, both discussed in Note 23 . (e) Earns a return on outstanding balance in North Carolina. (f) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina. (g) Recovered over the life of the associated assets. (h) Includes incentives on DSM/EE investments and is recovered through an annual rider mechanism. (i) Earns a debt and equity return on coal ash expenditures for North Carolina and South Carolina retail customers as permitted by various regulatory orders. (j) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail. 2017 North Carolina Rate Case On August 25, 2017, Duke Energy Carolinas filed an application with the NCUC for a rate increase for retail customers of approximately $647 million , which represented an approximate 13.6 percent increase in annual base revenues. The rate increase was driven by capital investments subsequent to the previous base rate case, including the W.S. Lee CC discussed below, grid improvement projects, AMI, investments in customer service technologies, costs of complying with CCR regulations and the Coal Ash Act and recovery of costs related to licensing and development of the Lee Nuclear Station discussed below. On February 28, 2018, Duke Energy Carolinas and the North Carolina Public Staff (Public Staff) filed an Agreement and Stipulation of Partial Settlement resolving certain portions of the proceeding. Terms of the settlement included a return on equity of 9.9 percent and a capital structure of 52 percent equity and 48 percent debt. As a result of the settlement, Duke Energy Carolinas recorded a pretax charge of approximately $4 million to Operation, maintenance and other on the Consolidated Statements of Operations. On June 1, 2018, Duke Energy Carolinas and certain intervenors filed a Pilot Grid Rider Agreement and Stipulation (Grid Rider Stipulation) in which the parties agreed to the proposal Duke Energy Carolinas introduced in a post-hearing brief on April 27, 2018, along with additional commitments by Duke Energy Carolinas. Also on June 1, 2018, Duke Energy Carolinas and the Commercial Group filed a Partial Stipulation and Settlement Agreement to be considered in conjunction with the Stipulation. Components of the Grid Rider Stipulation included: • Duke Energy Carolinas would recover grid improvement costs through a pilot, three-year Grid Rider except for costs related to targeted undergrounding of power lines, cable and conduit replacement, and power pole replacement; • Excluded costs were to be deferred with a return until Duke Energy Carolinas’ next base rate case proceeding; and • Costs incurred during the three-year pilot, both rider recoverable and deferred, were subject to a 4.5 percent cumulative cap of total annual electric service revenue. On June 22, 2018, the NCUC issued an order approving the Stipulation of Partial Settlement and requiring a revenue reduction. The order also included the following material components not covered in the Stipulation: • Recovery of $554 million of deferred coal ash basin closure costs over a five -year period with a return at Duke Energy Carolinas' WACC; • Assessment of a $70 million management penalty ratably over a five-year period by reducing the annual recovery of the deferred coal ash costs; • Denial of Duke Energy Carolinas' request for recovery of future estimated ongoing annual coal ash costs of $201 million with approval to defer such costs with a return at Duke Energy Carolinas' WACC, to be considered for recovery in the next rate case; • Inclusion in rates of costs related to the W.S. Lee CC, two new solar facilities, and AMI deployment as requested; • Recovery of Lee Nuclear Station licensing and development cost of $347 million over a 12 -year period, but denial of a return on the deferred balance of costs; • Reduction in revenue related to lower income tax expense resulting from the Tax Act, and a requirement to maintain all excess deferred income tax (EDIT) resulting from the Tax Act in a regulatory liability account pending flow back to customers as approved by the commission at the earlier of three years or Duke Energy Carolinas’ next general rate case proceeding; and • Denial of the proposed Grid Rider Stipulation related to grid improvement costs and denial of deferral accounting treatment of the costs at this time. Duke Energy Carolinas may petition for deferral of grid modernization costs outside of a general rate case proceeding if it can show financial hardship or a stipulation that includes greater consensus among intervening parties on costs being classified as grid modernization. As a result of the Order, Duke Energy Carolinas recorded a pretax charge of approximately $150 million to Impairment charges and Operation, maintenance and other on the Consolidated Statements of Operations. The charge is primarily related to the denial of a return on the Lee Nuclear Project and for previously recognized return impacted by the coal ash management penalty described above. On July 27, 2018, NCUC approved Duke Energy Carolinas' compliance filing. As a result, revised customer rates were effective on August 1, 2018. On July 20, 2018, the North Carolina Attorney General filed a Notice of Appeal to the North Carolina Supreme Court from the June 22, 2018, Order Accepting Stipulation, Deciding Contested Issues and Requiring Revenue Reduction issued by the NCUC. The Attorney General contends the commission’s order should be reversed and remanded, as it is in excess of the commission’s statutory authority; affected by errors of law; unsupported by competent, material and substantial evidence in view of the entire record as submitted; and arbitrary or capricious. The Sierra Club, North Carolina Sustainable Energy Association, North Carolina Justice Center, North Carolina Housing Coalition, Natural Resource Defense Council and Southern Alliance for Clean Energy have also filed Notices of Appeal to the North Carolina Supreme Court from the June 22, 2018, Order Accepting Stipulation, Deciding Contested Issues and Requiring Revenue Reduction. On August 8, 2018, the Public Staff filed a Notice of Cross Appeal to the North Carolina Supreme Court from the June 22, 2018, Order Accepting Stipulation, Deciding Contested Issues and Requiring Revenue Reduction issued by the NCUC. The Public Staff contends the commission’s order should be reversed and remanded, as it is affected by errors of law, and is unsupported by substantial evidence with regard to the commission’s failure to consider substantial evidence of coal ash related environmental violations. On November 29, 2018, the North Carolina Attorney General's Office filed a motion with the North Carolina Supreme Court requesting the court consolidate the Duke Energy Carolinas and Duke Energy Progress appeals and enter an order adopting the parties’ proposed briefing schedule as set out in the filing. On November 29, 2018, the North Carolina Supreme Court adopted a schedule for briefing set forth in the motion to consolidate the Duke Energy Carolinas and Duke Energy Progress appeals. The Appellee response briefs are due July 29, 2019. Duke Energy Carolinas cannot predict the outcome of this matter. 2018 South Carolina Rate Case On November 8, 2018, Duke Energy Carolinas filed an application with the PSCSC for a rate increase for retail customers of approximately $168 million , which represents an approximate 10.0 percent increase in retail revenues. The rate increase is driven by capital investments and environmental compliance progress made by Duke Energy Carolinas since its previous rate case, including the further implementation of Duke Energy Carolinas’ generation modernization program, which consists of retiring, replacing and upgrading generation plants, investments in customer service technologies and continued investments in base work to maintain its transmission and distribution systems. The request includes net tax benefits resulting from the Tax Act of $66 million to reflect the change in ongoing tax expense, primarily from the reduction in the federal income tax rate from 35 to 21 percent, and $46 million to return EDIT resulting from the federal tax rate change and deferred revenues since January 2018 related to the change and benefits of $17 million from a reduction in North Carolina state income taxes allocable to South Carolina. Duke Energy Carolinas also requested approval of its proposed Grid Improvement Plan, adjustments to its Prepaid Advantage Program and a variety of accounting orders related to ongoing costs for environmental compliance, including recovery over a five -year period of $242 million of deferred coal ash related compliance costs, grid investments between rate changes, incremental depreciation expense, a result of new depreciation rates from the depreciation study approved in the 2017 North Carolina Rate Case above, and the balance of development costs associated with the cancellation of the Lee Nuclear Project. Finally, Duke Energy Carolinas sought approval to establish a reserve and accrual for end of life nuclear costs for nuclear fuel and materials and supplies. An evidentiary hearing is scheduled to begin on March 21, 2019, and a decision and revised customer rates are expected by mid-2019. Duke Energy Carolinas cannot predict the outcome of this matter. FERC Formula Rate Matter On July 31, 2017, PMPA filed a complaint with FERC alleging that Duke Energy Carolinas misapplied the formula rate under the PPA between the parties by including in its rates amortization expense associated with regulatory assets and recorded in a certain account without FERC approval. On February 15, 2018, FERC issued an order ruling in favor of PMPA and ordered Duke Energy Carolinas to refund to PMPA all amounts improperly collected under the PPA. Duke Energy Carolinas has issued to PMPA and similarly situated wholesale customers refunds of approximately $25 million . FERC also set the matter for settlement and hearing. PMPA and other customers filed a protest to Duke Energy Carolinas' refund report claiming that the refunds are inadequate in that (1) Duke Energy Carolinas invoked the limitations periods in the contracts to limit the time period for which the refunds were paid and the customers disagree that this limitation applies, and (2) Duke Energy Carolinas refunded only amounts recovered through a certain account and the customers have asserted that the order applies to all regulatory assets. On July 3, 2018, FERC issued an order accepting Duke Energy Carolinas' refund report and ruling that these two claims are outside the scope of FERC's February order. The settlement agreements and revised formula rates for all parties to the proceeding were filed on December 28, 2018. Duke Energy Carolinas cannot predict the outcome of this matter. W.S. Lee CC On April 9, 2014, the PSCSC granted Duke Energy Carolinas and NCEMC a CECPCN for the construction and operation of a 750-megawatt (MW) combined-cycle natural gas-fired generating plant at Duke Energy Carolinas' existing William States Lee Generating Station in Anderson, South Carolina. Duke Energy Carolinas began construction in July 2015 and its share of the cost to build the facility was approximately $650 million , including AFUDC. Approximately $600 million is being recovered through base rate or deferral filings in North Carolina and South Carolina. The remaining amount will be included in future rate filings. The project commenced commercial operation on April 5, 2018. NCEMC owns approximately 13 percent of the project. Lee Nuclear Station In December 2007, Duke Energy Carolinas applied to the NRC for COLs for two Westinghouse AP1000 reactors for the proposed William States Lee III Nuclear Station to be located at a site in Cherokee County, South Carolina. The NCUC and PSCSC concurred with the prudency of Duke Energy Carolinas incurring certain project development and preconstruction costs through several separately issued orders, although full cost recovery is not guaranteed. In December 2016, the NRC issued a COL for each reactor. Duke Energy Carolinas is not required to build the nuclear reactors as a result of the COLs being issued. The Duke Energy Carolinas 2017 North Carolina Rate Case filing discussed above included a request to cancel the development of the Lee Nuclear project, recover incurred licensing and development costs and maintain the license issued by the NRC as an option for potential future development. The cancellation request was due to the Westinghouse bankruptcy filing and other market activity. The NCUC Order issued on June 22, 2018, approved the cancellation of the Lee Nuclear Project, allowed Duke Energy Carolinas to continue to maintain the COLs, provided for recovery of the North Carolina retail allocation of project development costs, including AFUDC accrued through December 31, 2017, over 12 years and disallowed any return on the unamortized balance during the 12-year recovery period. Given the repeal of certain sections of the Base Load Review Act in South Carolina combined with the cancellation of the project, Duke Energy Carolinas determined that it was no longer probable it would be allowed a return on its share of project development costs attributable to South Carolina. As a result, Duke Energy Carolinas recorded a pretax impairment in the second quarter of 2018 of $29 million within Impairment charges on the Consolidated Statements of Operations and Comprehensive I

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES INSURANCE General Insurance The Duke Energy Registrants have insurance and reinsurance coverage either directly or through indemnification from Duke Energy’s captive insurance company, Bison, and its affiliates, consistent with companies engaged in similar commercial operations with similar type properties. The Duke Energy Registrants’ coverage includes (i) commercial general liability coverage for liabilities arising to third parties for bodily injury and property damage; (ii) workers’ compensation; (iii) automobile liability coverage; and (iv) property coverage for all real and personal property damage. Real and personal property damage coverage excludes electric transmission and distribution lines, but includes damages arising from boiler and machinery breakdowns, earthquakes, flood damage and extra expense, but not outage or replacement power coverage. All coverage is subject to certain deductibles or retentions, sublimits, exclusions, terms and conditions common for companies with similar types of operations. The Duke Energy Registrants self-insure their electric transmission and distribution lines against loss due to storm damage and other natural disasters. As discussed further in Note 4 , Duke Energy Florida maintains a storm damage reserve and has a regulatory mechanism to recover the cost of named storms on an expedited basis. The cost of the Duke Energy Registrants’ coverage can fluctuate from year to year reflecting claims history and conditions of the insurance and reinsurance markets. In the event of a loss, terms and amounts of insurance and reinsurance available might not be adequate to cover claims and other expenses incurred. Uninsured losses and other expenses, to the extent not recovered by other sources, could have a material effect on the Duke Energy Registrants’ results of operations, cash flows or financial position. Each company is responsible to the extent losses may be excluded or exceed limits of the coverage available. Nuclear Insurance Duke Energy Carolinas owns and operates McGuire and Oconee and operates and has a partial ownership interest in Catawba. McGuire and Catawba each have two reactors. Oconee has three reactors. The other joint owners of Catawba reimburse Duke Energy Carolinas for certain expenses associated with nuclear insurance per the Catawba joint owner agreements. Duke Energy Progress owns and operates Robinson, Brunswick and Harris. Robinson and Harris each have one reactor. Brunswick has two reactors. Duke Energy Florida owns Crystal River Unit 3, which permanently ceased operation in 2013 and reached a SAFSTOR condition in January 2018 after the successful transfer of all used nuclear fuel assemblies to an on-site dry cask storage facility. In the event of a loss, terms and amounts of insurance available might not be adequate to cover property damage and other expenses incurred. Uninsured losses and other expenses, to the extent not recovered by other sources, could have a material effect on Duke Energy Carolinas’, Duke Energy Progress’ and Duke Energy Florida’s results of operations, cash flows or financial position. Each company is responsible to the extent losses may be excluded or exceed limits of the coverage available. Nuclear Liability Coverage The Price-Anderson Act requires owners of nuclear reactors to provide for public nuclear liability protection per nuclear incident up to a maximum total financial protection liability. The maximum total financial protection liability, which is approximately $14.1 billion , is subject to change every five years for inflation and for the number of licensed reactors. Total nuclear liability coverage consists of a combination of private primary nuclear liability insurance coverage and a mandatory industry risk-sharing program to provide for excess nuclear liability coverage above the maximum reasonably available private primary coverage. The U.S. Congress could impose revenue-raising measures on the nuclear industry to pay claims. Primary Liability Insurance Duke Energy Carolinas and Duke Energy Progress have purchased the maximum reasonably available private primary nuclear liability insurance as required by law, which is $450 million per station. Duke Energy Florida has purchased $100 million primary nuclear liability insurance in compliance with the law. Excess Liability Program This program provides $13.6 billion of coverage per incident through the Price-Anderson Act’s mandatory industrywide excess secondary financial protection program of risk pooling. This amount is the product of potential cumulative retrospective premium assessments of $138 million times the current 99 licensed commercial nuclear reactors in the U.S. Under this program, licensees could be assessed retrospective premiums to compensate for public nuclear liability damages in the event of a nuclear incident at any licensed facility in the U.S. Retrospective premiums may be assessed at a rate not to exceed $20.5 million per year per licensed reactor for each incident. The assessment may be subject to state premium taxes. Nuclear Property and Accidental Outage Coverage Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida are members of NEIL, an industry mutual insurance company, which provides property damage, nuclear accident decontamination and premature decommissioning insurance for each station for losses resulting from damage to its nuclear plants, either due to accidents or acts of terrorism. Additionally, NEIL provides accidental outage coverage for each station for losses in the event of a major accidental outage at an insured nuclear station. Pursuant to regulations of the NRC, each company’s property damage insurance policies provide that all proceeds from such insurance be applied, first, to place the plant in a safe and stable condition after a qualifying accident and second, to decontaminate the plant before any proceeds can be used for decommissioning, plant repair or restoration. Losses resulting from acts of terrorism are covered as common occurrences, such that if terrorist acts occur against one or more commercial nuclear power plants insured by NEIL within a 12-month period, they would be treated as one event and the owners of the plants where the act occurred would share one full limit of liability. The full limit of liability is currently $3.2 billion . NEIL sublimits the total aggregate for all of their policies for non-nuclear terrorist events to approximately $1.8 billion . Each nuclear facility has accident property damage, nuclear accident decontamination and premature decommissioning liability insurance from NEIL with limits of $1.5 billion , except for Crystal River Unit 3. Crystal River Unit 3’s limit is $50 million and is on an actual cash value basis. All nuclear facilities except for Catawba and Crystal River Unit 3 also share an additional $1.25 billion nuclear accident insurance limit above their dedicated underlying limit. This shared additional excess limit is not subject to reinstatement in the event of a loss. Catawba has a dedicated $1.25 billion of additional nuclear accident insurance limit above its dedicated underlying limit. Catawba and Oconee also have an additional $750 million of non-nuclear accident property damage limit. All coverages are subject to sublimits and significant deductibles. NEIL’s Accidental Outage policy provides some coverage, such as business interruption, for losses in the event of a major accident property damage outage of a nuclear unit. Coverage is provided on a weekly limit basis after a significant waiting period deductible and at 100 percent of the available weekly limits for 52 weeks and 80 percent of the available weekly limits for the next 110 weeks. Coverage is provided until these available weekly periods are met where the accidental outage policy limit will not exceed $490 million for McGuire, Catawba and Harris, $476 million for Brunswick, $462 million for Oconee and $392 million for Robinson. NEIL sublimits the accidental outage recovery to the first 104 weeks of coverage not to exceed $328 million from non-nuclear accidental property damage. Coverage amounts decrease in the event more than one unit at a station is out of service due to a common accident. All coverages are subject to sublimits and significant deductibles. Potential Retroactive Premium Assessments In the event of NEIL losses, NEIL’s board of directors may assess member companies' retroactive premiums of amounts up to 10 times their annual premiums for up to six years after a loss. NEIL has never exercised this assessment. The maximum aggregate annual retrospective premium obligations for Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida are $159 million , $97 million and $1 million , respectively. Duke Energy Carolinas' maximum assessment amount includes 100 percent of potential obligations to NEIL for jointly owned reactors. Duke Energy Carolinas would seek reimbursement from the joint owners for their portion of these assessment amounts. ENVIRONMENTAL The Duke Energy Registrants are subject to federal, state and local regulations regarding air and water quality, hazardous and solid waste disposal and other environmental matters. These regulations can be changed from time to time, imposing new obligations on the Duke Energy Registrants. The following environmental matters impact all of the Duke Energy Registrants. Remediation Activities In addition to the ARO recorded as a result of various environmental regulations, discussed in Note 9 , the Duke Energy Registrants are responsible for environmental remediation at various sites. These include certain properties that are part of ongoing operations and sites formerly owned or used by Duke Energy entities. These sites are in various stages of investigation, remediation and monitoring. Managed in conjunction with relevant federal, state and local agencies, remediation activities vary based upon site conditions and location, remediation requirements, complexity and sharing of responsibility. If remediation activities involve joint and several liability provisions, strict liability, or cost recovery or contribution actions, the Duke Energy Registrants could potentially be held responsible for environmental impacts caused by other potentially responsible parties and may also benefit from insurance policies or contractual indemnities that cover some or all cleanup costs. Liabilities are recorded when losses become probable and are reasonably estimable. The total costs that may be incurred cannot be estimated because the extent of environmental impact, allocation among potentially responsible parties, remediation alternatives and/or regulatory decisions have not yet been determined at all sites. Additional costs associated with remediation activities are likely to be incurred in the future and could be significant. Costs are typically expensed as Operation, maintenance and other in the Consolidated Statements of Operations unless regulatory recovery of the costs is deemed probable. The following tables contain information regarding reserves for probable and estimable costs related to the various environmental sites. These reserves are recorded in Accounts payable within Current Liabilities and Other within Other Noncurrent Liabilities on the Consolidated Balance Sheets. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Balance at December 31, 2015 $ 94 $ 10 $ 17 $ 3 $ 14 $ 54 $ 12 Provisions/adjustments 19 4 7 2 4 7 1 Cash reductions (15 ) (4 ) (6 ) (2 ) (4 ) (2 ) (3 ) Balance at December 31, 2016 98 10 18 3 14 59 10 Provisions/adjustments 8 3 3 2 2 3 (4 ) Cash reductions (25 ) (3 ) (6 ) (2 ) (4 ) (15 ) (1 ) Balance at December 31, 2017 81 10 15 3 12 47 5 Provisions/adjustments 26 3 2 3 (2 ) 21 1 Cash reductions (30 ) (2 ) (6 ) (2 ) (4 ) (20 ) (1 ) Balance at December 31, 2018 $ 77 $ 11 $ 11 $ 4 $ 6 $ 48 $ 5 As of December 31, 2016, and October 31, 2016 and 2015, Piedmont's environmental reserve was $1 million . As of December 31, 2018, and 2017, the reserve was $2 million . Additional losses in excess of recorded reserves that could be incurred for the stages of investigation, remediation and monitoring for environmental sites that have been evaluated at this time are not material except as presented in the table below. (in millions) Duke Energy $ 46 Duke Energy Carolinas 17 Duke Energy Ohio 19 Piedmont 2 North Carolina and South Carolina Ash Basins In February 2014, a break in a stormwater pipe beneath an ash basin at Duke Energy Carolinas’ retired Dan River Steam Station caused a release of ash basin water and ash into the Dan River. In July 2014, Duke Energy completed remediation work identified by the EPA and continues to cooperate with the EPA's civil enforcement process. The NCDEQ has historically assessed Duke Energy Carolinas and Duke Energy Progress with NOVs for violations that were most often resolved through satisfactory corrective actions and minor, if any, fines or penalties. Subsequent to the Dan River ash release, Duke Energy Carolinas and Duke Energy Progress have been served with a higher level of NOVs, including assessed penalties for violations at Sutton and Dan River Steam Station. Duke Energy Carolinas and Duke Energy Progress continue to resolve violations through corrective actions, and associated penalties related to existing unresolved NOVs are not expected to be material. LITIGATION Duke Energy Carolinas and Duke Energy Progress Coal Ash Insurance Coverage Litigation In March 2017, Duke Energy Carolinas and Duke Energy Progress filed a civil action in the North Carolina Superior Court against various insurance providers. The lawsuit seeks payment for coal ash-related liabilities covered by third-party liability insurance policies. The insurance policies were issued between 1971 and 1986 and provide third-party liability insurance for property damage. The civil action seeks damages for breach of contract and indemnification for costs arising from the Coal Ash Act and the EPA CCR rule at 15 coal-fired plants in North Carolina and South Carolina. On January 23, 2019, the court granted the parties’ joint motion for a four month stay of the proceedings, until June 3, 2019, to allow the parties to discuss potential resolution. If the case is not fully resolved at that time, litigation will resume. The trial remains scheduled for August 2020. Duke Energy Carolinas and Duke Energy Progress cannot predict the outcome of this matter. NCDEQ State Enforcement Actions In the first quarter of 2013, SELC sent notices of intent to sue Duke Energy Carolinas and Duke Energy Progress related to alleged CWA violations from coal ash basins at two coal-fired power plants in North Carolina. The NCDEQ filed enforcement actions against Duke Energy Carolinas and Duke Energy Progress alleging violations of water discharge permits and North Carolina groundwater standards. The cases have been consolidated and are being heard before a single judge in the North Carolina Superior Court. On August 16, 2013, the NCDEQ filed an enforcement action against Duke Energy Carolinas and Duke Energy Progress related to the remaining coal-fired power plants in North Carolina, alleging violations of the CWA and violations of the North Carolina groundwater standards. Both of these cases have been assigned to the judge handling the enforcement actions discussed above. SELC is representing several environmental groups who have been permitted to intervene in these cases. The court issued orders in 2016 granting Motions for Partial Summary Judgment for seven of the 14 North Carolina plants with coal ash basins named in the enforcement actions. On February 13, 2017, the court issued an order denying motions for partial summary judgment brought by both the environmental groups and Duke Energy Carolinas and Duke Energy Progress for the remaining seven plants. On March 15, 2017, Duke Energy Carolinas and Duke Energy Progress filed a Notice of Appeal with the North Carolina Court of Appeals to challenge the trial court’s order. The parties were unable to reach an agreement at mediation in April 2017 and submitted briefs to the trial court on remaining issues to be tried. On August 1, 2018, the Court of Appeals dismissed the appeal and the matter is proceeding before the trial court. No trial date has been scheduled. Duke Energy Carolinas and Duke Energy Progress cannot predict the outcome of this matter. Federal Citizens Suits On June 13, 2016, RRBA filed a federal citizen suit in the Middle District of North Carolina alleging unpermitted discharges to surface water and groundwater violations at the Mayo Plant. On August 19, 2016, Duke Energy Progress filed a Motion to Dismiss. On April 26, 2017, the court entered an order dismissing four of the claims in the federal citizen suit. Two claims relating to alleged violations of NPDES permit provisions survived the motion to dismiss, and Duke Energy Progress filed its response on May 10, 2017. Duke Energy Progress and RRBA each filed motions for summary judgment on March 23, 2018. The court has not yet ruled on these motions. On May 16, 2017, RRBA filed a federal citizen suit in the U.S. District Court for the Middle District of North Carolina, which asserts two claims relating to alleged violations of NPDES permit provisions at the Roxboro Plant and one claim relating to the use of nearby water bodies. Duke Energy Progress and RRBA each filed motions for summary judgment on April 17, 2018, and the court has not yet ruled on these motions. On May 8, 2018, on motion from Duke Energy Progress, the court ordered trial in both of the above matters to be consolidated. Trial is currently scheduled to begin July 15, 2019. On June 20, 2017, RRBA filed a federal citizen suit in the U.S. District Court for the Middle District of North Carolina challenging the closure plans at the Mayo Plant under the EPA CCR Rule. Duke Energy Progress filed a motion to dismiss, which was granted by the court on March 30, 2018. RRBA had until April 30, 2018, to file an appeal to the Fourth Circuit but did not do so. On August 2, 2017, RRBA filed a federal citizen suit in the U.S. District Court for the Middle District of North Carolina challenging the closure plans at the Roxboro Plant under the EPA CCR Rule. Duke Energy Progress filed a motion to dismiss on October 2, 2017, which was granted by the court on May 29, 2018. RRBA had until June 28, 2018, to file an appeal to the Fourth Circuit but did not do so. On December 5, 2017, various parties filed a federal citizen suit in the U.S. District Court for the Middle District of North Carolina for alleged violations at Duke Energy Carolinas' Belews Creek under the CWA. Duke Energy Carolinas' answer to the complaint was filed on August 27, 2018. On October 10, 2018, Duke Energy Carolinas filed Motions to Dismiss for lack of standing, Motion for Judgment on the Pleadings and Motion to Stay Discovery. On January 9, 2019, the court entered an order denying Duke Energy Carolinas' motion to stay discovery. There has been no ruling on the other pending motions. Duke Energy Carolinas and Duke Energy Progress cannot predict the outcome of these matters. Groundwater Contamination Claims Beginning in May 2015, a number of residents living in the vicinity of the North Carolina facilities with ash basins received letters from the NCDEQ advising them not to drink water from the private wells on their land tested by the NCDEQ as the samples were found to have certain substances at levels higher than the criteria set by the DHHS. Results of CSAs testing performed by Duke Energy under the Coal Ash Act have been consistent with historical data provided to state regulators over many years. The DHHS and NCDEQ sent follow-up letters on October 15, 2015, to residents near coal ash basins who have had their wells tested, stating that private well samplings at a considerable distance from coal ash basins, as well as some municipal water supplies, contain similar levels of vanadium and hexavalent chromium, which led investigators to believe these constituents are naturally occurring. In March 2016, DHHS rescinded the advisories. Duke Energy Carolinas and Duke Energy Progress have received formal demand letters from residents near Duke Energy Carolinas' and Duke Energy Progress' coal ash basins. The residents claim damages for nuisance and diminution in property value, among other things. The parties held three days of mediation discussions, which ended at impasse. On January 6, 2017, Duke Energy Carolinas and Duke Energy Progress received the plaintiffs' notice of their intent to file suits should the matter not settle. The NCDEQ preliminarily approved Duke Energy’s permanent water solution plans on January 13, 2017, and as a result shortly thereafter, Duke Energy issued a press release, providing additional details regarding the homeowner compensation package. This package consists of three components: (i) a $5,000 goodwill payment to each eligible well owner to support the transition to a new water supply, (ii) where a public water supply is available and selected by the eligible well owner, a stipend to cover 25 years of water bills and (iii) the Property Value Protection Plan. The Property Value Protection Plan is a program offered by Duke Energy designed to guarantee eligible plant neighbors the fair market value of their residential property should they decide to sell their property during the time that the plan is offered. Payments are being made and the remaining reserves are not material. On August 23, 2017, a class-action suit was filed in Wake County Superior Court, North Carolina, against Duke Energy Carolinas and Duke Energy Progress on behalf of certain property owners living near coal ash impoundments at Allen, Asheville, Belews Creek, Buck, Cliffside, Lee, Marshall, Mayo and Roxboro. The class is defined as those who are well-eligible under the Coal Ash Act or those to whom Duke Energy has promised a permanent replacement water supply and seeks declaratory and injunctive relief, along with compensatory damages. Plaintiffs allege that Duke Energy’s improper maintenance of coal ash impoundments caused harm, particularly through groundwater contamination. Despite NCDEQ’s preliminary approval, Plaintiffs contend that Duke Energy’s proposed permanent water solutions plan fails to comply with the Coal Ash Act. On September 28, 2017, Duke Energy Carolinas and Duke Energy Progress filed a Motion to Dismiss and Motion to Strike the class designation. The parties entered into a Settlement Agreement on January 24, 2018, which resulted in the dismissal of the underlying class action on January 25, 2018. On September 14, 2017, a complaint was filed against Duke Energy Progress in New Hanover County Superior Court by a group of homeowners residing approximately 1 mile from Duke Energy Progress' Sutton Steam Plant. The homeowners allege that coal ash constituents have been migrating from ash impoundments at Sutton into their groundwater for decades and that in 2015, Duke Energy Progress discovered these releases of coal ash, but failed to notify any officials or neighbors and failed to take remedial action. The homeowners claim unspecified physical and mental injuries as a result of consuming their well water and seek actual damages for personal injury, medical monitoring and punitive damages. On March 6, 2018, Plaintiffs' counsel voluntarily dismissed the action without prejudice. Duke Energy Carolinas Asbestos-related Injuries and Damages Claims Duke Energy Carolinas has experienced numerous claims for indemnification and medical cost reimbursement related to asbestos exposure. These claims relate to damages for bodily injuries alleged to have arisen from exposure to or use of asbestos in connection with construction and maintenance activities conducted on its electric generation plants prior to 1985. As of December 31, 2018 , there were 164 asserted claims for non-malignant cases with the cumulative relief sought of up to $42 million and 87 asserted claims for malignant cases with the cumulative relief sought of up to $21 million . Based on Duke Energy Carolinas’ experience, it is expected that the ultimate resolution of most of these claims likely will be less than the amount claimed. Duke Energy Carolinas has recognized asbestos-related reserves of $630 million and $489 million at December 31, 2018 , and 2017 , respectively. These reserves are classified in Other within Other Noncurrent Liabilities and Other within Current Liabilities on the Consolidated Balance Sheets. These reserves are based upon Duke Energy Carolinas' best estimate for current and future asbestos claims through 2038 and are recorded on an undiscounted basis. In light of the uncertainties inherent in a longer-term forecast, management does not believe they can reasonably estimate the indemnity and medical costs that might be incurred after 2038 related to such potential claims. It is possible Duke Energy Carolinas may incur asbestos liabilities in excess of the recorded reserves. Duke Energy Carolinas has third-party insurance to cover certain losses related to asbestos-related injuries and damages above an aggregate self-insured retention. Duke Energy Carolinas’ cumulative payments began to exceed the self-insurance retention in 2008. Future payments up to the policy limit will be reimbursed by the third-party insurance carrier. The insurance policy limit for potential future insurance recoveries indemnification and medical cost claim payments is $764 million in excess of the self-insured retention. Receivables for insurance recoveries were $739 million and $585 million at December 31, 2018 , and 2017 , respectively. These amounts are classified in Other within Other Noncurrent Assets and Receivables within Current Assets on the Consolidated Balance Sheets. Duke Energy Carolinas is not aware of any uncertainties regarding the legal sufficiency of insurance claims. Duke Energy Carolinas believes the insurance recovery asset is probable of recovery as the insurance carrier continues to have a strong financial strength rating. Duke Energy Progress and Duke Energy Florida Spent Nuclear Fuel Matters On October 16, 2014, Duke Energy Progress and Duke Energy Florida sued the U.S. in the U.S. Court of Federal Claims. The lawsuit claimed the Department of Energy breached a contract in failing to accept spent nuclear fuel under the Nuclear Waste Policy Act of 1982 and asserted damages for the cost of on-site storage. Duke Energy Progress and Duke Energy Florida asserted damages for the period January 1, 2011, through December 31, 2013, of $48 million and $25 million , respectively. On November 17, 2017, the Court awarded Duke Energy Progress and Duke Energy Florida $48 million and $21 million , respectively, subject to appeal. No appeals were filed and Duke Energy Progress and Duke Energy Florida recognized the recoveries in the first quarter of 2018. Claims for all periods through 2013 have been resolved. On June 22, 2018, Duke Energy Progress and Duke Energy Florida filed a complaint for damages incurred for 2014 through first quarter 2018. Duke Energy Progress Gypsum Supply Agreements Matter On June 30, 2017, CertainTeed filed a declaratory judgment action against Duke Energy Progress in the North Carolina Business Court relating to a gypsum supply agreement. In its complaint, CertainTeed sought an order from the court declaring that the minimum amount of gypsum Duke Energy Progress must provide to CertainTeed under the supply agreement was 50,000 tons per month through 2029. Trial in this matter was completed on July 16, 2018. On August 29, 2018, the court issued an order and opinion finding that Duke Energy Progress is required to supply 50,000 tons of gypsum/month, but that CertainTeed’s sole remedy for Duke Energy Progress’ long-term discontinuance under the agreement is liquidated damages. On November 14, 2018, the parties reached a settlement agreement. The amount owed under the liquidated damages provision is approximately $90 million on an undiscounted basis over 10 years. Approximately $3 million was paid in 2018. As of December 31, 2018, $9 million is recorded in Accounts payable within Current Liabilities and $63 million in Other within Other Noncurrent Liabilities on the Consolidated Balance Sheets. The liability is recorded on a discounted basis at a rate of approximately 4 percent . These costs are probable of recovery from customers and are recorded in Regulatory Assets within Other Noncurrent Assets on the Consolidated Balance Sheets. Duke Energy Florida Fluor Contract Litigation On January 29, 2019, Fluor filed a breach of contract lawsuit in the U.S. District Court for the Middle District of Florida against Duke Energy Florida related to an EPC agreement for the combined-cycle natural gas plant in Citrus County, Florida. Fluor filed an amended complaint on February, 13, 2019. Fluor’s multicount complaint seeks civil, statutory and contractual remedies related to Duke Energy Florida’s $67 million draw in early 2019, on Fluor’s letter of credit and offset of invoiced amounts. Duke Energy Florida is attempting to recover from Fluor $110 million in additional costs incurred by Duke Energy Florida. Duke Energy Florida cannot predict the outcome of this matter. See Note 4 for additional information. Class-Action Lawsuit On February 22, 2016, a lawsuit was filed in the U.S. District Court for the Southern District of Florida on behalf of a class of Duke Energy Florida and FP&L’s customers in Florida. The suit alleges the State of Florida’s NCRS are unconstitutional and pre-empted by federal law. Plaintiffs claim they are entitled to repayment of all money paid by customers of Duke Energy Florida and FP&L as a result of the NCRS, as well as an injunction against any future charges under those statutes. The constitutionality of the NCRS has been challenged unsuccessfully in a number of prior cases on alternative grounds. Duke Energy Florida and FP&L filed motions to dismiss the complaint on May 5, 2016. On September 21, 2016, the Court granted the motions to dismiss with prejudice. Plaintiffs filed a motion for reconsideration, which was denied. On January 4, 2017, plaintiffs filed a notice of appeal to the Eleventh Circuit U.S. Court of Appeals (Eleventh Circuit). On July 11, 2018, the Eleventh Circuit affirmed the U.S. District Court's dismissal of the lawsuit. The deadline to file a petition for cert was October 9, 2018, and no petition was filed; therefore, the dismissal of the lawsuit is final. Westinghouse Contract Litigation On March 28, 2014, Duke Energy Florida filed a lawsuit against Westinghouse in the U.S. District Court for the Western District of North Carolina. The lawsuit seeks recovery of $54 million in milestone payments in excess of work performed under an EPC for Levy as well as a determination by the court of the amounts due to Westinghouse as a result of the termination of an EPC contract. Duke Energy Florida recognized an exit obligation as a result of the termination of the EPC. On March 31, 2014, Westinghouse filed a separate lawsuit against Duke Energy Florida in U.S. District Court for the Western District of Pennsylvania alleging damages under the same EPC contract in excess of $510 million for engineering and design work, costs to end supplier contracts and an alleged termination fee. On June 9, 2014, the judge in the North Carolina case ruled that the litigation will proceed in the Western District of North Carolina. On July 11, 2016, Duke Energy Florida and Westinghouse filed separate Motions for Summary Judgment. On September 29, 2016, the court issued its ruling, granting Westinghouse a $30 million termination fee claim and dismissing Duke Energy Florida's $54 million refund claim. Westinghouse's claim for termination costs continued to trial. Following a trial on the matter, the court issued an order in December 2016 denying Westinghouse’s claim for termination costs and reaffirming its earlier ruling in favor of Westinghouse on the $30 million termination fee. Judgment was entered against Duke Energy Florida in the amount of approximately $34 million , which includes prejudgment interest. Westinghouse appealed the trial court's order to the Fourth Circuit and Duke Energy Florida cross-appealed. On March 29, 2017, Westinghouse filed Chapter 11 bankruptcy in the Southern District of New York, which automatically stayed the appeal. On May 23, 2017, the bankruptcy court entered an order lifting the sta

Debt and Credit Facilities

Debt and Credit Facilities	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt and Credit Facilities	DEBT AND CREDIT FACILITIES Summary of Debt and Related Terms The following tables summarize outstanding debt. December 31, 2018 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unsecured debt, maturing 2019-2078 4.26 % $ 20,955 $ 1,150 $ 3,800 $ 50 $ 350 $ 1,000 $ 408 $ 2,150 Secured debt, maturing 2020-2037 3.69 % 4,297 450 1,703 300 1,403 — — — First mortgage bonds, maturing 2019-2048 (a) 4.32 % 25,628 8,759 13,100 7,574 5,526 1,099 2,670 — Capital leases, maturing 2019-2051 (b) 5.06 % 941 109 251 137 114 2 10 — Tax-exempt bonds, maturing 2019-2041 (c) 3.40 % 941 243 48 48 — 77 572 — Notes payable and commercial paper (d) 2.73 % 4,035 — — — — — — — Money pool/intercompany borrowings — 739 1,385 444 108 299 317 198 Fair value hedge carrying value adjustment 5 5 — — — — — — Unamortized debt discount and premium, net (e) 1,434 (23 ) (29 ) (15 ) (11 ) (31 ) (8 ) (1 ) Unamortized debt issuance costs (f) (297 ) (54 ) (112 ) (40 ) (61 ) (7 ) (20 ) (11 ) Total debt 4.13 % $ 57,939 $ 11,378 $ 20,146 $ 8,498 $ 7,429 $ 2,439 $ 3,949 $ 2,336 Short-term notes payable and commercial paper (3,410 ) — — — — — — — Short-term money pool/intercompany borrowings — (439 ) (1,235 ) (294 ) (108 ) (274 ) (167 ) (198 ) Current maturities of long-term debt (g) (3,406 ) (6 ) (1,672 ) (603 ) (270 ) (551 ) (63 ) (350 ) Total long-term debt (g) $ 51,123 $ 10,933 $ 17,239 $ 7,601 $ 7,051 $ 1,614 $ 3,719 $ 1,788 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $63 million and $531 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds, letters of credit or the Master Credit Facility. (d) Includes $625 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that backstop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for Duke Energy's commercial paper program was 16 days. (e) Duke Energy includes $1,380 million and $156 million in purchase accounting adjustments related to Progress Energy and Piedmont, respectively. (f) Duke Energy includes $41 million in purchase accounting adjustments primarily related to the merger with Progress Energy. (g) Refer to Note 17 for additional information on amounts from consolidated VIEs. December 31, 2017 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unsecured debt, maturing 2018-2073 4.17 % $ 20,409 $ 1,150 $ 3,950 $ — $ 550 $ 900 $ 411 $ 2,050 Secured debt, maturing 2018-2037 3.15 % 4,458 450 1,757 300 1,457 — — — First mortgage bonds, maturing 2018-2047 (a) 4.51 % 23,529 7,959 11,801 6,776 5,025 1,100 2,669 — Capital leases, maturing 2018-2051 (b) 4.55 % 1,000 61 269 139 129 5 11 — Tax-exempt bonds, maturing 2019-2041 (c) 3.23 % 941 243 48 48 — 77 572 — Notes payable and commercial paper (d) 1.57 % 2,788 — — — — — — — Money pool/intercompany borrowings — 404 955 390 — 54 311 364 Fair value hedge carrying value adjustment 6 6 — — — — — — Unamortized debt discount and premium, net (e) 1,582 (19 ) (30 ) (16 ) (10 ) (33 ) (9 ) (1 ) Unamortized debt issuance costs (f) (271 ) (47 ) (108 ) (40 ) (56 ) (7 ) (21 ) (12 ) Total debt 4.09 % $ 54,442 $ 10,207 $ 18,642 $ 7,597 $ 7,095 $ 2,096 $ 3,944 $ 2,401 Short-term notes payable and commercial paper (2,163 ) — — — — — — — Short-term money pool/intercompany borrowings — (104 ) (805 ) (240 ) — (29 ) (161 ) (364 ) Current maturities of long-term debt (g) (3,244 ) (1,205 ) (771 ) (3 ) (768 ) (3 ) (3 ) (250 ) Total long-term debt (g) $ 49,035 $ 8,898 $ 17,066 $ 7,354 $ 6,327 $ 2,064 $ 3,780 $ 1,787 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $81 million and $603 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds, letters of credit or the Master Credit Facility. (d) Includes $625 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that backstop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for Duke Energy's commercial paper programs was 14 days. (e) Duke Energy includes $1,509 million and $176 million purchase accounting adjustments related to the mergers with Progress Energy and Piedmont, respectively. (f) Duke Energy includes $47 million in purchase accounting adjustments primarily related to the merger with Progress Energy. (g) Refer to Note 17 for additional information on amounts from consolidated VIEs. Current Maturities of Long-Term Debt The following table shows the significant components of Current maturities of Long-Term Debt on the Consolidated Balance Sheets. The Duke Energy Registrants currently anticipate satisfying these obligations with cash on hand and proceeds from additional borrowings. (in millions) Maturity Date Interest Rate December 31, 2018 Unsecured Debt Progress Energy March 2019 7.050 % $ 450 Duke Energy (Parent) September 2019 5.050 % 500 Piedmont September 2019 3.155 % (b) 350 Duke Energy Kentucky October 2019 4.65 % 100 Progress Energy December 2019 4.875 % 350 First Mortgage Bonds Duke Energy Progress January 2019 5.300 % 600 Duke Energy Ohio April 2019 5.450 % 450 Other (a) 606 Current maturities of long-term debt $ 3,406 (a) Includes capital lease obligations, amortizing debt and small bullet maturities. (b) Debt has a floating interest rate. Maturities and Call Options The following table shows the annual maturities of long-term debt for the next five years and thereafter. Amounts presented exclude short-term notes payable and commercial paper and money pool borrowings for the Subsidiary Registrants. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy (a) Carolinas Energy Progress Florida Ohio Indiana Piedmont 2019 $ 3,408 $ 6 $ 1,674 $ 603 $ 270 552 $ 63 $ 350 2020 3,765 907 926 354 572 — 503 — 2021 4,803 503 2,004 904 600 50 70 160 2022 2,745 353 1,032 505 77 — 94 — 2023 3,375 1,303 535 456 79 350 153 45 Thereafter 35,288 7,940 12,880 5,437 5,793 1,251 2,925 1,595 Total long-term debt, including current maturities $ 53,384 $ 11,012 $ 19,051 $ 8,259 $ 7,391 $ 2,203 $ 3,808 $ 2,150 (a) Excludes $1,578 million in purchase accounting adjustments related to the Progress Energy merger and the Piedmont acquisition. The Duke Energy Registrants have the ability under certain debt facilities to call and repay the obligation prior to its scheduled maturity. Therefore, the actual timing of future cash repayments could be materially different than as presented above. Short-Term Obligations Classified as Long-Term Debt Tax-exempt bonds that may be put to the Duke Energy Registrants at the option of the holder and certain commercial paper issuances and money pool borrowings are classified as Long-Term Debt on the Consolidated Balance Sheets. These tax-exempt bonds, commercial paper issuances and money pool borrowings, which are short-term obligations by nature, are classified as long term due to Duke Energy’s intent and ability to utilize such borrowings as long-term financing. As Duke Energy’s Master Credit Facility and other bilateral letter of credit agreements have non-cancelable terms in excess of one year as of the balance sheet date, Duke Energy has the ability to refinance these short-term obligations on a long-term basis. The following tables show short-term obligations classified as long-term debt. December 31, 2018 Duke Duke Duke Duke Duke Energy Energy Energy Energy (in millions) Energy Carolinas Progress Ohio Indiana Tax-exempt bonds $ 312 $ — $ — $ 27 $ 285 Commercial paper (a) 625 300 150 25 150 Total $ 937 $ 300 $ 150 $ 52 $ 435 December 31, 2017 Duke Duke Duke Duke Duke Energy Energy Energy Energy (in millions) Energy Carolinas Progress Ohio Indiana Tax-exempt bonds $ 312 $ — $ — $ 27 $ 285 Commercial paper (a) 625 300 150 25 150 Total $ 937 $ 300 $ 150 $ 52 $ 435 (a) Progress Energy amounts are equal to Duke Energy Progress amounts. Summary of Significant Debt Issuances In January 2019, Duke Energy Ohio issued $800 million of first mortgage bonds. The issuance was split between a $400 million , 10 -year tranche at 3.65 percent and a $400 million , 30 -year tranche at 4.30 percent . The net proceeds will be used to refinance $450 million of Duke Energy Ohio bonds maturing in April 2019, to pay down short-term debt and for general corporate purposes. The following tables summarize significant debt issuances (in millions). Year Ended December 31, 2018 Duke Duke Duke Duke Maturity Interest Duke Energy Energy Energy Energy Issuance Date Date Rate Energy (Parent) Carolinas Progress Florida Unsecured Debt March 2018 (a) April 2025 3.950 % $ 250 $ 250 $ — $ — $ — May 2018 (b) May 2021 3.114 % 500 500 — — — September 2018 (c) September 2078 5.625 % 500 500 — — — First Mortgage Bonds March 2018 (d) March 2023 3.050 % 500 — 500 — — March 2018 (d) March 2048 3.950 % 500 — 500 — — June 2018 (e) July 2028 3.800 % 600 — — — 600 June 2018 (e) July 2048 4.200 % 400 — — — 400 August 2018 (f) September 2023 3.375 % 300 — — 300 — August 2018 (f) September 2028 3.700 % 500 — — 500 — November 2018 (g) May 2022 3.350 % 350 — 350 — — November 2018 (g) November 2028 3.950 % 650 — 650 — — Total issuances $ 5,050 $ 1,250 $ 2,000 $ 800 $ 1,000 (a) Debt issued to pay down short-term debt. (b) Debt issued to pay down short-term debt. Debt issuance has a floating debt rate. (c) Callable after September 2023 at par. Junior subordinated hybrid debt issued to pay down short-term debt and for general corporate purposes. (d) Debt issued to repay at maturity a $300 million first mortgage bond due April 2018, pay down intercompany short-term debt and for general corporate purposes. (e) Debt issued to repay a portion of intercompany short-term debt under the money pool borrowing arrangement and for general corporate purposes. (f) Debt issued to repay short-term debt and for general corporate purposes. (g) Debt issued to fund eligible green energy projects, including zero-carbon solar and energy storage, in the Carolinas. Year Ended December 31, 2017 Duke Duke Duke Duke Duke Maturity Interest Duke Energy Energy Energy Energy Energy Issuance Date Date Rate Energy (Parent) Carolinas Progress Florida Ohio Unsecured Debt April 2017 (a) April 2025 3.364 % $ 420 $ 420 $ — $ — $ — $ — June 2017 (b) June 2020 2.100 % 330 330 — — — — August 2017 (c) August 2022 2.400 % 500 500 — — — — August 2017 (c) August 2027 3.150 % 750 750 — — — — August 2017 (c) August 2047 3.950 % 500 500 — — — — December 2017 (d) December 2019 (k) 2.100 % 400 — — — 400 — Secured Debt February 2017 (e) June 2034 4.120 % 587 — — — — — August 2017 (f) December 2036 4.110 % 233 — — — — — First Mortgage Bonds January 2017 (g) January 2020 1.850 % 250 — — — 250 — January 2017 (g) January 2027 3.200 % 650 — — — 650 — March 2017 (h) June 2046 3.700 % 100 — — — — 100 September 2017 (i) September 2020 1.500 % (l) 300 — — 300 — — September 2017 (i) September 2047 3.600 % 500 — — 500 — — November 2017 (j) December 2047 3.700 % 550 — 550 — — — Total issuances $ 6,070 $ 2,500 $ 550 $ 800 $ 1,300 $ 100 (a) Proceeds were used to refinance $400 million of unsecured debt at maturity and to repay a portion of outstanding commercial paper. (b) Debt issued to repay a portion of outstanding commercial paper. (c) Debt issued to repay at maturity $700 million of unsecured debt, to repay outstanding commercial paper and for general corporate purposes. (d) Debt issued to fund storm restoration costs related to Hurricane Irma and for general corporate purposes. (e) Portfolio financing of four Texas and Oklahoma wind facilities. Duke Energy pledged substantially all of the assets of these wind facilities and is nonrecourse to Duke Energy. Proceeds were used to reimburse Duke Energy for a portion of previously funded construction expenditures. (f) Portfolio financing of eight solar facilities located in California, Colorado and New Mexico. Duke Energy pledged substantially all of the assets of these solar facilities and is nonrecourse to Duke Energy. Proceeds were used to reimburse Duke Energy for a portion of previously funded construction expenditures. (g) Debt issued to fund capital expenditures for ongoing construction and capital maintenance, to repay a $250 million aggregate principal amount of bonds at maturity and for general corporate purposes. (h) Proceeds were used to fund capital expenditures for ongoing construction, capital maintenance and for general corporate purposes. (i) Debt issued to repay at maturity a $200 million aggregate principal amount of bonds at maturity, pay down intercompany short-term debt and for general corporate purposes, including capital expenditures. (j) Debt issued to refinance $400 million aggregate principal amount of bonds due January 2018, pay down intercompany short-term debt and for general corporate purposes. (k) Principal balance will be repaid in equal quarterly installments beginning in March 2018. (l) Debt issuance has a floating interest rate. Available Credit Facilities In January 2018, Duke Energy extended the termination date of substantially all of its existing $8 billion Master Credit Facility capacity from March 16, 2022, to March 16, 2023. In May 2018, Duke Energy completed the extension process with 100 percent of all commitments to the Master Credit Facility extending to March 16, 2023 . The Duke Energy Registrants, excluding Progress Energy (Parent), have borrowing capacity under the Master Credit Facility up to specified sublimits for each borrower. Duke Energy has the unilateral ability at any time to increase or decrease the borrowing sublimits of each borrower, subject to a maximum sublimit for each borrower. The amount available under the Master Credit Facility has been reduced to backstop issuances of commercial paper, certain letters of credit and variable-rate demand tax-exempt bonds that may be put to the Duke Energy Registrants at the option of the holder. Duke Energy Carolinas and Duke Energy Progress are also required to each maintain $250 million of available capacity under the Master Credit Facility as security to meet obligations under plea agreements reached with the U.S. Department of Justice in 2015 related to violations at North Carolina facilities with ash basins. The table below includes the current borrowing sublimits and available capacity under these credit facilities. December 31, 2018 Duke Duke Duke Duke Duke Duke Duke Energy Energy Energy Energy Energy Energy (in millions) Energy (Parent) Carolinas Progress Florida Ohio Indiana Piedmont Facility size (a) $ 8,000 $ 2,650 $ 1,750 $ 1,400 $ 650 $ 450 $ 600 $ 500 Reduction to backstop issuances Commercial paper (b) (3,022 ) (917 ) (739 ) (444 ) (108 ) (299 ) (317 ) (198 ) Outstanding letters of credit (53 ) (45 ) (4 ) (2 ) — — — (2 ) Tax-exempt bonds (81 ) — — — — — (81 ) — Coal ash set-aside (500 ) — (250 ) (250 ) — — — — Available capacity $ 4,344 $ 1,688 $ 757 $ 704 $ 542 $ 151 $ 202 $ 300 (a) Represents the sublimit of each borrower. (b) Duke Energy issued $625 million of commercial paper and loaned the proceeds through the money pool to Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio and Duke Energy Indiana. The balances are classified as Long-Term Debt Payable to Affiliated Companies in the Consolidated Balance Sheets. Three-Year Revolving Credit Facility Duke Energy (Parent) has a $1.0 billion revolving credit facility through June 2020. Borrowings under this facility will be used for general corporate purposes. As of December 31, 2018, $500 million has been drawn under the Three Year Revolver. This balance is classified as Long-term debt on Duke Energy's Consolidated Balance Sheets. Any undrawn commitments can be drawn, and borrowings can be prepaid, at any time throughout the term of the facility. The terms and conditions of the Three Year Revolver are generally consistent with those governing Duke Energy's Master Credit Facility. Duke Energy Progress Term Loan Facility In December 2018, Duke Energy Progress entered into a two-year term loan facility with commitments totaling $700 million . Borrowings under the facility will be used to pay storm-related costs, pay down commercial paper and to partially finance an upcoming bond maturity. As of December 31, 2018, $50 million has been drawn under the term loan. The balance is classified as Long-term debt on Duke Energy Progress' Consolidated Balance Sheets. In January and February 2019, the remaining $650 million was drawn under the term loan. Piedmont Term Loan Facility In September 2018, Piedmont executed an amendment to its existing senior unsecured term loan facility. The amendment increased commitments from $250 million to $350 million and extended the maturity date to September 2019. Borrowings under the facility will be used for general corporate purposes. As of December 31, 2018 , the entire $350 million has been drawn under the Piedmont Term Loan. This balance is classified as Current maturities of long-term debt on Piedmont's Consolidated Balance Sheets. The terms and conditions of the Piedmont Term Loan are generally consistent with those governing Duke Energy's Master Credit Facility. Other Debt Matters In September 2016, Duke Energy filed a Form S-3 with the SEC. Under this Form S-3, which is uncapped, the Duke Energy Registrants, excluding Progress Energy, may issue debt and other securities in the future at amounts, prices and with terms to be determined at the time of future offerings. The registration statement was filed to replace a similar prior filing upon expiration of its three-year term and also allows for the issuance of common stock by Duke Energy. Duke Energy has an effective Form S-3 with the SEC to sell up to $3 billion of variable denomination floating-rate demand notes, called PremierNotes. The Form S-3 states that no more than $1.5 billion of the notes will be outstanding at any particular time. The notes are offered on a continuous basis and bear interest at a floating rate per annum determined by the Duke Energy PremierNotes Committee, or its designee, on a weekly basis. The interest rate payable on notes held by an investor may vary based on the principal amount of the investment. The notes have no stated maturity date, are non-transferable and may be redeemed in whole or in part by Duke Energy or at the investor’s option at any time. The balance as of December 31, 2018 , and 2017 was $1,010 million and $986 million , respectively. The notes are short-term debt obligations of Duke Energy and are reflected as Notes payable and commercial paper on Duke Energy’s Consolidated Balance Sheets. In January 2017, Duke Energy amended its Form S-3 to add Piedmont as a registrant and included in the amendment a prospectus for Piedmont under which it may issue debt securities in the same manner as other Duke Energy Registrants. Money Pool The Subsidiary Registrants, excluding Progress Energy (Parent), are eligible to receive support for their short-term borrowing needs through participation with Duke Energy and certain of its subsidiaries in a money pool arrangement. Under this arrangement, those companies with short-term funds may provide short-term loans to affiliates participating in this arrangement. The money pool is structured such that the Subsidiary Registrants, excluding Progress Energy (Parent), separately manage their cash needs and working capital requirements. Accordingly, there is no net settlement of receivables and payables between money pool participants. Duke Energy (Parent), may loan funds to its participating subsidiaries, but may not borrow funds through the money pool. Accordingly, as the money pool activity is between Duke Energy and its wholly owned subsidiaries, all money pool balances are eliminated within Duke Energy’s Consolidated Balance Sheets. Money pool receivable balances are reflected within Notes receivable from affiliated companies on the Subsidiary Registrants’ Consolidated Balance Sheets. Money pool payable balances are reflected within either Notes payable to affiliated companies or Long-Term Debt Payable to Affiliated Companies on the Subsidiary Registrants’ Consolidated Balance Sheets. Restrictive Debt Covenants The Duke Energy Registrants’ debt and credit agreements contain various financial and other covenants. Duke Energy's Master Credit Facility contains a covenant requiring the debt-to-total capitalization ratio not to exceed 65 percent for each borrower, excluding Piedmont, and 70 percent for Piedmont. Failure to meet those covenants beyond applicable grace periods could result in accelerated due dates and/or termination of the agreements. As of December 31, 2018 , each of the Duke Energy Registrants was in compliance with all covenants related to their debt agreements. In addition, some credit agreements may allow for acceleration of payments or termination of the agreements due to nonpayment, or acceleration of other significant indebtedness of the borrower or some of its subsidiaries. None of the debt or credit agreements contain material adverse change clauses. Other Loans As of December 31, 2018 , and 2017 , Duke Energy had loans outstanding of $741 million , including $37 million at Duke Energy Progress and $701 million , including $38 million at Duke Energy Progress, respectively, against the cash surrender value of life insurance policies it owns on the lives of its executives. The amounts outstanding were carried as a reduction of the related cash surrender value that is included in Other within Other Noncurrent Assets on the Consolidated Balance Sheets.

Guarantees and Indemnifications

Guarantees and Indemnifications	12 Months Ended
	Dec. 31, 2018
Guarantees [Abstract]
Guarantees and Indemnifications	GUARANTEES AND INDEMNIFICATIONS Duke Energy and Progress Energy have various financial and performance guarantees and indemnifications, which are issued in the normal course of business. As discussed below, these contracts include performance guarantees, standby letters of credit, debt guarantees, surety bonds and indemnifications. Duke Energy and Progress Energy enter into these arrangements to facilitate commercial transactions with third parties by enhancing the value of the transaction to the third party. At December 31, 2018 , Duke Energy and Progress Energy do not believe conditions are likely for significant performance under these guarantees. To the extent liabilities are incurred as a result of the activities covered by the guarantees, such liabilities are included on the accompanying Consolidated Balance Sheets. On January 2, 2007, Duke Energy completed the spin-off of its natural gas businesses to shareholders. Guarantees issued by Duke Energy or its affiliates, or assigned to Duke Energy prior to the spin-off, remained with Duke Energy subsequent to the spin-off. Guarantees issued by Spectra Capital or its affiliates prior to the spin-off remained with Spectra Capital subsequent to the spin-off, except for guarantees that were later assigned to Duke Energy. Duke Energy has indemnified Spectra Capital against any losses incurred under certain of the guarantee obligations that remain with Spectra Capital. At December 31, 2018 , the maximum potential amount of future payments associated with these guarantees was $205 million , the majority of which expires by 2028. Duke Energy has issued performance guarantees to customers and other third parties that guarantee the payment and performance of other parties, including certain non-wholly owned entities, as well as guarantees of debt of certain non-consolidated entities and less than wholly owned consolidated entities. If such entities were to default on payments or performance, Duke Energy would be required under the guarantees to make payments on the obligations of the less than wholly owned entity. The maximum potential amount of future payments required under these guarantees as of December 31, 2018 , was $296 million . Of this amount, $11 million relates to guarantees issued on behalf of less than wholly owned consolidated entities, with the remainder related to guarantees issued on behalf of third parties and unconsolidated affiliates of Duke Energy. Of the guarantees noted above, $248 million of the guarantees expire between 2019 and 2030, with the remaining performance guarantees having no contractual expiration. In October 2017, ACP executed a $3.4 billion revolving credit facility with a stated maturity date of October 2021. Duke Energy entered into a guarantee agreement to support its share of the ACP revolving credit facility. Duke Energy's maximum exposure to loss under the terms of the guarantee is $677 million as of December 31, 2018 . This amount represents 47 percent of the outstanding borrowings under the credit facility. Duke Energy guaranteed debt issued by Duke Energy Carolinas of $650 million as of December 31, 2018 , and 2017 . Duke Energy has guaranteed certain issuers of surety bonds, obligating itself to make payment upon the failure of a wholly owned and former non-wholly owned entity to honor its obligations to a third party. Under these arrangements, Duke Energy has payment obligations that are triggered by a draw by the third party or customer due to the failure of the wholly owned or former non-wholly owned entity to perform according to the terms of its underlying contract. At December 31, 2018 , Duke Energy had guaranteed $63 million of outstanding surety bonds, most of which have no set expiration. Duke Energy uses bank-issued standby letters of credit to secure the performance of wholly owned and non-wholly owned entities to a third party or customer. Under these arrangements, Duke Energy has payment obligations to the issuing bank that are triggered by a draw by the third party or customer due to the failure of the wholly owned or non-wholly owned entity to perform according to the terms of its underlying contract. At December 31, 2018 , Duke Energy had issued a total of $454 million in letters of credit, which expire between 2019 and 2022. The unused amount under these letters of credit was $60 million . Duke Energy recognized $23 million and $21 million , as of December 31, 2018 , and 2017 , respectively, primarily in Other within Other Noncurrent Liabilities on the Consolidated Balance Sheets, for the guarantees discussed above. As current estimates change, additional losses related to guarantees and indemnifications to third parties, which could be material, may be recorded by the Duke Energy Registrants in the future.

Joint Ownership of Generating a

Joint Ownership of Generating and Transmission Facilities	12 Months Ended
	Dec. 31, 2018
Joint Ownership Of Generating And Transmission Facilities [Abstract]
Joint Ownership of Generating and Transmission Facilities	JOINT OWNERSHIP OF GENERATING AND TRANSMISSION FACILITIES The Duke Energy Registrants maintain ownership interests in certain jointly owned generating and transmission facilities. The Duke Energy Registrants are entitled to a share of the generating capacity and output of each unit equal to their respective ownership interests. The Duke Energy Registrants pay their ownership share of additional construction costs, fuel inventory purchases and operating expenses. The Duke Energy Registrants share of revenues and operating costs of the jointly owned facilities is included within the corresponding line in the Consolidated Statements of Operations. Each participant in the jointly owned facilities must provide its own financing. The following table presents the Duke Energy Registrants' interest of jointly owned plant or facilities and amounts included on the Consolidated Balance Sheets. All facilities are operated by the Duke Energy Registrants and are included in the Electric Utilities and Infrastructure segment. December 31, 2018 Construction Ownership Property, Plant Accumulated Work in (in millions except for ownership interest) Interest and Equipment Depreciation Progress Duke Energy Carolinas Catawba (units 1 and 2) (a) 19.25 % $ 989 $ 483 $ 17 W.S. Lee CC (b) 86.67 % 593 12 4 Duke Energy Indiana Gibson (unit 5) (c) 50.05 % 390 173 3 Vermillion (d) 62.50 % 168 135 — Transmission and local facilities (c) Various 5,037 1,769 — (a) Jointly owned with North Carolina Municipal Power Agency Number 1, NCEMC and PMPA. (b) Jointly owned with NCEMC. (c) Jointly owned with WVPA and Indiana Municipal Power Agency. (d) Jointly owned with WVPA. Effective June 30, 2018, Duke Energy Ohio, Ohio Power Company, and The Dayton Power and Light Company, completed an asset exchange that reallocated their ownership interest in certain jointly owned transmission facilities. This transaction was approved by FERC and PUCO. The transaction eliminated the joint owner relationships for these assets. Assets were exchanged at net book value and the net increase in Duke Energy Ohio's assets are shown within Capital expenditures in Duke Energy Ohio's Consolidated Statements of Cash Flows.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS Duke Energy records an ARO when it has a legal obligation to incur retirement costs associated with the retirement of a long-lived asset and the obligation can be reasonably estimated. Certain assets of the Duke Energy Registrants have an indeterminate life, such as transmission and distribution facilities, and thus the fair value of the retirement obligation is not reasonably estimable. A liability for these AROs will be recorded when a fair value is determinable. The Duke Energy Registrants’ regulated operations accrue costs of removal for property that does not have an associated legal retirement obligation based on regulatory orders from state commissions. These costs of removal are recorded as a regulatory liability in accordance with regulatory accounting treatment. The Duke Energy Registrants do not accrue the estimated cost of removal for any nonregulated assets. See Note 4 for the estimated cost of removal for assets without an associated legal retirement obligation, which are included in Regulatory liabilities on the Consolidated Balance Sheets. The following table presents the AROs recorded on the Consolidated Balance Sheets. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Decommissioning of nuclear power facilities (a) $ 5,696 $ 2,335 $ 3,209 $ 2,679 $ 530 $ — $ — $ — Closure of ash impoundments 4,446 1,568 2,123 2,103 20 52 702 — Other (b) 325 46 79 38 41 41 20 19 Total asset retirement obligation $ 10,467 $ 3,949 $ 5,411 $ 4,820 $ 591 $ 93 $ 722 $ 19 Less: current portion 919 290 514 509 5 6 109 — Total noncurrent asset retirement obligation $ 9,548 $ 3,659 $ 4,897 $ 4,311 $ 586 $ 87 $ 613 $ 19 (a) Duke Energy amount includes purchase accounting adjustments related to the merger with Progress Energy. (b) Primarily includes obligations related to asbestos removal. Duke Energy Ohio and Piedmont also include AROs related to the retirement of natural gas mains and services. Duke Energy includes AROs related to the removal of renewable energy generation assets. Nuclear Decommissioning Liability AROs related to nuclear decommissioning are based on site-specific cost studies. The NCUC, PSCSC and FPSC require updated cost estimates for decommissioning nuclear plants every five years. The following table summarizes information about the most recent site-specific nuclear decommissioning cost studies. Decommissioning costs are stated in 2018 dollars for Duke Energy Carolinas, 2017 dollars for Duke Energy Florida and 2014 dollars for Duke Energy Progress, and include costs to decommission plant components not subject to radioactive contamination. Annual Funding Decommissioning (in millions) Requirement (a) Costs (a) Year of Cost Study Duke Energy $ 24 $ 8,737 2014 and 2018 Duke Energy Carolinas (b)(c) — 4,291 2018 Duke Energy Progress 24 3,550 2014 Duke Energy Florida (d) — 896 2018 (a) Amounts for Progress Energy equal the sum of Duke Energy Progress and Duke Energy Florida. (b) Decommissioning cost for Duke Energy Carolinas reflects its ownership interest in jointly owned reactors. Other joint owners are responsible for decommissioning costs related to their interest in the reactors. (c) Duke Energy Carolinas' site-specific nuclear decommissioning cost study completed in 2018 is expected to be filed with the NCUC and PSCSC by the second quarter 2019. Duke Energy Carolinas will also complete a new funding study, which will be completed and filed with the NCUC and PSCSC in 2019. (d) Duke Energy Florida's site-specific nuclear decommissioning cost study and a new funding study were completed and filed with the FPSC in 2018. Nuclear Decommissioning Trust Funds Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida each maintain NDTFs that are intended to pay for the decommissioning costs of their respective nuclear power plants. The NDTF investments are managed and invested in accordance with applicable requirements of various regulatory bodies including the NRC, FERC, NCUC, PSCSC, FPSC and the IRS. Use of the NDTF investments is restricted to nuclear decommissioning activities including license termination, spent fuel and site restoration. The license termination and spent fuel obligations relate to contaminated decommissioning and are recorded as AROs. The site restoration obligation relates to non-contaminated decommissioning and is recorded to cost of removal within Regulatory liabilities on the Consolidated Balance Sheets. The following table presents the fair value of NDTF assets legally restricted for purposes of settling AROs associated with nuclear decommissioning. Duke Energy Florida is actively decommissioning Crystal River Unit 3 and was granted an exemption from the NRC, which allows for use of the NDTF for all aspects of nuclear decommissioning. The entire balance of Duke Energy Florida's NDTF may be applied toward license termination, spent fuel and site restoration costs incurred to decommission Crystal River Unit 3 and is excluded from the table below. See Note 16 for additional information related to the fair value of the Duke Energy Registrants' NDTFs. December 31, (in millions) 2018 2017 Duke Energy $ 5,579 $ 5,864 Duke Energy Carolinas 3,133 3,321 Duke Energy Progress 2,446 2,543 Nuclear Operating Licenses Operating licenses for nuclear units are potentially subject to extension. The following table includes the current expiration of nuclear operating licenses. Unit Year of Expiration Duke Energy Carolinas Catawba Units 1 and 2 2043 McGuire Unit 1 2041 McGuire Unit 2 2043 Oconee Units 1 and 2 2033 Oconee Unit 3 2034 Duke Energy Progress Brunswick Unit 1 2036 Brunswick Unit 2 2034 Harris 2046 Robinson 2030 The NRC has acknowledged permanent cessation of operation and permanent removal of fuel from the reactor vessel at Crystal River Unit 3. Therefore, the license no longer authorizes operation of the reactor. In January 2018, Crystal River Unit 3 reached a SAFSTOR status. Closure of Ash Impoundments The Duke Energy Registrants are subject to state and federal regulations covering the closure of coal ash impoundments, including the EPA CCR rule and the Coal Ash Act, and other agreements. AROs recorded on the Duke Energy Registrants' Consolidated Balance Sheets include the legal obligation for closure of coal ash basins and the disposal of related ash as a result of these regulations and agreements. The ARO amount recorded on the Consolidated Balance Sheets is based upon estimated closure costs for impacted ash impoundments. The amount recorded represents the discounted cash flows for estimated closure costs based upon either specific closure plans or the probability weightings of the potential closure methods as evaluated on a site-by-site basis. Actual costs to be incurred will be dependent upon factors that vary from site to site. The most significant factors are the method and time frame of closure at the individual sites. Closure methods considered include removing the water from ash basins, consolidating material as necessary and capping the ash with a synthetic barrier, excavating and relocating the ash to a lined structural fill or lined landfill or recycling the ash for concrete or some other beneficial use. The ultimate method and timetable for closure will be in compliance with standards set by federal and state regulations and other agreements. The ARO amount will be adjusted as additional information is gained through the closure and post-closure process, including acceptance and approval of compliance approaches, which may change management assumptions, and may result in a material change to the balance. See ARO Liability Rollforward section below for information on revisions made to the coal ash liability during 2018 and 2017. Asset retirement costs associated with the AROs for operating plants and retired plants are included in Net property, plant and equipment and Regulatory assets, respectively, on the Consolidated Balance Sheets. See Note 4 for additional information on Regulatory assets related to AROs. Cost recovery for future expenditures will be pursued through the normal ratemaking process with federal and state utility commissions, which permit recovery of necessary and prudently incurred costs associated with Duke Energy’s regulated operations. See Note 4 for additional information on recovery of coal ash costs. ARO Liability Rollforward The following tables present changes in the liability associated with AROs. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at December 31, 2016 $ 10,611 $ 3,895 $ 5,475 $ 4,697 $ 778 $ 77 $ 866 $ 14 Accretion expense (a) 435 184 228 195 33 3 32 1 Liabilities settled (b) (619 ) (282 ) (270 ) (204 ) (65 ) (7 ) (49 ) (8 ) Liabilities incurred in the current year (c) 51 5 — — — 7 29 8 Revisions in estimates of cash flows (303 ) (192 ) (19 ) (15 ) (4 ) 4 (97 ) — Balance at December 31, 2017 10,175 3,610 5,414 4,673 742 84 781 15 Accretion expense (a) 427 179 225 196 29 4 29 1 Liabilities settled (b) (638 ) (281 ) (272 ) (227 ) (45 ) (5 ) (79 ) — Liabilities incurred in the current year (c) 39 8 5 — 5 — 25 — Revisions in estimates of cash flows (d) 464 433 39 178 (140 ) 10 (34 ) 3 Balance at December 31, 2018 $ 10,467 $ 3,949 $ 5,411 $ 4,820 $ 591 $ 93 $ 722 $ 19 (a) Substantially all accretion expense for the years ended December 31, 2018 , and 2017 relates to Duke Energy’s regulated operations and has been deferred in accordance with regulatory accounting treatment. (b) Amounts primarily relate to ash impoundment closures and nuclear decommissioning of Crystal River Unit 3. (c) Amounts primarily relate to AROs recorded as a result of state agency closure requirements at Duke Energy Indiana. (d) Amounts primarily relate to increases in groundwater monitoring estimates for closure of ash impoundments and an increase for nuclear decommissioning costs at Duke Energy Carolinas' nuclear sites compared to original estimates, partially offset by a reduction for nuclear decommissioning at Crystal River Unit 3 compared to original estimates and modifications to the timing of expected cash flows for coal ash AROs.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT The following tables summarize the property, plant and equipment for Duke Energy and its subsidiary registrants. December 31, 2018 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Land $ 2,072 $ 472 $ 868 $ 445 $ 423 $ 136 $ 116 $ 448 Plant – Regulated Electric generation, distribution and transmission 15-100 100,706 38,468 42,760 26,147 16,613 5,182 14,292 — Natural gas transmission and distribution 12-80 8,808 — — — — 2,719 — 6,089 Other buildings and improvements 24-90 1,966 681 636 295 341 270 253 126 Plant – Nonregulated Electric generation, distribution and transmission 5-30 4,410 — — — — — — — Other buildings and improvements 25-35 494 — — — — — — — Nuclear fuel 3,460 1,898 1,562 1,562 — — — — Equipment 3-55 2,141 467 565 399 166 384 178 141 Construction in process 5,726 1,678 2,515 1,659 856 412 325 382 Other 3-40 4,675 1,077 1,354 952 393 257 279 300 Total property, plant and equipment (a)(d) 134,458 44,741 50,260 31,459 18,792 9,360 15,443 7,486 Total accumulated depreciation – regulated (b)(c)(d) (41,079 ) (15,496 ) (16,398 ) (11,423 ) (4,968 ) (2,717 ) (4,914 ) (1,575 ) Total accumulated depreciation – nonregulated (c)(d) (2,047 ) — — — — — — — Generation facilities to be retired, net 362 — 362 362 — — — — Total net property, plant and equipment $ 91,694 $ 29,245 $ 34,224 $ 20,398 $ 13,824 $ 6,643 $ 10,529 $ 5,911 (a) Includes capitalized leases of $1,237 million , $135 million , $257 million , $137 million , $120 million , $73 million and $35 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana, respectively, primarily within Plant – Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $131 million , $14 million and $117 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,947 million , $1,087 million , $860 million and $860 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $61 million , $12 million , $20 million and $10 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $4,007 million and accumulated depreciation of consolidated VIEs of $698 million at Duke Energy. December 31, 2017 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Land $ 1,559 $ 467 $ 767 $ 424 $ 343 $ 134 $ 111 $ 41 Plant – Regulated Electric generation, distribution and transmission 8-100 93,687 35,657 39,419 24,502 14,917 4,870 13,741 — Natural gas transmission and distribution 12-80 8,292 — — — — 2,559 — 5,733 Other buildings and improvements 15-100 1,936 647 652 316 336 243 240 154 Plant – Nonregulated Electric generation, distribution and transmission (a) 5-30 4,273 — — — — — — — Other buildings and improvements 25-35 465 — — — — — — — Nuclear fuel 3,680 2,120 1,560 1,560 — — — — Equipment 3-55 2,122 402 555 416 139 348 169 266 Construction in process 6,995 2,614 3,059 1,434 1,625 350 416 231 Other 3-40 4,498 1,032 1,311 931 370 228 271 300 Total property, plant and equipment (b)(e) 127,507 42,939 47,323 29,583 17,730 8,732 14,948 6,725 Total accumulated depreciation – regulated (c)(d)(e) (39,742 ) (15,063 ) (15,857 ) (10,903 ) (4,947 ) (2,691 ) (4,662 ) (1,479 ) Total accumulated depreciation – nonregulated (d)(e) (1,795 ) — — — — — — — Generation facilities to be retired, net 421 — 421 421 — — — — Total net property, plant and equipment $ 86,391 $ 27,876 $ 31,887 $ 19,101 $ 12,783 $ 6,041 $ 10,286 $ 5,246 (a) Includes a pretax impairment charge of $58 million on a wholly owned non-contracted wind project. See discussion below. (b) Includes capitalized leases of $1,294 million , $81 million , $272 million , $139 million , $133 million , $80 million and $35 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana, respectively, primarily within Plant – Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $114 million , $11 million and $103 million , respectively, of accumulated amortization of capitalized leases. (c) Includes $2,113 million , $1,283 million , $831 million and $831 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (d) Includes accumulated amortization of capitalized leases of $57 million , $11 million , $21 million and $9 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (e) Includes gross property, plant and equipment cost of consolidated VIEs of $3,941 million and accumulated depreciation of consolidated VIEs of $598 million at Duke Energy. During the year ended December 31, 2017, Duke Energy recorded a pretax impairment charge of $69 million on a wholly owned non-contracted wind project. The impairment was recorded within Impairment charges on Duke Energy’s Consolidated Statements of Operations. $58 million of the impairment related to property, plant and equipment and $11 million of the impairment related to a net intangible asset; see Note 11 for additional information. The charge represents the excess carrying value over the estimated fair value of the project, which was based on a Level 3 Fair Value measurement that was determined from the income approach using discounted cash flows. The impairment was primarily due to the non-contracted wind project being located in a market that has experienced continued declining market pricing during 2017 and declining long-term forecasted energy and capacity prices, driven by low natural gas prices, additional renewable generation placed in service and lack of significant load growth. The following tables present capitalized interest, which includes the debt component of AFUDC. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy $ 161 $ 128 $ 100 Duke Energy Carolinas 35 45 38 Progress Energy 51 45 31 Duke Energy Progress 26 21 17 Duke Energy Florida 25 24 14 Duke Energy Ohio 17 10 8 Duke Energy Indiana 27 9 7 Years Ended December 31, Two Months Ended December 31, Year Ended October 31, (in millions) 2018 2017 2016 2016 Piedmont $ 17 $ 12 $ 2 $ 12 Operating Leases Duke Energy's Commercial Renewables segment operates various renewable energy projects and sells the generated output to utilities, electric cooperatives, municipalities and commercial and industrial customers through long-term contracts. In certain situations, these long-term contracts and the associated renewable energy projects qualify as operating leases. Rental income from these leases is accounted for as Operating Revenues in the Consolidated Statements of Operations. There are no minimum lease payments as all payments are contingent based on actual electricity generated by the renewable energy projects. Contingent lease payments were $268 million , $262 million , and $216 million for the years ended December 31, 2018 , 2017 and 2016 . As of December 31, 2018 , renewable energy projects owned by Duke Energy and accounted for as operating leases had a cost basis of $3,358 million and accumulated depreciation of $602 million . These assets are principally classified as nonregulated electric generation and transmission assets.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	GOODWILL AND INTANGIBLE ASSETS Goodwill Duke Energy The following table presents goodwill by reportable segment for Duke Energy included on Duke Energy's Consolidated Balance Sheets at December 31, 2018 , and 2017 . Electric Utilities Gas Utilities Commercial (in millions) and Infrastructure and Infrastructure Renewables Total Goodwill Balance at December 31, 2017 $ 17,379 $ 1,924 $ 122 $ 19,425 Accumulated impairment charges (a) — — (29 ) (29 ) Goodwill balance at December 31, 2017, adjusted for accumulated impairment charges $ 17,379 $ 1,924 $ 93 $ 19,396 Goodwill Balance at December 31, 2018 $ 17,379 $ 1,924 $ 122 $ 19,425 Accumulated impairment charges (a) $ — $ — $ (122 ) $ (122 ) Goodwill balance at December 31, 2018, adjusted for accumulated impairment charges $ 17,379 $ 1,924 $ — $ 19,303 (a) Duke Energy evaluated the recoverability of goodwill during 2017 and recorded impairment charges of $29 million related to the Energy Management Solutions reporting unit within the Commercial Renewables segment. The fair value of the reporting unit was determined based on the market approach. See "Goodwill Impairment Testing" below for the results of the 2018 goodwill impairment test. Duke Energy Ohio Duke Energy Ohio's Goodwill balance of $920 million , allocated $596 million to Electric Utilities and Infrastructure and $324 million to Gas Utilities and Infrastructure, is presented net of accumulated impairment charges of $216 million on the Consolidated Balance Sheets at December 31, 2018 , and 2017 . Progress Energy Progress Energy's Goodwill is included in the Electric Utilities and Infrastructure segment and there are no accumulated impairment charges. Piedmont Piedmont's Goodwill is included in the Gas Utilities and Infrastructure segment and there are no accumulated impairment charges. Goodwill Impairment Testing Duke Energy, Progress Energy, Duke Energy Ohio and Piedmont are required to perform an annual goodwill impairment test as of the same date each year and, accordingly, perform their annual impairment testing of goodwill as of August 31. Duke Energy, Progress Energy, Duke Energy Ohio and Piedmont update their test between annual tests if events or circumstances occur that would more likely than not reduce the fair value of a reporting unit below its carrying value. In the third quarter of 2018, based on the results of the annual quantitative goodwill impairment test, management determined that the fair value of the Commercial Renewables reporting unit was below its respective carrying value, including goodwill. Determination of the Commercial Renewables reporting unit fair value was based on an income approach, which estimates the fair value based on discounted future cash flows. The fair value of the Commercial Renewables reporting unit is impacted by several factors, including forecasted tax credit utilization, the cost of capital, current and forecasted solar and wind volumes, and legislative developments. Certain assumptions used in determining the fair value of the reporting unit in the 2018 impairment test changed from those used in the 2017 annual impairment test including the cost of capital as a result of rising interest rates and the timing of tax credit utilization due to tax reform and IRS clarification on bonus depreciation in August 2018. Based on the quantitative impairment test, the estimated fair value of the Commercial Renewables reporting unit was below its carrying value by an immaterial amount but still more than the goodwill balance assigned to the reporting unit. As such, the entire remaining goodwill balance of approximately $93 million was impaired during the third quarter of 2018. The fair value of all other reporting units for Duke Energy, Progress Energy, Duke Energy Ohio and Piedmont exceeded their respective carrying values at the date of the annual impairment analysis. Intangible Assets The following tables show the carrying amount and accumulated amortization of intangible assets included in Other within Other Noncurrent Assets on the Consolidated Balance Sheets of the Duke Energy Registrants at December 31, 2018 , and 2017 . December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Emission allowances $ 18 $ — $ 5 $ 2 $ 3 $ — $ 12 $ — Renewable energy certificates 168 46 120 120 — 2 — — Natural gas, coal and power contracts 24 — — — — — 24 — Renewable operating and development projects 84 — — — — — — — Other 6 — — — — — — 3 Total gross carrying amounts 300 46 125 122 3 2 36 3 Accumulated amortization – natural gas, coal and power contracts (20 ) — — — — — (20 ) — Accumulated amortization – renewable operating and development projects (29 ) — — — — — — — Accumulated amortization – other (5 ) — — — — — — (3 ) Total accumulated amortization (54 ) — — — — — (20 ) (3 ) Total intangible assets, net $ 246 $ 46 $ 125 $ 122 $ 3 $ 2 $ 16 $ — December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Emission allowances $ 19 $ 1 $ 5 $ 2 $ 3 $ — $ 13 $ — Renewable energy certificates 148 38 107 107 — 3 — — Natural gas, coal and power contracts 24 — — — — — 24 — Renewable operating and development projects 79 — — — — — — — Other 6 — — — — — — 3 Total gross carrying amounts 276 39 112 109 3 3 37 3 Accumulated amortization – natural gas, coal and power contracts (19 ) — — — — — (19 ) — Accumulated amortization – renewable operating and development projects (22 ) — — — — — — — Accumulated amortization – other (5 ) — — — — — — (3 ) Total accumulated amortization (46 ) — — — — — (19 ) (3 ) Total intangible assets, net $ 230 $ 39 $ 112 $ 109 $ 3 $ 3 $ 18 $ — During the year ended December 31, 2017, Duke Energy recorded a pretax impairment charge of $69 million on a wholly owned non-contracted wind project. The impairment was recorded within Impairment charges on Duke Energy’s Consolidated Statements of Operations. $58 million of the impairment related to property, plant and equipment and $11 million of the impairment related to a net intangible asset that was recorded in 2007 when the project was acquired. Prior to the impairment, the gross amount of the intangible asset was $18 million and the accumulated amortization was $7 million . The intangible asset was fully impaired. See Note 10 for additional information. Amortization Expense Amortization expense amounts for natural gas, coal and power contracts, renewable operating projects and other intangible assets are immaterial for the years ended December 31, 2018 , 2017 and 2016 , and are expected to be immaterial for the next five years as of December 31, 2018 .

Investments in Unconsolidated A

Investments in Unconsolidated Affiliates	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investment in Unconsolidated Affiliates	INVESTMENTS IN UNCONSOLIDATED AFFILIATES EQUITY METHOD INVESTMENTS Investments in affiliates that are not controlled by Duke Energy, but over which it has significant influence, are accounted for using the equity method. The following table presents Duke Energy’s investments in unconsolidated affiliates accounted for under the equity method, as well as the respective equity in earnings, by segment. Years Ended December 31, 2018 2017 2016 Equity in Equity in Equity in (in millions) Investments earnings Investments earnings Investments earnings Electric Utilities and Infrastructure $ 97 $ 6 $ 89 $ 5 $ 93 $ 5 Gas Utilities and Infrastructure 1,003 27 763 62 566 19 Commercial Renewables 201 (1 ) 190 (5 ) 185 (82 ) Other 108 51 133 57 81 43 Total $ 1,409 $ 83 $ 1,175 $ 119 $ 925 $ (15 ) During the years ended December 31, 2018 , 2017 and 2016 , Duke Energy received distributions from equity investments of $108 million , $13 million and $31 million , respectively, which are included in Other assets within Cash Flows from Operating Activities on the Consolidated Statements of Cash Flows. During the years ended December 31, 2018 , and 2017 , Duke Energy received distributions from equity investments of $137 million and $281 million , respectively, which are included in Return of investment capital within Cash Flows from Investing Activities on the Consolidated Statements of Cash Flows. During the years ended December 31, 2018 , and 2017 , and the two months ended December 31, 2016 , and the year ended October 31, 2016, Piedmont received distributions from equity investments of $1 million , $4 million , $1 million and $26 million , respectively, which are included in Other assets within Cash Flows from Operating Activities and $3 million , $2 million , $1 million and $18 million , respectively, which are included within Cash Flows from Investing Activities on the Consolidated Statements of Cash Flows. Significant investments in affiliates accounted for under the equity method are discussed below. Electric Utilities and Infrastructure Duke Energy owns a 50 percent interest in DATC and in Pioneer, which build, own and operate electric transmission facilities in North America. Gas Utilities and Infrastructure The table below outlines Duke Energy's ownership interests in natural gas pipeline companies and natural gas storage facilities. Investment Amount (in millions) Ownership December 31, December 31, Entity Name Interest 2018 2017 Pipeline Investments Atlantic Coast Pipeline, LLC (a) 47 % $ 797 $ 397 Sabal Trail Transmission, LLC 7.5 % 112 (d) 219 Constitution Pipeline, LLC (a) 24 % 25 81 Cardinal Pipeline Company, LLC (b) 21.49 % 10 11 Storage Facilities Pine Needle LNG Company, LLC (b) 45 % 13 13 Hardy Storage Company, LLC (b) 50 % 46 42 Total Investments (c) $ 1,003 $ 763 (a) During the year ended December 31, 2017, Piedmont transferred its share of ownership interest in ACP and Constitution to a wholly owned subsidiary of Duke Energy at book value. (b) Piedmont owns the Cardinal, Pine Needle and Hardy Storage investments. (c) Duke Energy includes purchase accounting adjustments related to Piedmont. (d) Sabal Trail returned capital of $112 million during the year ended December 31, 2018. In October 2017, Duke Energy entered into a guarantee agreement to support its share of the ACP revolving credit facility. See Note 7 for additional information. As a result of the financing, ACP returned capital of $265 million to Duke Energy. Piedmont sold its 15 percent membership interest in SouthStar on October 3, 2016, for $160 million resulting in an after tax gain of $81 million during the year ended October 31, 2016. Piedmont's Equity in Earnings in SouthStar was $19 million for the year ended October 31, 2016. During the fourth quarter of 2018, ACP received several adverse court rulings as described in Note 4. As a result, Duke Energy evaluated this investment for impairment and determined that fair value approximated carrying value and therefore no impairment was necessary. For regulatory matters and other information on the ACP, Sabal Trail and Constitution investments, see Notes 4 and 17 . Commercial Renewables Duke Energy has a 50 percent interest in DS Cornerstone, LLC, which owns wind farm projects in the U.S. Impairment of Equity Method Investments During the year ended December 31, 2018, Duke Energy recorded an OTTI of the Constitution investment of $55 million within Equity in earnings of unconsolidated affiliates on Duke Energy's Consolidated Statements of Operations. The charge represents the excess carrying value over the estimated fair value of the project, which was based on a Level 3 Fair Value measurement that was determined from the income approach using discounted cash flows. The impairment was primarily due to the recent actions taken by the courts and regulators to uphold the NYSDEC's denial of the certification and uncertainty associated with the remaining legal and regulatory challenges. For additional information on the Constitution investment, see Note 4 . During the year ended December 31, 2016, Duke Energy recorded an OTTI of certain wind project investments. The $71 million pretax impairment was recorded within Equity in earnings (losses) of unconsolidated affiliates on Duke Energy's Consolidated Statements of Operations. The other-than-temporary decline in value of these investments was primarily attributable to a sustained decline in market pricing where the wind investments are located, projected net losses for the projects and a reduction in the projected cash distribution to the class of investment owned by Duke Energy. Other Duke Energy owns a 17.5 percent indirect interest in NMC, which owns and operates a methanol and MTBE business in Jubail, Saudi Arabia. Duke Energy's economic ownership interest decreased from 25 to 17.5 percent with the successful startup of NMC's polyacetal production facility in 2017. Duke Energy retains 25 percent of the board representation and voting rights of NMC.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS The Subsidiary Registrants engage in related party transactions in accordance with the applicable state and federal commission regulations. Refer to the Consolidated Balance Sheets of the Subsidiary Registrants for balances due to or due from related parties. Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 985 $ 858 $ 831 Indemnification coverages (b) 22 23 22 JDA revenue (c) 84 49 38 JDA expense (c) 207 145 156 Intercompany natural gas purchases (d) 15 9 2 Progress Energy Corporate governance and shared service expenses (a) $ 906 $ 736 $ 710 Indemnification coverages (b) 34 38 35 JDA revenue (c) 207 145 156 JDA expense (c) 84 49 38 Intercompany natural gas purchases (d) 78 77 19 Duke Energy Progress Corporate governance and shared service expenses (a) $ 577 $ 438 $ 397 Indemnification coverages (b) 13 15 14 JDA revenue (c) 207 145 156 JDA expense (c) 84 49 38 Intercompany natural gas purchases (d) 78 77 19 Duke Energy Florida Corporate governance and shared service expenses (a) $ 329 $ 298 $ 313 Indemnification coverages (b) 21 23 21 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 374 $ 363 $ 356 Indemnification coverages (b) 5 5 5 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 405 $ 370 $ 366 Indemnification coverages (b) 7 8 8 Piedmont Corporate governance and shared service expenses (a) $ 170 $ 50 Indemnification coverages (b) 2 2 Intercompany natural gas sales (d) 93 86 Natural gas storage and transportation costs (e) 25 25 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, information technology, legal and accounting fees, as well as other third-party costs. These amounts are primarily recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA, which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power and expenses from the purchase of power pursuant to the JDA are recorded in Operating Revenues and Fuel used in electric generation and purchased power, respectively, on the Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to certain Duke Energy Carolinas and Duke Energy Progress natural gas-fired generation facilities. Piedmont records the sales in Operating Revenues, and Duke Energy Carolinas and Duke Energy Progress record the related purchases as a component of Fuel used in electric generation and purchased power on their respective Consolidated Statements of Operations and Comprehensive Income. These intercompany revenues and expenses are eliminated in consolidation. For the two months ended December 31, 2016, and for sales made subsequent to the acquisition for the year ended October 31, 2016, Piedmont recorded $14 million and $7 million , respectively, of natural gas sales with Duke Energy. For sales made prior to the acquisition for the year ended October 31, 2016, Piedmont recorded $74 million of natural gas sales with Duke Energy. (e) Piedmont has related party transactions as a customer of its equity method investments in Pine Needle, Hardy Storage, and Cardinal natural gas storage and transportation facilities. These expenses are included in Cost of natural gas on Piedmont's Consolidated Statements of Operations and Comprehensive Income. For the two months ended December 31, 2016, and for the year ended October 31, 2016, Piedmont recorded $6 million and $29 million , respectively, of natural gas storage and transportation costs. In addition to the amounts presented above, the Subsidiary Registrants have other affiliate transactions, including rental of office space, participation in a money pool arrangement, other operational transactions and their proportionate share of certain charged expenses. See Note 6 for more information regarding money pool. These transactions of the Subsidiary Registrants are incurred in the ordinary course of business and are eliminated in consolidation. As discussed in Note 17 , certain trade receivables have been sold by Duke Energy Ohio and Duke Energy Indiana to CRC, an affiliate formed by a subsidiary of Duke Energy. The proceeds obtained from the sales of receivables are largely cash but do include a subordinated note from CRC for a portion of the purchase price. Intercompany Income Taxes Duke Energy and the Subsidiary Registrants file a consolidated federal income tax return and other state and jurisdictional returns. The Subsidiary Registrants have a tax sharing agreement with Duke Energy for the allocation of consolidated tax liabilities and benefits. Income taxes recorded represent amounts the Subsidiary Registrants would incur as separate C-Corporations. The following table includes the balance of intercompany income tax receivables and payables for the Subsidiary Registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana Piedmont December 31, 2018 Intercompany income tax receivable $ 52 $ 47 $ 29 $ — $ — $ 8 $ — Intercompany income tax payable — — — 16 3 — 45 December 31, 2017 Intercompany income tax receivable $ — $ 168 $ — $ 44 $ 22 $ — $ 7 Intercompany income tax payable 44 — 21 — — 35 —

Derivatives and Hedging

Derivatives and Hedging	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives and Hedging	DERIVATIVES AND HEDGING The Duke Energy Registrants use commodity and interest rate contracts to manage commodity price risk and interest rate risk. The primary use of commodity derivatives is to hedge the generation portfolio against changes in the prices of electricity and natural gas. Piedmont enters into natural gas supply contracts to provide diversification, reliability and natural gas cost benefits to its customers. Interest rate swaps are used to manage interest rate risk associated with borrowings. All derivative instruments not identified as NPNS are recorded at fair value as assets or liabilities on the Consolidated Balance Sheets. Cash collateral related to derivative instruments executed under master netting arrangements is offset against the collateralized derivatives on the Consolidated Balance Sheets. The cash impacts of settled derivatives are recorded as operating activities on the Consolidated Statements of Cash Flows. INTEREST RATE RISK The Duke Energy Registrants are exposed to changes in interest rates as a result of their issuance or anticipated issuance of variable-rate and fixed-rate debt and commercial paper. Interest rate risk is managed by limiting variable-rate exposures to a percentage of total debt and by monitoring changes in interest rates. To manage risk associated with changes in interest rates, the Duke Energy Registrants may enter into interest rate swaps, U.S. Treasury lock agreements and other financial contracts. In anticipation of certain fixed-rate debt issuances, a series of forward-starting interest rate swaps or Treasury locks may be executed to lock in components of current market interest rates. These instruments are later terminated prior to or upon the issuance of the corresponding debt. Cash Flow Hedges For a derivative designated as hedging the exposure to variable cash flows of a future transaction, referred to as a cash flow hedge, the effective portion of the derivative's gain or loss is initially reported as a component of other comprehensive income and subsequently reclassified into earnings once the future transaction impacts earnings. Amounts for interest rate contracts are reclassified to earnings as interest expense over the term of the related debt. Gains and losses reclassified out of AOCI for the years ended December 31, 2018 , 2017 and 2016 were not material. Duke Energy's interest rate derivatives designated as hedges include interest rate swaps used to hedge existing debt within the Commercial Renewables business. Undesignated Contracts Undesignated contracts primarily include contracts not designated as a hedge because they are accounted for under regulatory accounting or contracts that do not qualify for hedge accounting. Duke Energy’s interest rate swaps for its regulated operations employ regulatory accounting. With regulatory accounting, the mark-to-market gains or losses on the swaps are deferred as regulatory liabilities or regulatory assets, respectively. Regulatory assets and liabilities are amortized consistent with the treatment of the related costs in the ratemaking process. The accrual of interest on the swaps is recorded as Interest Expense on the Duke Energy Registrant's Consolidated Statements of Operations and Comprehensive Income. In August 2016, Duke Energy unwound $1.4 billion of forward-starting interest rate swaps associated with the Piedmont acquisition financing. The swaps were considered undesignated as they did not qualify for hedge accounting. Losses on the swaps of $190 million are included within Interest Expense on the Consolidated Statements of Operations for the year ended December 31, 2016. See Note 2 for additional information related to the Piedmont acquisition. The following tables show notional amounts of outstanding derivatives related to interest rate risk. December 31, 2018 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Cash flow hedges $ 923 $ — $ — $ — $ — $ — Undesignated contracts 1,721 300 1,200 650 550 27 Total notional amount (a) $ 2,644 $ 300 $ 1,200 $ 650 $ 550 $ 27 December 31, 2017 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Cash flow hedges (a) $ 660 $ — $ — $ — $ — $ — Undesignated contracts 927 400 500 250 250 27 Total notional amount $ 1,587 $ 400 $ 500 $ 250 $ 250 $ 27 (a) Duke Energy includes amounts related to consolidated VIEs of $422 million in cash flow hedges and $194 million in undesignated contracts as of December 31, 2018 , and $660 million in cash flow hedges as of December 31, 2017 . COMMODITY PRICE RISK The Duke Energy Registrants are exposed to the impact of changes in the prices of electricity purchased and sold in bulk power markets and coal and natural gas purchases, including Piedmont's natural gas supply contracts. Exposure to commodity price risk is influenced by a number of factors including the term of contracts, the liquidity of markets and delivery locations. For the Subsidiary Registrants, bulk power electricity and coal and natural gas purchases flow through fuel adjustment clauses, formula based contracts or other cost sharing mechanisms. Differences between the costs included in rates and the incurred costs, including undesignated derivative contracts, are largely deferred as regulatory assets or regulatory liabilities. Piedmont policies allow for the use of financial instruments to hedge commodity price risks. The strategy and objective of these hedging programs are to use the financial instruments to reduce gas cost volatility for customers. Volumes The tables below include volumes of outstanding commodity derivatives. Amounts disclosed represent the absolute value of notional volumes of commodity contracts excluding NPNS. The Duke Energy Registrants have netted contractual amounts where offsetting purchase and sale contracts exist with identical delivery locations and times of delivery. Where all commodity positions are perfectly offset, no quantities are shown. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Electricity (gigawatt-hours) 15,286 — — — — 1,786 13,500 — Natural gas (millions of dekatherms) 739 121 169 166 3 — 1 448 December 31, 2017 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Carolinas Energy Progress Florida Indiana Piedmont Electricity (gigawatt-hours) 34 — — — — 34 — Natural gas (millions of dekatherms) 770 105 183 133 50 2 480 LOCATION AND FAIR VALUE OF DERIVATIVE ASSETS AND LIABILITIES RECOGNIZED IN THE CONSOLIDATED BALANCE SHEETS The following tables show the fair value and balance sheet location of derivative instruments. Although derivatives subject to master netting arrangements are netted on the Consolidated Balance Sheets, the fair values presented below are shown gross and cash collateral on the derivatives has not been netted against the fair values shown. Derivative Assets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 35 $ 2 $ 2 $ 2 $ — $ 6 $ 23 $ 3 Noncurrent 4 1 2 2 — — — — Total Derivative Assets – Commodity Contracts $ 39 $ 3 $ 4 $ 4 $ — $ 6 $ 23 $ 3 Interest Rate Contracts Designated as Hedging Instruments Current $ 1 $ — $ — $ — $ — $ — $ — $ — Noncurrent 3 — — — — — — — Not Designated as Hedging Instruments Current 2 — — — — — — — Noncurrent 12 — — — — — — — Total Derivative Assets – Interest Rate Contracts $ 18 $ — $ — $ — $ — $ — $ — $ — Total Derivative Assets $ 57 $ 3 $ 4 $ 4 $ — $ 6 $ 23 $ 3 Derivative Liabilities December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 33 $ 14 $ 10 $ 5 $ 6 $ — $ — $ 8 Noncurrent 158 10 15 6 — — — 133 Total Derivative Liabilities – Commodity Contracts $ 191 $ 24 $ 25 $ 11 $ 6 $ — $ — $ 141 Interest Rate Contracts Designated as Hedging Instruments Current $ 12 $ — $ — $ — $ — $ — $ — $ — Noncurrent 6 — — — — — — — Not Designated as Hedging Instruments Current 23 9 13 11 2 1 — — Noncurrent 10 — 6 5 1 4 — — Total Derivative Liabilities – Interest Rate Contracts $ 51 $ 9 $ 19 $ 16 $ 3 $ 5 $ — $ — Total Derivative Liabilities $ 242 $ 33 $ 44 $ 27 $ 9 $ 5 $ — $ 141 Derivative Assets December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 34 $ 2 $ 2 $ 1 $ 1 $ 1 $ 27 $ 2 Noncurrent 1 — 1 1 — — — — Total Derivative Assets – Commodity Contracts $ 35 $ 2 $ 3 $ 2 $ 1 $ 1 $ 27 $ 2 Interest Rate Contracts Designated as Hedging Instruments Current $ 1 $ — $ — $ — $ — $ — $ — $ — Noncurrent 15 — — — — — — — Total Derivative Assets – Interest Rate Contracts $ 16 $ — $ — $ — $ — $ — $ — $ — Total Derivative Assets $ 51 $ 2 $ 3 $ 2 $ 1 $ 1 $ 27 $ 2 Derivative Liabilities December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 36 $ 6 $ 18 $ 8 $ 10 $ — $ — $ 11 Noncurrent 146 4 10 4 — — — 131 Total Derivative Liabilities – Commodity Contracts $ 182 $ 10 $ 28 $ 12 $ 10 $ — $ — $ 142 Interest Rate Contracts Designated as Hedging Instruments Current $ 29 $ 25 $ — $ — $ — $ — $ — $ — Noncurrent 6 — — — — — — — Not Designated as Hedging Instruments Current 1 — 1 — — 1 — — Noncurrent 12 — 7 6 2 4 — — Total Derivative Liabilities – Interest Rate Contracts $ 48 $ 25 $ 8 $ 6 $ 2 $ 5 $ — $ — Total Derivative Liabilities $ 230 $ 35 $ 36 $ 18 $ 12 $ 5 $ — $ 142 OFFSETTING ASSETS AND LIABILITIES The following tables present the line items on the Consolidated Balance Sheets where derivatives are reported. Substantially all of Duke Energy's outstanding derivative contracts are subject to enforceable master netting arrangements. The gross amounts offset in the tables below show the effect of these netting arrangements on financial position and include collateral posted to offset the net position. The amounts shown are calculated by counterparty. Accounts receivable or accounts payable may also be available to offset exposures in the event of bankruptcy. These amounts are not included in the tables below. Derivative Assets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 38 $ 2 $ 2 $ 2 $ — $ 6 $ 23 $ 3 Gross amounts offset (3 ) (2 ) (2 ) (2 ) — — — — Net amounts presented in Current Assets: Other $ 35 $ — $ — $ — $ — $ 6 $ 23 $ 3 Noncurrent Gross amounts recognized $ 19 $ 1 $ 2 $ 2 $ — $ — $ — $ — Gross amounts offset (3 ) (1 ) (2 ) (2 ) — — — — Net amounts presented in Other Noncurrent Assets: Other $ 16 $ — $ — $ — $ — $ — $ — $ — Derivative Liabilities December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 68 $ 23 $ 23 $ 16 $ 8 $ 1 $ — $ 8 Gross amounts offset (4 ) (2 ) (2 ) (2 ) — — — — Net amounts presented in Current Liabilities: Other $ 64 $ 21 $ 21 $ 14 $ 8 $ 1 $ — $ 8 Noncurrent Gross amounts recognized $ 174 $ 10 $ 21 $ 11 $ 1 $ 4 $ — $ 133 Gross amounts offset (3 ) (1 ) (2 ) (2 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 171 $ 9 $ 19 $ 9 $ 1 $ 4 $ — $ 133 Derivative Assets December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 35 $ 2 $ 2 $ 1 $ 1 $ 1 $ 27 $ 2 Gross amounts offset — — — — — — — — Net amounts presented in Current Assets: Other $ 35 $ 2 $ 2 $ 1 $ 1 $ 1 $ 27 $ 2 Noncurrent Gross amounts recognized $ 16 $ — $ 1 $ 1 $ — $ — $ — $ — Gross amounts offset — — — — — — — — Net amounts presented in Other Noncurrent Assets: Other $ 16 $ — $ 1 $ 1 $ — $ — $ — $ — Derivative Liabilities December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 66 $ 31 $ 19 $ 8 $ 10 $ 1 $ — $ 11 Gross amounts offset (3 ) (2 ) (2 ) (2 ) — — — — Net amounts presented in Current Liabilities: Other $ 63 $ 29 $ 17 $ 6 $ 10 $ 1 $ — $ 11 Noncurrent Gross amounts recognized $ 164 $ 4 $ 17 $ 10 $ 2 $ 4 $ — $ 131 Gross amounts offset (1 ) — (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 163 $ 4 $ 16 $ 9 $ 2 $ 4 $ — $ 131 OBJECTIVE CREDIT CONTINGENT FEATURES Certain derivative contracts contain objective credit contingent features. These features include the requirement to post cash collateral or letters of credit if specific events occur, such as a credit rating downgrade below investment grade. The following tables show information with respect to derivative contracts that are in a net liability position and contain objective credit-risk-related payment provisions. December 31, 2018 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Aggregate fair value of derivatives in a net liability position $ 44 $ 19 $ 25 $ 25 $ — Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 44 19 25 25 — December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Aggregate fair value of derivatives in a net liability position $ 59 $ 35 $ 25 $ 15 $ 10 Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 59 35 25 15 10 The Duke Energy Registrants have elected to offset cash collateral and fair values of derivatives. For amounts to be netted, the derivative and cash collateral must be executed with the same counterparty under the same master netting arrangement.

Investments in Debt and Equity

Investments in Debt and Equity Securities	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Investments in Debt and Equity Securities	INVESTMENTS IN DEBT AND EQUITY SECURITIES Duke Energy's investments in debt and equity securities are primarily comprised of investments held in (i) the NDTF at Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida, (ii) the grantor trusts at Duke Energy Progress, Duke Energy Florida and Duke Energy Indiana related to OPEB plans and (iii) Bison. The Duke Energy Registrants classify investments in debt securities as AFS and investments in equity securities as FV-NI. For investments in debt securities classified as AFS, the unrealized gains and losses are included in other comprehensive income until realized, at which time, they are reported though net income. For investments in equity securities classified as FV-NI, both realized and unrealized gains and losses are reported through net income. Substantially all of Duke Energy's investments in debt and equity securities qualify for regulatory accounting, and accordingly, all associated realized and unrealized gains and losses on these investments are deferred as a regulatory asset or liability. Duke Energy classifies the majority of investments in debt and equity securities as long term, unless otherwise noted. Investment Trusts The investments within the NDTF and the Investment Trusts are managed by independent investment managers with discretion to buy, sell and invest pursuant to the objectives set forth by the trust agreements. The Duke Energy Registrants have limited oversight of the day-to-day management of these investments. As a result, the ability to hold investments in unrealized loss positions is outside the control of the Duke Energy Registrants. Accordingly, all unrealized losses associated with debt securities within the Investment Trusts are considered OTTIs and are recognized immediately and deferred to regulatory accounts where appropriate. Other AFS Securities Unrealized gains and losses on all other AFS securities are included in other comprehensive income until realized, unless it is determined the carrying value of an investment is other-than-temporarily impaired. The Duke Energy Registrants analyze all investment holdings each reporting period to determine whether a decline in fair value should be considered other-than-temporary. If an OTTI exists, the unrealized credit loss is included in earnings. There were no material credit losses as of December 31, 2018 , and 2017 . Other Investments amounts are recorded in Other within Other Noncurrent Assets on the Consolidated Balance Sheets. DUKE ENERGY The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 88 $ — $ — $ 115 Equity securities 2,402 95 4,475 2,805 27 4,914 Corporate debt securities 4 13 566 17 2 570 Municipal bonds 1 4 353 4 3 344 U.S. government bonds 14 12 1,076 11 7 1,027 Other debt securities — 2 148 — 1 118 Total NDTF Investments $ 2,421 $ 126 $ 6,706 $ 2,837 $ 40 $ 7,088 Other Investments Cash and cash equivalents $ — $ — $ 22 $ — $ — $ 15 Equity securities 36 1 99 59 — 123 Corporate debt securities — 2 60 1 — 57 Municipal bonds — 1 85 2 1 83 U.S. government bonds 1 — 45 — — 41 Other debt securities — 1 58 — 1 44 Total Other Investments $ 37 $ 5 $ 369 $ 62 $ 2 $ 363 Total Investments $ 2,458 $ 131 $ 7,075 $ 2,899 $ 42 $ 7,451 The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 98 Due after one through five years 501 Due after five through 10 years 570 Due after 10 years 1,222 Total $ 2,391 Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 168 Realized losses 126 AFS: Realized gains 22 Realized losses 51 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 202 $ 246 Realized losses 160 187 DUKE ENERGY CAROLINAS The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 29 $ — $ — $ 32 Equity securities 1,309 54 2,484 1,531 12 2,692 Corporate debt securities 2 9 341 9 2 359 Municipal bonds — 1 81 — 1 60 U.S. government bonds 5 8 475 3 4 503 Other debt securities — 2 143 — 1 112 Total NDTF Investments $ 1,316 $ 74 $ 3,553 $ 1,543 $ 20 $ 3,758 The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 6 Due after one through five years 142 Due after five through 10 years 303 Due after 10 years 589 Total $ 1,040 Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 89 Realized losses 73 AFS: Realized gains 19 Realized losses 35 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 135 $ 157 Realized losses 103 121 PROGRESS ENERGY The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 59 $ — $ — $ 83 Equity securities 1,093 41 1,991 1,274 15 2,222 Corporate debt securities 2 4 225 8 — 211 Municipal bonds 1 3 272 4 2 284 U.S. government bonds 9 4 601 8 3 524 Other debt securities — — 5 — — 6 Total NDTF Investments $ 1,105 $ 52 $ 3,153 $ 1,294 $ 20 $ 3,330 Other Investments Cash and cash equivalents $ — $ — $ 17 $ — $ — $ 12 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 64 $ 2 $ — $ 59 Total Investments $ 1,105 $ 52 $ 3,217 $ 1,296 $ 20 $ 3,389 The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 87 Due after one through five years 306 Due after five through 10 years 216 Due after 10 years 541 Total $ 1,150 Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 79 Realized losses 53 AFS: Realized gains 3 Realized losses 15 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 65 $ 84 Realized losses 56 64 DUKE ENERGY PROGRESS The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 46 $ — $ — $ 50 Equity securities 833 30 1,588 980 12 1,795 Corporate debt securities 2 3 171 6 — 149 Municipal bonds 1 3 271 4 2 283 U.S. government bonds 6 3 415 5 2 310 Other debt securities — — 3 — — 4 Total NDTF Investments $ 842 $ 39 $ 2,494 $ 995 $ 16 $ 2,591 Other Investments Cash and cash equivalents $ — $ — $ 6 $ — $ — $ 1 Total Other Investments $ — $ — $ 6 $ — $ — $ 1 Total Investments $ 842 $ 39 $ 2,500 $ 995 $ 16 $ 2,592 The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 49 Due after one through five years 231 Due after five through 10 years 161 Due after 10 years 419 Total $ 860 Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 68 Realized losses 48 AFS: Realized gains $ 2 Realized losses 10 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 54 $ 71 Realized losses 48 55 DUKE ENERGY FLORIDA The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 13 $ — $ — $ 33 Equity securities 260 11 403 294 3 427 Corporate debt securities — 1 54 2 — 62 Municipal bonds — — 1 — — 1 U.S. government bonds 3 1 186 3 1 214 Other debt securities — — 2 — — 2 Total NDTF Investments (a) $ 263 $ 13 $ 659 $ 299 $ 4 $ 739 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 1 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 48 $ 2 $ — $ 48 Total Investments $ 263 $ 13 $ 707 $ 301 $ 4 $ 787 (a) During the year ended December 31, 2018 , Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 nuclear plant. The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 38 Due after one through five years 75 Due after five through 10 years 55 Due after 10 years 122 Total $ 290 Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 11 Realized losses 5 AFS: Realized gains 1 Realized losses 5 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 11 $ 13 Realized losses 8 9 DUKE ENERGY INDIANA The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value Investments Equity securities $ 29 $ — $ 67 $ 49 $ — $ 97 Corporate debt securities — — 8 — — 3 Municipal bonds — 1 33 — 1 28 Total Investments $ 29 $ 1 $ 108 $ 49 $ 1 $ 128 The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 3 Due after one through five years 20 Due after five through 10 years 4 Due after 10 years 14 Total $ 41 Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were insignificant.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair value is the exchange price to sell an asset or transfer a liability in an orderly transaction between market participants at the measurement date. The fair value definition focuses on an exit price versus the acquisition cost. Fair value measurements use market data or assumptions market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs may be readily observable, corroborated by market data, or generally unobservable. Valuation techniques maximize the use of observable inputs and minimize use of unobservable inputs. A midmarket pricing convention (the midpoint price between bid and ask prices) is permitted for use as a practical expedient. Fair value measurements are classified in three levels based on the fair value hierarchy as defined by GAAP. Certain investments are not categorized within the fair value hierarchy. These investments are measured at fair value using the NAV per share practical expedient. The NAV is derived based on the investment cost, less any impairment, plus or minus changes resulting from observable price changes for an identical or similar investment of the same issuer. Fair value accounting guidance permits entities to elect to measure certain financial instruments that are not required to be accounted for at fair value, such as equity method investments or the company’s own debt, at fair value. The Duke Energy Registrants have not elected to record any of these items at fair value. Transfers between levels represent assets or liabilities that were previously (i) categorized at a higher level for which the inputs to the estimate became less observable or (ii) classified at a lower level for which the inputs became more observable during the period. The Duke Energy Registrant’s policy is to recognize transfers between levels of the fair value hierarchy at the end of the period. There were no transfers between levels during the years ended December 31, 2018 , 2017 and 2016 . In addition, for Piedmont, there were no transfers between levels during the two months ended December 31, 2016, and the year ended October 31, 2016. Valuation methods of the primary fair value measurements disclosed below are as follows. Investments in equity securities The majority of investments in equity securities are valued using Level 1 measurements. Investments in equity securities are typically valued at the closing price in the principal active market as of the last business day of the quarter. Principal active markets for equity prices include published exchanges such as the NYSE and the Nasdaq Stock Market. Foreign equity prices are translated from their trading currency using the currency exchange rate in effect at the close of the principal active market. There was no after-hours market activity that was required to be reflected in the reported fair value measurements. Investments in debt securities Most investments in debt securities are valued using Level 2 measurements because the valuations use interest rate curves and credit spreads applied to the terms of the debt instrument (maturity and coupon interest rate) and consider the counterparty credit rating. If the market for a particular fixed-income security is relatively inactive or illiquid, the measurement is Level 3. Commodity derivatives Commodity derivatives with clearinghouses are classified as Level 1. Other commodity derivatives, including Piedmont's natural gas supply contracts, are primarily valued using internally developed discounted cash flow models that incorporate forward price, adjustments for liquidity (bid-ask spread) and credit or non-performance risk (after reflecting credit enhancements such as collateral), and are discounted to present value. Pricing inputs are derived from published exchange transaction prices and other observable data sources. In the absence of an active market, the last available price may be used. If forward price curves are not observable for the full term of the contract and the unobservable period had more than an insignificant impact on the valuation, the commodity derivative is classified as Level 3. In isolation, increases (decreases) in natural gas forward prices result in favorable (unfavorable) fair value adjustments for natural gas purchase contracts; and increases (decreases) in electricity forward prices result in unfavorable (favorable) fair value adjustments for electricity sales contracts. Duke Energy regularly evaluates and validates pricing inputs used to estimate the fair value of natural gas commodity contracts by a market participant price verification procedure. This procedure provides a comparison of internal forward commodity curves to market participant generated curves. Interest rate derivatives Most over-the-counter interest rate contract derivatives are valued using financial models that utilize observable inputs for similar instruments and are classified as Level 2. Inputs include forward interest rate curves, notional amounts, interest rates and credit quality of the counterparties. Other fair value considerations See Note 11 for a discussion of the valuation of goodwill and intangible assets. DUKE ENERGY The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the tables below for all Duke Energy Registrants exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type for the Duke Energy Registrants. December 31, 2018 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not Categorized NDTF equity securities $ 4,475 $ 4,410 $ — $ — $ 65 NDTF debt securities 2,231 576 1,655 — — Other equity securities 99 99 — — — Other debt securities 270 67 203 — — Derivative assets 57 4 25 28 — Total assets 7,132 5,156 1,883 28 65 Derivative liabilities (242 ) (11 ) (90 ) (141 ) — Net assets (liabilities) $ 6,890 $ 5,145 $ 1,793 $ (113 ) $ 65 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not Categorized NDTF equity securities $ 4,914 $ 4,840 $ — $ — $ 74 NDTF debt securities 2,174 635 1,539 — — Other equity securities 123 123 — — — Other debt securities 241 57 184 — — Derivative assets 51 3 20 28 — Total assets 7,503 5,658 1,743 28 74 Derivative liabilities (230 ) (2 ) (86 ) (142 ) — Net assets (liabilities) $ 7,273 $ 5,656 $ 1,657 $ (114 ) $ 74 The following tables provide reconciliations of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Amounts included in earnings for derivatives are primarily included in Cost of natural gas on the Duke Energy Registrants' Consolidated Statements of Operations and Comprehensive Income. Amounts included in changes of net assets on the Duke Energy Registrants' Consolidated Balance Sheets are included in regulatory assets or liabilities. All derivative assets and liabilities are presented on a net basis. December 31, 2018 December 31, 2017 (in millions) Derivatives (net) Investments Derivatives (net) Total Balance at beginning of period $ (114 ) $ 5 $ (166 ) $ (161 ) Total pretax realized or unrealized gains included in comprehensive income — 1 — 1 Purchases, sales, issuances and settlements: Purchases 57 — 55 55 Sales — (6 ) — (6 ) Settlements (57 ) — (47 ) (47 ) Total gains included on the Consolidated Balance Sheet 1 — 44 44 Balance at end of period $ (113 ) $ — $ (114 ) $ (114 ) DUKE ENERGY CAROLINAS The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 (in millions) Total Fair Value Level 1 Level 2 Not Categorized NDTF equity securities $ 2,484 $ 2,419 $ — $ 65 NDTF debt securities 1,069 149 920 — Derivative assets 3 — 3 — Total assets 3,556 2,568 923 65 Derivative liabilities (33 ) — (33 ) — Net assets $ 3,523 $ 2,568 $ 890 $ 65 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Not Categorized NDTF equity securities $ 2,692 $ 2,618 $ — $ 74 NDTF debt securities 1,066 204 862 — Derivative assets 2 — 2 — Total assets 3,760 2,822 864 74 Derivative liabilities (35 ) (1 ) (34 ) — Net assets $ 3,725 $ 2,821 $ 830 $ 74 The following table provides reconciliations of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Investments Year Ended December 31, (in millions) 2017 Balance at beginning of period $ 3 Total pretax realized or unrealized gains included in comprehensive income 1 Purchases, sales, issuances and settlements: Sales (4 ) Balance at end of period $ — PROGRESS ENERGY The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Total Fair Value Level 1 Level 2 NDTF equity securities $ 1,991 $ 1,991 $ — $ 2,222 $ 2,222 $ — NDTF debt securities 1,162 427 735 1,108 431 677 Other debt securities 64 17 47 59 12 47 Derivative assets 4 — 4 3 1 2 Total assets 3,221 2,435 786 3,392 2,666 726 Derivative liabilities (44 ) — (44 ) (36 ) (1 ) (35 ) Net assets $ 3,177 $ 2,435 $ 742 $ 3,356 $ 2,665 $ 691 DUKE ENERGY PROGRESS The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Total Fair Value Level 1 Level 2 NDTF equity securities $ 1,588 $ 1,588 $ — $ 1,795 $ 1,795 $ — NDTF debt securities 906 294 612 796 243 553 Other debt securities 6 6 — 1 1 — Derivative assets 4 — 4 2 1 1 Total assets 2,504 1,888 616 2,594 2,040 554 Derivative liabilities (27 ) — (27 ) (18 ) (1 ) (17 ) Net assets $ 2,477 $ 1,888 $ 589 $ 2,576 $ 2,039 $ 537 DUKE ENERGY FLORIDA The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Total Fair Value Level 1 Level 2 NDTF equity securities $ 403 $ 403 $ — $ 427 $ 427 $ — NDTF debt securities 256 133 123 312 188 124 Other debt securities 48 1 47 48 1 47 Derivative assets — — — 1 — 1 Total assets 707 537 170 788 616 172 Derivative liabilities (9 ) — (9 ) (12 ) — (12 ) Net assets $ 698 $ 537 $ 161 $ 776 $ 616 $ 160 DUKE ENERGY OHIO The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 2 Level 3 Total Fair Value Level 2 Level 3 Derivative assets $ 6 $ — $ 6 $ 1 $ — $ 1 Derivative liabilities (5 ) (5 ) — (5 ) (5 ) — Net assets (liabilities) $ 1 $ (5 ) $ 6 $ (4 ) $ (5 ) $ 1 The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2018 2017 Balance at beginning of period $ 1 $ 5 Purchases, sales, issuances and settlements: Purchases 7 3 Settlements (4 ) (4 ) Total gains included on the Consolidated Balance Sheet 2 (3 ) Balance at end of period $ 6 $ 1 DUKE ENERGY INDIANA The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Total Fair Value Level 1 Level 2 Level 3 Other equity securities $ 67 $ 67 $ — $ — $ 97 $ 97 $ — $ — Other debt securities 41 — 41 — 31 — 31 — Derivative assets 23 1 — 22 27 — — 27 Total assets $ 131 $ 68 $ 41 $ 22 $ 155 $ 97 $ 31 $ 27 The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2018 2017 Balance at beginning of period $ 27 $ 16 Purchases, sales, issuances and settlements: Purchases 50 52 Settlements (53 ) (43 ) Total (losses) gains included on the Consolidated Balance Sheet (2 ) 2 Balance at end of period $ 22 $ 27 PIEDMONT The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 3 Total Fair Value Level 1 Level 3 Other debt securities $ — $ — $ — $ 1 $ 1 $ — Derivative assets 3 3 — 2 2 — Total assets 3 3 — 3 3 — Derivative liabilities (141 ) — (141 ) (142 ) — (142 ) Net (liabilities) assets $ (138 ) $ 3 $ (141 ) $ (139 ) $ 3 $ (142 ) The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2018 2017 Balance at beginning of period $ (142 ) $ (187 ) Total gains and settlements 1 45 Balance at end of period $ (141 ) $ (142 ) QUANTITATIVE INFORMATION ABOUT UNOBSERVABLE INPUTS The following tables include quantitative information about the Duke Energy Registrants' derivatives classified as Level 3. December 31, 2018 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio FTRs $ 6 RTO auction pricing FTR price – per MWh $ 1.19 – $ 4.59 Duke Energy Indiana FTRs 22 RTO auction pricing FTR price – per MWh (2.07 ) – 8.27 Piedmont Natural gas contracts (141 ) Discounted cash flow Forward natural gas curves — price per MMBtu 1.87 – 2.95 Duke Energy Total Level 3 derivatives $ (113 ) December 31, 2017 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio FTRs $ 1 RTO auction pricing FTR price – per MWh $ 0.07 – $ 1.41 Duke Energy Indiana FTRs 27 RTO auction pricing FTR price – per MWh (0.77 ) – 7.44 Piedmont Natural gas contracts (142 ) Discounted cash flow Forward natural gas curves — price per MMBtu 2.10 – 2.88 Duke Energy Total Level 3 derivatives $ (114 ) OTHER FAIR VALUE DISCLOSURES The fair value and book value of long-term debt, including current maturities, is summarized in the following table. Estimates determined are not necessarily indicative of amounts that could have been settled in current markets. Fair value of long-term debt uses Level 2 measurements. December 31, 2018 December 31, 2017 (in millions) Book Value Fair Value Book Value Fair Value Duke Energy (a) $ 54,529 $ 54,534 $ 52,279 $ 55,331 Duke Energy Carolinas 10,939 11,471 10,103 11,372 Progress Energy 18,911 19,885 17,837 20,000 Duke Energy Progress 8,204 8,300 7,357 7,992 Duke Energy Florida 7,321 7,742 7,095 7,953 Duke Energy Ohio 2,165 2,239 2,067 2,249 Duke Energy Indiana 3,782 4,158 3,783 4,464 Piedmont 2,138 2,180 2,037 2,209 (a) Book value of long-term debt includes $1.6 billion as of December 31, 2018 , and $1.7 billion as of December 31, 2017 , of unamortized debt discount and premium, net in purchase accounting adjustments related to the mergers with Progress Energy and Piedmont that are excluded from fair value of long-term debt. At both December 31, 2018 , and December 31, 2017 , fair value of cash and cash equivalents, accounts and notes receivable, accounts payable, notes payable and commercial paper, and nonrecourse notes payable of VIEs are not materially different from their carrying amounts because of the short-term nature of these instruments and/or because the stated rates approximate market rates.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2018
Variable Interest Entities [Abstract]
Variable Interest Entities	VARIABLE INTEREST ENTITIES A VIE is an entity that is evaluated for consolidation using more than a simple analysis of voting control. The analysis to determine whether an entity is a VIE considers contracts with an entity, credit support for an entity, the adequacy of the equity investment of an entity and the relationship of voting power to the amount of equity invested in an entity. This analysis is performed either upon the creation of a legal entity or upon the occurrence of an event requiring reevaluation, such as a significant change in an entity’s assets or activities. A qualitative analysis of control determines the party that consolidates a VIE. This assessment is based on (i) what party has the power to direct the activities of the VIE that most significantly impact its economic performance and (ii) what party has rights to receive benefits or is obligated to absorb losses that could potentially be significant to the VIE. The analysis of the party that consolidates a VIE is a continual reassessment. CONSOLIDATED VIEs The obligations of these VIEs discussed in the following paragraphs are nonrecourse to the Duke Energy Registrants. The registrants have no requirement to provide liquidity to, purchase assets of or guarantee performance of these VIEs unless noted in the following paragraphs. No financial support was provided to any of the consolidated VIEs during the years ended December 31, 2018 , 2017 and 2016 , or is expected to be provided in the future, that was not previously contractually required. Receivables Financing – DERF/DEPR/DEFR DERF, DEPR and DEFR are bankruptcy remote, special purpose subsidiaries of Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida, respectively. DERF, DEPR and DEFR are wholly owned limited liability companies with separate legal existence from their parent companies and their assets are not generally available to creditors of their parent companies. On a revolving basis, DERF, DEPR and DEFR buy certain accounts receivable arising from the sale of electricity and related services from their parent companies. DERF, DEPR and DEFR borrow amounts under credit facilities to buy these receivables. Borrowing availability from the credit facilities is limited to the amount of qualified receivables purchased. The sole source of funds to satisfy the related debt obligations is cash collections from the receivables. Amounts borrowed under the credit facilities are reflected on the Consolidated Balance Sheets as Long-Term Debt. The most significant activity that impacts the economic performance of DERF, DEPR and DEFR are the decisions made to manage delinquent receivables. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida are considered the primary beneficiaries and consolidate DERF, DEPR and DEFR, respectively, as they make those decisions. Receivables Financing – CRC CRC is a bankruptcy remote, special purpose entity indirectly owned by Duke Energy. On a revolving basis, CRC buys certain accounts receivable arising from the sale of electricity, natural gas and related services from Duke Energy Ohio and Duke Energy Indiana. CRC borrows amounts under a credit facility to buy the receivables from Duke Energy Ohio and Duke Energy Indiana. Borrowing availability from the credit facility is limited to the amount of qualified receivables sold to CRC. The sole source of funds to satisfy the related debt obligation is cash collections from the receivables. Amounts borrowed under the credit facility are reflected on Duke Energy's Consolidated Balance Sheets as Long-Term Debt. The proceeds Duke Energy Ohio and Duke Energy Indiana receive from the sale of receivables to CRC are approximately 75 percent cash and 25 percent in the form of a subordinated note from CRC. The subordinated note is a retained interest in the receivables sold. Depending on collection experience, additional equity infusions to CRC may be required by Duke Energy to maintain a minimum equity balance of $3 million . CRC is considered a VIE because (i) equity capitalization is insufficient to support its operations, (ii) power to direct the activities that most significantly impact the economic performance of the entity are not performed by the equity holder and (iii) deficiencies in net worth of CRC are funded by Duke Energy. The most significant activities that impact the economic performance of CRC are decisions made to manage delinquent receivables. Duke Energy is considered the primary beneficiary and consolidates CRC as it makes these decisions. Neither Duke Energy Ohio nor Duke Energy Indiana consolidate CRC. Receivables Financing – Credit Facilities The following table outlines amounts and expiration dates of the credit facilities described above. Duke Energy Duke Energy Duke Energy Duke Energy Carolinas Progress Florida CRC DERF DEPR DEFR Expiration date December 2020 December 2020 February 2021 April 2021 Credit facility amount (in millions) $ 325 $ 450 $ 300 $ 225 Amounts borrowed at December 31, 2018 325 450 300 225 Amounts borrowed at December 31, 2017 325 450 300 225 Restricted Receivables at December 31, 2018 564 699 547 357 Restricted Receivables at December 31, 2017 545 640 459 317 Nuclear Asset-Recovery Bonds – DEFPF DEFPF is a bankruptcy remote, wholly owned special purpose subsidiary of Duke Energy Florida. DEFPF was formed in 2016 for the sole purpose of issuing nuclear asset-recovery bonds to finance Duke Energy Florida's unrecovered regulatory asset related to Crystal River Unit 3. In 2016, DEFPF issued senior secured bonds and used the proceeds to acquire nuclear asset-recovery property from Duke Energy Florida. The nuclear asset-recovery property acquired includes the right to impose, bill, collect and adjust a non-bypassable nuclear asset-recovery charge from all Duke Energy Florida retail customers until the bonds are paid in full and all financing costs have been recovered. The nuclear asset-recovery bonds are secured by the nuclear asset-recovery property and cash collections from the nuclear asset-recovery charges are the sole source of funds to satisfy the debt obligation. The bondholders have no recourse to Duke Energy Florida. For additional information see Notes 4 and 6 . DEFPF is considered a VIE primarily because the equity capitalization is insufficient to support its operations. Duke Energy Florida has the power to direct the significant activities of the VIE as described above and therefore Duke Energy Florida is considered the primary beneficiary and consolidates DEFPF. The following table summarizes the impact of DEFPF on Duke Energy Florida's Consolidated Balance Sheets. (in millions) December 31, 2018 December 31, 2017 Receivables of VIEs $ 5 $ 4 Regulatory Assets: Current 52 51 Current Assets: Other 39 40 Other Noncurrent Assets: Regulatory assets 1,041 1,091 Current Liabilities: Other 10 10 Current maturities of long-term debt 53 53 Long-Term Debt 1,111 1,164 Commercial Renewables Certain of Duke Energy’s renewable energy facilities are VIEs due to Duke Energy issuing guarantees for debt service and operations and maintenance reserves in support of debt financings. Assets are restricted and cannot be pledged as collateral or sold to third parties without prior approval of debt holders. Additionally, Duke Energy has VIEs associated with tax equity arrangements entered into with third–party investors in order to finance the cost of solar energy systems eligible for tax credits. The activities that most significantly impacted the economic performance of these renewable energy facilities were decisions associated with siting, negotiating PPAs and EPC agreements, and decisions associated with ongoing operations and maintenance-related activities. Duke Energy is considered the primary beneficiary and consolidates the entities as it is responsible for all of these decisions. The table below presents material balances reported on Duke Energy's Consolidated Balance Sheets related to renewables VIEs. (in millions) December 31, 2018 December 31, 2017 Current Assets: Other $ 123 $ 174 Property, plant and equipment, cost 4,007 3,923 Accumulated depreciation and amortization (698 ) (591 ) Other Noncurrent Assets: Other 261 50 Current maturities of long-term debt 174 170 Long-Term Debt 1,587 1,700 Other Noncurrent Liabilities: Deferred income taxes — (148 ) Other Noncurrent Liabilities: Asset Retirement Obligations 106 83 Other Noncurrent Liabilities: Other 212 241 NON-CONSOLIDATED VIEs The following tables summarize the impact of non-consolidated VIEs on the Consolidated Balance Sheets. December 31, 2018 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Receivables from affiliated companies $ — $ — $ — $ — $ 93 $ 118 Investments in equity method unconsolidated affiliates 822 190 48 1,060 — — Total assets $ 822 $ 190 $ 48 $ 1,060 $ 93 $ 118 Taxes accrued (1 ) — — (1 ) — — Other current liabilities — — 4 4 — — Deferred income taxes 21 — — 21 — — Other noncurrent liabilities — — 12 12 — — Total liabilities $ 20 $ — $ 16 $ 36 $ — $ — Net assets $ 802 $ 190 $ 32 $ 1,024 $ 93 $ 118 December 31, 2017 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Receivables from affiliated companies $ — $ — $ — $ — $ 87 $ 106 Investments in equity method unconsolidated affiliates 697 180 42 919 — — Other noncurrent assets 17 — — 17 — — Total assets $ 714 $ 180 $ 42 $ 936 $ 87 $ 106 Taxes accrued (29 ) — — (29 ) — — Other current liabilities — — 4 4 — — Deferred income taxes 42 — — 42 — — Other noncurrent liabilities — — 12 12 — — Total liabilities $ 13 $ — $ 16 $ 29 $ — $ — Net assets $ 701 $ 180 $ 26 $ 907 $ 87 $ 106 The Duke Energy Registrants are not aware of any situations where the maximum exposure to loss significantly exceeds the carrying values shown above except for the power purchase agreement with OVEC, which is discussed below, and various guarantees, including Duke Energy's guarantee agreement to support its share of the ACP revolving credit facility. Duke Energy's maximum exposure to loss under the terms of the guarantee is $677 million as of December 31, 2018 . For more information on various guarantees, refer to Note 7 . Pipeline Investments Duke Energy has investments in various joint ventures with pipeline projects currently under construction. These entities are considered VIEs due to having insufficient equity to finance their own activities without subordinated financial support. Duke Energy does not have the power to direct the activities that most significantly impact the economic performance, the obligation to absorb losses or the right to receive benefits of these VIEs and therefore does not consolidate these entities. The table below presents Duke Energy's ownership interest and investment balance in these joint ventures. Investment Amount (in millions) Ownership December 31, December 31, Entity Name Interest 2018 2017 ACP 47 % $ 797 $ 397 Sabal Trail (a) 7.5 % — 219 Constitution (b) 24 % 25 81 Total $ 822 $ 697 (a) At December 31, 2017 , Sabal Trail was considered a VIE due to having insufficient equity to finance their own activities without subordinated financial support. However, Sabal Trail is now a fully operational, well capitalized entity. As a result, Sabal Trail has sufficient equity to finance its own activities, and therefore, is no longer considered a VIE. Duke Energy's investment in Sabal Trail was $112 million at December 31, 2018 . (b) During the year ended December 31, 2018 , Duke Energy recorded an OTTI of $55 million related to Constitution within Equity in earnings of unconsolidated affiliates on Duke Energy's Consolidated Statements of Income. See Note 4 for additional information. Commercial Renewables Duke Energy has investments in various renewable energy project entities. Some of these entities are VIEs due to Duke Energy issuing guarantees for debt service and operations and maintenance reserves in support of debt financings. Duke Energy does not consolidate these VIEs because power to direct and control key activities is shared jointly by Duke Energy and other owners. Pioneer Duke Energy holds a 50 percent equity interest in Pioneer. Pioneer is considered a VIE due to having insufficient equity to finance their own activities without subordinated financial support. The activities that most significantly impact Pioneer's economic performance are decisions related to the development of new transmission facilities. The power to direct these activities is jointly and equally shared by Duke Energy and the other joint venture partner, American Electric Power; therefore, Duke Energy does not consolidate Pioneer. OVEC Duke Energy Ohio’s 9 percent ownership interest in OVEC is considered a non-consolidated VIE due to having insufficient equity to finance its activities without subordinated financial support. The activities that most significantly impact OVEC's economic performance include fuel strategy and supply activities and decisions associated with ongoing operations and maintenance-related activities. Duke Energy Ohio does not have the unilateral power to direct these activities, and therefore, does not consolidate OVEC. As a counterparty to an ICPA, Duke Energy Ohio has a contractual arrangement to receive entitlements to capacity and energy from OVEC’s power plants through June 2040 commensurate with its power participation ratio, which is equivalent to Duke Energy Ohio's ownership interest. Costs, including fuel, operating expenses, fixed costs, debt amortization, and interest expense, are allocated to counterparties to the ICPA based on their power participation ratio. The value of the ICPA is subject to variability due to fluctuation in power prices and changes in OVEC's cost of business. On March 31, 2018, FES, a subsidiary of FirstEnergy and an ICPA counterparty with a power participation ratio of 4.85 percent, filed for Chapter 11 bankruptcy, which could increase costs allocated to the counterparties. On July 31, 2018, the bankruptcy court rejected the FES ICPA, which means OVEC is an unsecured creditor in the FES bankruptcy proceeding. Duke Energy Ohio cannot predict the impact of the bankruptcy filing on its OVEC interests. In addition, certain proposed environmental rulemaking could result in future increased OVEC cost allocations. See Note 4 for additional information. CRC See discussion under Consolidated VIEs for additional information related to CRC. Amounts included in Receivables from affiliated companies in the above table for Duke Energy Ohio and Duke Energy Indiana reflect their retained interest in receivables sold to CRC. These subordinated notes held by Duke Energy Ohio and Duke Energy Indiana are stated at fair value. Carrying values of retained interests are determined by allocating carrying value of the receivables between assets sold and interests retained based on relative fair value. The allocated bases of the subordinated notes are not materially different than their face value because (i) the receivables generally turnover in less than two months, (ii) credit losses are reasonably predictable due to the broad customer base and lack of significant concentration and (iii) the equity in CRC is subordinate to all retained interests and thus would absorb losses first. The hypothetical effect on fair value of the retained interests assuming both a 10 percent and a 20 percent unfavorable variation in credit losses or discount rates is not material due to the short turnover of receivables and historically low credit loss history. Interest accrues to Duke Energy Ohio and Duke Energy Indiana on the retained interests using the acceptable yield method. This method generally approximates the stated rate on the notes since the allocated basis and the face value are nearly equivalent. An impairment charge is recorded against the carrying value of both retained interests and purchased beneficial interest whenever it is determined that an OTTI has occurred. Key assumptions used in estimating fair value are detailed in the following table. Duke Energy Ohio Duke Energy Indiana 2018 2017 2018 2017 Anticipated credit loss ratio 0.5 % 0.5 % 0.3 % 0.3 % Discount rate 3.0 % 2.1 % 3.0 % 2.1 % Receivable turnover rate 13.5 % 13.5 % 11.0 % 10.7 % The following table shows the gross and net receivables sold. Duke Energy Ohio Duke Energy Indiana (in millions) 2018 2017 2018 2017 Receivables sold $ 269 $ 273 $ 336 $ 312 Less: Retained interests 93 87 118 106 Net receivables sold $ 176 $ 186 $ 218 $ 206 The following table shows sales and cash flows related to receivables sold. Duke Energy Ohio Duke Energy Indiana Years Ended December 31, Years Ended December 31, (in millions) 2018 2017 2016 2018 2017 2016 Sales Receivables sold $ 1,987 $ 1,879 $ 1,926 $ 2,842 $ 2,711 $ 2,635 Loss recognized on sale 13 10 9 16 12 11 Cash Flows Cash proceeds from receivables sold 1,967 1,865 1,882 2,815 2,694 2,583 Collection fees received 1 1 1 1 1 1 Return received on retained interests 6 3 2 9 7 5 Cash flows from the sales of receivables are reflected within Cash Flows From Operating Activities on Duke Energy Ohio’s and Duke Energy Indiana’s Consolidated Statements of Cash Flows. Collection fees received in connection with servicing transferred accounts receivable are included in Operation, maintenance and other on Duke Energy Ohio’s and Duke Energy Indiana’s Consolidated Statements of Operations and Comprehensive Income. The loss recognized on sales of receivables is calculated monthly by multiplying receivables sold during the month by the required discount. The required discount is derived monthly utilizing a three-year weighted average formula that considers charge-off history, late charge history and turnover history on the sold receivables, as well as a component for the time value of money. The discount rate, or component for the time value of money, is the prior month-end LIBOR plus a fixed rate of 1.00 percent .

Revenue

Revenue	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
REVENUE	REVENUE As described in Note 1 , Duke Energy adopted Revenue from Contracts with Customers effective January 1, 2018, using the modified retrospective method of adoption, which does not require restatement of prior year reported results. No cumulative effect adjustment was recorded as the vast majority of Duke Energy’s revenues are at-will and without a defined contractual term. Additionally, comparative disclosures for 2018 operating results with the previous revenue recognition rules are not applicable as Duke Energy’s revenue recognition has not materially changed as a result of the new standard. Duke Energy recognizes revenue consistent with amounts billed under tariff offerings or at contractually agreed upon rates based on actual physical delivery of electric or natural gas service, including estimated volumes delivered when billings have not yet occurred. As such, the majority of Duke Energy’s revenues have fixed pricing based on the contractual terms of the published tariffs, with variability in expected cash flows attributable to the customer’s volumetric demand and ultimate quantities of energy or natural gas supplied and used during the billing period. The stand-alone selling price of related sales are designed to support recovery of prudently incurred costs and an appropriate return on invested assets and are primarily governed by published tariff rates or contractual agreements approved by relevant regulatory bodies. As described in Note 1 , certain excise taxes and franchise fees levied by state or local governments are required to be paid even if not collected from the customer. These taxes are recognized on a gross basis as part of revenues. Duke Energy elects to account for all other taxes net of revenues. Performance obligations are satisfied over time as energy or natural gas is delivered and consumed with billings generally occurring monthly and related payments due within 30 days, depending on regulatory requirements. In no event does the timing between payment and delivery of the goods and services exceed one year. Using this output method for revenue recognition provides a faithful depiction of the transfer of electric and natural gas service as customers obtain control of the commodity and benefit from its use at delivery. Additionally, Duke Energy has an enforceable right to consideration for energy or natural gas delivered at any discrete point in time, and will recognize revenue at an amount that reflects the consideration to which Duke Energy is entitled for the energy or natural gas delivered. As described above, the majority of Duke Energy’s tariff revenues are at-will and, as such, related contracts with customers have an expected duration of one year or less and will not have future performance obligations for disclosure. Additionally, other long-term revenue streams, including wholesale contracts, generally provide services that are part of a single performance obligation, the delivery of electricity or natural gas. As such, other than material fixed consideration under long-term contracts, related disclosures for future performance obligations are also not applicable. Duke Energy earns substantially all of its revenues through its reportable segments, Electric Utilities and Infrastructure, Gas Utilities and Infrastructure and Commercial Renewables. Electric Utilities and Infrastructure Electric Utilities and Infrastructure earns the majority of its revenues through retail and wholesale electric service through the generation, transmission, distribution and sale of electricity. Duke Energy generally provides retail and wholesale electric service customers with their full electric load requirements or with supplemental load requirements when the customer has other sources of electricity. Retail electric service is generally marketed throughout Duke Energy's electric service territory through standard service offers. The standard service offers are through tariffs determined by regulators in Duke Energy's regulated service territory. Each tariff, which is assigned to customers based on customer class, has multiple components such as an energy charge, a demand charge, a basic facilities charge and applicable riders. Duke Energy considers each of these components to be aggregated into a single performance obligation for providing electric service, or in the case of distribution only customers in Duke Energy Ohio, for delivering electricity. Electricity is considered a single performance obligation satisfied over time consistent with the series guidance and is provided and consumed over the billing period, generally one month. Retail electric service is typically provided to at-will customers who can cancel service at any time, without a substantive penalty. Additionally, Duke Energy adheres to applicable regulatory requirements in each jurisdiction to ensure the collectability of amounts billed and appropriate mitigating procedures are followed when necessary. As such, revenue from contracts with customers for such contracts is equivalent to the electricity supplied and billed in that period (including unbilled estimates). Wholesale electric service is generally provided under long-term contracts using cost-based pricing. FERC regulates costs that may be recovered from customers and the amount of return companies are permitted to earn. Wholesale contracts include both energy and demand charges. For full requirements contracts, Duke Energy considers both charges as a single performance obligation for providing integrated electric service. For contracts where energy and demand charges are considered separate performance obligations, energy and demand are each a distinct performance obligation under the series guidance and are satisfied as energy is delivered and stand-ready service is provided on a monthly basis. This service represents consumption over the billing period and revenue is recognized consistent with billings and unbilled estimates, which generally occur monthly. Contractual amounts owed are typically trued up annually based upon incurred costs in accordance with FERC published filings and the specific customer’s actual peak demand. Estimates of variable consideration related to potential additional billings or refunds owed are updated quarterly. The majority of wholesale revenues are full requirements contracts where the customers purchase the substantial majority of their energy needs and do not have a fixed quantity of contractually required energy or capacity. As such, related forecasted revenues are considered optional purchases. Supplemental requirements contracts that include contracted blocks of energy and capacity at contractually fixed prices have the following estimated remaining performance obligations: Remaining Performance Obligations (in millions) 2019 2020 2021 2022 2023 Thereafter Total Progress Energy $ 112 $ 121 $ 80 $ 82 $ 39 $ 42 $ 476 Duke Energy Progress 9 9 9 9 9 9 54 Duke Energy Florida 103 112 71 73 30 33 422 Duke Energy Indiana 9 10 5 — — — 24 Revenues for block sales are recognized monthly as energy is delivered and stand-ready service is provided, consistent with invoiced amounts and unbilled estimates. Gas Utilities and Infrastructure Gas Utilities and Infrastructure earns its revenue through retail and wholesale natural gas service through the transportation, distribution and sale of natural gas. Duke Energy generally provides retail and wholesale natural gas service customers with all natural gas load requirements. Additionally, while natural gas can be stored, substantially all natural gas provided by Duke Energy is consumed by customers simultaneously with receipt of delivery. Retail natural gas service is marketed throughout Duke Energy's natural gas service territory using published tariff rates. The tariff rates are established by regulators in Duke Energy's service territories. Each tariff, which is assigned to customers based on customer class, have multiple components, such as a commodity charge, demand charge, customer or monthly charge and transportation costs. Duke Energy considers each of these components to be aggregated into a single performance obligation for providing natural gas service. For contracts where Duke Energy provides all of the customer’s natural gas needs, the delivery of natural gas is considered a single performance obligation satisfied over time, and revenue is recognized monthly based on billings and unbilled estimates as service is provided and the commodity is consumed over the billing period. Additionally, natural gas service is typically at-will and customers can cancel service at any time, without a substantive penalty. Duke Energy also adheres to applicable regulatory requirements to ensure the collectability of amounts billed and receivable and appropriate mitigating procedures are followed when necessary. Certain long-term individually negotiated contracts exist to provide natural gas service. These contracts are regulated and approved by state commissions. The negotiated contracts have multiple components, including a natural gas and a demand charge, similar to retail natural gas contracts. Duke Energy considers each of these components to be a single performance obligation for providing natural gas service. This service represents consumption over the billing period, generally one month. Fixed capacity payments under long-term contracts for the Gas Utilities and Infrastructure segment include minimum margin contracts and supply arrangements with municipalities and power generation facilities. Revenues for related sales are recognized monthly as natural gas is delivered and stand-ready service is provided, consistent with invoiced amounts and unbilled estimates. Estimated remaining performance obligations are as follows: Remaining Performance Obligations (in millions) 2019 2020 2021 2022 2023 Thereafter Total Piedmont $ 70 $ 68 $ 63 $ 63 $ 60 $ 430 $ 754 Commercial Renewables Commercial Renewables earns the majority of its revenues through long-term PPAs and generally sells all of its wind and solar facility output, electricity and RECs to customers. The majority of these PPAs have historically been accounted for as leases. For PPAs that are not accounted for as leases, the delivery of electricity and the delivery of RECs are considered separate performance obligations. The delivery of electricity is a performance obligation satisfied over time and represents generation and consumption of the electricity over the billing period, generally one month. The delivery of RECs is a performance obligation satisfied at a point in time and represents delivery of each REC generated by the wind or solar facility. The majority of self-generated RECs are bundled with energy in Duke Energy’s contracts and, as such, related revenues are recognized as energy is generated and delivered as that pattern is consistent with Duke Energy’s performance. Commercial Renewables recognizes revenue based on the energy generated and billed for the period, generally one month, at contractual rates (including unbilled estimates) according to the invoice practical expedient. Amounts are typically due within 30 days of invoice. Commercial Renewables also earns revenues from installation of distributed solar generation resources, which is primarily composed of EPC projects to deliver functioning solar power systems, generally completed within two to 12 months from commencement of construction. The installation of distributed solar generation resources is a performance obligation that is satisfied over time. Revenue from fixed-price EPC contracts is recognized using the input method as work is performed based on the estimated ratio of incurred costs to estimated total costs. Other The remainder of Duke Energy’s operations is presented as Other, which does not include material revenues from contracts with customers. Disaggregated Revenues For the Electric and Gas Utility and Infrastructure segments, revenue by customer class is most meaningful to Duke Energy as each respective customer class collectively represents unique customer expectations of service, generally has different energy and demand requirements, and operates under tailored, regulatory approved pricing structures. Additionally, each customer class is impacted differently by weather and a variety of economic factors including the level of population growth, economic investment, employment levels, and regulatory activities in each of Duke Energy’s jurisdictions. As such, analyzing revenues disaggregated by customer class allows Duke Energy to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. For the Commercial Renewables segment, the majority of revenues from contracts with customers are from selling all of the unit-contingent output at contractually defined pricing under long-term PPAs with consistent expectations regarding the timing and certainty of cash flows. Disaggregated revenues are presented as follows: Year Ended December 31, 2018 Duke Duke Duke Duke Duke (in millions) Duke Energy Progress Energy Energy Energy Energy By market or type of customer Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Electric Utilities and Infrastructure Residential $ 9,587 $ 2,981 $ 4,785 $ 2,019 $ 2,766 $ 743 $ 1,076 $ — General 6,127 2,119 2,809 1,280 1,529 422 778 — Industrial 2,974 1,180 904 642 262 131 760 — Wholesale 2,324 508 1,462 1,303 159 57 298 — Other revenues 717 320 502 320 182 73 91 — Total Electric Utilities and Infrastructure revenue from contracts with customers $ 21,729 $ 7,108 $ 10,462 $ 5,564 $ 4,898 $ 1,426 $ 3,003 $ — Gas Utilities and Infrastructure Residential $ 1,000 $ — $ — $ — $ — $ 331 $ — $ 669 Commercial 514 — — — — 135 — 378 Industrial 147 — — — — 18 — 128 Power Generation — — — — — — — 54 Other revenues 139 — — — — 19 — 120 Total Gas Utilities and Infrastructure revenue from contracts with customers $ 1,800 $ — $ — $ — $ — $ 503 $ — $ 1,349 Commercial Renewables Revenue from contracts with customers $ 209 $ — $ — $ — $ — $ — $ — $ — Other Revenue from contracts with customers $ 19 $ — $ — $ — $ — $ 1 $ — $ — Total revenue from contracts with customers $ 23,757 $ 7,108 $ 10,462 $ 5,564 $ 4,898 $ 1,930 $ 3,003 $ 1,349 Other revenue sources (a) $ 764 $ 192 $ 266 $ 135 $ 123 $ 27 $ 56 $ 26 Total revenues $ 24,521 $ 7,300 $ 10,728 $ 5,699 $ 5,021 $ 1,957 $ 3,059 $ 1,375 (a) Other revenue sources include revenues from leases, derivatives and alternative revenue programs that are not considered revenues from contracts with customers. Alternative revenue programs in certain jurisdictions include regulatory mechanisms that periodically adjust for over or under collection of related revenues. IMPACT OF WEATHER AND THE TIMING OF BILLING PERIODS Revenues and costs are influenced by seasonal weather patterns. Peak sales of electricity occur during the summer and winter months, which results in higher revenue and cash flows during these periods. By contrast, lower sales of electricity occur during the spring and fall, allowing for scheduled plant maintenance. Residential and general service customers are more impacted by weather than industrial customers. Estimated weather impacts are based on actual current period weather compared to normal weather conditions. Normal weather conditions are defined as the long-term average of actual historical weather conditions. Heating-degree days measure the variation in weather based on the extent the average daily temperature falls below a base temperature. Cooling-degree days measure the variation in weather based on the extent the average daily temperature rises above the base temperature. Each degree of temperature below the base temperature counts as one heating-degree day and each degree of temperature above the base temperature counts as one cooling-degree day. The estimated impact of weather on earnings for Electric Utilities and Infrastructure is based on the temperature variances from a normal condition and customers' historic usage patterns. The methodology used to estimate the impact of weather does not consider all variables that may impact customer response to weather conditions, such as humidity in the summer or wind chill in the winter. The precision of this estimate may also be impacted by applying long-term weather trends to shorter-term periods. Gas Utilities and Infrastructure's costs and revenues are influenced by seasonal patterns due to peak natural gas sales occurring during the winter months as a result of space heating requirements. Residential customers are the most impacted by weather. There are certain regulatory mechanisms for the North Carolina, South Carolina, Tennessee and Ohio service territories that normalize the margins collected from certain customer classes during the winter. In North Carolina, rate design provides protection from both weather and other usage variations such as conservation, while South Carolina and Tennessee revenues are adjusted solely based on weather. Ohio primarily employs a fixed charge each month regardless of the season and usage. UNBILLED REVENUE Unbilled revenues are recognized by applying customer billing rates to the estimated volumes of energy or natural gas delivered but not yet billed. Unbilled revenues can vary significantly from period to period as a result of seasonality, weather, customer usage patterns, customer mix, average price in effect for customer classes, timing of rendering customer bills and meter reading schedules, and the impact of weather normalization or margin decoupling mechanisms. Unbilled revenues are included within Receivables and Receivables of VIEs on the Consolidated Balance Sheets as shown in the following table. December 31, (in millions) 2018 2017 Duke Energy $ 896 $ 944 Duke Energy Carolinas 313 342 Progress Energy 244 228 Duke Energy Progress 148 143 Duke Energy Florida 96 85 Duke Energy Ohio 2 4 Duke Energy Indiana 23 21 Piedmont 73 86 Additionally, Duke Energy Ohio and Duke Energy Indiana sell, on a revolving basis, nearly all of their retail accounts receivable, including receivables for unbilled revenues, to an affiliate, CRC and accounts for the transfers of receivables as sales. Accordingly, the receivables sold are not reflected on the Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana. See Note 17 for further information. These receivables for unbilled revenues are shown in the table below. December 31, (in millions) 2018 2017 Duke Energy Ohio $ 86 $ 104 Duke Energy Indiana 128 132

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Common Stock	COMMON STOCK Basic EPS is computed by dividing net income attributable to Duke Energy common stockholders, as adjusted for distributed and undistributed earnings allocated to participating securities, by the weighted average number of common shares outstanding during the period. Diluted EPS is computed by dividing net income attributable to Duke Energy common stockholders, as adjusted for distributed and undistributed earnings allocated to participating securities, by the diluted weighted average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that could occur if securities or other agreements to issue common shares, such as stock options and equity forward sale agreements, were exercised or settled. Duke Energy’s participating securities are restricted stock units that are entitled to dividends declared on Duke Energy common stock during the restricted stock unit’s vesting periods. The following table presents Duke Energy’s basic and diluted EPS calculations and reconciles the weighted average number of common stock outstanding to the diluted weighted average number of common stock outstanding. Years Ended December 31, (in millions, except per share amounts) 2018 2017 2016 Income from continuing operations attributable to Duke Energy common stockholders excluding impact of participating securities $ 2,642 $ 3,059 $ 2,567 Weighted average shares outstanding – basic 708 700 691 Weighted average shares outstanding – diluted 708 700 691 Earnings per share from continuing operations attributable to Duke Energy common stockholders Basic $ 3.73 $ 4.37 $ 3.71 Diluted $ 3.73 $ 4.37 $ 3.71 Potentially dilutive items excluded from the calculation (a) 2 2 2 Dividends declared per common share $ 3.64 $ 3.49 $ 3.36 (a) Performance stock awards were not included in the dilutive securities calculation because the performance measures related to the awards had not been met. Equity Issuances On February 20, 2018, Duke Energy filed a prospectus supplement and executed an EDA under which it may sell up to $1 billion of its common stock through an ATM offering program, including an equity forward sales component. The EDA was entered into with Wells Fargo Securities, LLC, Citigroup Global Markets Inc., and J.P. Morgan Securities LLC (the Agents). Under the terms of the EDA, Duke Energy may issue and sell, through any of the Agents, shares of common stock during the period ending September 23, 2019. In June 2018, Duke Energy marketed two separate tranches, each for 1.3 million shares, of common stock. The first tranche was marketed with Wells Fargo Bank at an initial forward price of $72.02 per share and the second tranche was marketed with Citibank at an initial forward price of $78.71 per share through equity forward transactions under the ATM program. The Equity Forwards require Duke Energy to either physically settle the transactions by issuing 2.6 million shares in exchange for net proceeds at the then-applicable forward sale price specified by the agreements or net settle in whole or in part through the delivery or receipt of cash or shares. The settlement alternative was at Duke Energy's election. In December 2018, Duke Energy physically settled these equity forwards by delivering 2.6 million shares of common stock in exchange for net proceeds of approximately $195 million . Separately, in March 2018, Duke Energy marketed an equity offering of 21.3 million shares of common stock through an Underwriting Agreement with Credit Suisse Securities (USA) LLC, J.P. Morgan Securities LLC, Barclays Capital Inc. and Goldman Sachs & Co. LLC, as representatives of several underwriters, Credit Suisse Capital LLC and J.P. Morgan Securities LLC as Forward Sellers, and Credit Suisse Capital LLC and J.P. Morgan Chase Bank, National Association, acting as forward purchasers. In connection with the offering, Duke Energy entered into equity forward sale agreements with Credit Suisse Securities (USA) LLC as Agent for Credit Suisse Capital LLC and J.P. Morgan Chase Bank, National Association. The sale price was $75 per share less certain net adjustments for an initial forward price of $74.07 per share. The Equity Forwards require Duke Energy to either physically settle the transactions by issuing 21.3 million shares in exchange for net proceeds at the then-applicable forward sale price specified by the agreements, or net settle in whole or in part through the delivery or receipt of cash or shares. The settlement alternative was at Duke Energy's election. In June 2018, Duke Energy physically settled one-half of the equity forwards by delivering approximately 10.6 million shares of common stock in exchange for net cash proceeds of approximately $781 million . In December 2018, Duke Energy physically settled the remaining equity forward by delivering 10.6 million shares of common stock in exchange for net cash proceeds of approximately $766 million . For the year ended December 31, 2018, Duke Energy issued 2.2 million shares through its DRIP with an increase in additional paid-in capital of approximately $174 million . In March 2016, Duke Energy marketed an equity offering of 10.6 million shares of common stock. In lieu of issuing equity at the time of the offering, Duke Energy entered into Equity Forwards with Barclays. The Equity Forwards required Duke Energy to either physically settle the transactions by issuing 10.6 million shares, or net settle in whole or in part through the delivery or receipt of cash or shares. On October 5, 2016, following the close of the Piedmont acquisition, Duke Energy physically settled the Equity Forwards in full by delivering 10.6 million shares of common stock in exchange for net cash proceeds of approximately $723 million . The net proceeds were used to finance a portion of the Piedmont acquisition. As a result of the acquisition, all of Piedmont's issued and outstanding stock became the issued and outstanding shares of a wholly owned subsidiary of Duke Energy. See Note 2 for additional information related to the Piedmont acquisition.

Severance

Severance	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Severance	SEVERANCE During 2018, Duke Energy reviewed its operations and identified opportunities for improvement to better serve its customers. This operational review included the company's workforce strategy and staffing levels to ensure the company is staffed with the right skillsets and number of teammates to execute the long-term vision for Duke Energy. As such, Duke Energy extended voluntary and involuntary severance benefits to certain employees in specific areas as a part of workforce planning and digital transformation efforts. During 2016, Duke Energy and Piedmont announced severance plans covering certain eligible employees whose employment will be involuntarily terminated without cause as a result of Duke Energy's acquisition of Piedmont. These reductions continued into 2017 and were a part of the synergies expected to be realized with the acquisition. Refer to Note 2 for additional information on the Piedmont acquisition. Severance benefit charges for initiatives and plans discussed above were accrued for a total of approximately 1,900 employees in 2018, 100 employees in 2017 and 600 employees in 2016. The following table presents the direct and allocated severance and related charges recorded by the Duke Energy Registrants. Amounts are included within Operation, maintenance and other on the Consolidated Statements of Operations. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont (a) Year Ended December 31, 2018 $ 187 $ 102 $ 69 $ 52 $ 17 $ 6 $ 7 $ 2 Year Ended December 31, 2017 15 2 2 1 1 — 1 9 Year Ended December 31, 2016 118 39 40 23 17 3 7 (a) Piedmont severance benefit charges were $3 million for the two months ended December 31, 2016, and $19 million for the year ended October 31, 2016. The table below presents the severance liability for past and ongoing severance plans including the plans described above. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at December 31, 2017 $ 19 $ 5 $ 2 $ 1 $ — $ — $ — $ 5 Provision/Adjustments 200 98 50 40 10 2 2 — Cash Reductions (14 ) (3 ) (1 ) — (1 ) — — (5 ) Balance at December 31, 2018 $ 205 $ 100 $ 51 $ 41 $ 9 $ 2 $ 2 $ —

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION The 2015 Plan provides for the grant of stock-based compensation awards to employees and outside directors. The 2015 Plan reserves 10 million shares of common stock for issuance. Duke Energy has historically issued new shares upon exercising or vesting of share-based awards. However, Duke Energy may use a combination of new share issuances and open market repurchases for share-based awards that are exercised or vest in the future. Duke Energy has not determined with certainty the amount of such new share issuances or open market repurchases. The following table summarizes the total expense recognized by the Duke Energy Registrants, net of tax, for stock-based compensation. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy $ 56 $ 43 $ 35 Duke Energy Carolinas 20 15 12 Progress Energy 21 16 12 Duke Energy Progress 13 10 7 Duke Energy Florida 8 6 5 Duke Energy Ohio 4 3 2 Duke Energy Indiana 5 4 3 Piedmont (a) 3 3 (a) Piedmont's stock-based compensation costs were not material for the two months ended December 31, 2016. See discussion below for information on Piedmont's pre-merger stock-based compensation plans. Duke Energy's pretax stock-based compensation costs, the tax benefit associated with stock-based compensation expense and stock-based compensation costs capitalized are included in the following table. Years Ended December 31, (in millions) 2018 2017 2016 Restricted stock unit awards $ 43 $ 41 $ 36 Performance awards 35 27 19 Pretax stock-based compensation cost $ 78 $ 68 $ 55 Stock-based compensation costs capitalized 5 4 2 Stock-based compensation expense $ 73 $ 64 $ 53 Tax benefit associated with stock-based compensation expense $ 17 $ 25 $ 20 RESTRICTED STOCK UNIT AWARDS RSU awards generally vest over periods from immediate to three years . Fair value amounts are based on the market price of Duke Energy's common stock on the grant date. The following table includes information related to RSU awards. Years Ended December 31, 2018 2017 2016 Shares awarded (in thousands) 649 583 684 Fair value (in millions) $ 49 $ 47 $ 52 The following table summarizes information about RSU awards outstanding. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2017 1,121 $ 78 Granted 649 76 Vested (545 ) 78 Forfeited (72 ) 77 Outstanding at December 31, 2018 1,153 77 Restricted stock unit awards expected to vest 1,101 77 The total grant date fair value of shares vested during the years ended December 31, 2018 , 2017 and 2016 , was $43 million , $42 million and $38 million , respectively. At December 31, 2018 , Duke Energy had $29 million of unrecognized compensation cost, which is expected to be recognized over a weighted average period of 23 months . PERFORMANCE AWARDS Stock-based performance awards generally vest after three years if performance targets are met. The actual number of shares issued will range from zero to 200 percent of target shares, depending on the level of performance achieved. Performance awards contain market conditions based on relative TSR compared to a predefined peer group, as well as a performance condition based on Duke Energy's cumulative adjusted EPS. Performance awards granted in 2018 and 2017 also contain a performance condition based on the total incident case rate, one of our key employee safety metrics. The market condition component of Duke Energy's performance awards is valued using a path-dependent model that incorporates expected relative TSR into the fair value determination of Duke Energy’s performance-based share awards. The model uses three-year historical volatilities and correlations for all companies in the predefined peer group, including Duke Energy, to simulate Duke Energy’s relative TSR as of the end of the performance period. For each simulation, Duke Energy’s relative TSR associated with the simulated stock price at the end of the performance period plus expected dividends within the period results in a value per share for the award portfolio. The average of these simulations is the expected portfolio value per share. Actual life to date results of Duke Energy’s relative TSR for each grant are incorporated within the model. For performance awards granted in 2018 , the model used a risk-free interest rate of 2.4 percent , which reflects the yield on three-year Treasury bonds as of the grant date, and an expected volatility of 16.0 percent based on Duke Energy's historical volatility over three years using daily stock prices. The following table includes information related to stock-based performance awards. Years Ended December 31, 2018 2017 2016 Shares granted assuming target performance (in thousands) 372 461 338 Fair value (in millions) $ 27 $ 37 $ 25 The following table summarizes information about stock-based performance awards outstanding and assumes payout at the target level. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2017 1,065 $ 79 Granted 372 73 Vested (155 ) 81 Forfeited (165 ) 80 Outstanding at December 31, 2018 1,117 77 Stock-based performance awards expected to vest 1,086 77 The total grant date fair value of shares vested during the years ended December 31, 2018, and 2016 , was $13 million and $25 million , respectively. No performance awards vested during the year ended December 31, 2017. At December 31, 2018 , Duke Energy had $30 million of unrecognized compensation cost, which is expected to be recognized over a weighted average period of 21 months . PIEDMONT Prior to Duke Energy's acquisition of Piedmont, Piedmont had an incentive compensation plan that had a series of three-year performance and RSU awards for eligible officers and other participants. The Merger Agreement provided for the conversion of the 2014-2016 and 2015-2017 performance awards and the nonvested 2016 RSU award into the right to receive $60 cash per share upon the close of the transaction. In December 2015, Piedmont's board of directors authorized the accelerated vesting, payment and taxation of the 2014-2016 and 2015-2017 performance awards, as well as the 2016 RSU award, at the election of the participant. Substantially all participants elected to accelerate the settlement of these awards. As a result of the settlement of these awards, 194 thousand shares of Piedmont shares were issued to participants, net of shares withheld for applicable federal and state income taxes, at a closing price of $56.85 and a fair value of $11 million . The 2016-2018 performance award cycle was approved subsequent to the Merger Agreement and was converted into a Duke Energy RSU award at the consummation of the acquisition. Piedmont's stock-based compensation costs and the tax benefit associated with stock-based compensation expense are included in the following table. (in millions) Year Ended October 31, 2016 Pretax stock-based compensation cost $ 16 Tax benefit associated with stock-based compensation expense 6 Net of tax stock-based compensation cost $ 10

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS DEFINED BENEFIT RETIREMENT PLANS Duke Energy and certain subsidiaries maintain, and the Subsidiary Registrants participate in, qualified, non-contributory defined benefit retirement plans. The Duke Energy plans cover most employees using a cash balance formula. Under a cash balance formula, a plan participant accumulates a retirement benefit consisting of pay credits based upon a percentage of current eligible earnings, age or age and years of service and interest credits. Certain employees are eligible for benefits that use a final average earnings formula. Under these final average earnings formulas, a plan participant accumulates a retirement benefit equal to the sum of percentages of their (i) highest three-year, four-year, or five-year average earnings, (ii) highest three-year, four-year, or five-year average earnings in excess of covered compensation per year of participation (maximum of 35 years ) or (iii) highest three-year average earnings times years of participation in excess of 35 years . Duke Energy also maintains, and the Subsidiary Registrants participate in, non-qualified, non-contributory defined benefit retirement plans that cover certain executives. The qualified and non-qualified, non-contributory defined benefit plans are closed to new participants. Duke Energy approved plan amendments to restructure its qualified non-contributory defined benefit retirement plans, effective January 1, 2018. The restructuring involved (i) the spin-off of the majority of inactive participants from two plans into a separate inactive plan and (ii) the merger of the active participant portions of such plans, along with a pension plan acquired as part of the Piedmont transaction, into a single active plan. Benefits offered to the plan participants remain unchanged except that the Piedmont plan's final average earnings formula was frozen as of December 31, 2017, and affected participants were moved into the active plan's cash balance formula. Actuarial gains and losses associated with the Inactive Plan will be amortized over the remaining life expectancy of the inactive participants. The longer amortization period lowered Duke Energy's 2018 pretax qualified pension plan expense by approximately $33 million . Duke Energy uses a December 31 measurement date for its defined benefit retirement plan assets and obligations. Net periodic benefit costs disclosed in the tables below represent the cost of the respective benefit plan for the periods presented prior to capitalization of amounts reflected as Net property, plant and equipment, on the Consolidated Balance Sheets. Only the service cost component of net periodic benefit costs is eligible to be capitalized. The remaining non-capitalized portions of net periodic benefit costs are classified as either: (1) service cost, which is recorded in Operations, maintenance and other on the Consolidated Statements of Operations; or as (2) components of non-service cost, which is recorded in Other income and expenses, net, on the Consolidated Statements of Operations. Amounts presented in the tables below for the Subsidiary Registrants represent the amounts of pension and other post-retirement benefit cost allocated by Duke Energy for employees of the Subsidiary Registrants. Additionally, the Consolidated Statements of Operations of the Subsidiary Registrants also include allocated net periodic benefit costs for their proportionate share of pension and post-retirement benefit cost for employees of Duke Energy’s shared services affiliate that provide support to the Subsidiary Registrants. However, in the tables below, these amounts are only presented within the Duke Energy column. These allocated amounts are included in the governance and shared service costs discussed in Note 13 . Duke Energy’s policy is to fund amounts on an actuarial basis to provide assets sufficient to meet benefit payments to be paid to plan participants. Duke Energy does not anticipate making any contributions in 2019. The following table includes information related to the Duke Energy Registrants’ contributions to its qualified defined benefit pension plans. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont (a) Contributions Made: 2018 $ 141 $ 46 $ 45 $ 25 $ 20 $ — $ 8 $ — 2017 19 — — — — 4 — 11 2016 155 43 43 24 20 5 9 (a) Piedmont contributed $10 million to its U.S. qualified defined benefit pension plan during the two months ended December 31, 2016, and $10 million for the year ended October 31, 2016. QUALIFIED PENSION PLANS Components of Net Periodic Pension Costs Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 182 $ 58 $ 51 $ 29 $ 22 $ 5 $ 11 $ 7 Interest cost on projected benefit obligation 299 72 94 43 50 17 23 11 Expected return on plan assets (559 ) (147 ) (178 ) (85 ) (91 ) (28 ) (42 ) (22 ) Amortization of actuarial loss 132 29 44 21 23 5 10 11 Amortization of prior service credit (32 ) (8 ) (3 ) (2 ) (1 ) — (2 ) (10 ) Net periodic pension costs (a)(b) $ 22 $ 4 $ 8 $ 6 $ 3 $ (1 ) $ — $ (3 ) Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 159 $ 48 $ 45 $ 26 $ 19 $ 4 $ 9 $ 10 Interest cost on projected benefit obligation 328 79 100 47 53 18 26 14 Expected return on plan assets (545 ) (142 ) (167 ) (82 ) (85 ) (27 ) (42 ) (24 ) Amortization of actuarial loss 146 31 52 23 29 5 12 11 Amortization of prior service credit (24 ) (8 ) (3 ) (2 ) (1 ) (1 ) (2 ) (2 ) Settlement charge 12 — — — — — — 12 Other 8 2 2 1 1 — 1 1 Net periodic pension costs (a)(b) $ 84 $ 10 $ 29 $ 13 $ 16 $ (1 ) $ 4 $ 22 Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 147 $ 48 $ 42 $ 24 $ 19 $ 4 $ 9 Interest cost on projected benefit obligation 335 86 106 49 55 19 28 Expected return on plan assets (519 ) (142 ) (168 ) (82 ) (84 ) (27 ) (42 ) Amortization of actuarial loss 134 33 51 23 29 4 11 Amortization of prior service credit (17 ) (8 ) (3 ) (2 ) (1 ) — (1 ) Settlement charge 3 — — — — — — Other 8 2 3 1 1 1 1 Net periodic pension costs (a)(b) $ 91 $ 19 $ 31 $ 13 $ 19 $ 1 $ 6 (a) Duke Energy amounts exclude $5 million , $7 million and $8 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $2 million , $3 million and $4 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. Piedmont Two Months Ended Year Ended (in millions) December 31, 2016 October 31, 2016 Service cost $ 2 $ 11 Interest cost on projected benefit obligation 2 9 Expected return on plan assets (4 ) (24 ) Amortization of actuarial loss 2 8 Amortization of prior service credit (1 ) (2 ) Settlement charge 3 — Net periodic pension costs $ 4 $ 2 Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net increase (decrease) $ 298 $ 170 $ 40 $ 31 $ 9 $ 10 $ 30 $ 8 Accumulated other comprehensive loss (income) Deferred income tax expense $ (2 ) — 1 — — — — — Amortization of prior year service credit 1 — — — — — — — Amortization of prior year actuarial losses 10 — (4 ) — — — — — Net amount recognized in accumulated other comprehensive income $ 9 $ — $ (3 ) $ — $ — $ — $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net (decrease) increase $ (212 ) $ (70 ) $ (49 ) $ (37 ) $ (11 ) $ 9 $ (19 ) $ (64 ) Accumulated other comprehensive (income) loss Deferred income tax expense $ — $ — $ 3 $ — $ — $ — $ — $ — Prior year service credit arising during the year 1 — — — — — — — Amortization of prior year actuarial losses (7 ) — (7 ) — — — — — Net amount recognized in accumulated other comprehensive income $ (6 ) $ — $ (4 ) $ — $ — $ — $ — $ — Piedmont's regulatory asset net increase was $34 million and $35 million for the two months ended December 31, 2016, and for the year ended October 31, 2016, respectively. Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 8,448 $ 2,029 $ 2,637 $ 1,211 $ 1,410 $ 479 $ 669 $ 313 Service cost 174 56 49 28 21 5 10 7 Interest cost 299 72 94 43 50 17 23 11 Actuarial gain (485 ) (44 ) (204 ) (87 ) (114 ) (29 ) (29 ) (18 ) Transfers — — — — — — — (16 ) Benefits paid (567 ) (159 ) (143 ) (70 ) (72 ) (37 ) (55 ) (33 ) Obligation at measurement date $ 7,869 $ 1,954 $ 2,433 $ 1,125 $ 1,295 $ 435 $ 618 $ 264 Accumulated Benefit Obligation at measurement date $ 7,818 $ 1,954 $ 2,404 $ 1,125 $ 1,265 $ 425 $ 614 $ 264 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 9,003 $ 2,372 $ 2,814 $ 1,366 $ 1,429 $ 458 $ 684 $ 368 Employer contributions 141 46 45 25 20 — 8 — Actual return on plan assets (344 ) (91 ) (110 ) (53 ) (55 ) (16 ) (26 ) (14 ) Benefits paid (567 ) (159 ) (143 ) (70 ) (72 ) (37 ) (55 ) (33 ) Transfers — — — — — — — (16 ) Plan assets at measurement date $ 8,233 $ 2,168 $ 2,606 $ 1,268 $ 1,322 $ 405 $ 611 $ 305 Funded status of plan $ 364 $ 214 $ 173 $ 143 $ 27 $ (30 ) $ (7 ) $ 41 Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 8,131 $ 1,952 $ 2,512 $ 1,158 $ 1,323 $ 447 $ 658 $ 344 Service cost 159 48 45 26 19 4 9 10 Interest cost 328 79 100 47 53 18 26 14 Actuarial loss 455 68 158 57 99 35 26 38 Transfers — 27 (32 ) (2 ) (15 ) 12 — — Plan amendments (61 ) — — — — — — (61 ) Benefits paid (537 ) (145 ) (146 ) (75 ) (69 ) (37 ) (50 ) (5 ) Benefits paid — settlements (27 ) — — — — — — (27 ) Obligation at measurement date $ 8,448 $ 2,029 $ 2,637 $ 1,211 $ 1,410 $ 479 $ 669 $ 313 Accumulated Benefit Obligation at measurement date $ 8,369 $ 2,029 $ 2,601 $ 1,211 $ 1,375 $ 468 $ 652 $ 313 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 8,531 $ 2,225 $ 2,675 $ 1,290 $ 1,352 $ 428 $ 657 $ 346 Employer contributions 19 — — — — 4 — 11 Actual return on plan assets 1,017 265 317 153 161 51 77 43 Benefits paid (537 ) (145 ) (146 ) (75 ) (69 ) (37 ) (50 ) (5 ) Benefits paid — settlements (27 ) — — — — — — (27 ) Transfers — 27 (32 ) (2 ) (15 ) 12 — — Plan assets at measurement date $ 9,003 $ 2,372 $ 2,814 $ 1,366 $ 1,429 $ 458 $ 684 $ 368 Funded status of plan $ 555 $ 343 $ 177 $ 155 $ 19 $ (21 ) $ 15 $ 55 Amounts Recognized in the Consolidated Balance Sheets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Prefunded pension (a) $ 433 $ 214 $ 242 $ 143 $ 96 $ 24 $ 39 $ 41 Noncurrent pension liability (b) $ 69 $ — $ 69 $ — $ 69 $ 54 $ 46 $ — Net asset (liability) recognized $ 364 $ 214 $ 173 $ 143 $ 27 $ (30 ) $ (7 ) $ 41 Regulatory assets $ 2,184 $ 576 $ 796 $ 372 $ 424 $ 100 $ 182 $ 81 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (43 ) $ — $ (2 ) $ — $ — $ — $ — $ — Prior service credit (4 ) — — — — — — — Net actuarial loss 126 — 5 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 79 $ — $ 3 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension costs in the next year Unrecognized net actuarial loss $ 97 $ 22 $ 37 $ 13 $ 24 $ 3 $ 5 $ 7 Unrecognized prior service credit (32 ) (8 ) (3 ) (2 ) (1 ) — (2 ) (9 ) December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Prefunded pension (a) $ 680 $ 343 $ 245 $ 155 $ 87 $ 8 $ 16 $ 55 Noncurrent pension liability (b) $ 125 $ — $ 68 $ — $ 68 $ 29 $ 1 $ — Net asset recognized $ 555 $ 343 $ 177 $ 155 $ 19 $ (21 ) $ 15 $ 55 Regulatory assets $ 1,886 $ 406 $ 756 $ 341 $ 415 $ 90 $ 152 $ 73 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (41 ) $ — $ (3 ) $ — $ — $ — $ — $ — Prior service credit (5 ) — — — — — — — Net actuarial loss 116 — 9 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 70 $ — $ 6 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension costs in the next year Unrecognized net actuarial loss $ 132 $ 29 $ 44 $ 21 $ 23 $ 5 $ 7 $ 11 Unrecognized prior service credit $ (32 ) $ (8 ) $ (3 ) $ (2 ) $ (1 ) $ — $ (2 ) $ (9 ) (a) Included in Other within Other Noncurrent Assets on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets. Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2018 Duke Duke Duke Duke Progress Energy Energy Energy (in millions) Energy Energy Florida Ohio Indiana Projected benefit obligation $ 679 $ 679 $ 679 $ 123 $ 203 Accumulated benefit obligation 651 651 651 115 199 Fair value of plan assets 610 610 610 69 159 December 31, 2017 Duke Duke Duke Progress Energy Energy (in millions) Energy Energy Florida Ohio Projected benefit obligation $ 1,386 $ 718 $ 718 $ 337 Accumulated benefit obligation 1,326 683 683 326 Fair value of plan assets 1,260 650 650 308 Assumptions Used for Pension Benefits Accounting The discount rate used to determine the current year pension obligation and following year’s pension expense is based on a bond selection-settlement portfolio approach. This approach develops a discount rate by selecting a portfolio of high quality corporate bonds that generate sufficient cash flow to provide for projected benefit payments of the plan. The selected bond portfolio is derived from a universe of non-callable corporate bonds rated Aa quality or higher. After the bond portfolio is selected, a single interest rate is determined that equates the present value of the plan’s projected benefit payments discounted at this rate with the market value of the bonds selected. The average remaining service period for participants in active plans and life expectancy of participants in inactive plans is 13 years for Duke Energy and Duke Energy Progress, 12 years for Duke Energy Carolinas, Progress Energy, and Duke Energy Florida, 14 years for Duke Energy Ohio and Duke Energy Indiana, and 10 years for Piedmont. The following tables present the assumptions or range of assumptions used for pension benefit accounting. December 31, 2018 2017 2016 Benefit Obligations Discount rate 4.30% 3.60% 4.10% Salary increase 3.50 % – 4.00% 3.50 % – 4.00% 4.00 % – 4.50% Net Periodic Benefit Cost Discount rate 3.60% 4.10% 4.40% Salary increase 3.50 % – 4.00% 4.00 % – 4.50% 4.00 % – 4.40% Expected long-term rate of return on plan assets 6.50% 6.50 % – 6.75% 6.50 % – 6.75% Piedmont Two Months Ended Year Ended December 31, 2016 October 31, 2016 Benefit Obligations Discount rate 4.10 % 3.80 % Salary increase 4.50 % 4.05 % Net Periodic Benefit Cost Discount rate 3.80 % 4.34 % Salary increase 4.05 % 4.07 % Expected long-term rate of return on plan assets 6.75 % 7.25 % Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Years ending December 31, 2019 $ 662 $ 210 $ 179 $ 105 $ 73 $ 33 $ 47 $ 20 2020 651 177 171 90 80 37 51 24 2021 663 182 177 95 81 37 51 23 2022 662 189 179 94 84 37 49 22 2023 655 185 181 95 85 35 47 22 2024-2028 2,993 794 902 451 447 158 217 96 NON-QUALIFIED PENSION PLANS Components of Net Periodic Pension Costs Year Ended December 31, 2018 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Service cost $ 2 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 12 — 4 1 2 Amortization of actuarial loss 8 — 2 1 1 Amortization of prior service credit (2 ) — — — — Net periodic pension costs $ 20 $ 1 $ 6 $ 2 $ 3 Year Ended December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Service cost $ 2 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 13 1 5 1 2 Amortization of actuarial loss 8 — 2 1 1 Amortization of prior service credit (2 ) — — — — Net periodic pension costs $ 21 $ 2 $ 7 $ 2 $ 3 Year Ended December 31, 2016 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Service cost $ 2 $ — $ — $ — $ — Interest cost on projected benefit obligation 14 1 5 1 2 Amortization of actuarial loss 8 1 1 1 1 Amortization of prior service credit (1 ) — — — — Net periodic pension costs $ 23 $ 2 $ 6 $ 2 $ 3 Piedmont Year Ended (in millions) October 31, 2016 Amortization of prior service cost $ — Settlement charge 1 Net periodic pension costs $ 1 Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2018 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Regulatory assets, net (decrease) increase $ (16 ) $ 1 $ (6 ) $ (3 ) $ (3 ) Accumulated other comprehensive (income) loss Deferred income tax benefit $ 1 $ — $ 1 $ — $ — Actuarial gain arising during the year (4 ) — (3 ) — — Net amount recognized in accumulated other comprehensive loss (income) $ (3 ) $ — $ (2 ) $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Regulatory assets, net increase (decrease) $ 5 $ (1 ) $ 3 $ 1 $ 2 Accumulated other comprehensive (income) loss Prior service credit arising during the year $ (1 ) $ — $ — $ — $ — Actuarial loss arising during the year 2 — — — — Net amount recognized in accumulated other comprehensive loss (income) $ 1 $ — $ — $ — $ — Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Service cost 2 1 — — — — — — Interest cost 12 — 4 1 2 — — — Actuarial gain (17 ) — (6 ) (2 ) (3 ) (1 ) — (1 ) Benefits paid (24 ) (1 ) (8 ) (3 ) (3 ) — — — Obligation at measurement date $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Accumulated Benefit Obligation at measurement date $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Change in Fair Value of Plan Assets Benefits paid $ (24 ) $ (1 ) $ (8 ) $ (3 ) $ (3 ) $ — $ — $ — Employer contributions 24 1 8 3 3 — — — Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 332 $ 14 $ 114 $ 33 $ 46 $ 4 $ 3 $ 4 Service cost 2 1 — — — — — — Interest cost 13 1 5 1 2 — — — Actuarial loss (gain) 15 — 5 4 2 — — — Benefits paid (31 ) (2 ) (8 ) (3 ) (3 ) — — — Obligation at measurement date $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Accumulated Benefit Obligation at measurement date $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Change in Fair Value of Plan Assets Benefits paid $ (31 ) $ (2 ) $ (8 ) $ (3 ) $ (3 ) $ — $ — $ — Employer contributions 31 2 8 3 3 — — — Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — $ — Amounts Recognized in the Consolidated Balance Sheets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current pension liability (a) $ 21 $ 2 $ 8 $ 3 $ 3 $ — $ — $ — Noncurrent pension liability (b) 283 12 98 28 40 3 3 3 Total accrued pension liability $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Regulatory assets $ 62 $ 5 $ 15 $ 5 $ 10 $ 1 $ — $ 1 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (3 ) $ — $ (2 ) $ — $ — $ — $ — $ — Prior service credit (1 ) — — — — — — — Net actuarial loss 8 — 6 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 4 $ — $ 4 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss $ 6 $ — $ 2 $ 1 $ 1 $ — $ — $ — Unrecognized prior service credit (2 ) — — — — — — — December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current pension liability (a) $ 23 $ 2 $ 8 $ 3 $ 3 $ — $ — $ — Noncurrent pension liability (b) 308 12 108 32 44 4 3 4 Total accrued pension liability $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Regulatory assets $ 78 $ 4 $ 21 $ 8 $ 13 $ 1 $ — $ 1 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (4 ) $ — $ (3 ) $ — $ — $ — $ — $ — Prior service credit (1 ) — — — — — — — Net actuarial loss 12 — 9 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 7 $ — $ 6 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss $ 8 $ — $ 2 $ 1 $ 1 $ — $ — $ — Unrecognized prior service credit $ (2 ) $ — $ — $ — $ — $ — $ — $ — (a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets. Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Projected benefit obligation $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Accumulated benefit obligation 304 14 106 31 43 3 3 3 December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Projected benefit obligation $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Accumulated benefit obligation 331 14 116 35 47 4 3 4 Assumptions Used for Pension Benefits Accounting The discount rate used to determine the current year pension obligation and following year’s pension expense is based on a bond selection-settlement portfolio approach. This approach develops a discount rate by selecting a portfolio of high quality corporate bonds that generate sufficient cash flow to provide for projected benefit payments of the plan. The selected bond portfolio is derived from a universe of non-callable corporate bonds rated Aa quality or higher. After the bond portfolio is selected, a single interest rate is determined that equates the present value of the plan’s projected benefit payments discounted at this rate with the market value of the bonds selected. The average remaining service period of active covered employees is 10 years for Duke Energy, 13 years for Progress Energy, 11 years for Duke Energy Progress, 15 years for Duke Energy Florida, eight years for Duke Energy Carolinas, Duke Energy Ohio, Duke Energy Indiana and Piedmont. The following tables present the assumptions used for pension benefit accounting. December 31, 2018 2017 2016 Benefit Obligations Discount rate 4.30 % 3.60 % 4.10 % Salary increase 3.50 % – 4.00 % 3.50 % – 4.00 % 4.40 % Net Periodic Benefit Cost Discount rate 3.60 % 4.10 % 4.40 % Salary increase 3.50 % – 4.00 % 4.40 % 4.40 % Piedmont Two Months Ended Year Ended December 31, 2016 October 31, 2016 Benefit Obligations Discount rate 4.10 % 3.80 % Net Periodic Benefit Cost Discount rate 3.80 % 3.85 % Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Years ending December 31, 2019 $ 22 $ 2 $ 8 $ 3 $ 3 $ — $ — $ — 2020 21 1 8 2 3 — — — 2021 23 1 8 2 3 — — — 2022 25 1 8 2 3 — — — 2023 25 3 7 2 3 — — — 2024-2028 125 10 37 11 15 1 1 2 OTHER POST-RETIREMENT BENEFIT PLANS Duke Energy provides, and the Subsidiary Registrants participate in, some health care and life insurance benefits for retired employees on a contributory and non-contributory basis. Employees are eligible for these benefits if they have met age and service requirements at retirement, as defined in the plans. The health care benefits include medical, dental and prescription drug coverage and are subject to certain limitations, such as deductibles and copayments. Duke Energy did not make any pre-funding contributions to its other post-retirement benefit plans during the years ended December 31, 2018 , 2017 or 2016 . Components of Net Periodic Other Post-Retirement Benefit Costs Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 6 $ 1 $ 1 $ — $ 1 $ 1 $ 1 $ 1 Interest cost on accumulated post-retirement benefit obligation 28 7 12 6 6 1 3 1 Expected return on plan assets (13 ) (8 ) — — — — — (2 ) Amortization of actuarial loss 6 3 1 1 — — 4 — Amortization of prior service credit (19 ) (5 ) (8 ) (1 ) (7 ) (1 ) (1 ) (2 ) Net periodic post-retirement benefit costs (a)(b) $ 8 $ (2 ) $ 6 $ 6 $ — $ 1 $ 7 $ (2 ) Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 4 $ 1 $ — $ — $ — $ — $ — $ 1 Interest cost on accumulated post-retirement benefit obligation 34 8 13 7 6 1 3 1 Expected return on plan assets (14 ) (8 ) — — — — (1 ) (2 ) Amortization of actuarial loss (gain) 10 (2 ) 21 12 9 (2 ) (1 ) 1 Amortization of prior service credit (115 ) (10 ) (84 ) (54 ) (30 ) — (1 ) — Curtailment credit (c) (30 ) (4 ) (16 ) — (16 ) (2 ) (2 ) — Net periodic post-retirement benefit costs (a)(b) $ (111 ) $ (15 ) $ (66 ) $ (35 ) $ (31 ) $ (3 ) $ (2 ) $ 1 Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ 1 $ 1 $ — $ 1 $ — $ — Interest cost on accumulated post-retirement benefit obligation 35 8 15 8 7 1 4 Expected return on plan assets (12 ) (8 ) — — — — (1 ) Amortization of actuarial loss (gain) 6 (3 ) 22 13 9 (2 ) (1 ) Amortization of prior service credit (141 ) (14 ) (103 ) (68 ) (35 ) — (1 ) Net periodic post-retirement benefit costs (a)(b) $ (109 ) $ (16 ) $ (65 ) $ (47 ) $ (18 ) $ (1 ) $ 1 (a) Duke Energy amounts exclude $7 million , $7 million and $8 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $2 million , $2 million and $2 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (c) Curtailment credit resulted from a reduction in average future service of plan participants due to a plan amendment. Piedmont Year Ended (in millions) October 31, 2016 Service cost $ 1 Interest cost on projected benefit obligation 1 Expected return on plan assets (2 ) Amortization of actuarial loss 1 Net periodic pension costs $ 1 Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net increase (decrease) $ 137 $ — $ 133 $ 84 $ 49 $ — $ (5 ) $ 4 Regulatory liabilities, net increase (decrease) $ 154 $ (6 ) $ 149 $ 93 $ 56 $ 2 $ 3 $ — Accumulated other comprehensive (income) loss Deferred income tax benefit $ (1 ) $ — $ — $ — $ — $ — $ — $ — Amortization of prior year actuarial gain 1 — — — — — — — Net amount recognized in accumulated other comprehensive income $ — $ — $ — $ — $ — $ — $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net increase (decrease) $ 71 $ — $ 81 $ 42 $ 39 $ — $ (5 ) $ (11 ) Regulatory liabilities, net increase (decrease) $ (27 ) $ (2 ) $ — $ — $ — $ (3 ) $ (7 ) $ — Accumulated other comprehensive (income) loss Deferred income tax benefit $ (1 ) $ — $ — $ — $ — $ — $ — $ — Amortization of prior year prior service credit 3 — — — — — — — Net amount recognized in accumulated other comprehensive income $ 2 $ — $ — $ — $ — $ — $ — $ — Piedmont's regulatory assets net decreased $1 million for the two months ended December 31, 2016, and increased $2 million for the year ended October 31, 2016. Reconciliation of Funded Status to Accrued Other Post-Retirement Benefit Costs Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 813 $ 189 $ 342 $ 184 $ 156 $ 30 $ 78 $ 32 Service cost 6 1 1 — 1 1 1 1 Interest cost 28 7 12 6 6 1 3 1 Plan participants' contributions 18 3 6 4 3 1 2 — Actuarial gains (51 ) (8 ) (23 ) (9 ) (13 ) (2 ) (5 ) (1 ) Transfers — — — — — — — (1 ) Benefits paid (86 ) (18 ) (35 ) (19 ) (16 ) (2 ) (12 ) (2 ) Accumulated post-retirement benefit obligation at measurement date $ 728 $ 174 $ 303 $ 166 $ 137 $ 29 $ 67 $ 30 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 225 $ 133 $ — $ — $ — $ 7 $ 11 $ 31 Actual return on plan assets (8 ) (5 ) — — — — — (1 ) Benefits paid (86 ) (18 ) (35 ) (19 ) (16 ) (2 ) (12 ) (2 ) Employer contributions 46 2 29 15 13 2 4 1 Plan participants' contributions 18 3 6 4 3 1 2 — Plan assets at measurement date $ 195 $ 115 $ — $ — $ — $ 8 $ 5 $ 29 Funded status of plan $ (533 ) $ (59 ) $ (303 ) $ (166 ) $ (137 ) $ (21 ) $ (62 ) $ (1 ) Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 868 $ 201 $ 357 $ 191 $ 164 $ 32 $ 83 $ 39 Service cost 4 1 — — — — — 1 Interest cost 34 8 13 7 6 1 3 1 Plan participants' contributions 17 3 6 3 3 1 2 — Actuarial losses (gains) 4 (3 ) 4 1 3 — 3 1 Transfers — 2 (1 ) — (1 ) 1 — — Plan amendments (28 ) (5 ) (3 ) (1 ) (2 ) (2 ) (2 ) (9 ) Benefits paid (86 ) (18 ) (34 ) (17 ) (17 ) (3 ) (11 ) (1 ) Accumulated post-retirement benefit obligation at measurement date $ 813 $ 189 $ 342 $ 184 $ 156 $ 30 $ 78 $ 32 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 244 $ 137 $ 1 $ — $ — $ 7 $ 22 $ 29 Actual return on plan assets 25 15 1 — — 2 1 3 Benefits paid (86 ) (18 ) (34 ) (17 ) (17 ) (3 ) (11 ) (1 ) Employer contributions (reimbursements) 25 (4 ) 26 14 14 — (3 ) — Plan participants' contributions 17 3 6 3 3 1 2 — Plan assets at measurement date $ 225 $ 133 $ — $ — $ — $ 7 $ 11 $ 31 Funded status of plan $ (588 ) $ (56 ) $ (342 ) $ (184 ) $ (156 ) $ (23 ) $ (67 ) $ (1 ) Amounts Recognized in the Consolidated Balance Sheets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energ

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Tax Act On December 22, 2017, President Trump signed the Tax Act into law. Among other provisions, the Tax Act lowered the corporate federal income tax rate from 35 to 21 percent, limits interest deductions outside of regulated utility operations, requires the normalization of excess deferred taxes associated with property under the average rate assumption method as a prerequisite to qualifying for accelerated depreciation and repealed the federal manufacturing deduction. The Tax Act also repealed the corporate AMT and stipulates a refund of 50 percent of remaining AMT credit carryforwards (to the extent the credits exceed regular tax for the year) for tax years 2018, 2019 and 2020 with all remaining AMT credits to be refunded in tax year 2021. On December 22, 2017, the SEC staff issued SAB 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act, which provides guidance on accounting for the Tax Act’s impact. SAB 118 provides a measurement period, which in no case should extend beyond one year from the Tax Act enactment date, during which a company acting in good faith may complete the accounting for the impacts of the Tax Act under ASC Topic 740. In accordance with SAB 118, a company must reflect the income tax effects of the Tax Act in the reporting period in which the accounting under ASC Topic 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete, a company can determine a reasonable estimate for those effects and record a provisional estimate in the financial statements in the first reporting period in which a reasonable estimate can be determined. As of December 31, 2018, the accounting for the effects of the Tax Act is complete. During the year ended December 31, 2018, Duke Energy recorded the following measurement period adjustments in accordance with SAB 118: • Additional tax expense of $23 million related to the completion of the analysis of Duke Energy’s existing regulatory liability related to deferred taxes; • A $10 million tax benefit for the remeasurement of deferred tax assets and deferred tax liabilities primarily related to the guidance on bonus depreciation issued by the IRS in August 2018 affecting the computation of the Company's 2017 Federal income tax liability; • Additional tax expense of $7 million related to the portion of the deferred tax asset as of December 31, 2017, that represents nondeductible long-term incentives under the Tax Act’s limitation on the deductibility of executive compensation; and • During the fourth quarter of 2018, the Company released the $76 million valuation allowance that it recorded in the first quarter of 2018 as a result of additional guidance published by the IRS that stated refundable AMT credits would not be subject to sequestration. • The majority of Duke Energy’s operations are regulated and it is expected that the Subsidiary Registrants will ultimately pass on the savings associated with the amount representing the remeasurement of deferred tax balances related to regulated operations to customers. For Duke Energy's regulated operations, where the reduction is expected to be returned to customers in future rates, the remeasurement has been deferred as a regulatory liability. During 2018, Duke Energy recorded an additional regulatory liability of $83 million , representing the revaluation of those deferred tax balances. The Subsidiary Registrants continue to respond to requests from regulators in various jurisdictions to determine the timing and magnitude of savings they will pass on to customers. In addition, during 2018 Duke Energy reclassified $573 million of AMT credit carryforwards from noncurrent deferred tax liabilities to a current federal income tax receivable as the Company expects to receive this amount via a refund from the IRS in 2019, based on the expected filing of Duke Energy's 2018 income tax return in the second quarter of 2019. Income Tax Expense Components of Income Tax Expense Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current income taxes Federal $ (647 ) $ (8 ) $ (135 ) $ (71 ) $ (49 ) $ 20 $ 29 $ 67 State (11 ) 6 (5 ) (5 ) (10 ) (1 ) 3 1 Foreign 3 — — — — — — — Total current income taxes (655 ) (2 ) (140 ) (76 ) (59 ) 19 32 68 Deferred income taxes Federal 1,064 299 341 256 115 21 74 (36 ) State 49 11 20 (17 ) 45 3 22 5 Total deferred income taxes (a)(b) 1,113 310 361 239 160 24 96 (31 ) Investment tax credit amortization (10 ) (5 ) (3 ) (3 ) — — — — Income tax expense from continuing operations 448 303 218 160 101 43 128 37 Tax benefit from discontinued operations (26 ) — — — — — — — Total income tax expense included in Consolidated Statements of Operations $ 422 $ 303 $ 218 $ 160 $ 101 $ 43 $ 128 $ 37 (a) Includes benefits of NOL carryforwards and tax credit carryforwards of $22 million at Duke Energy Carolinas, $293 million at Progress Energy, $59 million at Duke Energy Progress, $219 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $21 million at Duke Energy Indiana and $39 million at Piedmont. In addition, total deferred income taxes includes utilization of NOL carryforwards and tax credit carryforwards of $18 million at Duke Energy. (b) For the year ended December 31, 2018, the Company has revised the December 31, 2017, estimates of the income tax effects of the Tax Act, in accordance with SAB 118. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense. Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current income taxes Federal $ (247 ) $ 221 $ (436 ) $ (95 ) $ (188 ) $ (37 ) $ 128 $ (90 ) State 4 20 (5 ) 2 (11 ) 2 21 (3 ) Foreign 3 — — — — — — — Total current income taxes (240 ) 241 (441 ) (93 ) (199 ) (35 ) 149 (93 ) Deferred income taxes Federal 1,344 381 664 378 194 99 138 147 State 102 35 44 10 51 (4 ) 14 8 Total deferred income taxes (a)(b) 1,446 416 708 388 245 95 152 155 Investment tax credit amortization (10 ) (5 ) (3 ) (3 ) — (1 ) — — Income tax expense from continuing operations 1,196 652 264 292 46 59 301 62 Tax benefit from discontinued operations (6 ) — — — — — — — Total income tax expense included in Consolidated Statements of Operations $ 1,190 $ 652 $ 264 $ 292 $ 46 $ 59 $ 301 $ 62 (a) Includes utilization of NOL carryforwards and tax credit carryforwards of $428 million at Duke Energy, $74 million at Progress Energy, $36 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $42 million at Duke Energy Indiana and $79 million at Piedmont. In addition, total deferred income taxes includes benefits of NOL carryforwards and tax credit carryforwards of $10 million at Duke Energy Carolinas and $1 million at Duke Energy Progress. (b) As a result of the Tax Act, Duke Energy's deferred tax assets and liabilities were revalued as of December 31, 2017. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense. Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ — $ 139 $ 15 $ (59 ) $ 76 $ (7 ) $ 7 State (15 ) 25 (19 ) (25 ) 22 (13 ) 6 Foreign 2 — — — — — — Total current income taxes (13 ) 164 (4 ) (84 ) 98 (20 ) 13 Deferred income taxes Federal 1,064 430 486 350 199 88 202 State 117 45 50 40 25 11 11 Total deferred income taxes (a) 1,181 475 536 390 224 99 213 Investment tax credit amortization (12 ) (5 ) (5 ) (5 ) — (1 ) (1 ) Income tax expense from continuing operations 1,156 634 527 301 322 78 225 Tax (benefit) expense from discontinued operations (30 ) — 1 — — (36 ) — Total income tax expense included in Consolidated Statements of Operations $ 1,126 $ 634 $ 528 $ 301 $ 322 $ 42 $ 225 (a) Includes benefits of NOL carryforwards and utilization of NOL and tax credit carryforwards of $648 million at Duke Energy, $4 million at Duke Energy Carolinas, $190 million at Progress Energy, $60 million at Duke Energy Progress, $49 million at Duke Energy Florida, $26 million at Duke Energy Ohio and $58 million at Duke Energy Indiana. Piedmont Two Months Ended Year Ended October 31, (in millions) December 31, 2016 2016 Current income taxes Federal $ 4 $ 27 State (2 ) 12 Total current income taxes 2 39 Deferred income taxes Federal 24 79 State 6 6 Total deferred income taxes (a) 30 85 Total income tax expense from continuing operations included in Consolidated Statements of Operations $ 32 $ 124 (a) Includes benefits of NOL and tax carryforwards of $17 million and $91 million for the two months ended December 31, 2016, and the year ended October 31, 2016, respectively. Duke Energy Income from Continuing Operations before Income Taxes Years Ended December 31, (in millions) 2018 2017 2016 Domestic (a) $ 3,018 $ 4,207 $ 3,689 Foreign 55 59 45 Income from continuing operations before income taxes $ 3,073 $ 4,266 $ 3,734 (a) Includes a $16 million expense in 2017 related to the Tax Act impact on equity earnings included within Equity in earnings (losses) of unconsolidated affiliates on the Consolidated Statement of Operations. Taxes on Foreign Earnings In February 2016, Duke Energy announced it had initiated a process to divest the International Disposal Group and, accordingly, no longer intended to indefinitely reinvest post-2014 undistributed foreign earnings. This change in the company's intent, combined with the extension of bonus depreciation by Congress in late 2015, allowed Duke Energy to more efficiently utilize foreign tax credits and reduce U.S. deferred tax liabilities associated with the historical unremitted foreign earnings by approximately $95 million during the year ended December 31, 2016. Due to the classification of the International Disposal Group as discontinued operations beginning in the fourth quarter of 2016, income tax amounts related to the International Disposal Group's foreign earnings are presented within Income (Loss) From Discontinued Operations, net of tax on the Consolidated Statements of Operations. In December 2016, Duke Energy closed on the sale of the International Disposal Group in two separate transactions to execute the divestiture. See Note 2 for additional information on the sale. Statutory Rate Reconciliation The following tables present a reconciliation of income tax expense at the U.S. federal statutory tax rate to the actual tax expense from continuing operations. Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Income tax expense, computed at the statutory rate of 21 percent $ 645 $ 288 $ 263 $ 174 $ 137 $ 46 $ 109 $ 35 State income tax, net of federal income tax effect 30 14 13 (17 ) 28 2 20 4 Amortization of excess deferred income tax (61 ) — (55 ) (1 ) (54 ) (3 ) (2 ) — AFUDC equity income (42 ) (15 ) (22 ) (12 ) (10 ) (2 ) (2 ) — AFUDC equity depreciation 31 18 9 5 4 1 4 — Renewable energy production tax credits (129 ) — — — — — — — Other tax credits (28 ) (7 ) (13 ) (5 ) (8 ) (1 ) (1 ) (3 ) Tax Act (a) 20 1 25 19 — 2 — — Other items, net (18 ) 4 (2 ) (3 ) 4 (2 ) — 1 Income tax expense from continuing operations $ 448 $ 303 $ 218 $ 160 $ 101 $ 43 $ 128 $ 37 Effective tax rate 14.6 % 22.1 % 17.4 % 19.3 % 15.4 % 19.6 % 24.6 % 22.3 % (a) For the year ended December 31, 2018, the Company revised the December 31, 2017 estimates of the income tax effects of the Tax Act, in accordance with SAB 118. Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits. Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Income tax expense, computed at the statutory rate of 35 percent $ 1,493 $ 653 $ 536 $ 353 $ 265 $ 88 $ 229 $ 70 State income tax, net of federal income tax effect 69 36 25 8 26 (1 ) 23 3 AFUDC equity income (81 ) (37 ) (32 ) (17 ) (16 ) (4 ) (8 ) — Renewable energy production tax credits (132 ) — — — — — — — Tax Act (a) (112 ) 15 (246 ) (40 ) (226 ) (23 ) 55 (12 ) Tax true up (52 ) (24 ) (19 ) (13 ) (7 ) (5 ) (6 ) — Other items, net 11 9 — 1 4 4 8 1 Income tax expense from continuing operations $ 1,196 $ 652 $ 264 $ 292 $ 46 $ 59 $ 301 $ 62 Effective tax rate 28.0 % 34.9 % 17.2 % 29.0 % 6.1 % 23.4 % 46.0 % 30.8 % (a) Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related to abandoned or impaired assets, certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits. Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,307 $ 630 $ 548 $ 315 $ 306 $ 95 $ 212 State income tax, net of federal income tax effect 64 46 20 10 30 (2 ) 11 AFUDC equity income (70 ) (36 ) (26 ) (17 ) (9 ) (2 ) (6 ) Renewable energy production tax credits (97 ) — — — — — — Audit adjustment 5 3 — — — — — Tax true up (14 ) (14 ) (11 ) (3 ) (9 ) (16 ) 2 Other items, net (39 ) 5 (4 ) (4 ) 4 3 6 Income tax expense from continuing operations $ 1,156 $ 634 $ 527 $ 301 $ 322 $ 78 $ 225 Effective tax rate 31.0 % 35.2 % 33.7 % 33.4 % 36.9 % 28.9 % 37.1 % Piedmont Two Months Ended Year Ended October 31, (in millions) December 31, 2016 2016 Income tax expense, computed at the statutory rate of 35 percent $ 30 $ 111 State income tax, net of federal income tax effect 1 11 Other items, net 1 2 Income tax expense from continuing operations $ 32 $ 124 Effective tax rate 37.2 % 39.1 % Valuation allowances have been established for certain state NOL carryforwards and state income tax credits that reduce deferred tax assets to an amount that will be realized on a more-likely-than-not basis. The net change in the total valuation allowance is included in the State income tax, net of federal income tax effect in the above tables. DEFERRED TAXES Net Deferred Income Tax Liability Components December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Deferred credits and other liabilities $ 164 $ 64 $ 35 $ 53 $ — $ 17 $ 6 $ 17 Capital lease obligations 60 26 — — — — 2 — Pension, post-retirement and other employee benefits 347 24 110 47 58 16 24 (1 ) Progress Energy merger purchase accounting adjustments (a) 483 — — — — — — — Tax credits and NOL carryforwards 4,580 257 693 215 363 42 237 110 Regulatory liabilities and deferred credits — — — — — 56 — 48 Investments and other assets — — — — — 18 — 16 Other 25 6 5 5 — 1 (1 ) — Valuation allowance (484 ) — — — — — — — Total deferred income tax assets 5,175 377 843 320 421 150 268 190 Investments and other assets (1,317 ) (795 ) (430 ) (272 ) (163 ) — (5 ) — Accelerated depreciation rates (10,124 ) (3,207 ) (3,369 ) (1,735 ) (1,670 ) (967 ) (1,081 ) (733 ) Regulatory assets and deferred debits, net (1,540 ) (64 ) (985 ) (432 ) (574 ) — (191 ) — Other — — — — — — — (8 ) Total deferred income tax liabilities (12,981 ) (4,066 ) (4,784 ) (2,439 ) (2,407 ) (967 ) (1,277 ) (741 ) Net deferred income tax liabilities $ (7,806 ) $ (3,689 ) $ (3,941 ) $ (2,119 ) $ (1,986 ) $ (817 ) $ (1,009 ) $ (551 ) (a) Primarily related to capital lease obligations and debt fair value adjustments. The following table presents the expiration of tax credits and NOL carryforwards. December 31, 2018 (in millions) Amount Expiration Year Investment tax credits $ 1,614 2024 — 2038 Alternative minimum tax credits 574 Refundable by 2021 Federal NOL carryforwards (a)(e) 788 2022 — Indefinite State NOL carryforwards and credits (b)(e) 301 2019 — Indefinite Foreign NOL carryforwards (c) 12 2027 — 2037 Foreign Tax Credits (d) 1,271 2024 — 2027 Charitable contribution carryforwards 20 2019 — 2023 Total tax credits and NOL carryforwards $ 4,580 (a) A valuation allowance of $4 million has been recorded on the Federal NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (b) A valuation allowance of $85 million has been recorded on the state NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (c) A valuation allowance of $12 million has been recorded on the foreign NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (d) A valuation allowance of $383 million has been recorded on the foreign tax credits, as presented in the Net Deferred Income Tax Liability Components table. (e) Indefinite carryforward for Federal NOLs, and NOLs for states that have adopted the Tax Act's NOL provisions, generated in tax years beginning after December 31, 2017. December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Deferred credits and other liabilities $ 143 $ 33 $ 78 $ 23 $ 49 $ 11 $ 6 $ (5 ) Capital lease obligations 49 14 — — — — 2 — Pension, post-retirement and other employee benefits 295 (17 ) 111 44 60 14 18 (4 ) Progress Energy merger purchase accounting adjustments (a) 536 — — — — — — — Tax credits and NOL carryforwards 4,527 234 402 156 143 25 216 70 Regulatory liabilities and deferred credits — 222 — — — 65 — 61 Investments and other assets — — — — — — 1 18 Other 73 10 1 4 — — — — Valuation allowance (519 ) — (14 ) — — — — — Total deferred income tax assets 5,104 496 578 227 252 115 243 140 Investments and other assets (1,419 ) (849 ) (470 ) (289 ) (187 ) — (14 ) — Accelerated depreciation rates (9,216 ) (3,060 ) (2,803 ) (1,583 ) (1,257 ) (896 ) (966 ) (697 ) Regulatory assets and deferred debits, net (1,090 ) — (807 ) (238 ) (569 ) — (188 ) — Other — — — — — — — (7 ) Total deferred income tax liabilities (11,725 ) (3,909 ) (4,080 ) (2,110 ) (2,013 ) (896 ) (1,168 ) (704 ) Net deferred income tax liabilities $ (6,621 ) $ (3,413 ) $ (3,502 ) $ (1,883 ) $ (1,761 ) $ (781 ) $ (925 ) $ (564 ) (a) Primarily related to capital lease obligations and debt fair value adjustments. On June 28, 2017, the North Carolina General Assembly amended N.C. Gen. Stat. 105-130.3, reducing the North Carolina corporate income tax rate from a statutory rate of 3.0 to 2.5 percent beginning January 1, 2019. Duke Energy recorded a net reduction of approximately $55 million to their North Carolina deferred tax liabilities in the second quarter of 2017. The significant majority of this deferred tax liability reduction was offset by recording a regulatory liability pending NCUC determination of the disposition of amounts related to Duke Energy Carolinas, Duke Energy Progress and Piedmont. The impact did not have a significant impact on the financial position, results of operation or cash flows of Duke Energy, Duke Energy Carolinas, Progress Energy or Duke Energy Progress. UNRECOGNIZED TAX BENEFITS The following tables present changes to unrecognized tax benefits. Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unrecognized tax benefits – January 1 $ 25 $ 5 $ 5 $ 5 $ 5 $ 1 $ 1 $ 3 Unrecognized tax benefits increases (decreases) Gross decreases – tax positions in prior periods (2 ) (1 ) — — (4 ) — — — Gross increases – current period tax positions 7 2 4 1 2 — — 1 Decreases due to settlements (6 ) — — — — — — — Total changes (1 ) 1 4 1 (2 ) — — 1 Unrecognized tax benefits – December 31 $ 24 $ 6 $ 9 $ 6 $ 3 $ 1 $ 1 $ 4 Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unrecognized tax benefits – January 1 $ 17 $ 1 $ 2 $ 2 $ 4 $ 4 $ — $ — Unrecognized tax benefits increases (decreases) Gross increases – tax positions in prior periods 12 4 3 3 1 1 1 3 Gross decreases – tax positions in prior periods (4 ) — — — — (4 ) — — Total changes 8 4 3 3 1 (3 ) 1 3 Unrecognized tax benefits – December 31 $ 25 $ 5 $ 5 $ 5 $ 5 $ 1 $ 1 $ 3 Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Unrecognized tax benefits – January 1 $ 88 $ 72 $ 1 $ 3 $ — $ — $ 1 Unrecognized tax benefits increases (decreases) Gross increases – tax positions in prior periods — — — — 4 4 — Gross decreases – tax positions in prior periods (4 ) (4 ) (1 ) (1 ) — — — Decreases due to settlements (68 ) (67 ) — — — — (1 ) Reduction due to lapse of statute of limitations 1 — 2 — — — — Total changes (71 ) (71 ) 1 (1 ) 4 4 (1 ) Unrecognized tax benefits – December 31 $ 17 $ 1 $ 2 $ 2 $ 4 $ 4 $ — The following table includes additional information regarding the Duke Energy Registrants' unrecognized tax benefits at December 31, 2018 . All Duke Energy Registrants do not anticipate a material increase or decrease in unrecognized tax benefits within the next 12 months. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Amount that if recognized, would affect the effective tax rate or regulatory liability (a) $ 21 $ 6 $ 9 $ 6 $ 3 $ 1 $ 1 $ 4 Amount that if recognized, would be recorded as a component of discontinued operations 2 — — — — — — — (a) Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana and Piedmont are unable to estimate the specific amounts that would affect the effective tax rate versus the regulatory liability. OTHER TAX MATTERS The following tables include interest recognized in the Consolidated Statements of Operations and the Consolidated Balance Sheets. Year Ended December 31, 2018 Duke Duke Progress Energy (in millions) Energy Energy Progress Net interest income recognized related to income taxes $ 2 $ — $ — Interest payable related to income taxes 3 1 1 Year Ended December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Net interest income recognized related to income taxes $ — $ — $ 1 $ — $ 1 Net interest expense recognized related to income taxes — 2 — — — Interest payable related to income taxes 5 25 1 1 — Year Ended December 31, 2016 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Net interest income recognized related to income taxes $ — $ — $ 1 $ — $ 2 Net interest expense recognized related to income taxes — 7 — — — Interest payable related to income taxes 4 23 1 1 — Piedmont recognized $1 million in net interest income related to income taxes in the Consolidated Statements of Operations for the year ended October 31, 2016. Duke Energy and its subsidiaries are no longer subject to U.S. federal examination for years before 2015. With few exceptions, Duke Energy and its subsidiaries are no longer subject to state, local or non-U.S. income tax examinations by tax authorities for years before 2015.

Other Income and Expenses, Net

Other Income and Expenses, Net	12 Months Ended
	Dec. 31, 2018
Other Income and Expenses [Abstract]
Other Income and Expenses, Net	OTHER INCOME AND EXPENSES, NET The components of Other income and expenses, net on the Consolidated Statements of Operations are as follows. Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Interest income $ 20 $ 1 $ 18 $ 1 $ 18 $ 7 $ 9 $ 1 AFUDC equity 221 73 104 57 47 11 32 — Post in-service equity returns 15 9 5 5 — 1 — — Nonoperating income, other 143 70 38 24 21 4 4 13 Other income and expense, net $ 399 $ 153 $ 165 $ 87 $ 86 $ 23 $ 45 $ 14 Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Interest income $ 13 $ 2 $ 6 $ 2 $ 5 $ 6 $ 8 $ — AFUDC equity 237 106 92 47 45 11 28 — Post in-service equity returns 40 28 12 12 — — — — Nonoperating income, other 218 63 99 54 46 6 11 (11 ) Other income and expense, net $ 508 $ 199 $ 209 $ 115 $ 96 $ 23 $ 47 $ (11 ) Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 21 $ 4 $ 4 $ 3 $ 2 $ 5 $ 6 AFUDC equity 200 102 76 50 26 6 16 Post in-service equity returns 67 55 12 12 — — — Nonoperating income, other 175 53 94 67 35 — 4 Other income and expense, net (a) $ 463 $ 214 $ 186 $ 132 $ 63 $ 11 $ 26 (a) Amounts for Piedmont for the two months ended December 31, 2016, and for the year ended October 31, 2016, were not material.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS For information on subsequent events related to the adoption of the new lease accounting standard, regulatory matters, commitments and contingencies and debt and credit facilities, see Notes 1, 4, 5 and 6, respectively.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	QUARTERLY FINANCIAL DATA (UNAUDITED) DUKE ENERGY Quarterly EPS amounts may not sum to the full-year total due to changes in the weighted average number of common shares outstanding and rounding. First Second Third Fourth (in millions, except per share data) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 6,135 $ 5,643 $ 6,628 $ 6,115 $ 24,521 Operating income 1,256 979 1,579 871 4,685 Income from continuing operations 622 507 1,062 434 2,625 (Loss) Income from discontinued operations, net of tax — (5 ) 4 20 19 Net income 622 502 1,066 454 2,644 Net income attributable to Duke Energy Corporation 620 500 1,082 464 2,666 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 0.88 $ 0.72 $ 1.51 $ 0.62 $ 3.73 Diluted $ 0.88 $ 0.72 $ 1.51 $ 0.62 $ 3.73 (Loss) Income from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ — $ (0.01 ) $ — $ 0.03 $ 0.03 Diluted $ — $ (0.01 ) $ — $ 0.03 $ 0.03 Net income attributable to Duke Energy Corporation common stockholders Basic $ 0.88 $ 0.71 $ 1.51 $ 0.65 $ 3.76 Diluted $ 0.88 $ 0.71 $ 1.51 $ 0.65 $ 3.76 2017 Operating revenues $ 5,729 $ 5,555 $ 6,482 $ 5,799 $ 23,565 Operating income 1,402 1,353 1,661 1,209 5,625 Income from continuing operations 717 691 957 705 3,070 Loss from discontinued operations, net of tax — (2 ) (2 ) (2 ) (6 ) Net income 717 689 955 703 3,064 Net income attributable to Duke Energy Corporation 716 686 954 703 3,059 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.37 Diluted $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.37 Loss from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ — $ — $ — $ — $ (0.01 ) Diluted $ — $ — $ — $ — $ (0.01 ) Net income attributable to Duke Energy Corporation common stockholders Basic $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.36 Diluted $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.36 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (17 ) $ (20 ) $ (16 ) $ (31 ) $ (84 ) Regulatory and Legislative Impacts (see Note 4) (86 ) (179 ) — — (265 ) Sale of Retired Plant (see Note 3) (107 ) — — — (107 ) Impairment Charges (see Notes 4, 11 and 12) (55 ) — (93 ) (60 ) (208 ) Severance Charges (see Note 20) — — — (187 ) (187 ) Impacts of the Tax Act (see Note 23) (76 ) — 3 53 (20 ) Total $ (341 ) $ (199 ) $ (106 ) $ (225 ) $ (871 ) 2017 Costs to Achieve Mergers (see Note 2) $ (16 ) $ (30 ) $ (23 ) $ (34 ) $ (103 ) Regulatory Settlements (see Note 4) — — (135 ) (23 ) (158 ) Commercial Renewables Impairments (see Notes 10 and 11) — — (84 ) (18 ) (102 ) Impacts of the Tax Act (see Note 23) — — — 102 102 Total $ (16 ) $ (30 ) $ (242 ) $ 27 $ (261 ) DUKE ENERGY CAROLINAS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 1,763 $ 1,672 $ 2,090 $ 1,775 $ 7,300 Operating income 482 224 713 241 1,660 Net income 323 117 496 135 1,071 2017 Operating revenues $ 1,716 $ 1,729 $ 2,136 $ 1,721 $ 7,302 Operating income 471 471 763 384 2,089 Net income 270 273 466 205 1,214 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (2 ) $ (2 ) $ (1 ) $ (9 ) Regulatory and Legislative Impacts (see Note 4) (19 ) (179 ) — — (198 ) Severance Charges (see Note 20) — — — (102 ) (102 ) Impacts of the Tax Act (see Note 23) — — (1 ) — (1 ) Total $ (23 ) $ (181 ) $ (3 ) $ (103 ) $ (310 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (6 ) $ (5 ) $ (5 ) $ (20 ) Impacts of the Tax Act (see Note 23) — — — (15 ) (15 ) Total $ (4 ) $ (6 ) $ (5 ) $ (20 ) $ (35 ) PROGRESS ENERGY First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 2,576 $ 2,498 $ 3,045 $ 2,609 $ 10,728 Operating income 447 484 663 334 1,928 Net income 237 267 406 123 1,033 Net income attributable to Parent 235 265 404 123 1,027 2017 Operating revenues $ 2,179 $ 2,392 $ 2,864 $ 2,348 $ 9,783 Operating income 471 576 641 459 2,147 Net income 201 277 343 447 1,268 Net income attributable to Parent 199 274 341 444 1,258 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (3 ) $ (1 ) $ (2 ) $ (10 ) Regulatory and Legislative Impacts (see Note 4) (67 ) — — — (67 ) Impairment Charges (see Note 4) — — — (60 ) (60 ) Severance Charges (see Note 20) — — — (69 ) (69 ) Impacts of the Tax Act (see Note 23) (1 ) — (5 ) (19 ) (25 ) Total $ (72 ) $ (3 ) $ (6 ) $ (150 ) $ (231 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (7 ) $ (6 ) $ (6 ) $ (23 ) Regulatory Settlements (see Note 4) — — (135 ) (23 ) (158 ) Impacts of the Tax Act (see Note 23) — — — 246 246 Total $ (4 ) $ (7 ) $ (141 ) $ 217 $ 65 DUKE ENERGY PROGRESS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 1,460 $ 1,291 $ 1,582 $ 1,366 $ 5,699 Operating income 269 233 330 227 1,059 Net income 177 139 216 135 667 2017 Operating revenues $ 1,219 $ 1,199 $ 1,460 $ 1,251 $ 5,129 Operating income 274 270 398 243 1,185 Net income 147 154 246 168 715 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (2 ) $ (1 ) $ (1 ) $ (6 ) Regulatory and Legislative Impacts (see Note 4) (67 ) — — — (67 ) Severance Charges (see Note 20) — — — (52 ) (52 ) Impacts of the Tax Act (see Note 23) — — (4 ) (15 ) (19 ) Total $ (69 ) $ (2 ) $ (5 ) $ (68 ) $ (144 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (4 ) $ (4 ) $ (4 ) $ (14 ) Regulatory Settlements (see Note 4) — — — (23 ) (23 ) Impacts of the Tax Act (see Note 23) — — — 40 40 Total $ (2 ) $ (4 ) $ (4 ) $ 13 $ 3 DUKE ENERGY FLORIDA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 1,115 $ 1,203 $ 1,462 $ 1,241 $ 5,021 Operating income 173 245 331 107 856 Net income 103 168 243 40 554 2017 Operating revenues $ 959 $ 1,191 $ 1,401 $ 1,095 $ 4,646 Operating income 192 301 236 212 941 Net income 90 158 120 344 712 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (1 ) $ — $ (1 ) $ (4 ) Impairment Charges (see Note 4) — — — (60 ) (60 ) Severance Charges (see Note 20) — — — (17 ) (17 ) Impacts of the Tax Act (see Note 23) — — (2 ) 2 — Total $ (2 ) $ (1 ) $ (2 ) $ (76 ) $ (81 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (3 ) $ (2 ) $ (2 ) $ (9 ) Regulatory Settlements (see Note 4) — — (135 ) — (135 ) Impacts of the Tax Act (see Note 23) — — — 226 226 Total $ (2 ) $ (3 ) $ (137 ) $ 224 $ 82 DUKE ENERGY OHIO First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 524 $ 459 $ 469 $ 505 $ 1,957 Operating (loss) income (21 ) 77 139 93 288 Net (loss) income (25 ) 46 100 55 176 2017 Operating revenues $ 518 $ 437 $ 471 $ 497 $ 1,923 Operating income 82 64 101 73 320 Loss from discontinued operations, net of tax — — (1 ) — (1 ) Net income 42 30 55 65 192 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (3 ) $ (5 ) $ — $ (6 ) $ (14 ) Sale of Retired Plant (see Note 3) (107 ) — — — (107 ) Severance Charges (see Note 20) — — — (6 ) (6 ) Impacts of the Tax Act (see Note 23) — — — (2 ) (2 ) Total $ (110 ) $ (5 ) $ — $ (14 ) $ (129 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (1 ) $ (1 ) $ (2 ) $ (2 ) $ (6 ) Impacts of the Tax Act (see Note 23) — — — 23 23 Total $ (1 ) $ (1 ) $ (2 ) $ 21 $ 17 DUKE ENERGY INDIANA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 731 $ 738 $ 819 $ 771 $ 3,059 Operating income 168 169 173 133 643 Net income 100 98 119 76 393 2017 Operating revenues $ 758 $ 742 $ 802 $ 745 $ 3,047 Operating income 184 208 228 166 786 Net income 91 106 121 36 354 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ — $ — $ (2 ) $ — $ (2 ) Severance Charges (see Note 20) — — — (7 ) (7 ) Total $ — $ — $ (2 ) $ (7 ) $ (9 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (1 ) $ (2 ) $ (2 ) $ (1 ) $ (6 ) Impacts of the Tax Act (see Note 23) — — — (55 ) (55 ) Total $ (1 ) $ (2 ) $ (2 ) $ (56 ) $ (61 ) PIEDMONT First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 553 $ 215 $ 172 $ 435 $ 1,375 Operating income (loss) 161 5 (19 ) 79 226 Net income (loss) 110 (8 ) (21 ) 48 129 2017 Operating revenues $ 500 $ 201 $ 183 $ 444 $ 1,328 Operating income (loss) 170 5 (4 ) 126 297 Net income (loss) 95 (8 ) (11 ) 63 139 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (6 ) $ (9 ) $ (11 ) $ (22 ) $ (48 ) Severance Charges (see Note 20) — — — (2 ) (2 ) Total $ (6 ) $ (9 ) $ (11 ) $ (24 ) $ (50 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (6 ) $ (13 ) $ (8 ) $ (19 ) $ (46 ) Impacts of the Tax Act (see Note 23) — — — 2 2 Total $ (6 ) $ (13 ) $ (8 ) $ (17 ) $ (44 )

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2018
Policy Text Block [Line Items]
Nature of Operations and Basis of Consolidation	Nature of Operations and Basis of Consolidation Duke Energy is an energy company headquartered in Charlotte, North Carolina, subject to regulation by the FERC and other regulatory agencies listed below. Duke Energy operates in the U.S. primarily through its direct and indirect subsidiaries. Certain Duke Energy subsidiaries are also subsidiary registrants, including Duke Energy Carolinas; Progress Energy; Duke Energy Progress; Duke Energy Florida; Duke Energy Ohio; Duke Energy Indiana and Piedmont. When discussing Duke Energy’s consolidated financial information, it necessarily includes the results of its separate Subsidiary Registrants, which along with Duke Energy, are collectively referred to as the Duke Energy Registrants. In October 2016, Duke Energy completed the acquisition of Piedmont. Duke Energy's consolidated financial statements include Piedmont's results of operations and cash flows activity subsequent to the acquisition date. Effective November 1, 2016, Piedmont's fiscal year-end was changed from October 31 to December 31, the year-end of Duke Energy. A transition report was filed on Form 10-Q (Form 10-QT) for the transition period from November 1, 2016, to December 31, 2016. See Note 2 for additional information regarding the acquisition. In December 2016, Duke Energy completed an exit of the Latin American market to focus on its domestic regulated business, which was further bolstered by the acquisition of Piedmont. The sale of the International Energy business segment, excluding an equity method investment in NMC, was completed through two transactions including a sale of assets in Brazil to CTG and a sale of Duke Energy's remaining Latin American assets in Peru, Chile, Ecuador, Guatemala, El Salvador and Argentina to I Squared (collectively, the International Disposal Group). See Note 2 for additional information on the sale of International Energy. The information in these combined notes relates to each of the Duke Energy Registrants as noted in the Index to Combined Notes to Consolidated Financial Statements. However, none of the Subsidiary Registrants make any representation as to information related solely to Duke Energy or the Subsidiary Registrants of Duke Energy other than itself. These Consolidated Financial Statements include, after eliminating intercompany transactions and balances, the accounts of the Duke Energy Registrants and subsidiaries or VIEs where the respective Duke Energy Registrants have control. See Note 17 for additional information on VIEs. These Consolidated Financial Statements also reflect the Duke Energy Registrants’ proportionate share of certain jointly owned generation and transmission facilities. See Note 8 for additional information on joint ownership. Substantially all of the Subsidiary Registrants' operations qualify for regulatory accounting. Duke Energy Carolinas is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of North Carolina and South Carolina. Duke Energy Carolinas is subject to the regulatory provisions of the NCUC, PSCSC, NRC and FERC. Progress Energy is a public utility holding company, which conducts operations through its wholly owned subsidiaries, Duke Energy Progress and Duke Energy Florida. Progress Energy is subject to regulation by FERC and other regulatory agencies listed below. Duke Energy Progress is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of North Carolina and South Carolina. Duke Energy Progress is subject to the regulatory provisions of the NCUC, PSCSC, NRC and FERC. Duke Energy Florida is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of Florida. Duke Energy Florida is subject to the regulatory provisions of the FPSC, NRC and FERC. Duke Energy Ohio is a regulated public utility primarily engaged in the transmission and distribution of electricity in portions of Ohio and Kentucky, the generation and sale of electricity in portions of Kentucky and the transportation and sale of natural gas in portions of Ohio and Kentucky. Duke Energy Ohio conducts competitive auctions for retail electricity supply in Ohio whereby the energy price is recovered from retail customers and recorded in Operating Revenues on the Consolidated Statements of Operations and Comprehensive Income. Operations in Kentucky are conducted through its wholly owned subsidiary, Duke Energy Kentucky. References herein to Duke Energy Ohio collectively include Duke Energy Ohio and its subsidiaries, unless otherwise noted. Duke Energy Ohio is subject to the regulatory provisions of the PUCO, KPSC and FERC. Duke Energy Indiana is a regulated public utility primarily engaged in the generation, transmission, distribution and sale of electricity in portions of Indiana. Duke Energy Indiana is subject to the regulatory provisions of the IURC and FERC. Piedmont is a regulated public utility primarily engaged in the distribution of natural gas in portions of North Carolina, South Carolina and Tennessee. Piedmont is subject to the regulatory provisions of the NCUC, PSCSC, TPUC and FERC. Certain prior year amounts have been reclassified to conform to the current year presentation.
Discontinued Operations	Discontinued Operations The results of operations of the International Disposal Group have been classified as Discontinued Operations on Duke Energy's Consolidated Statements of Operations. Duke Energy has elected to present cash flows of discontinued operations combined with cash flows of continuing operations. Unless otherwise noted, the notes to these consolidated financial statements exclude amounts related to discontinued operations for all periods presented. See Note 2 for additional information.
Use of Estimates	Use of Estimates In preparing financial statements that conform to GAAP, the Duke Energy Registrants must make estimates and assumptions that affect the reported amounts of assets and liabilities, the reported amounts of revenues and expenses and the disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates.
Regulatory Accounting	Regulatory Accounting The majority of the Duke Energy Registrants’ operations are subject to price regulation for the sale of electricity and natural gas by state utility commissions or FERC. When prices are set on the basis of specific costs of the regulated operations and an effective franchise is in place such that sufficient natural gas or electric services can be sold to recover those costs, the Duke Energy Registrants apply regulatory accounting. Regulatory accounting changes the timing of the recognition of costs or revenues relative to a company that does not apply regulatory accounting. As a result, regulatory assets and regulatory liabilities are recognized on the Consolidated Balance Sheets. Regulatory assets and liabilities are amortized consistent with the treatment of the related cost in the ratemaking process. See Note 4 for further information. Regulatory accounting rules also require recognition of a disallowance (also called "impairment") loss if it becomes probable that part of the cost of a plant under construction (or a recently completed plant or an abandoned plant) will be disallowed for ratemaking purposes and a reasonable estimate of the amount of the disallowance can be made. For example, if a cost cap is set for a plant still under construction, the amount of the disallowance is a result of a judgment as to the ultimate cost of the plant. These disallowances can require judgments on allowed future rate recovery. When it becomes probable that regulated generation, transmission or distribution assets will be abandoned, the cost of the asset is removed from plant in service. The value that may be retained as a regulatory asset on the balance sheet for the abandoned property is dependent upon amounts that may be recovered through regulated rates, including any return. As such, an impairment charge could be partially or fully offset by the establishment of a regulatory asset if rate recovery is probable. The impairment charge for a disallowance of costs for regulated plants under construction, recently completed or abandoned is based on discounted cash flows.
Regulated Fuel Costs and Purchased Power	The Duke Energy Registrants utilize cost-tracking mechanisms, commonly referred to as fuel adjustment clauses or PGA clauses. These clauses allow for the recovery of fuel and fuel-related costs, portions of purchased power, natural gas costs and hedging costs through surcharges on customer rates. The difference between the costs incurred and the surcharge revenues is recorded either as an adjustment to Operating Revenues, Operating Expenses – Fuel used in electric generation or Operating Expenses – Cost of natural gas on the Consolidated Statements of Operations, with an off-setting impact on regulatory assets or liabilities
Cash and Cash Equivalents	Cash, Cash Equivalents and Restricted Cash All highly liquid investments with maturities of three months or less at the date of acquisition are considered cash equivalents.
Restricted Cash	Duke Energy, Progress Energy and Duke Energy Florida have restricted cash balances related primarily to collateral assets, escrow deposits and VIEs. See Note 17 for additional information. Restricted cash amounts are included in Other within Current Assets and Other Noncurrent Assets on the Consolidated Balance Sheets. The following table presents the components of cash, cash equivalents and restricted cash included in the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 Duke Duke Duke Progress Energy Duke Progress Energy Energy Energy Florida Energy Energy Florida Current Assets Cash and cash equivalents $ 442 $ 67 $ 36 $ 358 $ 40 $ 13 Other 141 39 39 138 40 40 Other Noncurrent Assets Other 8 6 — 9 7 — Total cash, cash equivalents and restricted cash $ 591 $ 112 $ 75 $ 505 $ 87 $ 53
Inventory	Inventory Inventory is used for operations and is recorded primarily using the average cost method. Inventory related to regulated operations is valued at historical cost. Inventory related to nonregulated operations is valued at the lower of cost or market. Materials and supplies are recorded as inventory when purchased and subsequently charged to expense or capitalized to property, plant and equipment when installed. Inventory, including excess or obsolete inventory, is written-down to the lower of cost or market value. Once inventory has been written-down, it creates a new cost basis for the inventory that is not subsequently written-up. Provisions for inventory write-offs were not material at December 31, 2018 , and 2017 . The components of inventory are presented in the tables below.
Investments in Debt and Equity Securities	Investments in Debt and Equity Securities The Duke Energy Registrants classify investments in equity securities as FV-NI and investments in debt securities as AFS. Both categories are recorded at fair value on the Consolidated Balance Sheets. Realized and unrealized gains and losses on securities classified as FV-NI are reported through net income. Unrealized gains and losses for debt securities classified as AFS are included in AOCI until realized, except OTTIs that are included in earnings immediately. At the time gains and losses for debt securities are realized, they are reported through net income. For certain investments of regulated operations, such as substantially all of the NDTF, realized and unrealized gains and losses (including any OTTIs) on debt securities are recorded as a regulatory asset or liability. The credit loss portion of debt securities of nonregulated operations are included in earnings. Investments in debt and equity securities are classified as either current or noncurrent based on management’s intent and ability to sell these securities, taking into consideration current market liquidity. See Note 15 for further information.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill Duke Energy, Progress Energy, Duke Energy Ohio and Piedmont perform annual goodwill impairment tests as of August 31 each year at the reporting unit level, which is determined to be a business segment or one level below. Duke Energy, Progress Energy, Duke Energy Ohio and Piedmont update these tests between annual tests if events or circumstances occur that would more likely than not reduce the fair value of a reporting unit below its carrying value. See Note 11 for further information. Intangible Assets Intangible assets are included in Other in Other Noncurrent Assets on the Consolidated Balance Sheets. Generally, intangible assets are amortized using an amortization method that reflects the pattern in which the economic benefits of the intangible asset are consumed or on a straight-line basis if that pattern is not readily determinable. Amortization of intangibles is reflected in Depreciation and amortization on the Consolidated Statements of Operations. Intangible assets are subject to impairment testing and if impaired, the carrying value is accordingly reduced. Emission allowances permit the holder of the allowance to emit certain gaseous byproducts of fossil fuel combustion, including SO 2 and NO X . Allowances are issued by the EPA at zero cost and may also be bought and sold via third-party transactions. Allowances allocated to or acquired by the Duke Energy Registrants are held primarily for consumption. Carrying amounts for emission allowances are based on the cost to acquire the allowances or, in the case of a business combination, on the fair value assigned in the allocation of the purchase price of the acquired business. Emission allowances are expensed to Fuel used in electric generation and purchased power on the Consolidated Statements of Operations. RECs are used to measure compliance with renewable energy standards and are held primarily for consumption. See Note 11 for further information.
Long-Lived Asset Impairments	Long-Lived Asset Impairments The Duke Energy Registrants evaluate long-lived assets, excluding goodwill, for impairment when circumstances indicate the carrying value of those assets may not be recoverable. An impairment exists when a long-lived asset’s carrying value exceeds the estimated undiscounted cash flows expected to result from the use and eventual disposition of the asset. The estimated cash flows may be based on alternative expected outcomes that are probability weighted. If the carrying value of the long-lived asset is not recoverable based on these estimated future undiscounted cash flows, the carrying value of the asset is written-down to its then-current estimated fair value and an impairment charge is recognized. The Duke Energy Registrants assess fair value of long-lived assets using various methods, including recent comparable third-party sales, internally developed discounted cash flow analysis and analysis from outside advisors. Triggering events to reassess cash flows may include, but are not limited to, significant changes in commodity prices, the condition of an asset or management’s interest in selling the asset.
Property, Plant and Equipment	In general, when the Duke Energy Registrants retire regulated property, plant and equipment, the original cost plus the cost of retirement, less salvage value and any depreciation already recognized, is charged to accumulated depreciation. However, when it becomes probable the asset will be retired substantially in advance of its original expected useful life or is abandoned, the cost of the asset and the corresponding accumulated depreciation is recognized as a separate asset. If the asset is still in operation, the net amount is classified as Generation facilities to be retired, net on the Consolidated Balance Sheets. If the asset is no longer operating, the net amount is classified in Regulatory assets on the Consolidated Balance Sheets if deemed recoverable (see discussion of long-lived asset impairments above). When it becomes probable an asset will be abandoned, the cost of the asset and accumulated depreciation is reclassified to Regulatory assets on the Consolidated Balance Sheets for amounts recoverable in rates. The carrying value of the asset is based on historical cost if the Duke Energy Registrants are allowed to recover the remaining net book value and a return equal to at least the incremental borrowing rate. If not, an impairment is recognized to the extent the net book value of the asset exceeds the present value of future revenues discounted at the incremental borrowing rate. When the Duke Energy Registrants sell entire regulated operating units, or retire or sell nonregulated properties, the original cost and accumulated depreciation and amortization balances are removed from Property, Plant and Equipment on the Consolidated Balance Sheets. Any gain or loss is recorded in earnings, unless otherwise required by the applicable regulatory body. See Note 10 for additional information. Property, Plant and Equipment Property, plant and equipment are stated at the lower of depreciated historical cost net of any disallowances or fair value, if impaired. The Duke Energy Registrants capitalize all construction-related direct labor and material costs, as well as indirect construction costs such as general engineering, taxes and financing costs. See “Allowance for Funds Used During Construction and Interest Capitalized” for information on capitalized financing costs. Costs of renewals and betterments that extend the useful life of property, plant and equipment are also capitalized. The cost of repairs, replacements and major maintenance projects, which do not extend the useful life or increase the expected output of the asset, are expensed as incurred. Depreciation is generally computed over the estimated useful life of the asset using the composite straight-line method. Depreciation studies are conducted periodically to update composite rates and are approved by state utility commissions and/or the FERC when required. The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows.
Nuclear Fuel	Nuclear Fuel Nuclear fuel is classified as Property, Plant and Equipment on the Consolidated Balance Sheets. Nuclear fuel in the front-end fuel processing phase is considered work in progress and not amortized until placed in service. Amortization of nuclear fuel is included within Fuel used in electric generation and purchased power on the Consolidated Statements of Operations. Amortization is recorded using the units-of-production method.
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalized	Allowance for Funds Used During Construction and Interest Capitalized For regulated operations, the debt and equity costs of financing the construction of property, plant and equipment are reflected as AFUDC and capitalized as a component of the cost of property, plant and equipment. AFUDC equity is reported on the Consolidated Statements of Operations as non-cash income in Other income and expenses, net. AFUDC debt is reported as a non-cash offset to Interest Expense. After construction is completed, the Duke Energy Registrants are permitted to recover these costs through their inclusion in rate base and the corresponding subsequent depreciation or amortization of those regulated assets. AFUDC equity, a permanent difference for income taxes, reduces the ETR when capitalized and increases the ETR when depreciated or amortized. See Note 23 for additional information. For nonregulated operations, interest is capitalized during the construction phase with an offsetting non-cash credit to Interest Expense on the Consolidated Statements of Operations.
Asset Retirement Obligations	Asset Retirement Obligations AROs are recognized for legal obligations associated with the retirement of property, plant and equipment. Substantially all AROs are related to regulated operations. When recording an ARO, the present value of the projected liability is recognized in the period in which it is incurred, if a reasonable estimate of fair value can be made. The liability is accreted over time. For operating plants, the present value of the liability is added to the cost of the associated asset and depreciated over the remaining life of the asset. For retired plants, the present value of the liability is recorded as a regulatory asset unless determined not to be probable of recovery. The present value of the initial obligation and subsequent updates are based on discounted cash flows, which include estimates regarding timing of future cash flows, selection of discount rates and cost escalation rates, among other factors. These estimates are subject to change. Depreciation expense is adjusted prospectively for any changes to the carrying amount of the associated asset. The Duke Energy Registrants receive amounts to fund the cost of the ARO for regulated operations through a combination of regulated revenues and earnings on the NDTF. As a result, amounts recovered in regulated revenues, earnings on the NDTF, accretion expense and depreciation of the associated asset are netted and deferred as a regulatory asset or liability. Obligations for nuclear decommissioning are based on site-specific cost studies. Duke Energy Carolinas and Duke Energy Progress assume prompt dismantlement of the nuclear facilities after operations are ceased. Duke Energy Florida assumes Crystal River Unit 3 will be placed into a safe storage configuration until eventual dismantlement is completed by 2074. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida also assume that spent fuel will be stored on-site until such time that it can be transferred to a yet to be built DOE facility. Obligations for closure of ash basins are based upon discounted cash flows of estimated costs for site-specific plans, if known, or probability weightings of the potential closure methods if the closure plans are under development and multiple closure options are being considered and evaluated on a site-by-site basis. See Note 9 for additional information
Revenue Recognition	Revenue Recognition Duke Energy recognizes revenue as customers obtain control of promised goods and services in an amount that reflects consideration expected in exchange for those goods or services. Generally, the delivery of electricity and natural gas results in the transfer of control to customers at the time the commodity is delivered and the amount of revenue recognized is equal to the amount billed to each customer, including estimated volumes delivered when billings have not yet occurred. See Note 18 for further information.
Derivatives and Hedging	Derivatives and Hedging Derivative and non-derivative instruments may be used in connection with commodity price and interest rate activities, including swaps, futures, forwards and options. All derivative instruments, except those that qualify for the NPNS exception, are recorded on the Consolidated Balance Sheets at fair value. Qualifying derivative instruments may be designated as either cash flow hedges or fair value hedges. Other derivative instruments (undesignated contracts) either have not been designated or do not qualify as hedges. The effective portion of the change in the fair value of cash flow hedges is recorded in AOCI. The effective portion of the change in the fair value of a fair value hedge is offset in net income by changes in the hedged item. For activity subject to regulatory accounting, gains and losses on derivative contracts are reflected as regulatory assets or liabilities and not as other comprehensive income or current period income. As a result, changes in fair value of these derivatives have no immediate earnings impact. Formal documentation, including transaction type and risk management strategy, is maintained for all contracts accounted for as a hedge. At inception and at least every three months thereafter, the hedge contract is assessed to see if it is highly effective in offsetting changes in cash flows or fair values of hedged items. See Note 14 for further information.
Captive Insurance Reserves	Captive Insurance Reserves Duke Energy has captive insurance subsidiaries that provide coverage, on an indemnity basis, to the Subsidiary Registrants as well as certain third parties, on a limited basis, for financial losses, primarily related to property, workers’ compensation and general liability. Liabilities include provisions for estimated losses IBNR, as well as estimated provisions for known claims. IBNR reserve estimates are primarily based upon historical loss experience, industry data and other actuarial assumptions. Reserve estimates are adjusted in future periods as actual losses differ from experience. Duke Energy, through its captive insurance entities, also has reinsurance coverage with third parties for certain losses above a per occurrence and/or aggregate retention. Receivables for reinsurance coverage are recognized when realization is deemed probable.
Unamortized Debt Premium, Discount and Expense	Unamortized Debt Premium, Discount and Expense Premiums, discounts and expenses incurred with the issuance of outstanding long-term debt are amortized over the term of the debt issue. The gain or loss on extinguishment associated with refinancing higher-cost debt obligations in the regulated operations is amortized. Amortization expense is recorded as Interest Expense in the Consolidated Statements of Operations and is reflected as Depreciation, amortization and accretion within Net cash provided by operating activities on the Consolidated Statements of Cash Flows. Premiums, discounts and expenses are presented as an adjustment to the carrying value of the debt amount and included in Long-Term Debt on the Consolidated Balance Sheets presented.
Loss Contingencies and Environmental Liabilities	Loss Contingencies and Environmental Liabilities Contingent losses are recorded when it is probable a loss has occurred and can be reasonably estimated. When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, the minimum amount in the range is recorded. Unless otherwise required by GAAP, legal fees are expensed as incurred. Environmental liabilities are recorded on an undiscounted basis when environmental remediation or other liabilities become probable and can be reasonably estimated. Environmental expenditures related to past operations that do not generate current or future revenues are expensed. Environmental expenditures related to operations that generate current or future revenues are expensed or capitalized, as appropriate. Certain environmental expenditures receive regulatory accounting treatment and are recorded as regulatory assets. See Notes 4 and 5 for further information.
Pension and Other Post-Retirement Benefit Plans	Pension and Other Post-Retirement Benefit Plans Duke Energy maintains qualified, non-qualified and other post-retirement benefit plans. Eligible employees of the Subsidiary Registrants participate in the respective qualified, non-qualified and other post-retirement benefit plans and the Subsidiary Registrants are allocated their proportionate share of benefit costs. See Note 22 for further information, including significant accounting policies associated with these plans.
Severance and Special Termination Benefits	Severance and Special Termination Benefits Duke Energy has severance plans under which in general, the longer a terminated employee worked prior to termination the greater the amount of severance benefits. A liability for involuntary severance is recorded once an involuntary severance plan is committed to by management if involuntary severances are probable and can be reasonably estimated. For involuntary severance benefits incremental to its ongoing severance plan benefits, the fair value of the obligation is expensed at the communication date if there are no future service requirements or over the required future service period. Duke Energy also offers special termination benefits under voluntary severance programs. Special termination benefits are recorded immediately upon employee acceptance absent a significant retention period. Otherwise, the cost is recorded over the remaining service period. Employee acceptance of voluntary severance benefits is determined by management based on the facts and circumstances of the benefits being offered. See Note 20 for further information.
Guarantees	Guarantees If necessary, liabilities are recognized at the time of issuance or material modification of a guarantee for the estimated fair value of the obligation it assumes. Fair value is estimated using a probability-weighted approach. The obligation is reduced over the term of the guarantee or related contract in a systematic and rational method as risk is reduced. Any additional contingent loss for guarantee contracts subsequent to the initial recognition of a liability is accounted for and recognized at the time a loss is probable and can be reasonably estimated. See Note 7 for further information.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation represents costs related to stock-based awards granted to employees and Board of Directors members. Duke Energy recognizes stock-based compensation based upon the estimated fair value of awards, net of estimated forfeitures at the date of issuance. The recognition period for these costs begins at either the applicable service inception date or grant date and continues throughout the requisite service period. Compensation cost is recognized as expense or capitalized as a component of property, plant and equipment. See Note 21 for further information.
Income Taxes	Income Taxes Duke Energy and its subsidiaries file a consolidated federal income tax return and other state and foreign jurisdictional returns. The Subsidiary Registrants are parties to a tax-sharing agreement with Duke Energy. Income taxes recorded represent amounts the Subsidiary Registrants would incur as separate C-Corporations. Deferred income taxes have been provided for temporary differences between GAAP and tax bases of assets and liabilities because the differences create taxable or tax-deductible amounts for future periods. ITCs associated with regulated operations are deferred and amortized as a reduction of income tax expense over the estimated useful lives of the related properties. Accumulated deferred income taxes are valued using the enacted tax rate expected to apply to taxable income in the periods in which the deferred tax asset or liability is expected to be settled or realized. In the event of a change in tax rates, deferred tax assets and liabilities are remeasured as of the enactment date of the new rate. To the extent that the change in the value of the deferred tax represents an obligation to customers, the impact of the remeasurement is deferred to a regulatory liability. Remaining impacts are recorded in income from continuing operations. If Duke Energy's estimate of the tax effect of reversing temporary differences is not reflective of actual outcomes, is modified to reflect new developments or interpretations of the tax law, revised to incorporate new accounting principles, or changes in the expected timing or manner of the reversal then Duke Energy's results of operations could be impacted. Tax-related interest and penalties are recorded in Interest Expense and Other Income and Expenses, net in the Consolidated Statements of Operations. See Note 23 for further information.
Accounting for Renewable Energy Tax Credits and Cash Grants	Accounting for Renewable Energy Tax Credits When Duke Energy receives ITCs on wind or solar facilities, it reduces the basis of the property recorded on the Consolidated Balance Sheets by the amount of the ITC and, therefore, the ITC benefit is ultimately recognized in the statement of operations through reduced depreciation expense. Additionally, certain tax credits and government grants result in an initial tax depreciable base in excess of the book carrying value by an amount equal to one half of the ITC. Deferred tax benefits are recorded as a reduction to income tax expense in the period that the basis difference is created.
Excise Taxes	Excise Taxes Certain excise taxes levied by state or local governments are required to be paid even if not collected from the customer. These taxes are recognized on a gross basis. Otherwise, the taxes are accounted for net. Excise taxes accounted for on a gross basis within both Operating Revenues and Property and other taxes in the Consolidated Statements of Operations were as follows.
Dividend Restrictions and Unappropriated Retained Earnings	Dividend Restrictions and Unappropriated Retained Earnings Duke Energy does not have any legal, regulatory or other restrictions on paying common stock dividends to shareholders. However, as further described in Note 4 , due to conditions established by regulators in conjunction with merger transaction approvals, Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio, Duke Energy Indiana and Piedmont have restrictions on paying dividends or otherwise advancing funds to Duke Energy. At December 31, 2018 , and 2017 , an insignificant amount of Duke Energy’s consolidated Retained earnings balance represents undistributed earnings of equity method investments.
New Accounting Standards	New Accounting Standards The new accounting standards adopted for 2018 and 2017 had no material impact on the presentation or results of operations, cash flows or financial position of the Duke Energy Registrants. The following accounting standards were adopted by the Duke Energy Registrants during 2018. Revenue from Contracts with Customers. In May 2014, the FASB issued revised accounting guidance for revenue recognition from contracts with customers. The core principle of this guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration expected in exchange for those goods or services. The amendments also required disclosure of sufficient information to allow users to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The majority of Duke Energy’s revenue is in scope of the new guidance. Other revenue arrangements, such as alternative revenue programs and certain PPAs and lighting agreements accounted for as leases, are excluded from the scope of this guidance and, therefore, are accounted for and evaluated for separate presentation and disclosure under other relevant accounting guidance. Duke Energy elected the modified retrospective method of adoption effective January 1, 2018. Under the modified retrospective method of adoption, prior year reported results are not restated. Adoption of this standard did not result in a material change in the timing or pattern of revenue recognition and a cumulative-effect adjustment was not recorded at January 1, 2018. Duke Energy utilized certain practical expedients including applying this guidance to open contracts at the date of adoption, expensing costs to obtain a contract where the amortization period of the asset would have been one year or less, ignoring the effects of a significant financing when the period between transfer of the good or service and payment is one year or less and recognizing revenues for certain contracts under the invoice practical expedient, which allows revenue recognition to be consistent with invoiced amounts (including unbilled estimates) provided certain criteria are met, including consideration of whether the invoiced amounts reasonably represent the value provided to customers. In preparation for adoption, Duke Energy identified material revenue streams and reviewed representative contracts and tariffs, including those associated with certain long-term customer contracts such as wholesale contracts, PPAs and other customer arrangements. Duke Energy also monitored the activities of the power and utilities industry revenue recognition task force and has reviewed published positions on specific industry issues to evaluate the impact, if any, on Duke Energy’s specific contracts and conclusions. Duke Energy applied the available practical expedient to portfolios of tariffs and contracts with similar characteristics. The vast majority of sales, including energy provided to retail customers, are from tariff offerings that provide natural gas or electricity without a defined contractual term ("at-will"). In most circumstances, revenue from contracts with customers is equivalent to the electricity or natural gas supplied and billed in that period (including unbilled estimates). As such, adoption of the new rules did not result in a shift in the timing or pattern of revenue recognition for such sales. While there have been changes to the captions and descriptions of revenues in Duke Energy’s financial statements, the most significant impact as a result of adopting the standard are additional disclosures around the nature, amount, timing and uncertainty of revenues and cash flows arising from contracts with customers. See Note 18 for further information. Financial Instruments Classification and Measurement. On January 1, 2018, Duke Energy adopted FASB guidance, which revised the classification and measurement of certain financial instruments. The adopted guidance changes the presentation of realized and unrealized gains and losses in certain equity securities that were previously recorded in AOCI. These gains and losses are now recorded in net income. An entity's equity investments that are accounted for under the equity method of accounting are not included within the scope of the new guidance. This guidance had a minimal impact on the Duke Energy Registrant's Consolidated Statements of Operations and Comprehensive Income as changes in the fair value of most of the Duke Energy Registrants' equity securities are deferred as regulatory assets or liabilities pursuant to accounting guidance for regulated operations. The resulting adjustment of unrealized gains and losses in AOCI to retained earnings was immaterial. The primary impact to Duke Energy as a result of implementing this guidance is adding disclosure requirements to present separately the financial assets and financial liabilities by measurement category and form of financial asset. See Notes 15 and 16 for further information. Statement of Cash Flows. In November 2016, the FASB issued revised accounting guidance to reduce diversity in practice for the presentation and classification of restricted cash on the Consolidated Statements of Cash Flows. Under the updated guidance, restricted cash and restricted cash equivalents are included within beginning-of-period and end-of-period cash and cash equivalents on the Consolidated Statements of Cash Flows. Duke Energy adopted this guidance on January 1, 2018. The guidance has been applied using a retrospective transition method to each period presented. The adoption by Duke Energy of the revised guidance resulted in a change to the amount of Cash, cash equivalents and restricted cash explained when reconciling the beginning-of-period and end-of-period total amounts shown on the Consolidated Statements of Cash Flows. In addition, a reconciliation has been provided of Cash, cash equivalents and restricted cash reported within the Consolidated Balance Sheets that sums to the total of the same such amounts in the Consolidated Statements of Cash Flows. Prior to adoption, the Duke Energy Registrants reflected changes in noncurrent restricted cash within Cash Flows from Investing Activities and changes in current restricted cash within Cash Flows from Operating Activities on the Consolidated Statements of Cash Flows. In August 2016, the FASB issued accounting guidance addressing diversity in practice for eight separate cash flow issues. The guidance requires entities to classify distributions received from equity method investees using either the cumulative earnings approach or the nature of the distribution approach. Duke Energy adopted this guidance on January 1, 2018, and elected the nature of distribution approach. This approach requires all distributions received to be categorized based on legal documentation describing the nature of the activities generating the distribution. Cash inflows resulting in a return on investment (surplus) will be reflected in Cash Flows from Operating Activities on the Consolidated Statements of Cash Flows, whereas cash inflows resulting in a return of investment (capital) will be reflected in Cash Flows from Investing Activities on the Consolidated Statements of Cash Flows. The guidance has been applied using the retrospective transition method to each period presented. There are no changes to the Consolidated Statements of Cash Flows for the periods presented as a result of this accounting change. Retirement Benefits. In March 2017, the FASB issued revised accounting guidance for the presentation of net periodic costs related to benefit plans. Previous guidance required the aggregation of all the components of net periodic costs on the Consolidated Statements of Operations and did not require the disclosure of the location of net periodic costs on the Consolidated Statements of Operations. Under the amended guidance, the service cost component of net periodic costs is included within Operating Income within the same line as other compensation expenses. All other components of net periodic costs are outside of Operating Income. In addition, the updated guidance permits only the service cost component of net periodic costs to be capitalized to Inventory or Property, Plant and Equipment. This represents a change from previous guidance, which permitted all components of net periodic costs to be eligible for capitalization. Duke Energy adopted this guidance on January 1, 2018. Under previous guidance, Duke Energy presented the total non-capitalized net periodic costs within Operation, maintenance and other on the Consolidated Statements of Operations. The adoption of this guidance resulted in a retrospective change to reclassify the presentation of the non-service cost (benefit) components of net periodic costs to Other income and expenses. Duke Energy utilized the practical expedient for retrospective presentation. The change in components of net periodic costs eligible for capitalization is applicable prospectively. Since Duke Energy’s service cost component is greater than the total net periodic costs, the change results in increased capitalization of net periodic costs, higher Operation, maintenance and other and higher Other income and expenses. The resulting prospective impact to Duke Energy is an immaterial increase in Net Income. See Note 22 for further information. For Duke Energy, the retrospective change resulted in higher Operation, maintenance and other and higher Other income and expenses, net, of $156 million and $139 million for the years ended December 31, 2017, and 2016, respectively. There was no change to Net Income for these prior periods. The following new accounting standards have been issued, but have not yet been adopted by the Duke Energy Registrants, as of December 31, 2018 . Leases. In February 2016, the FASB issued revised accounting guidance for leases. The core principle of this guidance is that a lessee should recognize the assets and liabilities that arise from leases on the balance sheet. For Duke Energy, this guidance is effective for interim and annual periods beginning January 1, 2019. The guidance will be applied using a modified retrospective approach. Under the modified retrospective approach of adoption, prior year reported results are not restated and a cumulative-effect adjustment, if applicable, is recorded to retained earnings at January 1, 2019. Upon adoption, agreements considered leases for the use of certain aircraft, space on communication towers, industrial equipment, fleet vehicles, fuel transportation (barges and railcars), land and office space will be recognized on the balance sheet. Duke Energy expects to adopt the following practical expedients: Practical Expedient Description Election Package of transition practical expedients (for leases commenced prior to adoption date and must be adopted as a package) Do not need to 1) reassess whether any expired or existing contracts are/or contain leases, 2) reassess the lease classification for any expired or existing leases and 3) reassess initial direct costs for any existing leases. Duke Energy plans to elect this practical expedient. Short-term lease expedient (elect by class of underlying asset) Elect as an accounting policy to not apply the recognition requirements to short-term leases by asset class. Duke Energy plans to elect this practical expedient for all asset classes. Lease and non-lease components (elect by class of underlying asset) Elect as an accounting policy to not separate non-lease components from lease components and instead account for each lease and associated non-lease component as a single lease component by asset class. Duke Energy plans to elect this practical expedient for all asset classes. Hindsight expedient (when determining lease term) Elect to use hindsight to determine the lease term. Duke Energy plans to elect this practical expedient. Existing and expired land easements not previously accounted for as leases Elect to not evaluate existing or expired easements under the new guidance and carry forward current accounting treatment. Duke Energy plans to elect this practical expedient. Comparative reporting requirements for initial adoption Elect to apply transition requirements at adoption date, recognize cumulative effect adjustment to retained earnings in period of adoption and not apply ASC 842 to comparative periods, including disclosures. Duke Energy plans to elect this practical expedient. Lessor expedient (elect by class of underlying asset) Elect as an accounting policy to aggregate non-lease components with the related lease component when specified conditions are met by asset class. Account for the combined component based on its predominant characteristic (revenue or operating lease). Duke Energy plans to elect this practical expedient for all asset classes. Duke Energy currently expects to record right-of-use assets and operating lease liabilities on its balance sheet as shown in approximate amounts in the table below: (in millions) Duke Energy $ 1,700 Duke Energy Carolinas 150 Progress Energy 850 Duke Energy Progress 400 Duke Energy Florida 450 Duke Energy Ohio 25 Duke Energy Indiana 60 Piedmont 30 In addition to the recognition of operating leases on the balance sheet, Duke Energy expects additional disclosures including both finance and operating lease costs, short-term lease costs, variable lease costs, weighted-average remaining lease term as well as weighted-average discount rates. Duke Energy does not expect a material change to its financial statements from adoption of the new standard for contracts where it is the lessor.
Earnings Per Share	Basic EPS is computed by dividing net income attributable to Duke Energy common stockholders, as adjusted for distributed and undistributed earnings allocated to participating securities, by the weighted average number of common shares outstanding during the period. Diluted EPS is computed by dividing net income attributable to Duke Energy common stockholders, as adjusted for distributed and undistributed earnings allocated to participating securities, by the diluted weighted average number of common shares outstanding during the period. Diluted EPS reflects the potential dilution that could occur if securities or other agreements to issue common shares, such as stock options and equity forward sale agreements, were exercised or settled.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Organization And Basis Of Presentation [Line Items]
Schedule of Current and Noncurrent Assets and Liabilities	The following table provides a description of amounts included in Other within Current Assets or Current Liabilities that exceed 5 percent of total Current Assets or Current Liabilities on the Duke Energy Registrants' Consolidated Balance Sheets at either December 31, 2018 , or 2017 . December 31, (in millions) Location 2018 2017 Duke Energy Income taxes receivable Current Assets $ 729 $ 330 Accrued compensation Current Liabilities 793 757 Duke Energy Carolinas Accrued compensation Current Liabilities $ 251 $ 252 Progress Energy Income taxes receivable Current Assets $ 66 $ 278 Customer deposits Current Liabilities 345 338 Duke Energy Progress Customer deposits Current Liabilities $ 137 $ 129 Accrued compensation Current Liabilities 130 132 Duke Energy Florida Customer deposits Current Liabilities $ 208 $ 208 Other accrued liabilities Current Liabilities 85 16 Duke Energy Ohio Income taxes receivable Current Assets $ 13 $ 36 Customer deposits Current Liabilities 44 46 Duke Energy Indiana Customer deposits Current Liabilities $ 47 $ 45 Piedmont Income taxes receivable Current Assets $ 11 $ 43
Schedule of Cash and Cash Equivalents	The following table presents the components of cash, cash equivalents and restricted cash included in the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 Duke Duke Duke Progress Energy Duke Progress Energy Energy Energy Florida Energy Energy Florida Current Assets Cash and cash equivalents $ 442 $ 67 $ 36 $ 358 $ 40 $ 13 Other 141 39 39 138 40 40 Other Noncurrent Assets Other 8 6 — 9 7 — Total cash, cash equivalents and restricted cash $ 591 $ 112 $ 75 $ 505 $ 87 $ 53
Components Of Inventory	The components of inventory are presented in the tables below. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Materials and supplies $ 2,238 $ 731 $ 1,049 $ 734 $ 315 $ 84 $ 312 $ 2 Coal 491 175 192 106 86 14 109 — Natural gas, oil and other 355 42 218 114 103 28 1 68 Total inventory $ 3,084 $ 948 $ 1,459 $ 954 $ 504 $ 126 $ 422 $ 70 December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Materials and supplies $ 2,293 $ 744 $ 1,118 $ 774 $ 343 $ 82 $ 309 $ 2 Coal 603 192 255 139 116 17 139 — Natural gas, oil and other 354 35 219 104 115 34 2 64 Total inventory $ 3,250 $ 971 $ 1,592 $ 1,017 $ 574 $ 133 $ 450 $ 66
Schedule Of Property, Plant And Equipment	The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows. Years Ended December 31, 2018 2017 2016 Duke Energy 3.0 % 2.8 % 2.8 % Duke Energy Carolinas 2.8 % 2.8 % 2.8 % Progress Energy 2.9 % 2.6 % 2.7 % Duke Energy Progress 2.9 % 2.6 % 2.6 % Duke Energy Florida 3.0 % 2.8 % 2.8 % Duke Energy Ohio 2.8 % 2.8 % 2.6 % Duke Energy Indiana 3.3 % 3.0 % 3.1 % Piedmont (a) 2.5 % 2.3 % (a) Piedmont's weighted average depreciation rate was 2.4 percent for the annualized two months ended December 31, 2016, and for the year ended October 31, 2016. The following tables summarize the property, plant and equipment for Duke Energy and its subsidiary registrants. December 31, 2018 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Land $ 2,072 $ 472 $ 868 $ 445 $ 423 $ 136 $ 116 $ 448 Plant – Regulated Electric generation, distribution and transmission 15-100 100,706 38,468 42,760 26,147 16,613 5,182 14,292 — Natural gas transmission and distribution 12-80 8,808 — — — — 2,719 — 6,089 Other buildings and improvements 24-90 1,966 681 636 295 341 270 253 126 Plant – Nonregulated Electric generation, distribution and transmission 5-30 4,410 — — — — — — — Other buildings and improvements 25-35 494 — — — — — — — Nuclear fuel 3,460 1,898 1,562 1,562 — — — — Equipment 3-55 2,141 467 565 399 166 384 178 141 Construction in process 5,726 1,678 2,515 1,659 856 412 325 382 Other 3-40 4,675 1,077 1,354 952 393 257 279 300 Total property, plant and equipment (a)(d) 134,458 44,741 50,260 31,459 18,792 9,360 15,443 7,486 Total accumulated depreciation – regulated (b)(c)(d) (41,079 ) (15,496 ) (16,398 ) (11,423 ) (4,968 ) (2,717 ) (4,914 ) (1,575 ) Total accumulated depreciation – nonregulated (c)(d) (2,047 ) — — — — — — — Generation facilities to be retired, net 362 — 362 362 — — — — Total net property, plant and equipment $ 91,694 $ 29,245 $ 34,224 $ 20,398 $ 13,824 $ 6,643 $ 10,529 $ 5,911 (a) Includes capitalized leases of $1,237 million , $135 million , $257 million , $137 million , $120 million , $73 million and $35 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana, respectively, primarily within Plant – Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $131 million , $14 million and $117 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,947 million , $1,087 million , $860 million and $860 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $61 million , $12 million , $20 million and $10 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $4,007 million and accumulated depreciation of consolidated VIEs of $698 million at Duke Energy. December 31, 2017 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Land $ 1,559 $ 467 $ 767 $ 424 $ 343 $ 134 $ 111 $ 41 Plant – Regulated Electric generation, distribution and transmission 8-100 93,687 35,657 39,419 24,502 14,917 4,870 13,741 — Natural gas transmission and distribution 12-80 8,292 — — — — 2,559 — 5,733 Other buildings and improvements 15-100 1,936 647 652 316 336 243 240 154 Plant – Nonregulated Electric generation, distribution and transmission (a) 5-30 4,273 — — — — — — — Other buildings and improvements 25-35 465 — — — — — — — Nuclear fuel 3,680 2,120 1,560 1,560 — — — — Equipment 3-55 2,122 402 555 416 139 348 169 266 Construction in process 6,995 2,614 3,059 1,434 1,625 350 416 231 Other 3-40 4,498 1,032 1,311 931 370 228 271 300 Total property, plant and equipment (b)(e) 127,507 42,939 47,323 29,583 17,730 8,732 14,948 6,725 Total accumulated depreciation – regulated (c)(d)(e) (39,742 ) (15,063 ) (15,857 ) (10,903 ) (4,947 ) (2,691 ) (4,662 ) (1,479 ) Total accumulated depreciation – nonregulated (d)(e) (1,795 ) — — — — — — — Generation facilities to be retired, net 421 — 421 421 — — — — Total net property, plant and equipment $ 86,391 $ 27,876 $ 31,887 $ 19,101 $ 12,783 $ 6,041 $ 10,286 $ 5,246 (a) Includes a pretax impairment charge of $58 million on a wholly owned non-contracted wind project. See discussion below. (b) Includes capitalized leases of $1,294 million , $81 million , $272 million , $139 million , $133 million , $80 million and $35 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana, respectively, primarily within Plant – Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $114 million , $11 million and $103 million , respectively, of accumulated amortization of capitalized leases. (c) Includes $2,113 million , $1,283 million , $831 million and $831 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (d) Includes accumulated amortization of capitalized leases of $57 million , $11 million , $21 million and $9 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (e) Includes gross property, plant and equipment cost of consolidated VIEs of $3,941 million and accumulated depreciation of consolidated VIEs of $598 million at Duke Energy.
Schedule of Excise Taxes	Excise taxes accounted for on a gross basis within both Operating Revenues and Property and other taxes in the Consolidated Statements of Operations were as follows. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy $ 405 $ 376 $ 362 Duke Energy Carolinas 35 36 31 Progress Energy 241 220 213 Duke Energy Progress 19 19 18 Duke Energy Florida 222 201 195 Duke Energy Ohio 105 98 100 Duke Energy Indiana 22 20 17 Piedmont (a) 2 2 (a) Piedmont's excise taxes were immaterial for the two months ended December 31, 2016, and $2 million for the year ended October 31, 2016.
Summary of Practical Expedients for New Accounting Pronouncements	Duke Energy expects to adopt the following practical expedients: Practical Expedient Description Election Package of transition practical expedients (for leases commenced prior to adoption date and must be adopted as a package) Do not need to 1) reassess whether any expired or existing contracts are/or contain leases, 2) reassess the lease classification for any expired or existing leases and 3) reassess initial direct costs for any existing leases. Duke Energy plans to elect this practical expedient. Short-term lease expedient (elect by class of underlying asset) Elect as an accounting policy to not apply the recognition requirements to short-term leases by asset class. Duke Energy plans to elect this practical expedient for all asset classes. Lease and non-lease components (elect by class of underlying asset) Elect as an accounting policy to not separate non-lease components from lease components and instead account for each lease and associated non-lease component as a single lease component by asset class. Duke Energy plans to elect this practical expedient for all asset classes. Hindsight expedient (when determining lease term) Elect to use hindsight to determine the lease term. Duke Energy plans to elect this practical expedient. Existing and expired land easements not previously accounted for as leases Elect to not evaluate existing or expired easements under the new guidance and carry forward current accounting treatment. Duke Energy plans to elect this practical expedient. Comparative reporting requirements for initial adoption Elect to apply transition requirements at adoption date, recognize cumulative effect adjustment to retained earnings in period of adoption and not apply ASC 842 to comparative periods, including disclosures. Duke Energy plans to elect this practical expedient. Lessor expedient (elect by class of underlying asset) Elect as an accounting policy to aggregate non-lease components with the related lease component when specified conditions are met by asset class. Account for the combined component based on its predominant characteristic (revenue or operating lease). Duke Energy plans to elect this practical expedient for all asset classes. Duke Energy currently expects to record right-of-use assets and operating lease liabilities on its balance sheet as shown in approximate amounts in the table below: (in millions) Duke Energy $ 1,700 Duke Energy Carolinas 150 Progress Energy 850 Duke Energy Progress 400 Duke Energy Florida 450 Duke Energy Ohio 25 Duke Energy Indiana 60 Piedmont 30

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Business Acquisition, Pro Forma Information	This information has been presented for illustrative purposes only and is not necessarily indicative of the consolidated results of operations that would have been achieved or the future consolidated results of operations of Duke Energy. Year Ended December 31, (in millions) 2016 Operating Revenues $ 23,504 Net Income Attributable to Duke Energy Corporation 2,442
Disposal Groups, Including Discontinued Operations	The following table presents the results of the International Disposal Group for the year ended December 31, 2016, which are included in Loss from Discontinued Operations, net of tax in Duke Energy's Consolidated Statements of Operations. Year Ended December 31, (in millions) 2016 Operating Revenues $ 988 Fuel used in electric generation and purchased power 227 Cost of natural gas 43 Operation, maintenance and other 341 Depreciation and amortization (a) 62 Property and other taxes 15 Impairment charges (b) 194 (Losses) Gains on Sales of Other Assets and Other, net (3 ) Other Income and Expenses, net 58 Interest Expense 82 Pretax loss on disposal (c) (514 ) Loss before income taxes (d) (435 ) Income tax expense (e)(f) 99 Loss from discontinued operations of the International Disposal Group $ (534 ) (a) Upon meeting the criteria for assets held for sale, beginning in the fourth quarter of 2016 depreciation expense ceased. (b) In conjunction with the advancements of marketing efforts during 2016, Duke Energy performed recoverability tests of the long-lived asset groups of International Energy. As a result, Duke Energy determined the carrying value of certain assets in Central America was not fully recoverable and recorded a pretax impairment charge of $194 million . The charge represents the excess of carrying value over the estimated fair value of the assets, which was based on a Level 3 Fair Value measurement that was primarily determined from the income approach using discounted cash flows but also considered market information obtained in 2016. (c) The pretax loss on disposal includes the recognition of cumulative foreign currency translation losses of $620 million as of the disposal date. See the Consolidated Statements of Changes in Equity for additional information. (d) Pretax Loss attributable to Duke Energy Corporation was $(445) million for the year ended December 31, 2016. (e) Amount includes $126 million of income tax expense on the disposal, which primarily reflects in-country taxes incurred as a result of the sale. The after-tax loss on disposal was $640 million . (f) Amount includes an income tax benefit of $95 million . See Note 23 , "Income Taxes," for additional information. The following table summarizes the Loss from Discontinued Operations, net of tax recorded on Duke Energy's Consolidated Statements of Operations for the year ended December 31, 2016: Year Ended December 31, (in millions) 2016 International Disposal Group $ (534 ) Other (a) 126 Loss from Discontinued Operations, net of tax $ (408 ) (a) Amount represents an income tax benefit resulting from immaterial out of period deferred tax liability adjustments for previously sold businesses not related to the International Disposal Group.
Schedule of Cash Flow, Supplemental Disclosures	The following table summarizes Duke Energy's cash flows from discontinued operations related to the International Disposal Group. Year Ended December 31, (in millions) 2016 Cash flows provided by (used in): Operating activities $ 204 Investing activities (434 )

Business Segments (Tables)

Business Segments (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting Information [Line Items]
Business Segment Data	Business segment information is presented in the following tables. Segment assets presented exclude intercompany assets. Year Ended December 31, 2018 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Total Unaffiliated Revenues $ 22,242 $ 1,783 $ 477 $ 24,502 $ 19 $ — $ 24,521 Intersegment Revenues 31 98 — 129 70 (199 ) — Total Revenues $ 22,273 $ 1,881 $ 477 $ 24,631 $ 89 $ (199 ) $ 24,521 Interest Expense $ 1,288 $ 106 $ 88 $ 1,482 $ 657 $ (45 ) $ 2,094 Depreciation and amortization 3,523 245 155 3,923 152 (1 ) 4,074 Equity in earnings (losses) of unconsolidated affiliates 5 27 (1 ) 31 52 — 83 Income tax expense (benefit) (a) 799 78 (147 ) 730 (282 ) — 448 Segment income (loss) (b)(c)(d)(e) 3,058 274 9 3,341 (694 ) — 2,647 Add back noncontrolling interest component (22 ) Income from discontinued operations, net of tax 19 Net income $ 2,644 Capital investments expenditures and acquisitions $ 8,086 $ 1,133 $ 193 $ 9,412 $ 256 $ — $ 9,668 Segment assets 125,364 12,361 4,204 141,929 3,275 188 145,392 (a) All segments include adjustments to the December 31, 2017 estimate of the income tax effects of the Tax Act. Electric Utilities and Infrastructure includes a $24 million expense, Gas Utilities and Infrastructure includes a $1 million expense, Commercial Renewables includes a $3 million benefit and Other includes a $2 million benefit. See Note 23 for additional information. (b) Electric Utilities and Infrastructure includes after-tax regulatory and legislative impairment charges of $202 million related to rate case orders, settlements or other actions of regulators or legislative bodies and an after-tax impairment charge of $46 million related to the Citrus County CC at Duke Energy Florida. See Note 4 for additional information. (c) Gas Utilities and Infrastructure includes an after-tax impairment charge of $42 million for the investment in Constitution. See Note 12 for additional information. (d) Commercial Renewables includes an impairment charge of $91 million , net of $2 million Noncontrolling interests, related to goodwill. See Note 11 for additional information. (e) Other includes $65 million of after-tax costs to achieve the Piedmont merger, $144 million of after-tax severance charges related to a companywide initiative and an $82 million after-tax loss on the sale of the retired Beckjord Generating Station described below. For additional information, see Note 2 for the Piedmont Merger and Note 20 for severance charges. In February 2018, Duke Energy sold Beckjord, a nonregulated facility retired during 2014, and recorded a pretax loss of $106 million within (Losses) Gains on Sales of Other Assets and Other, net and $1 million within Operation, maintenance and other on Duke Energy's Consolidated Statements of Operations for the year ended December 31, 2018. The sale included the transfer of coal ash basins and other real property and indemnification from any and all potential future claims related to the property, whether arising under environmental laws or otherwise. Year Ended December 31, 2017 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Total Unaffiliated Revenues $ 21,300 $ 1,743 $ 460 $ 23,503 $ 62 $ — $ 23,565 Intersegment Revenues 31 93 — 124 76 (200 ) — Total Revenues $ 21,331 $ 1,836 $ 460 $ 23,627 $ 138 $ (200 ) $ 23,565 Interest Expense $ 1,240 $ 105 $ 87 $ 1,432 $ 574 $ (20 ) $ 1,986 Depreciation and amortization 3,010 231 155 3,396 131 — 3,527 Equity in earnings (losses) of unconsolidated affiliates 5 62 (5 ) 62 57 — 119 Income tax expense (benefit) (a) 1,355 116 (628 ) 843 353 — 1,196 Segment income (loss) (b)(c)(d) 3,210 319 441 3,970 (905 ) — 3,065 Add back noncontrolling interest component 5 Loss from discontinued operations, net of tax (6 ) Net income $ 3,064 Capital investments expenditures and acquisitions $ 7,024 $ 907 $ 92 $ 8,023 $ 175 $ — $ 8,198 Segment assets 119,423 11,462 4,156 135,041 2,685 188 137,914 (a) All segments include impacts of the Tax Act. Electric Utilities and Infrastructure includes a $231 million benefit, Gas Utilities and Infrastructure includes a $26 million benefit, Commercial Renewables includes a $442 million benefit and Other includes charges of $597 million . (b) Electric Utilities and Infrastructure includes after-tax regulatory settlement charges of $98 million . See Note 4 for additional information. (c) Commercial Renewables includes after-tax impairment charges of $74 million related to certain wind projects and the Energy Management Solutions reporting unit. See Notes 10 and 11 for additional information. (d) Other includes $64 million of after-tax costs to achieve the Piedmont merger. See Note 2 for additional information. Year Ended December 31, 2016 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Total Unaffiliated Revenues $ 21,336 $ 875 $ 484 $ 22,695 $ 48 $ — $ 22,743 Intersegment Revenues 30 26 — 56 69 (125 ) — Total Revenues $ 21,366 $ 901 $ 484 $ 22,751 $ 117 $ (125 ) $ 22,743 Interest Expense $ 1,136 $ 46 $ 53 $ 1,235 $ 693 $ (12 ) $ 1,916 Depreciation and amortization 2,897 115 130 3,142 152 — 3,294 Equity in earnings (losses) of unconsolidated affiliates (a) 5 19 (82 ) (58 ) 43 — (15 ) Income tax expense (benefit) 1,672 90 (160 ) 1,602 (446 ) — 1,156 Segment income (loss) (b)(c) 3,040 152 23 3,215 (645 ) 1 2,571 Add back noncontrolling interest component 7 Loss from discontinued operations, net of tax (d) (408 ) Net income $ 2,170 Capital investments expenditures and acquisitions (e) $ 6,649 $ 5,519 $ 857 $ 13,025 $ 190 $ — $ 13,215 Segment assets 114,993 10,760 4,377 130,130 2,443 188 132,761 (a) Commercial Renewables includes a pretax impairment charge of $71 million . See Note 12 for additional information. (b) Other includes $329 million of after-tax costs to achieve mergers. See Note 2 for additional information on costs related to the Piedmont merger. (c) Other includes after-tax charges of $57 million related to cost savings initiatives. See Note 20 for further information. (d) Includes a loss on sale of the International Disposal Group. Refer to Note 2 for further information. (e) Other includes $26 million of capital investment expenditures related to the International Disposal Group. Gas Utilities and Infrastructure includes the Piedmont acquisition of $5 billion . See Note 2 for more information on the Piedmont acquisition.
Schedule of Revenue, By Products and Services	Products and Services The following table summarizes revenues of the reportable segments by type. Retail Wholesale Retail Total (in millions) Electric Electric Natural Gas Other Revenues 2018 Electric Utilities and Infrastructure $ 19,013 $ 2,345 $ — $ 915 $ 22,273 Gas Utilities and Infrastructure — — 1,817 64 1,881 Commercial Renewables — 375 — 102 477 Total Reportable Segments $ 19,013 $ 2,720 $ 1,817 $ 1,081 $ 24,631 2017 Electric Utilities and Infrastructure $ 18,177 $ 2,104 $ — $ 1,050 $ 21,331 Gas Utilities and Infrastructure — — 1,732 104 1,836 Commercial Renewables — 375 — 85 460 Total Reportable Segments $ 18,177 $ 2,479 $ 1,732 $ 1,239 $ 23,627 2016 Electric Utilities and Infrastructure $ 18,338 $ 2,095 $ — $ 933 $ 21,366 Gas Utilities and Infrastructure — — 871 30 901 Commercial Renewables — 303 — 181 484 Total Reportable Segments $ 18,338 $ 2,398 $ 871 $ 1,144 $ 22,751
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Business Segment Data	Year Ended December 31, 2018 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Total Total revenues $ 1,450 $ 506 $ 1,956 $ 1 $ 1,957 Interest expense $ 67 $ 24 $ 91 $ 1 $ 92 Depreciation and amortization 183 85 268 — 268 Income tax expense (benefit) 47 24 71 (28 ) 43 Segment income (loss)/Net income (a) 186 93 279 (103 ) 176 Capital expenditures $ 655 $ 172 $ 827 $ — $ 827 Segment assets 5,643 2,874 8,517 38 8,555 (a) Other includes the loss on the sale of Beckjord, see discussion above. Year Ended December 31, 2017 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Total Total revenues $ 1,373 $ 508 $ 1,881 $ 42 $ — $ 1,923 Interest expense $ 62 $ 28 $ 90 $ 1 $ — $ 91 Depreciation and amortization 178 83 261 — — 261 Income tax expense (benefit) 40 39 79 (20 ) — 59 Segment income (loss) 138 85 223 (30 ) — 193 Loss from discontinued operations, net of tax (1 ) Net income $ 192 Capital expenditures $ 491 $ 195 $ 686 $ — $ — $ 686 Segment assets 5,066 2,758 7,824 66 (15 ) 7,875 Year Ended December 31, 2016 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Total Total revenues $ 1,410 $ 503 $ 1,913 $ 31 $ — $ 1,944 Interest expense $ 58 $ 27 $ 85 $ 1 $ — $ 86 Depreciation and amortization 151 80 231 2 — 233 Income tax expense (benefit) 55 44 99 (21 ) — 78 Segment income (loss) 154 77 231 (39 ) — 192 Income from discontinued operations, net of tax 36 Net income $ 228 Capital expenditures $ 322 $ 154 $ 476 $ — $ — $ 476 Segment assets 4,782 2,696 7,478 62 (12 ) 7,528

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2018
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant. Duke Energy Progress Energy December 31, December 31, (in millions) 2018 2017 2018 2017 Regulatory Assets AROs – coal ash $ 4,255 $ 4,025 $ 2,061 $ 1,984 AROs – nuclear and other 772 852 601 655 Accrued pension and OPEB 2,654 2,249 1,074 906 Retired generation facilities 445 480 367 386 Debt fair value adjustment 1,099 1,197 — — Deferred asset – Lee COLA 383 — — — Storm cost deferrals 1,117 531 953 526 Nuclear asset securitized balance, net 1,093 1,142 1,093 1,142 Hedge costs deferrals 204 234 74 94 Derivatives – natural gas supply contracts 141 142 — — Demand side management (DSM)/Energy efficiency (EE) 449 530 256 281 Grid modernization 31 39 — — Vacation accrual 213 213 41 42 Deferred fuel and purchased power 838 507 600 349 Nuclear deferral 133 119 46 35 Post-in-service carrying costs (PISCC) and deferred operating expenses 320 366 36 38 Transmission expansion obligation 39 46 — — Manufactured gas plant (MGP) 99 91 — — Advanced metering infrastructure (AMI) 367 362 127 150 NCEMPA deferrals 50 53 50 53 East Bend deferrals 47 45 — — Deferred pipeline integrity costs 65 54 — — Amounts due from customers 24 64 — — Other 784 538 322 110 Total regulatory assets 15,622 13,879 7,701 6,751 Less: current portion 2,005 1,437 1,137 741 Total noncurrent regulatory assets $ 13,617 $ 12,442 $ 6,564 $ 6,010 Regulatory Liabilities Costs of removal $ 5,421 $ 5,968 $ 2,135 $ 2,537 AROs – nuclear and other 538 806 — — Net regulatory liability related to income taxes 8,058 8,113 2,710 2,802 Amounts to be refunded to customers 34 10 — — Storm reserve — 20 — — Accrued pension and OPEB 301 146 149 — Deferred fuel and purchased power 16 47 16 1 Other 1,064 622 319 179 Total regulatory liabilities 15,432 15,732 5,329 5,519 Less: current portion 598 402 280 213 Total noncurrent regulatory liabilities $ 14,834 $ 15,330 $ 5,049 $ 5,306
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant. Duke Energy Progress Energy December 31, December 31, (in millions) 2018 2017 2018 2017 Regulatory Assets AROs – coal ash $ 4,255 $ 4,025 $ 2,061 $ 1,984 AROs – nuclear and other 772 852 601 655 Accrued pension and OPEB 2,654 2,249 1,074 906 Retired generation facilities 445 480 367 386 Debt fair value adjustment 1,099 1,197 — — Deferred asset – Lee COLA 383 — — — Storm cost deferrals 1,117 531 953 526 Nuclear asset securitized balance, net 1,093 1,142 1,093 1,142 Hedge costs deferrals 204 234 74 94 Derivatives – natural gas supply contracts 141 142 — — Demand side management (DSM)/Energy efficiency (EE) 449 530 256 281 Grid modernization 31 39 — — Vacation accrual 213 213 41 42 Deferred fuel and purchased power 838 507 600 349 Nuclear deferral 133 119 46 35 Post-in-service carrying costs (PISCC) and deferred operating expenses 320 366 36 38 Transmission expansion obligation 39 46 — — Manufactured gas plant (MGP) 99 91 — — Advanced metering infrastructure (AMI) 367 362 127 150 NCEMPA deferrals 50 53 50 53 East Bend deferrals 47 45 — — Deferred pipeline integrity costs 65 54 — — Amounts due from customers 24 64 — — Other 784 538 322 110 Total regulatory assets 15,622 13,879 7,701 6,751 Less: current portion 2,005 1,437 1,137 741 Total noncurrent regulatory assets $ 13,617 $ 12,442 $ 6,564 $ 6,010 Regulatory Liabilities Costs of removal $ 5,421 $ 5,968 $ 2,135 $ 2,537 AROs – nuclear and other 538 806 — — Net regulatory liability related to income taxes 8,058 8,113 2,710 2,802 Amounts to be refunded to customers 34 10 — — Storm reserve — 20 — — Accrued pension and OPEB 301 146 149 — Deferred fuel and purchased power 16 47 16 1 Other 1,064 622 319 179 Total regulatory liabilities 15,432 15,732 5,329 5,519 Less: current portion 598 402 280 213 Total noncurrent regulatory liabilities $ 14,834 $ 15,330 $ 5,049 $ 5,306
Schedule of Potential Plant Retirements	The table below contains the net carrying value of generating facilities planned for retirement or included in recent IRPs as evaluated for potential retirement due to a lack of requisite environmental control equipment. Dollar amounts in the table below are included in Net property, plant and equipment on the Consolidated Balance Sheets as of December 31, 2018 , and exclude capitalized asset retirement costs. Remaining Net Capacity Book Value (in MW) (in millions) Duke Energy Carolinas Allen Steam Station Units 1-3 (a) 585 $ 162 Duke Energy Indiana Gallagher Units 2 and 4 (b) 280 121 Total Duke Energy 865 $ 283 (a) Duke Energy Carolinas will retire Allen Steam Station Units 1 through 3 by December 31, 2024, as part of the resolution of a lawsuit involving alleged New Source Review violations. (b) Duke Energy Indiana committed to either retire or stop burning coal at Gallagher Units 2 and 4 by December 31, 2022, as part of the 2016 settlement of Edwardsport IGCC matters.
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on Duke Energy Carolinas' Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 1,725 $ 1,645 (i) (b) Accrued pension and OPEB 581 410 (j) Retired generation facilities (c) 21 29 X 2023 Deferred Asset – Lee COLA 383 — (b) Storm cost deferrals 160 — X (b) Hedge costs deferrals (c) 101 109 X 2041 DSM/EE 169 210 (h) (h) Vacation accrual 78 83 (e) 2019 Deferred fuel and purchased power 196 140 (f) 2020 Nuclear deferral 87 84 2020 PISCC (c) 34 35 X (b) AMI 176 185 X (b) Other 266 222 (b) Total regulatory assets 3,977 3,152 Less: current portion 520 299 Total noncurrent regulatory assets $ 3,457 $ 2,853 Regulatory Liabilities (a) Costs of removal (c) $ 1,968 $ 2,054 X (g) ARO – nuclear and other 538 806 (b) Net regulatory liability related to income taxes (d) 3,082 3,028 (b) Storm reserve (c) — 20 (b) Accrued pension and OPEB 38 44 (j) Deferred fuel and purchased power — 46 (f) 2020 Other 572 359 (b) Total regulatory liabilities 6,198 6,357 Less: current portion 199 126 Total noncurrent regulatory liabilities $ 5,999 $ 6,231 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Includes regulatory liabilities related to the change in the federal tax rate as a result of the Tax Act and the change in the North Carolina tax rate, both discussed in Note 23 . (e) Earns a return on outstanding balance in North Carolina. (f) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina. (g) Recovered over the life of the associated assets. (h) Includes incentives on DSM/EE investments and is recovered through an annual rider mechanism. (i) Earns a debt and equity return on coal ash expenditures for North Carolina and South Carolina retail customers as permitted by various regulatory orders. (j) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on Duke Energy Carolinas' Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 1,725 $ 1,645 (i) (b) Accrued pension and OPEB 581 410 (j) Retired generation facilities (c) 21 29 X 2023 Deferred Asset – Lee COLA 383 — (b) Storm cost deferrals 160 — X (b) Hedge costs deferrals (c) 101 109 X 2041 DSM/EE 169 210 (h) (h) Vacation accrual 78 83 (e) 2019 Deferred fuel and purchased power 196 140 (f) 2020 Nuclear deferral 87 84 2020 PISCC (c) 34 35 X (b) AMI 176 185 X (b) Other 266 222 (b) Total regulatory assets 3,977 3,152 Less: current portion 520 299 Total noncurrent regulatory assets $ 3,457 $ 2,853 Regulatory Liabilities (a) Costs of removal (c) $ 1,968 $ 2,054 X (g) ARO – nuclear and other 538 806 (b) Net regulatory liability related to income taxes (d) 3,082 3,028 (b) Storm reserve (c) — 20 (b) Accrued pension and OPEB 38 44 (j) Deferred fuel and purchased power — 46 (f) 2020 Other 572 359 (b) Total regulatory liabilities 6,198 6,357 Less: current portion 199 126 Total noncurrent regulatory liabilities $ 5,999 $ 6,231 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Includes regulatory liabilities related to the change in the federal tax rate as a result of the Tax Act and the change in the North Carolina tax rate, both discussed in Note 23 . (e) Earns a return on outstanding balance in North Carolina. (f) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina. (g) Recovered over the life of the associated assets. (h) Includes incentives on DSM/EE investments and is recovered through an annual rider mechanism. (i) Earns a debt and equity return on coal ash expenditures for North Carolina and South Carolina retail customers as permitted by various regulatory orders. (j) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant. Duke Energy Progress Energy December 31, December 31, (in millions) 2018 2017 2018 2017 Regulatory Assets AROs – coal ash $ 4,255 $ 4,025 $ 2,061 $ 1,984 AROs – nuclear and other 772 852 601 655 Accrued pension and OPEB 2,654 2,249 1,074 906 Retired generation facilities 445 480 367 386 Debt fair value adjustment 1,099 1,197 — — Deferred asset – Lee COLA 383 — — — Storm cost deferrals 1,117 531 953 526 Nuclear asset securitized balance, net 1,093 1,142 1,093 1,142 Hedge costs deferrals 204 234 74 94 Derivatives – natural gas supply contracts 141 142 — — Demand side management (DSM)/Energy efficiency (EE) 449 530 256 281 Grid modernization 31 39 — — Vacation accrual 213 213 41 42 Deferred fuel and purchased power 838 507 600 349 Nuclear deferral 133 119 46 35 Post-in-service carrying costs (PISCC) and deferred operating expenses 320 366 36 38 Transmission expansion obligation 39 46 — — Manufactured gas plant (MGP) 99 91 — — Advanced metering infrastructure (AMI) 367 362 127 150 NCEMPA deferrals 50 53 50 53 East Bend deferrals 47 45 — — Deferred pipeline integrity costs 65 54 — — Amounts due from customers 24 64 — — Other 784 538 322 110 Total regulatory assets 15,622 13,879 7,701 6,751 Less: current portion 2,005 1,437 1,137 741 Total noncurrent regulatory assets $ 13,617 $ 12,442 $ 6,564 $ 6,010 Regulatory Liabilities Costs of removal $ 5,421 $ 5,968 $ 2,135 $ 2,537 AROs – nuclear and other 538 806 — — Net regulatory liability related to income taxes 8,058 8,113 2,710 2,802 Amounts to be refunded to customers 34 10 — — Storm reserve — 20 — — Accrued pension and OPEB 301 146 149 — Deferred fuel and purchased power 16 47 16 1 Other 1,064 622 319 179 Total regulatory liabilities 15,432 15,732 5,329 5,519 Less: current portion 598 402 280 213 Total noncurrent regulatory liabilities $ 14,834 $ 15,330 $ 5,049 $ 5,306
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets of Duke Energy and Progress Energy. See separate tables below for balances by individual registrant. Duke Energy Progress Energy December 31, December 31, (in millions) 2018 2017 2018 2017 Regulatory Assets AROs – coal ash $ 4,255 $ 4,025 $ 2,061 $ 1,984 AROs – nuclear and other 772 852 601 655 Accrued pension and OPEB 2,654 2,249 1,074 906 Retired generation facilities 445 480 367 386 Debt fair value adjustment 1,099 1,197 — — Deferred asset – Lee COLA 383 — — — Storm cost deferrals 1,117 531 953 526 Nuclear asset securitized balance, net 1,093 1,142 1,093 1,142 Hedge costs deferrals 204 234 74 94 Derivatives – natural gas supply contracts 141 142 — — Demand side management (DSM)/Energy efficiency (EE) 449 530 256 281 Grid modernization 31 39 — — Vacation accrual 213 213 41 42 Deferred fuel and purchased power 838 507 600 349 Nuclear deferral 133 119 46 35 Post-in-service carrying costs (PISCC) and deferred operating expenses 320 366 36 38 Transmission expansion obligation 39 46 — — Manufactured gas plant (MGP) 99 91 — — Advanced metering infrastructure (AMI) 367 362 127 150 NCEMPA deferrals 50 53 50 53 East Bend deferrals 47 45 — — Deferred pipeline integrity costs 65 54 — — Amounts due from customers 24 64 — — Other 784 538 322 110 Total regulatory assets 15,622 13,879 7,701 6,751 Less: current portion 2,005 1,437 1,137 741 Total noncurrent regulatory assets $ 13,617 $ 12,442 $ 6,564 $ 6,010 Regulatory Liabilities Costs of removal $ 5,421 $ 5,968 $ 2,135 $ 2,537 AROs – nuclear and other 538 806 — — Net regulatory liability related to income taxes 8,058 8,113 2,710 2,802 Amounts to be refunded to customers 34 10 — — Storm reserve — 20 — — Accrued pension and OPEB 301 146 149 — Deferred fuel and purchased power 16 47 16 1 Other 1,064 622 319 179 Total regulatory liabilities 15,432 15,732 5,329 5,519 Less: current portion 598 402 280 213 Total noncurrent regulatory liabilities $ 14,834 $ 15,330 $ 5,049 $ 5,306
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on Duke Energy Progress' Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 2,051 $ 1,975 (h) (b) AROs – nuclear and other 429 359 (c) Accrued pension and OPEB 542 430 (k) Retired generation facilities 148 170 X (b) Storm cost deferrals (d) 571 150 X (b) Hedge costs deferrals 54 64 (b) DSM/EE (e) 235 264 (i) (i) Vacation accrual 41 42 2019 Deferred fuel and purchased power 397 130 (f) 2020 Nuclear deferral 46 35 2020 PISCC and deferred operating expenses 36 38 X 2054 AMI 67 75 (b) NCEMPA deferrals 50 53 (g) 2042 Other 147 74 (b) Total regulatory assets 4,814 3,859 Less: current portion 703 352 Total noncurrent regulatory assets $ 4,111 $ 3,507 Regulatory Liabilities (a) Costs of removal $ 1,878 $ 2,122 X (j) Accrued pension and OPEB 93 — (k) Net regulatory liability related to income taxes (l) 1,863 1,854 (b) Deferred fuel and purchased power — 1 (f) 2020 Other 299 161 (b) Total regulatory liabilities 4,133 4,138 Less: current portion 178 139 Total noncurrent regulatory liabilities $ 3,955 $ 3,999 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Recovery period for costs related to nuclear facilities runs through the decommissioning period of each unit. (d) South Carolina storm costs are included in rate base. (e) Included in rate base. (f) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina. (g) South Carolina retail allocated costs are earning a return. (h) Earns a debt and equity return on coal ash expenditures for North Carolina and South Carolina retail customers as permitted by various regulatory orders. (i) Includes incentives on DSM/EE investments and is recovered through an annual rider mechanism. (j) Recovered over the life of the associated assets. (k) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail. (l) Includes regulatory liabilities related to the change in the federal tax rate as a result of the Tax Act and the change in the North Carolina tax rate, both discussed in Note 23.
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on Duke Energy Progress' Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 2,051 $ 1,975 (h) (b) AROs – nuclear and other 429 359 (c) Accrued pension and OPEB 542 430 (k) Retired generation facilities 148 170 X (b) Storm cost deferrals (d) 571 150 X (b) Hedge costs deferrals 54 64 (b) DSM/EE (e) 235 264 (i) (i) Vacation accrual 41 42 2019 Deferred fuel and purchased power 397 130 (f) 2020 Nuclear deferral 46 35 2020 PISCC and deferred operating expenses 36 38 X 2054 AMI 67 75 (b) NCEMPA deferrals 50 53 (g) 2042 Other 147 74 (b) Total regulatory assets 4,814 3,859 Less: current portion 703 352 Total noncurrent regulatory assets $ 4,111 $ 3,507 Regulatory Liabilities (a) Costs of removal $ 1,878 $ 2,122 X (j) Accrued pension and OPEB 93 — (k) Net regulatory liability related to income taxes (l) 1,863 1,854 (b) Deferred fuel and purchased power — 1 (f) 2020 Other 299 161 (b) Total regulatory liabilities 4,133 4,138 Less: current portion 178 139 Total noncurrent regulatory liabilities $ 3,955 $ 3,999 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Recovery period for costs related to nuclear facilities runs through the decommissioning period of each unit. (d) South Carolina storm costs are included in rate base. (e) Included in rate base. (f) Pays interest on over-recovered costs in North Carolina. Includes certain purchased power costs in North Carolina and South Carolina and costs of distributed energy in South Carolina. (g) South Carolina retail allocated costs are earning a return. (h) Earns a debt and equity return on coal ash expenditures for North Carolina and South Carolina retail customers as permitted by various regulatory orders. (i) Includes incentives on DSM/EE investments and is recovered through an annual rider mechanism. (j) Recovered over the life of the associated assets. (k) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail. (l) Includes regulatory liabilities related to the change in the federal tax rate as a result of the Tax Act and the change in the North Carolina tax rate, both discussed in Note 23.
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on Duke Energy Florida's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash (c) $ 10 $ 9 (b) AROs – nuclear and other (c) 172 296 (b) Accrued pension and OPEB (c) 532 476 X (g) Retired generation facilities (c) 219 216 X (b) Storm cost deferrals (c)(h) 382 376 (e) 2021 Nuclear asset securitized balance, net 1,093 1,142 2036 Hedge costs deferrals 20 30 2020 DSM/EE (c) 21 17 X 2023 Deferred fuel and purchased power (c) 203 219 (f) 2020 AMI (c) 60 75 X 2032 Other 176 36 (d) (b) Total regulatory assets 2,888 2,892 Less: current portion 434 389 Total noncurrent regulatory assets $ 2,454 $ 2,503 Regulatory Liabilities (a) Costs of removal (c) $ 257 $ 415 (d) (b) Net regulatory liability related to income taxes (c) 847 948 (b) Accrued pension and OPEB 56 — X (g) Deferred fuel and purchased power (c) 16 — (f) 2020 Other 20 18 (d) (b) Total regulatory liabilities 1,196 1,381 Less: current portion 102 74 Total noncurrent regulatory liabilities $ 1,094 $ 1,307 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Certain costs earn a return. (e) Earns a debt return/interest once collections begin. (f) Earns commercial paper rate. (g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail. (h) Balance includes $165 million for Hurricane Michael. Duke Energy Florida expects to seek recovery of these costs in the first half of 2019.
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on Duke Energy Florida's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash (c) $ 10 $ 9 (b) AROs – nuclear and other (c) 172 296 (b) Accrued pension and OPEB (c) 532 476 X (g) Retired generation facilities (c) 219 216 X (b) Storm cost deferrals (c)(h) 382 376 (e) 2021 Nuclear asset securitized balance, net 1,093 1,142 2036 Hedge costs deferrals 20 30 2020 DSM/EE (c) 21 17 X 2023 Deferred fuel and purchased power (c) 203 219 (f) 2020 AMI (c) 60 75 X 2032 Other 176 36 (d) (b) Total regulatory assets 2,888 2,892 Less: current portion 434 389 Total noncurrent regulatory assets $ 2,454 $ 2,503 Regulatory Liabilities (a) Costs of removal (c) $ 257 $ 415 (d) (b) Net regulatory liability related to income taxes (c) 847 948 (b) Accrued pension and OPEB 56 — X (g) Deferred fuel and purchased power (c) 16 — (f) 2020 Other 20 18 (d) (b) Total regulatory liabilities 1,196 1,381 Less: current portion 102 74 Total noncurrent regulatory liabilities $ 1,094 $ 1,307 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Certain costs earn a return. (e) Earns a debt return/interest once collections begin. (f) Earns commercial paper rate. (g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail. (h) Balance includes $165 million for Hurricane Michael. Duke Energy Florida expects to seek recovery of these costs in the first half of 2019.
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on Duke Energy Ohio's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 20 $ 17 X (b) Accrued pension and OPEB 146 139 (g) Storm cost deferrals 4 5 2023 Hedge costs deferrals 5 6 (b) DSM/EE 10 18 (f) (e) Grid modernization 31 39 X (e) Vacation accrual 5 5 2019 Deferred fuel and purchased power 2 — 2019 PISCC and deferred operating expenses (c) 17 19 X 2083 Transmission expansion obligation 43 50 (e) MGP 99 91 (b) AMI 46 6 (b) East Bend deferrals 47 45 X (b) Deferred pipeline integrity costs 14 12 X (b) Other 75 42 (b) Total regulatory assets 564 494 Less: current portion 33 49 Total noncurrent regulatory assets $ 531 $ 445 Regulatory Liabilities (a) Costs of removal $ 126 $ 189 (d) Net regulatory liability related to income taxes 678 688 (b) Accrued pension and OPEB 18 16 (g) Other 75 34 (b) Total regulatory liabilities 897 927 Less: current portion 57 36 Total noncurrent regulatory liabilities $ 840 $ 891 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Recovery over the life of the associated assets. (e) Recovered via a rider mechanism. (f) Includes incentives on DSM/EE investments. (g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on Duke Energy Ohio's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 20 $ 17 X (b) Accrued pension and OPEB 146 139 (g) Storm cost deferrals 4 5 2023 Hedge costs deferrals 5 6 (b) DSM/EE 10 18 (f) (e) Grid modernization 31 39 X (e) Vacation accrual 5 5 2019 Deferred fuel and purchased power 2 — 2019 PISCC and deferred operating expenses (c) 17 19 X 2083 Transmission expansion obligation 43 50 (e) MGP 99 91 (b) AMI 46 6 (b) East Bend deferrals 47 45 X (b) Deferred pipeline integrity costs 14 12 X (b) Other 75 42 (b) Total regulatory assets 564 494 Less: current portion 33 49 Total noncurrent regulatory assets $ 531 $ 445 Regulatory Liabilities (a) Costs of removal $ 126 $ 189 (d) Net regulatory liability related to income taxes 678 688 (b) Accrued pension and OPEB 18 16 (g) Other 75 34 (b) Total regulatory liabilities 897 927 Less: current portion 57 36 Total noncurrent regulatory liabilities $ 840 $ 891 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Recovery over the life of the associated assets. (e) Recovered via a rider mechanism. (f) Includes incentives on DSM/EE investments. (g) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.
Schedule of MISO Exit Fee Obligations	The following table provides a reconciliation of the beginning and ending balance of Duke Energy Ohio’s recorded liability for its exit obligation and share of MTEP costs recorded in Other within Current Liabilities and Other Noncurrent Liabilities on the Consolidated Balance Sheets. The retail portions of MTEP costs billed by MISO are recovered by Duke Energy Ohio through a non-bypassable rider. As of December 31, 2018, and 2017, $43 million and $50 million , respectively, are recorded in Regulatory assets on Duke Energy Ohio's Consolidated Balance Sheets. Provisions/ Cash (in millions) December 31, 2017 Adjustments Reductions December 31, 2018 Duke Energy Ohio $ 66 $ (4 ) $ (4 ) $ 58
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on Duke Energy Indiana's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 450 $ 380 (b) Accrued pension and OPEB 222 197 (f) Retired generation facilities (c) 57 65 X 2026 Hedge costs deferrals 24 25 (b) DSM/EE 14 21 (e) (e) Vacation accrual 11 11 2019 Deferred fuel and purchased power 40 18 2019 PISCC and deferred operating expenses (c) 233 274 X (b) AMI (c) 18 21 X (b) Other 88 131 (b) Total regulatory assets 1,157 1,143 Less: current portion 175 165 Total noncurrent regulatory assets $ 982 $ 978 Regulatory Liabilities (a) Costs of removal $ 628 $ 644 (d) Net regulatory liability related to income taxes 1,009 998 (b) Amounts to be refunded to customers 1 10 2019 Accrued pension and OPEB 67 64 (f) Other 42 31 (b) Total regulatory liabilities 1,747 1,747 Less: current portion 25 24 Total noncurrent regulatory liabilities $ 1,722 $ 1,723 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Recovery over the life of the associated assets. (e) Includes incentives on DSM/EE investments and is recovered through a tracker mechanism over a two-year period. (f) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on Duke Energy Indiana's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – coal ash $ 450 $ 380 (b) Accrued pension and OPEB 222 197 (f) Retired generation facilities (c) 57 65 X 2026 Hedge costs deferrals 24 25 (b) DSM/EE 14 21 (e) (e) Vacation accrual 11 11 2019 Deferred fuel and purchased power 40 18 2019 PISCC and deferred operating expenses (c) 233 274 X (b) AMI (c) 18 21 X (b) Other 88 131 (b) Total regulatory assets 1,157 1,143 Less: current portion 175 165 Total noncurrent regulatory assets $ 982 $ 978 Regulatory Liabilities (a) Costs of removal $ 628 $ 644 (d) Net regulatory liability related to income taxes 1,009 998 (b) Amounts to be refunded to customers 1 10 2019 Accrued pension and OPEB 67 64 (f) Other 42 31 (b) Total regulatory liabilities 1,747 1,747 Less: current portion 25 24 Total noncurrent regulatory liabilities $ 1,722 $ 1,723 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Recovery over the life of the associated assets. (e) Includes incentives on DSM/EE investments and is recovered through a tracker mechanism over a two-year period. (f) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.
Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	The following tables present the regulatory assets and liabilities recorded on Piedmont's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – other $ 19 $ 15 (d) Accrued pension and OPEB (c) 99 91 X (f) Derivatives – gas supply contracts (e) 141 142 Vacation accrual 12 10 Deferred pipeline integrity costs (c) 51 42 X (b) Amount due from customers 24 64 X (b) Other 11 14 (b) Total regulatory assets 357 378 Less: current portion 54 95 Total noncurrent regulatory assets $ 303 $ 283 Regulatory Liabilities (a) Costs of removal $ 564 $ 544 (d) Net regulatory liability related to income taxes 579 597 (b) Accrued pension and OPEB (c) 1 — X (f) Amount due to customers 33 — X (b) Other 41 3 (b) Total regulatory liabilities 1,218 1,144 Less: current portion 37 3 Total noncurrent regulatory liabilities $ 1,181 $ 1,141 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Recovery over the life of the associated assets. (e) Balance will fluctuate with changes in the market. Current contracts extend into 2031. (f) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.
Schedule Of Regulatory Liabilities	The following tables present the regulatory assets and liabilities recorded on Piedmont's Consolidated Balance Sheets. December 31, Earns/Pays Recovery/Refund (in millions) 2018 2017 a Return Period Ends Regulatory Assets (a) AROs – other $ 19 $ 15 (d) Accrued pension and OPEB (c) 99 91 X (f) Derivatives – gas supply contracts (e) 141 142 Vacation accrual 12 10 Deferred pipeline integrity costs (c) 51 42 X (b) Amount due from customers 24 64 X (b) Other 11 14 (b) Total regulatory assets 357 378 Less: current portion 54 95 Total noncurrent regulatory assets $ 303 $ 283 Regulatory Liabilities (a) Costs of removal $ 564 $ 544 (d) Net regulatory liability related to income taxes 579 597 (b) Accrued pension and OPEB (c) 1 — X (f) Amount due to customers 33 — X (b) Other 41 3 (b) Total regulatory liabilities 1,218 1,144 Less: current portion 37 3 Total noncurrent regulatory liabilities $ 1,181 $ 1,141 (a) Regulatory assets and liabilities are excluded from rate base unless otherwise noted. (b) The expected recovery or refund period varies or has not been determined. (c) Included in rate base. (d) Recovery over the life of the associated assets. (e) Balance will fluctuate with changes in the market. Current contracts extend into 2031. (f) Recovered primarily over the average remaining service periods or life expectancies of employees covered by the benefit plans. See Note 22 for additional detail.

Commitments and Contingencies (

Commitments and Contingencies (Table)	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Schedule of Legal Reserves	The table below presents recorded reserves based on management’s best estimate of probable loss for legal matters, excluding asbestos-related reserves, the CertainTeed liquidated damages obligation and the exit obligation in 2017 related to the termination of an EPC contract. Reserves are classified on the Consolidated Balance Sheets in Other within Other Noncurrent Liabilities and Other within Current Liabilities. The reasonably possible range of loss in excess of recorded reserves is not material, other than as described above. December 31, (in millions) 2018 2017 Reserves for Legal Matters Duke Energy $ 65 $ 88 Duke Energy Carolinas 9 30 Progress Energy 54 55 Duke Energy Progress 12 13 Duke Energy Florida 24 24 Piedmont 1 2
Schedule of Additional Possible Losses in Excess of Recorded Environmental Reserves	Additional losses in excess of recorded reserves that could be incurred for the stages of investigation, remediation and monitoring for environmental sites that have been evaluated at this time are not material except as presented in the table below. (in millions) Duke Energy $ 46 Duke Energy Carolinas 17 Duke Energy Ohio 19 Piedmont 2
Schedule of Purchase Power Obligations	The following table presents executory purchased power contracts with terms exceeding one year, excluding contracts classified as leases. Minimum Purchase Amount at December 31, 2018 Contract (in millions) Expiration 2019 2020 2021 2022 2023 Thereafter Total Duke Energy Progress (a) 2022-2031 $ 51 $ 52 $ 53 $ 30 $ 25 $ 215 $ 426 Duke Energy Florida (b) 2021-2025 363 380 365 363 382 361 2,214 Duke Energy Ohio (c)(d) 2020-2022 146 117 53 11 — — 327 (a) Contracts represent 100 percent of net plant output. (b) Contracts represent between 81 percent and 100 percent of net plant output. (c) Contracts represent between 1 percent and 8 percent of net plant output. (d) Excludes PPA with OVEC. See Note 17 for additional information.
Schedule of Natural Gas Supply Contract Commitments	The following table presents future unconditional purchase obligations under natural gas supply and capacity contracts as of December 31, 2018 . (in millions) Duke Energy Duke Energy Ohio Piedmont 2019 $ 314 $ 38 $ 276 2020 287 30 257 2021 255 29 226 2022 225 11 214 2023 148 4 144 Thereafter 1,067 — 1,067 Total $ 2,296 $ 112 $ 2,184
Schedule of Rent Expense	The following tables present rental expense for operating leases. These amounts are included in Operation, maintenance and other and Fuel used in electric generation and purchased power on the Consolidated Statements of Operations. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy $ 268 $ 241 $ 242 Duke Energy Carolinas 49 44 45 Progress Energy 143 130 140 Duke Energy Progress 75 75 68 Duke Energy Florida 68 55 72 Duke Energy Ohio 13 15 16 Duke Energy Indiana 21 23 23 Years Ended December 31, Two Months Ended December 31, Year Ended October 31, (in millions) 2018 2017 2016 2016 Piedmont $ 11 $ 7 $ 1 $ 5
Schedule of Future Minimum Rental Payments for Operating Leases	The following table presents future minimum lease payments under operating leases, which at inception had a non-cancelable term of more than one year. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont 2019 $ 239 $ 33 $ 97 $ 49 $ 48 $ 2 $ 6 $ 5 2020 219 29 90 46 44 2 5 5 2021 186 19 79 37 42 2 4 5 2022 170 19 76 34 42 2 4 5 2023 160 17 77 35 42 2 5 6 Thereafter 1,017 68 455 314 141 23 66 11 Total $ 1,991 $ 185 $ 874 $ 515 $ 359 $ 33 $ 90 $ 37
Schedule of Future Minimum Lease Payments for Capital Leases	The following table presents future minimum lease payments under capital leases. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana 2019 $ 170 $ 20 $ 45 $ 20 $ 25 $ 2 $ 1 2020 174 20 46 21 25 — 1 2021 177 15 45 20 25 — 1 2022 165 15 45 21 24 — 1 2023 165 15 45 21 24 — 1 Thereafter 577 204 230 209 21 — 27 Minimum annual payments 1,428 289 456 312 144 2 32 Less: amount representing interest (487 ) (180 ) (205 ) (175 ) (30 ) — (22 ) Total $ 941 $ 109 $ 251 $ 137 $ 114 $ 2 $ 10
SEC Schedule, 12-09, Reserve, Environmental Cost [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Schedule of Legal Reserves	The following tables contain information regarding reserves for probable and estimable costs related to the various environmental sites. These reserves are recorded in Accounts payable within Current Liabilities and Other within Other Noncurrent Liabilities on the Consolidated Balance Sheets. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Balance at December 31, 2015 $ 94 $ 10 $ 17 $ 3 $ 14 $ 54 $ 12 Provisions/adjustments 19 4 7 2 4 7 1 Cash reductions (15 ) (4 ) (6 ) (2 ) (4 ) (2 ) (3 ) Balance at December 31, 2016 98 10 18 3 14 59 10 Provisions/adjustments 8 3 3 2 2 3 (4 ) Cash reductions (25 ) (3 ) (6 ) (2 ) (4 ) (15 ) (1 ) Balance at December 31, 2017 81 10 15 3 12 47 5 Provisions/adjustments 26 3 2 3 (2 ) 21 1 Cash reductions (30 ) (2 ) (6 ) (2 ) (4 ) (20 ) (1 ) Balance at December 31, 2018 $ 77 $ 11 $ 11 $ 4 $ 6 $ 48 $ 5 As of December 31, 2016, and October 31, 2016 and 2015, Piedmont's environmental reserve was $1 million . As of December 31, 2018, and 2017, the reserve was $2 million .

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Debt	The following table shows the significant components of Current maturities of Long-Term Debt on the Consolidated Balance Sheets. The Duke Energy Registrants currently anticipate satisfying these obligations with cash on hand and proceeds from additional borrowings. (in millions) Maturity Date Interest Rate December 31, 2018 Unsecured Debt Progress Energy March 2019 7.050 % $ 450 Duke Energy (Parent) September 2019 5.050 % 500 Piedmont September 2019 3.155 % (b) 350 Duke Energy Kentucky October 2019 4.65 % 100 Progress Energy December 2019 4.875 % 350 First Mortgage Bonds Duke Energy Progress January 2019 5.300 % 600 Duke Energy Ohio April 2019 5.450 % 450 Other (a) 606 Current maturities of long-term debt $ 3,406 (a) Includes capital lease obligations, amortizing debt and small bullet maturities. (b) Debt has a floating interest rate. The following tables show short-term obligations classified as long-term debt. December 31, 2018 Duke Duke Duke Duke Duke Energy Energy Energy Energy (in millions) Energy Carolinas Progress Ohio Indiana Tax-exempt bonds $ 312 $ — $ — $ 27 $ 285 Commercial paper (a) 625 300 150 25 150 Total $ 937 $ 300 $ 150 $ 52 $ 435 December 31, 2017 Duke Duke Duke Duke Duke Energy Energy Energy Energy (in millions) Energy Carolinas Progress Ohio Indiana Tax-exempt bonds $ 312 $ — $ — $ 27 $ 285 Commercial paper (a) 625 300 150 25 150 Total $ 937 $ 300 $ 150 $ 52 $ 435 (a) Progress Energy amounts are equal to Duke Energy Progress amounts. The following tables summarize outstanding debt. December 31, 2018 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unsecured debt, maturing 2019-2078 4.26 % $ 20,955 $ 1,150 $ 3,800 $ 50 $ 350 $ 1,000 $ 408 $ 2,150 Secured debt, maturing 2020-2037 3.69 % 4,297 450 1,703 300 1,403 — — — First mortgage bonds, maturing 2019-2048 (a) 4.32 % 25,628 8,759 13,100 7,574 5,526 1,099 2,670 — Capital leases, maturing 2019-2051 (b) 5.06 % 941 109 251 137 114 2 10 — Tax-exempt bonds, maturing 2019-2041 (c) 3.40 % 941 243 48 48 — 77 572 — Notes payable and commercial paper (d) 2.73 % 4,035 — — — — — — — Money pool/intercompany borrowings — 739 1,385 444 108 299 317 198 Fair value hedge carrying value adjustment 5 5 — — — — — — Unamortized debt discount and premium, net (e) 1,434 (23 ) (29 ) (15 ) (11 ) (31 ) (8 ) (1 ) Unamortized debt issuance costs (f) (297 ) (54 ) (112 ) (40 ) (61 ) (7 ) (20 ) (11 ) Total debt 4.13 % $ 57,939 $ 11,378 $ 20,146 $ 8,498 $ 7,429 $ 2,439 $ 3,949 $ 2,336 Short-term notes payable and commercial paper (3,410 ) — — — — — — — Short-term money pool/intercompany borrowings — (439 ) (1,235 ) (294 ) (108 ) (274 ) (167 ) (198 ) Current maturities of long-term debt (g) (3,406 ) (6 ) (1,672 ) (603 ) (270 ) (551 ) (63 ) (350 ) Total long-term debt (g) $ 51,123 $ 10,933 $ 17,239 $ 7,601 $ 7,051 $ 1,614 $ 3,719 $ 1,788 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $63 million and $531 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds, letters of credit or the Master Credit Facility. (d) Includes $625 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that backstop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for Duke Energy's commercial paper program was 16 days. (e) Duke Energy includes $1,380 million and $156 million in purchase accounting adjustments related to Progress Energy and Piedmont, respectively. (f) Duke Energy includes $41 million in purchase accounting adjustments primarily related to the merger with Progress Energy. (g) Refer to Note 17 for additional information on amounts from consolidated VIEs. December 31, 2017 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unsecured debt, maturing 2018-2073 4.17 % $ 20,409 $ 1,150 $ 3,950 $ — $ 550 $ 900 $ 411 $ 2,050 Secured debt, maturing 2018-2037 3.15 % 4,458 450 1,757 300 1,457 — — — First mortgage bonds, maturing 2018-2047 (a) 4.51 % 23,529 7,959 11,801 6,776 5,025 1,100 2,669 — Capital leases, maturing 2018-2051 (b) 4.55 % 1,000 61 269 139 129 5 11 — Tax-exempt bonds, maturing 2019-2041 (c) 3.23 % 941 243 48 48 — 77 572 — Notes payable and commercial paper (d) 1.57 % 2,788 — — — — — — — Money pool/intercompany borrowings — 404 955 390 — 54 311 364 Fair value hedge carrying value adjustment 6 6 — — — — — — Unamortized debt discount and premium, net (e) 1,582 (19 ) (30 ) (16 ) (10 ) (33 ) (9 ) (1 ) Unamortized debt issuance costs (f) (271 ) (47 ) (108 ) (40 ) (56 ) (7 ) (21 ) (12 ) Total debt 4.09 % $ 54,442 $ 10,207 $ 18,642 $ 7,597 $ 7,095 $ 2,096 $ 3,944 $ 2,401 Short-term notes payable and commercial paper (2,163 ) — — — — — — — Short-term money pool/intercompany borrowings — (104 ) (805 ) (240 ) — (29 ) (161 ) (364 ) Current maturities of long-term debt (g) (3,244 ) (1,205 ) (771 ) (3 ) (768 ) (3 ) (3 ) (250 ) Total long-term debt (g) $ 49,035 $ 8,898 $ 17,066 $ 7,354 $ 6,327 $ 2,064 $ 3,780 $ 1,787 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $81 million and $603 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds, letters of credit or the Master Credit Facility. (d) Includes $625 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that backstop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for Duke Energy's commercial paper programs was 14 days. (e) Duke Energy includes $1,509 million and $176 million purchase accounting adjustments related to the mergers with Progress Energy and Piedmont, respectively. (f) Duke Energy includes $47 million in purchase accounting adjustments primarily related to the merger with Progress Energy. (g) Refer to Note 17 for additional information on amounts from consolidated VIEs.
Schedule of Maturities of Long-term Debt	The following table shows the annual maturities of long-term debt for the next five years and thereafter. Amounts presented exclude short-term notes payable and commercial paper and money pool borrowings for the Subsidiary Registrants. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy (a) Carolinas Energy Progress Florida Ohio Indiana Piedmont 2019 $ 3,408 $ 6 $ 1,674 $ 603 $ 270 552 $ 63 $ 350 2020 3,765 907 926 354 572 — 503 — 2021 4,803 503 2,004 904 600 50 70 160 2022 2,745 353 1,032 505 77 — 94 — 2023 3,375 1,303 535 456 79 350 153 45 Thereafter 35,288 7,940 12,880 5,437 5,793 1,251 2,925 1,595 Total long-term debt, including current maturities $ 53,384 $ 11,012 $ 19,051 $ 8,259 $ 7,391 $ 2,203 $ 3,808 $ 2,150 (a) Excludes $1,578 million in purchase accounting adjustments related to the Progress Energy merger and the Piedmont acquisition.
Schedule of Long-term Debt Instruments	The following tables summarize significant debt issuances (in millions). Year Ended December 31, 2018 Duke Duke Duke Duke Maturity Interest Duke Energy Energy Energy Energy Issuance Date Date Rate Energy (Parent) Carolinas Progress Florida Unsecured Debt March 2018 (a) April 2025 3.950 % $ 250 $ 250 $ — $ — $ — May 2018 (b) May 2021 3.114 % 500 500 — — — September 2018 (c) September 2078 5.625 % 500 500 — — — First Mortgage Bonds March 2018 (d) March 2023 3.050 % 500 — 500 — — March 2018 (d) March 2048 3.950 % 500 — 500 — — June 2018 (e) July 2028 3.800 % 600 — — — 600 June 2018 (e) July 2048 4.200 % 400 — — — 400 August 2018 (f) September 2023 3.375 % 300 — — 300 — August 2018 (f) September 2028 3.700 % 500 — — 500 — November 2018 (g) May 2022 3.350 % 350 — 350 — — November 2018 (g) November 2028 3.950 % 650 — 650 — — Total issuances $ 5,050 $ 1,250 $ 2,000 $ 800 $ 1,000 (a) Debt issued to pay down short-term debt. (b) Debt issued to pay down short-term debt. Debt issuance has a floating debt rate. (c) Callable after September 2023 at par. Junior subordinated hybrid debt issued to pay down short-term debt and for general corporate purposes. (d) Debt issued to repay at maturity a $300 million first mortgage bond due April 2018, pay down intercompany short-term debt and for general corporate purposes. (e) Debt issued to repay a portion of intercompany short-term debt under the money pool borrowing arrangement and for general corporate purposes. (f) Debt issued to repay short-term debt and for general corporate purposes. (g) Debt issued to fund eligible green energy projects, including zero-carbon solar and energy storage, in the Carolinas. Year Ended December 31, 2017 Duke Duke Duke Duke Duke Maturity Interest Duke Energy Energy Energy Energy Energy Issuance Date Date Rate Energy (Parent) Carolinas Progress Florida Ohio Unsecured Debt April 2017 (a) April 2025 3.364 % $ 420 $ 420 $ — $ — $ — $ — June 2017 (b) June 2020 2.100 % 330 330 — — — — August 2017 (c) August 2022 2.400 % 500 500 — — — — August 2017 (c) August 2027 3.150 % 750 750 — — — — August 2017 (c) August 2047 3.950 % 500 500 — — — — December 2017 (d) December 2019 (k) 2.100 % 400 — — — 400 — Secured Debt February 2017 (e) June 2034 4.120 % 587 — — — — — August 2017 (f) December 2036 4.110 % 233 — — — — — First Mortgage Bonds January 2017 (g) January 2020 1.850 % 250 — — — 250 — January 2017 (g) January 2027 3.200 % 650 — — — 650 — March 2017 (h) June 2046 3.700 % 100 — — — — 100 September 2017 (i) September 2020 1.500 % (l) 300 — — 300 — — September 2017 (i) September 2047 3.600 % 500 — — 500 — — November 2017 (j) December 2047 3.700 % 550 — 550 — — — Total issuances $ 6,070 $ 2,500 $ 550 $ 800 $ 1,300 $ 100 (a) Proceeds were used to refinance $400 million of unsecured debt at maturity and to repay a portion of outstanding commercial paper. (b) Debt issued to repay a portion of outstanding commercial paper. (c) Debt issued to repay at maturity $700 million of unsecured debt, to repay outstanding commercial paper and for general corporate purposes. (d) Debt issued to fund storm restoration costs related to Hurricane Irma and for general corporate purposes. (e) Portfolio financing of four Texas and Oklahoma wind facilities. Duke Energy pledged substantially all of the assets of these wind facilities and is nonrecourse to Duke Energy. Proceeds were used to reimburse Duke Energy for a portion of previously funded construction expenditures. (f) Portfolio financing of eight solar facilities located in California, Colorado and New Mexico. Duke Energy pledged substantially all of the assets of these solar facilities and is nonrecourse to Duke Energy. Proceeds were used to reimburse Duke Energy for a portion of previously funded construction expenditures. (g) Debt issued to fund capital expenditures for ongoing construction and capital maintenance, to repay a $250 million aggregate principal amount of bonds at maturity and for general corporate purposes. (h) Proceeds were used to fund capital expenditures for ongoing construction, capital maintenance and for general corporate purposes. (i) Debt issued to repay at maturity a $200 million aggregate principal amount of bonds at maturity, pay down intercompany short-term debt and for general corporate purposes, including capital expenditures. (j) Debt issued to refinance $400 million aggregate principal amount of bonds due January 2018, pay down intercompany short-term debt and for general corporate purposes. (k) Principal balance will be repaid in equal quarterly installments beginning in March 2018. (l) Debt issuance has a floating interest rate.
Schedule Of Line Of Credit Facilities	The table below includes the current borrowing sublimits and available capacity under these credit facilities. December 31, 2018 Duke Duke Duke Duke Duke Duke Duke Energy Energy Energy Energy Energy Energy (in millions) Energy (Parent) Carolinas Progress Florida Ohio Indiana Piedmont Facility size (a) $ 8,000 $ 2,650 $ 1,750 $ 1,400 $ 650 $ 450 $ 600 $ 500 Reduction to backstop issuances Commercial paper (b) (3,022 ) (917 ) (739 ) (444 ) (108 ) (299 ) (317 ) (198 ) Outstanding letters of credit (53 ) (45 ) (4 ) (2 ) — — — (2 ) Tax-exempt bonds (81 ) — — — — — (81 ) — Coal ash set-aside (500 ) — (250 ) (250 ) — — — — Available capacity $ 4,344 $ 1,688 $ 757 $ 704 $ 542 $ 151 $ 202 $ 300 (a) Represents the sublimit of each borrower. (b) Duke Energy issued $625 million of commercial paper and loaned the proceeds through the money pool to Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio and Duke Energy Indiana. The balances are classified as Long-Term Debt Payable to Affiliated Companies in the Consolidated Balance Sheets.

Joint Ownership of Generating_2

Joint Ownership of Generating and Transmission Facilities (Tables)	12 Months Ended
	Dec. 31, 2018
Jointly Owned Utility Plant Interests [Line Items]
Schedule Joint Ownership of Generating and Transmission Facilities	The following table presents the Duke Energy Registrants' interest of jointly owned plant or facilities and amounts included on the Consolidated Balance Sheets. All facilities are operated by the Duke Energy Registrants and are included in the Electric Utilities and Infrastructure segment. December 31, 2018 Construction Ownership Property, Plant Accumulated Work in (in millions except for ownership interest) Interest and Equipment Depreciation Progress Duke Energy Carolinas Catawba (units 1 and 2) (a) 19.25 % $ 989 $ 483 $ 17 W.S. Lee CC (b) 86.67 % 593 12 4 Duke Energy Indiana Gibson (unit 5) (c) 50.05 % 390 173 3 Vermillion (d) 62.50 % 168 135 — Transmission and local facilities (c) Various 5,037 1,769 — (a) Jointly owned with North Carolina Municipal Power Agency Number 1, NCEMC and PMPA. (b) Jointly owned with NCEMC. (c) Jointly owned with WVPA and Indiana Municipal Power Agency. (d) Jointly owned with WVPA.

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligations [Line Items]
Schedule of Asset Retirement Obligations by Category	The following table presents the AROs recorded on the Consolidated Balance Sheets. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Decommissioning of nuclear power facilities (a) $ 5,696 $ 2,335 $ 3,209 $ 2,679 $ 530 $ — $ — $ — Closure of ash impoundments 4,446 1,568 2,123 2,103 20 52 702 — Other (b) 325 46 79 38 41 41 20 19 Total asset retirement obligation $ 10,467 $ 3,949 $ 5,411 $ 4,820 $ 591 $ 93 $ 722 $ 19 Less: current portion 919 290 514 509 5 6 109 — Total noncurrent asset retirement obligation $ 9,548 $ 3,659 $ 4,897 $ 4,311 $ 586 $ 87 $ 613 $ 19 (a) Duke Energy amount includes purchase accounting adjustments related to the merger with Progress Energy. (b) Primarily includes obligations related to asbestos removal. Duke Energy Ohio and Piedmont also include AROs related to the retirement of natural gas mains and services. Duke Energy includes AROs related to the removal of renewable energy generation assets.
Public Utilities General Disclosures	The following table includes the current expiration of nuclear operating licenses. Unit Year of Expiration Duke Energy Carolinas Catawba Units 1 and 2 2043 McGuire Unit 1 2041 McGuire Unit 2 2043 Oconee Units 1 and 2 2033 Oconee Unit 3 2034 Duke Energy Progress Brunswick Unit 1 2036 Brunswick Unit 2 2034 Harris 2046 Robinson 2030 The following table presents the fair value of NDTF assets legally restricted for purposes of settling AROs associated with nuclear decommissioning. Duke Energy Florida is actively decommissioning Crystal River Unit 3 and was granted an exemption from the NRC, which allows for use of the NDTF for all aspects of nuclear decommissioning. The entire balance of Duke Energy Florida's NDTF may be applied toward license termination, spent fuel and site restoration costs incurred to decommission Crystal River Unit 3 and is excluded from the table below. See Note 16 for additional information related to the fair value of the Duke Energy Registrants' NDTFs. December 31, (in millions) 2018 2017 Duke Energy $ 5,579 $ 5,864 Duke Energy Carolinas 3,133 3,321 Duke Energy Progress 2,446 2,543 The following table summarizes information about the most recent site-specific nuclear decommissioning cost studies. Decommissioning costs are stated in 2018 dollars for Duke Energy Carolinas, 2017 dollars for Duke Energy Florida and 2014 dollars for Duke Energy Progress, and include costs to decommission plant components not subject to radioactive contamination. Annual Funding Decommissioning (in millions) Requirement (a) Costs (a) Year of Cost Study Duke Energy $ 24 $ 8,737 2014 and 2018 Duke Energy Carolinas (b)(c) — 4,291 2018 Duke Energy Progress 24 3,550 2014 Duke Energy Florida (d) — 896 2018 (a) Amounts for Progress Energy equal the sum of Duke Energy Progress and Duke Energy Florida. (b) Decommissioning cost for Duke Energy Carolinas reflects its ownership interest in jointly owned reactors. Other joint owners are responsible for decommissioning costs related to their interest in the reactors. (c) Duke Energy Carolinas' site-specific nuclear decommissioning cost study completed in 2018 is expected to be filed with the NCUC and PSCSC by the second quarter 2019. Duke Energy Carolinas will also complete a new funding study, which will be completed and filed with the NCUC and PSCSC in 2019. (d) Duke Energy Florida's site-specific nuclear decommissioning cost study and a new funding study were completed and filed with the FPSC in 2018.
Rollforward Schedule of Asset Retirement Obligations	The following tables present changes in the liability associated with AROs. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at December 31, 2016 $ 10,611 $ 3,895 $ 5,475 $ 4,697 $ 778 $ 77 $ 866 $ 14 Accretion expense (a) 435 184 228 195 33 3 32 1 Liabilities settled (b) (619 ) (282 ) (270 ) (204 ) (65 ) (7 ) (49 ) (8 ) Liabilities incurred in the current year (c) 51 5 — — — 7 29 8 Revisions in estimates of cash flows (303 ) (192 ) (19 ) (15 ) (4 ) 4 (97 ) — Balance at December 31, 2017 10,175 3,610 5,414 4,673 742 84 781 15 Accretion expense (a) 427 179 225 196 29 4 29 1 Liabilities settled (b) (638 ) (281 ) (272 ) (227 ) (45 ) (5 ) (79 ) — Liabilities incurred in the current year (c) 39 8 5 — 5 — 25 — Revisions in estimates of cash flows (d) 464 433 39 178 (140 ) 10 (34 ) 3 Balance at December 31, 2018 $ 10,467 $ 3,949 $ 5,411 $ 4,820 $ 591 $ 93 $ 722 $ 19 (a) Substantially all accretion expense for the years ended December 31, 2018 , and 2017 relates to Duke Energy’s regulated operations and has been deferred in accordance with regulatory accounting treatment. (b) Amounts primarily relate to ash impoundment closures and nuclear decommissioning of Crystal River Unit 3. (c) Amounts primarily relate to AROs recorded as a result of state agency closure requirements at Duke Energy Indiana. (d) Amounts primarily relate to increases in groundwater monitoring estimates for closure of ash impoundments and an increase for nuclear decommissioning costs at Duke Energy Carolinas' nuclear sites compared to original estimates, partially offset by a reduction for nuclear decommissioning at Crystal River Unit 3 compared to original estimates and modifications to the timing of expected cash flows for coal ash AROs.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Schedule Of Property, Plant And Equipment	The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows. Years Ended December 31, 2018 2017 2016 Duke Energy 3.0 % 2.8 % 2.8 % Duke Energy Carolinas 2.8 % 2.8 % 2.8 % Progress Energy 2.9 % 2.6 % 2.7 % Duke Energy Progress 2.9 % 2.6 % 2.6 % Duke Energy Florida 3.0 % 2.8 % 2.8 % Duke Energy Ohio 2.8 % 2.8 % 2.6 % Duke Energy Indiana 3.3 % 3.0 % 3.1 % Piedmont (a) 2.5 % 2.3 % (a) Piedmont's weighted average depreciation rate was 2.4 percent for the annualized two months ended December 31, 2016, and for the year ended October 31, 2016. The following tables summarize the property, plant and equipment for Duke Energy and its subsidiary registrants. December 31, 2018 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Land $ 2,072 $ 472 $ 868 $ 445 $ 423 $ 136 $ 116 $ 448 Plant – Regulated Electric generation, distribution and transmission 15-100 100,706 38,468 42,760 26,147 16,613 5,182 14,292 — Natural gas transmission and distribution 12-80 8,808 — — — — 2,719 — 6,089 Other buildings and improvements 24-90 1,966 681 636 295 341 270 253 126 Plant – Nonregulated Electric generation, distribution and transmission 5-30 4,410 — — — — — — — Other buildings and improvements 25-35 494 — — — — — — — Nuclear fuel 3,460 1,898 1,562 1,562 — — — — Equipment 3-55 2,141 467 565 399 166 384 178 141 Construction in process 5,726 1,678 2,515 1,659 856 412 325 382 Other 3-40 4,675 1,077 1,354 952 393 257 279 300 Total property, plant and equipment (a)(d) 134,458 44,741 50,260 31,459 18,792 9,360 15,443 7,486 Total accumulated depreciation – regulated (b)(c)(d) (41,079 ) (15,496 ) (16,398 ) (11,423 ) (4,968 ) (2,717 ) (4,914 ) (1,575 ) Total accumulated depreciation – nonregulated (c)(d) (2,047 ) — — — — — — — Generation facilities to be retired, net 362 — 362 362 — — — — Total net property, plant and equipment $ 91,694 $ 29,245 $ 34,224 $ 20,398 $ 13,824 $ 6,643 $ 10,529 $ 5,911 (a) Includes capitalized leases of $1,237 million , $135 million , $257 million , $137 million , $120 million , $73 million and $35 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana, respectively, primarily within Plant – Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $131 million , $14 million and $117 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,947 million , $1,087 million , $860 million and $860 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $61 million , $12 million , $20 million and $10 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $4,007 million and accumulated depreciation of consolidated VIEs of $698 million at Duke Energy. December 31, 2017 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Land $ 1,559 $ 467 $ 767 $ 424 $ 343 $ 134 $ 111 $ 41 Plant – Regulated Electric generation, distribution and transmission 8-100 93,687 35,657 39,419 24,502 14,917 4,870 13,741 — Natural gas transmission and distribution 12-80 8,292 — — — — 2,559 — 5,733 Other buildings and improvements 15-100 1,936 647 652 316 336 243 240 154 Plant – Nonregulated Electric generation, distribution and transmission (a) 5-30 4,273 — — — — — — — Other buildings and improvements 25-35 465 — — — — — — — Nuclear fuel 3,680 2,120 1,560 1,560 — — — — Equipment 3-55 2,122 402 555 416 139 348 169 266 Construction in process 6,995 2,614 3,059 1,434 1,625 350 416 231 Other 3-40 4,498 1,032 1,311 931 370 228 271 300 Total property, plant and equipment (b)(e) 127,507 42,939 47,323 29,583 17,730 8,732 14,948 6,725 Total accumulated depreciation – regulated (c)(d)(e) (39,742 ) (15,063 ) (15,857 ) (10,903 ) (4,947 ) (2,691 ) (4,662 ) (1,479 ) Total accumulated depreciation – nonregulated (d)(e) (1,795 ) — — — — — — — Generation facilities to be retired, net 421 — 421 421 — — — — Total net property, plant and equipment $ 86,391 $ 27,876 $ 31,887 $ 19,101 $ 12,783 $ 6,041 $ 10,286 $ 5,246 (a) Includes a pretax impairment charge of $58 million on a wholly owned non-contracted wind project. See discussion below. (b) Includes capitalized leases of $1,294 million , $81 million , $272 million , $139 million , $133 million , $80 million and $35 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana, respectively, primarily within Plant – Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $114 million , $11 million and $103 million , respectively, of accumulated amortization of capitalized leases. (c) Includes $2,113 million , $1,283 million , $831 million and $831 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (d) Includes accumulated amortization of capitalized leases of $57 million , $11 million , $21 million and $9 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (e) Includes gross property, plant and equipment cost of consolidated VIEs of $3,941 million and accumulated depreciation of consolidated VIEs of $598 million at Duke Energy.
Schedule Of Capitalized Interest	The following tables present capitalized interest, which includes the debt component of AFUDC. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy $ 161 $ 128 $ 100 Duke Energy Carolinas 35 45 38 Progress Energy 51 45 31 Duke Energy Progress 26 21 17 Duke Energy Florida 25 24 14 Duke Energy Ohio 17 10 8 Duke Energy Indiana 27 9 7 Years Ended December 31, Two Months Ended December 31, Year Ended October 31, (in millions) 2018 2017 2016 2016 Piedmont $ 17 $ 12 $ 2 $ 12

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill [Line Items]
Goodwill By Reportable Operating Segment	The following table presents goodwill by reportable segment for Duke Energy included on Duke Energy's Consolidated Balance Sheets at December 31, 2018 , and 2017 . Electric Utilities Gas Utilities Commercial (in millions) and Infrastructure and Infrastructure Renewables Total Goodwill Balance at December 31, 2017 $ 17,379 $ 1,924 $ 122 $ 19,425 Accumulated impairment charges (a) — — (29 ) (29 ) Goodwill balance at December 31, 2017, adjusted for accumulated impairment charges $ 17,379 $ 1,924 $ 93 $ 19,396 Goodwill Balance at December 31, 2018 $ 17,379 $ 1,924 $ 122 $ 19,425 Accumulated impairment charges (a) $ — $ — $ (122 ) $ (122 ) Goodwill balance at December 31, 2018, adjusted for accumulated impairment charges $ 17,379 $ 1,924 $ — $ 19,303 (a) Duke Energy evaluated the recoverability of goodwill during 2017 and recorded impairment charges of $29 million related to the Energy Management Solutions reporting unit within the Commercial Renewables segment. The fair value of the reporting unit was determined based on the market approach. See "Goodwill Impairment Testing" below for the results of the 2018 goodwill impairment test.
Schedule of Intangible Assets	The following tables show the carrying amount and accumulated amortization of intangible assets included in Other within Other Noncurrent Assets on the Consolidated Balance Sheets of the Duke Energy Registrants at December 31, 2018 , and 2017 . December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Emission allowances $ 18 $ — $ 5 $ 2 $ 3 $ — $ 12 $ — Renewable energy certificates 168 46 120 120 — 2 — — Natural gas, coal and power contracts 24 — — — — — 24 — Renewable operating and development projects 84 — — — — — — — Other 6 — — — — — — 3 Total gross carrying amounts 300 46 125 122 3 2 36 3 Accumulated amortization – natural gas, coal and power contracts (20 ) — — — — — (20 ) — Accumulated amortization – renewable operating and development projects (29 ) — — — — — — — Accumulated amortization – other (5 ) — — — — — — (3 ) Total accumulated amortization (54 ) — — — — — (20 ) (3 ) Total intangible assets, net $ 246 $ 46 $ 125 $ 122 $ 3 $ 2 $ 16 $ — December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Emission allowances $ 19 $ 1 $ 5 $ 2 $ 3 $ — $ 13 $ — Renewable energy certificates 148 38 107 107 — 3 — — Natural gas, coal and power contracts 24 — — — — — 24 — Renewable operating and development projects 79 — — — — — — — Other 6 — — — — — — 3 Total gross carrying amounts 276 39 112 109 3 3 37 3 Accumulated amortization – natural gas, coal and power contracts (19 ) — — — — — (19 ) — Accumulated amortization – renewable operating and development projects (22 ) — — — — — — — Accumulated amortization – other (5 ) — — — — — — (3 ) Total accumulated amortization (46 ) — — — — — (19 ) (3 ) Total intangible assets, net $ 230 $ 39 $ 112 $ 109 $ 3 $ 3 $ 18 $ —

Investments in Unconsolidated_2

Investments in Unconsolidated Affiliates (Tables)	12 Months Ended
	Dec. 31, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investments in Equity Method Unconsolidated Affiliates	The following table presents Duke Energy’s investments in unconsolidated affiliates accounted for under the equity method, as well as the respective equity in earnings, by segment. Years Ended December 31, 2018 2017 2016 Equity in Equity in Equity in (in millions) Investments earnings Investments earnings Investments earnings Electric Utilities and Infrastructure $ 97 $ 6 $ 89 $ 5 $ 93 $ 5 Gas Utilities and Infrastructure 1,003 27 763 62 566 19 Commercial Renewables 201 (1 ) 190 (5 ) 185 (82 ) Other 108 51 133 57 81 43 Total $ 1,409 $ 83 $ 1,175 $ 119 $ 925 $ (15 ) The table below outlines Duke Energy's ownership interests in natural gas pipeline companies and natural gas storage facilities. Investment Amount (in millions) Ownership December 31, December 31, Entity Name Interest 2018 2017 Pipeline Investments Atlantic Coast Pipeline, LLC (a) 47 % $ 797 $ 397 Sabal Trail Transmission, LLC 7.5 % 112 (d) 219 Constitution Pipeline, LLC (a) 24 % 25 81 Cardinal Pipeline Company, LLC (b) 21.49 % 10 11 Storage Facilities Pine Needle LNG Company, LLC (b) 45 % 13 13 Hardy Storage Company, LLC (b) 50 % 46 42 Total Investments (c) $ 1,003 $ 763 (a) During the year ended December 31, 2017, Piedmont transferred its share of ownership interest in ACP and Constitution to a wholly owned subsidiary of Duke Energy at book value. (b) Piedmont owns the Cardinal, Pine Needle and Hardy Storage investments. (c) Duke Energy includes purchase accounting adjustments related to Piedmont. (d) Sabal Trail returned capital of $112 million during the year ended December 31, 2018.

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2018
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 985 $ 858 $ 831 Indemnification coverages (b) 22 23 22 JDA revenue (c) 84 49 38 JDA expense (c) 207 145 156 Intercompany natural gas purchases (d) 15 9 2 Progress Energy Corporate governance and shared service expenses (a) $ 906 $ 736 $ 710 Indemnification coverages (b) 34 38 35 JDA revenue (c) 207 145 156 JDA expense (c) 84 49 38 Intercompany natural gas purchases (d) 78 77 19 Duke Energy Progress Corporate governance and shared service expenses (a) $ 577 $ 438 $ 397 Indemnification coverages (b) 13 15 14 JDA revenue (c) 207 145 156 JDA expense (c) 84 49 38 Intercompany natural gas purchases (d) 78 77 19 Duke Energy Florida Corporate governance and shared service expenses (a) $ 329 $ 298 $ 313 Indemnification coverages (b) 21 23 21 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 374 $ 363 $ 356 Indemnification coverages (b) 5 5 5 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 405 $ 370 $ 366 Indemnification coverages (b) 7 8 8 Piedmont Corporate governance and shared service expenses (a) $ 170 $ 50 Indemnification coverages (b) 2 2 Intercompany natural gas sales (d) 93 86 Natural gas storage and transportation costs (e) 25 25 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, information technology, legal and accounting fees, as well as other third-party costs. These amounts are primarily recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA, which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power and expenses from the purchase of power pursuant to the JDA are recorded in Operating Revenues and Fuel used in electric generation and purchased power, respectively, on the Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to certain Duke Energy Carolinas and Duke Energy Progress natural gas-fired generation facilities. Piedmont records the sales in Operating Revenues, and Duke Energy Carolinas and Duke Energy Progress record the related purchases as a component of Fuel used in electric generation and purchased power on their respective Consolidated Statements of Operations and Comprehensive Income. These intercompany revenues and expenses are eliminated in consolidation. For the two months ended December 31, 2016, and for sales made subsequent to the acquisition for the year ended October 31, 2016, Piedmont recorded $14 million and $7 million , respectively, of natural gas sales with Duke Energy. For sales made prior to the acquisition for the year ended October 31, 2016, Piedmont recorded $74 million of natural gas sales with Duke Energy. (e) Piedmont has related party transactions as a customer of its equity method investments in Pine Needle, Hardy Storage, and Cardinal natural gas storage and transportation facilities. These expenses are included in Cost of natural gas on Piedmont's Consolidated Statements of Operations and Comprehensive Income. For the two months ended December 31, 2016, and for the year ended October 31, 2016, Piedmont recorded $6 million and $29 million , respectively, of natural gas storage and transportation costs.
Progress Energy [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Income taxes recorded represent amounts the Subsidiary Registrants would incur as separate C-Corporations. The following table includes the balance of intercompany income tax receivables and payables for the Subsidiary Registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana Piedmont December 31, 2018 Intercompany income tax receivable $ 52 $ 47 $ 29 $ — $ — $ 8 $ — Intercompany income tax payable — — — 16 3 — 45 December 31, 2017 Intercompany income tax receivable $ — $ 168 $ — $ 44 $ 22 $ — $ 7 Intercompany income tax payable 44 — 21 — — 35 —

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	12 Months Ended
	Dec. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional Amounts of Outstanding Derivative Positions	The tables below include volumes of outstanding commodity derivatives. Amounts disclosed represent the absolute value of notional volumes of commodity contracts excluding NPNS. The Duke Energy Registrants have netted contractual amounts where offsetting purchase and sale contracts exist with identical delivery locations and times of delivery. Where all commodity positions are perfectly offset, no quantities are shown. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Electricity (gigawatt-hours) 15,286 — — — — 1,786 13,500 — Natural gas (millions of dekatherms) 739 121 169 166 3 — 1 448 December 31, 2017 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Carolinas Energy Progress Florida Indiana Piedmont Electricity (gigawatt-hours) 34 — — — — 34 — Natural gas (millions of dekatherms) 770 105 183 133 50 2 480 The following tables show notional amounts of outstanding derivatives related to interest rate risk. December 31, 2018 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Cash flow hedges $ 923 $ — $ — $ — $ — $ — Undesignated contracts 1,721 300 1,200 650 550 27 Total notional amount (a) $ 2,644 $ 300 $ 1,200 $ 650 $ 550 $ 27 December 31, 2017 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Cash flow hedges (a) $ 660 $ — $ — $ — $ — $ — Undesignated contracts 927 400 500 250 250 27 Total notional amount $ 1,587 $ 400 $ 500 $ 250 $ 250 $ 27 (a) Duke Energy includes amounts related to consolidated VIEs of $422 million in cash flow hedges and $194 million in undesignated contracts as of December 31, 2018 , and $660 million in cash flow hedges as of December 31, 2017 .
Location and Fair Value of Derivatives Recognized in the Consolidated Balance Sheets	The following tables show the fair value and balance sheet location of derivative instruments. Although derivatives subject to master netting arrangements are netted on the Consolidated Balance Sheets, the fair values presented below are shown gross and cash collateral on the derivatives has not been netted against the fair values shown. Derivative Assets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 35 $ 2 $ 2 $ 2 $ — $ 6 $ 23 $ 3 Noncurrent 4 1 2 2 — — — — Total Derivative Assets – Commodity Contracts $ 39 $ 3 $ 4 $ 4 $ — $ 6 $ 23 $ 3 Interest Rate Contracts Designated as Hedging Instruments Current $ 1 $ — $ — $ — $ — $ — $ — $ — Noncurrent 3 — — — — — — — Not Designated as Hedging Instruments Current 2 — — — — — — — Noncurrent 12 — — — — — — — Total Derivative Assets – Interest Rate Contracts $ 18 $ — $ — $ — $ — $ — $ — $ — Total Derivative Assets $ 57 $ 3 $ 4 $ 4 $ — $ 6 $ 23 $ 3 Derivative Liabilities December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 33 $ 14 $ 10 $ 5 $ 6 $ — $ — $ 8 Noncurrent 158 10 15 6 — — — 133 Total Derivative Liabilities – Commodity Contracts $ 191 $ 24 $ 25 $ 11 $ 6 $ — $ — $ 141 Interest Rate Contracts Designated as Hedging Instruments Current $ 12 $ — $ — $ — $ — $ — $ — $ — Noncurrent 6 — — — — — — — Not Designated as Hedging Instruments Current 23 9 13 11 2 1 — — Noncurrent 10 — 6 5 1 4 — — Total Derivative Liabilities – Interest Rate Contracts $ 51 $ 9 $ 19 $ 16 $ 3 $ 5 $ — $ — Total Derivative Liabilities $ 242 $ 33 $ 44 $ 27 $ 9 $ 5 $ — $ 141 Derivative Assets December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 34 $ 2 $ 2 $ 1 $ 1 $ 1 $ 27 $ 2 Noncurrent 1 — 1 1 — — — — Total Derivative Assets – Commodity Contracts $ 35 $ 2 $ 3 $ 2 $ 1 $ 1 $ 27 $ 2 Interest Rate Contracts Designated as Hedging Instruments Current $ 1 $ — $ — $ — $ — $ — $ — $ — Noncurrent 15 — — — — — — — Total Derivative Assets – Interest Rate Contracts $ 16 $ — $ — $ — $ — $ — $ — $ — Total Derivative Assets $ 51 $ 2 $ 3 $ 2 $ 1 $ 1 $ 27 $ 2 Derivative Liabilities December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Commodity Contracts Not Designated as Hedging Instruments Current $ 36 $ 6 $ 18 $ 8 $ 10 $ — $ — $ 11 Noncurrent 146 4 10 4 — — — 131 Total Derivative Liabilities – Commodity Contracts $ 182 $ 10 $ 28 $ 12 $ 10 $ — $ — $ 142 Interest Rate Contracts Designated as Hedging Instruments Current $ 29 $ 25 $ — $ — $ — $ — $ — $ — Noncurrent 6 — — — — — — — Not Designated as Hedging Instruments Current 1 — 1 — — 1 — — Noncurrent 12 — 7 6 2 4 — — Total Derivative Liabilities – Interest Rate Contracts $ 48 $ 25 $ 8 $ 6 $ 2 $ 5 $ — $ — Total Derivative Liabilities $ 230 $ 35 $ 36 $ 18 $ 12 $ 5 $ — $ 142
Offsetting Assets	Derivative Assets December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 35 $ 2 $ 2 $ 1 $ 1 $ 1 $ 27 $ 2 Gross amounts offset — — — — — — — — Net amounts presented in Current Assets: Other $ 35 $ 2 $ 2 $ 1 $ 1 $ 1 $ 27 $ 2 Noncurrent Gross amounts recognized $ 16 $ — $ 1 $ 1 $ — $ — $ — $ — Gross amounts offset — — — — — — — — Net amounts presented in Other Noncurrent Assets: Other $ 16 $ — $ 1 $ 1 $ — $ — $ — $ — The following tables present the line items on the Consolidated Balance Sheets where derivatives are reported. Substantially all of Duke Energy's outstanding derivative contracts are subject to enforceable master netting arrangements. The gross amounts offset in the tables below show the effect of these netting arrangements on financial position and include collateral posted to offset the net position. The amounts shown are calculated by counterparty. Accounts receivable or accounts payable may also be available to offset exposures in the event of bankruptcy. These amounts are not included in the tables below. Derivative Assets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 38 $ 2 $ 2 $ 2 $ — $ 6 $ 23 $ 3 Gross amounts offset (3 ) (2 ) (2 ) (2 ) — — — — Net amounts presented in Current Assets: Other $ 35 $ — $ — $ — $ — $ 6 $ 23 $ 3 Noncurrent Gross amounts recognized $ 19 $ 1 $ 2 $ 2 $ — $ — $ — $ — Gross amounts offset (3 ) (1 ) (2 ) (2 ) — — — — Net amounts presented in Other Noncurrent Assets: Other $ 16 $ — $ — $ — $ — $ — $ — $ —
Offsetting Liabilities	Derivative Liabilities December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 66 $ 31 $ 19 $ 8 $ 10 $ 1 $ — $ 11 Gross amounts offset (3 ) (2 ) (2 ) (2 ) — — — — Net amounts presented in Current Liabilities: Other $ 63 $ 29 $ 17 $ 6 $ 10 $ 1 $ — $ 11 Noncurrent Gross amounts recognized $ 164 $ 4 $ 17 $ 10 $ 2 $ 4 $ — $ 131 Gross amounts offset (1 ) — (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 163 $ 4 $ 16 $ 9 $ 2 $ 4 $ — $ 131 Derivative Liabilities December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current Gross amounts recognized $ 68 $ 23 $ 23 $ 16 $ 8 $ 1 $ — $ 8 Gross amounts offset (4 ) (2 ) (2 ) (2 ) — — — — Net amounts presented in Current Liabilities: Other $ 64 $ 21 $ 21 $ 14 $ 8 $ 1 $ — $ 8 Noncurrent Gross amounts recognized $ 174 $ 10 $ 21 $ 11 $ 1 $ 4 $ — $ 133 Gross amounts offset (3 ) (1 ) (2 ) (2 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 171 $ 9 $ 19 $ 9 $ 1 $ 4 $ — $ 133
Derivative Contracts with Contingent Credit Features	The following tables show information with respect to derivative contracts that are in a net liability position and contain objective credit-risk-related payment provisions. December 31, 2018 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Aggregate fair value of derivatives in a net liability position $ 44 $ 19 $ 25 $ 25 $ — Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 44 19 25 25 — December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Aggregate fair value of derivatives in a net liability position $ 59 $ 35 $ 25 $ 15 $ 10 Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 59 35 25 15 10 The Duke Energy Registrants have elected to offset cash collateral and fair values of derivatives. For amounts to be netted, the derivative and cash collateral must be executed with the same counterparty under the same master netting arrangement.

Investments in Debt and Equit_2

Investments in Debt and Equity Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Investment [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 88 $ — $ — $ 115 Equity securities 2,402 95 4,475 2,805 27 4,914 Corporate debt securities 4 13 566 17 2 570 Municipal bonds 1 4 353 4 3 344 U.S. government bonds 14 12 1,076 11 7 1,027 Other debt securities — 2 148 — 1 118 Total NDTF Investments $ 2,421 $ 126 $ 6,706 $ 2,837 $ 40 $ 7,088 Other Investments Cash and cash equivalents $ — $ — $ 22 $ — $ — $ 15 Equity securities 36 1 99 59 — 123 Corporate debt securities — 2 60 1 — 57 Municipal bonds — 1 85 2 1 83 U.S. government bonds 1 — 45 — — 41 Other debt securities — 1 58 — 1 44 Total Other Investments $ 37 $ 5 $ 369 $ 62 $ 2 $ 363 Total Investments $ 2,458 $ 131 $ 7,075 $ 2,899 $ 42 $ 7,451
Summary of Investments in Debt and Equity Securities	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 88 $ — $ — $ 115 Equity securities 2,402 95 4,475 2,805 27 4,914 Corporate debt securities 4 13 566 17 2 570 Municipal bonds 1 4 353 4 3 344 U.S. government bonds 14 12 1,076 11 7 1,027 Other debt securities — 2 148 — 1 118 Total NDTF Investments $ 2,421 $ 126 $ 6,706 $ 2,837 $ 40 $ 7,088 Other Investments Cash and cash equivalents $ — $ — $ 22 $ — $ — $ 15 Equity securities 36 1 99 59 — 123 Corporate debt securities — 2 60 1 — 57 Municipal bonds — 1 85 2 1 83 U.S. government bonds 1 — 45 — — 41 Other debt securities — 1 58 — 1 44 Total Other Investments $ 37 $ 5 $ 369 $ 62 $ 2 $ 363 Total Investments $ 2,458 $ 131 $ 7,075 $ 2,899 $ 42 $ 7,451
Debt Securities, Available-for-sale	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 88 $ — $ — $ 115 Equity securities 2,402 95 4,475 2,805 27 4,914 Corporate debt securities 4 13 566 17 2 570 Municipal bonds 1 4 353 4 3 344 U.S. government bonds 14 12 1,076 11 7 1,027 Other debt securities — 2 148 — 1 118 Total NDTF Investments $ 2,421 $ 126 $ 6,706 $ 2,837 $ 40 $ 7,088 Other Investments Cash and cash equivalents $ — $ — $ 22 $ — $ — $ 15 Equity securities 36 1 99 59 — 123 Corporate debt securities — 2 60 1 — 57 Municipal bonds — 1 85 2 1 83 U.S. government bonds 1 — 45 — — 41 Other debt securities — 1 58 — 1 44 Total Other Investments $ 37 $ 5 $ 369 $ 62 $ 2 $ 363 Total Investments $ 2,458 $ 131 $ 7,075 $ 2,899 $ 42 $ 7,451
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 98 Due after one through five years 501 Due after five through 10 years 570 Due after 10 years 1,222 Total $ 2,391
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 168 Realized losses 126 AFS: Realized gains 22 Realized losses 51 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 202 $ 246 Realized losses 160 187
Duke Energy Carolinas [Member]
Investment [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 29 $ — $ — $ 32 Equity securities 1,309 54 2,484 1,531 12 2,692 Corporate debt securities 2 9 341 9 2 359 Municipal bonds — 1 81 — 1 60 U.S. government bonds 5 8 475 3 4 503 Other debt securities — 2 143 — 1 112 Total NDTF Investments $ 1,316 $ 74 $ 3,553 $ 1,543 $ 20 $ 3,758
Summary of Investments in Debt and Equity Securities	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 29 $ — $ — $ 32 Equity securities 1,309 54 2,484 1,531 12 2,692 Corporate debt securities 2 9 341 9 2 359 Municipal bonds — 1 81 — 1 60 U.S. government bonds 5 8 475 3 4 503 Other debt securities — 2 143 — 1 112 Total NDTF Investments $ 1,316 $ 74 $ 3,553 $ 1,543 $ 20 $ 3,758
Debt Securities, Available-for-sale	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 29 $ — $ — $ 32 Equity securities 1,309 54 2,484 1,531 12 2,692 Corporate debt securities 2 9 341 9 2 359 Municipal bonds — 1 81 — 1 60 U.S. government bonds 5 8 475 3 4 503 Other debt securities — 2 143 — 1 112 Total NDTF Investments $ 1,316 $ 74 $ 3,553 $ 1,543 $ 20 $ 3,758
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 6 Due after one through five years 142 Due after five through 10 years 303 Due after 10 years 589 Total $ 1,040
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 89 Realized losses 73 AFS: Realized gains 19 Realized losses 35 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 135 $ 157 Realized losses 103 121
Progress Energy [Member]
Investment [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 59 $ — $ — $ 83 Equity securities 1,093 41 1,991 1,274 15 2,222 Corporate debt securities 2 4 225 8 — 211 Municipal bonds 1 3 272 4 2 284 U.S. government bonds 9 4 601 8 3 524 Other debt securities — — 5 — — 6 Total NDTF Investments $ 1,105 $ 52 $ 3,153 $ 1,294 $ 20 $ 3,330 Other Investments Cash and cash equivalents $ — $ — $ 17 $ — $ — $ 12 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 64 $ 2 $ — $ 59 Total Investments $ 1,105 $ 52 $ 3,217 $ 1,296 $ 20 $ 3,389
Summary of Investments in Debt and Equity Securities	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 59 $ — $ — $ 83 Equity securities 1,093 41 1,991 1,274 15 2,222 Corporate debt securities 2 4 225 8 — 211 Municipal bonds 1 3 272 4 2 284 U.S. government bonds 9 4 601 8 3 524 Other debt securities — — 5 — — 6 Total NDTF Investments $ 1,105 $ 52 $ 3,153 $ 1,294 $ 20 $ 3,330 Other Investments Cash and cash equivalents $ — $ — $ 17 $ — $ — $ 12 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 64 $ 2 $ — $ 59 Total Investments $ 1,105 $ 52 $ 3,217 $ 1,296 $ 20 $ 3,389
Debt Securities, Available-for-sale	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 59 $ — $ — $ 83 Equity securities 1,093 41 1,991 1,274 15 2,222 Corporate debt securities 2 4 225 8 — 211 Municipal bonds 1 3 272 4 2 284 U.S. government bonds 9 4 601 8 3 524 Other debt securities — — 5 — — 6 Total NDTF Investments $ 1,105 $ 52 $ 3,153 $ 1,294 $ 20 $ 3,330 Other Investments Cash and cash equivalents $ — $ — $ 17 $ — $ — $ 12 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 64 $ 2 $ — $ 59 Total Investments $ 1,105 $ 52 $ 3,217 $ 1,296 $ 20 $ 3,389
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 87 Due after one through five years 306 Due after five through 10 years 216 Due after 10 years 541 Total $ 1,150
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 79 Realized losses 53 AFS: Realized gains 3 Realized losses 15 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 65 $ 84 Realized losses 56 64
Duke Energy Progress [Member]
Investment [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 46 $ — $ — $ 50 Equity securities 833 30 1,588 980 12 1,795 Corporate debt securities 2 3 171 6 — 149 Municipal bonds 1 3 271 4 2 283 U.S. government bonds 6 3 415 5 2 310 Other debt securities — — 3 — — 4 Total NDTF Investments $ 842 $ 39 $ 2,494 $ 995 $ 16 $ 2,591 Other Investments Cash and cash equivalents $ — $ — $ 6 $ — $ — $ 1 Total Other Investments $ — $ — $ 6 $ — $ — $ 1 Total Investments $ 842 $ 39 $ 2,500 $ 995 $ 16 $ 2,592
Summary of Investments in Debt and Equity Securities	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 46 $ — $ — $ 50 Equity securities 833 30 1,588 980 12 1,795 Corporate debt securities 2 3 171 6 — 149 Municipal bonds 1 3 271 4 2 283 U.S. government bonds 6 3 415 5 2 310 Other debt securities — — 3 — — 4 Total NDTF Investments $ 842 $ 39 $ 2,494 $ 995 $ 16 $ 2,591 Other Investments Cash and cash equivalents $ — $ — $ 6 $ — $ — $ 1 Total Other Investments $ — $ — $ 6 $ — $ — $ 1 Total Investments $ 842 $ 39 $ 2,500 $ 995 $ 16 $ 2,592
Debt Securities, Available-for-sale	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 46 $ — $ — $ 50 Equity securities 833 30 1,588 980 12 1,795 Corporate debt securities 2 3 171 6 — 149 Municipal bonds 1 3 271 4 2 283 U.S. government bonds 6 3 415 5 2 310 Other debt securities — — 3 — — 4 Total NDTF Investments $ 842 $ 39 $ 2,494 $ 995 $ 16 $ 2,591 Other Investments Cash and cash equivalents $ — $ — $ 6 $ — $ — $ 1 Total Other Investments $ — $ — $ 6 $ — $ — $ 1 Total Investments $ 842 $ 39 $ 2,500 $ 995 $ 16 $ 2,592
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 49 Due after one through five years 231 Due after five through 10 years 161 Due after 10 years 419 Total $ 860
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 68 Realized losses 48 AFS: Realized gains $ 2 Realized losses 10 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 54 $ 71 Realized losses 48 55
Duke Energy Florida [Member]
Investment [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 13 $ — $ — $ 33 Equity securities 260 11 403 294 3 427 Corporate debt securities — 1 54 2 — 62 Municipal bonds — — 1 — — 1 U.S. government bonds 3 1 186 3 1 214 Other debt securities — — 2 — — 2 Total NDTF Investments (a) $ 263 $ 13 $ 659 $ 299 $ 4 $ 739 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 1 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 48 $ 2 $ — $ 48 Total Investments $ 263 $ 13 $ 707 $ 301 $ 4 $ 787 (a) During the year ended December 31, 2018 , Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 nuclear plant.
Summary of Investments in Debt and Equity Securities	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 13 $ — $ — $ 33 Equity securities 260 11 403 294 3 427 Corporate debt securities — 1 54 2 — 62 Municipal bonds — — 1 — — 1 U.S. government bonds 3 1 186 3 1 214 Other debt securities — — 2 — — 2 Total NDTF Investments (a) $ 263 $ 13 $ 659 $ 299 $ 4 $ 739 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 1 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 48 $ 2 $ — $ 48 Total Investments $ 263 $ 13 $ 707 $ 301 $ 4 $ 787 (a) During the year ended December 31, 2018 , Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 nuclear plant.
Debt Securities, Available-for-sale	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are classified as FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value NDTF Cash and cash equivalents $ — $ — $ 13 $ — $ — $ 33 Equity securities 260 11 403 294 3 427 Corporate debt securities — 1 54 2 — 62 Municipal bonds — — 1 — — 1 U.S. government bonds 3 1 186 3 1 214 Other debt securities — — 2 — — 2 Total NDTF Investments (a) $ 263 $ 13 $ 659 $ 299 $ 4 $ 739 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 1 Municipal bonds — — 47 2 — 47 Total Other Investments $ — $ — $ 48 $ 2 $ — $ 48 Total Investments $ 263 $ 13 $ 707 $ 301 $ 4 $ 787 (a) During the year ended December 31, 2018 , Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 nuclear plant.
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 38 Due after one through five years 75 Due after five through 10 years 55 Due after 10 years 122 Total $ 290
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of FV-NI and AFS securities for the year ended December 31, 2018 , and from sales of AFS securities for the years ended December 31, 2017 , and 2016 , were as follows. Year Ended December 31, (in millions) 2018 FV-NI: Realized gains $ 11 Realized losses 5 AFS: Realized gains 1 Realized losses 5 Years Ended December 31, (in millions) 2017 2016 Realized gains $ 11 $ 13 Realized losses 8 9
Duke Energy Indiana [Member]
Investment [Line Items]
Debt Securities, Trading, and Equity Securities, FV-NI	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value Investments Equity securities $ 29 $ — $ 67 $ 49 $ — $ 97 Corporate debt securities — — 8 — — 3 Municipal bonds — 1 33 — 1 28 Total Investments $ 29 $ 1 $ 108 $ 49 $ 1 $ 128
Summary of Investments in Debt and Equity Securities	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value Investments Equity securities $ 29 $ — $ 67 $ 49 $ — $ 97 Corporate debt securities — — 8 — — 3 Municipal bonds — 1 33 — 1 28 Total Investments $ 29 $ 1 $ 108 $ 49 $ 1 $ 128
Debt Securities, Available-for-sale	The following table presents the estimated fair value of investments in debt and equity securities; equity investments are measured at FV-NI and debt investments are classified as AFS. December 31, 2018 December 31, 2017 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses Fair Value Gains Losses Fair Value Investments Equity securities $ 29 $ — $ 67 $ 49 $ — $ 97 Corporate debt securities — — 8 — — 3 Municipal bonds — 1 33 — 1 28 Total Investments $ 29 $ 1 $ 108 $ 49 $ 1 $ 128
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2018 Due in one year or less $ 3 Due after one through five years 20 Due after five through 10 years 4 Due after 10 years 14 Total $ 41

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the tables below for all Duke Energy Registrants exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type for the Duke Energy Registrants. December 31, 2018 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not Categorized NDTF equity securities $ 4,475 $ 4,410 $ — $ — $ 65 NDTF debt securities 2,231 576 1,655 — — Other equity securities 99 99 — — — Other debt securities 270 67 203 — — Derivative assets 57 4 25 28 — Total assets 7,132 5,156 1,883 28 65 Derivative liabilities (242 ) (11 ) (90 ) (141 ) — Net assets (liabilities) $ 6,890 $ 5,145 $ 1,793 $ (113 ) $ 65 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not Categorized NDTF equity securities $ 4,914 $ 4,840 $ — $ — $ 74 NDTF debt securities 2,174 635 1,539 — — Other equity securities 123 123 — — — Other debt securities 241 57 184 — — Derivative assets 51 3 20 28 — Total assets 7,503 5,658 1,743 28 74 Derivative liabilities (230 ) (2 ) (86 ) (142 ) — Net assets (liabilities) $ 7,273 $ 5,656 $ 1,657 $ (114 ) $ 74
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following tables provide reconciliations of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Amounts included in earnings for derivatives are primarily included in Cost of natural gas on the Duke Energy Registrants' Consolidated Statements of Operations and Comprehensive Income. Amounts included in changes of net assets on the Duke Energy Registrants' Consolidated Balance Sheets are included in regulatory assets or liabilities. All derivative assets and liabilities are presented on a net basis. December 31, 2018 December 31, 2017 (in millions) Derivatives (net) Investments Derivatives (net) Total Balance at beginning of period $ (114 ) $ 5 $ (166 ) $ (161 ) Total pretax realized or unrealized gains included in comprehensive income — 1 — 1 Purchases, sales, issuances and settlements: Purchases 57 — 55 55 Sales — (6 ) — (6 ) Settlements (57 ) — (47 ) (47 ) Total gains included on the Consolidated Balance Sheet 1 — 44 44 Balance at end of period $ (113 ) $ — $ (114 ) $ (114 )
Quantitative Information Table - Level 3	The following tables include quantitative information about the Duke Energy Registrants' derivatives classified as Level 3. December 31, 2018 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio FTRs $ 6 RTO auction pricing FTR price – per MWh $ 1.19 – $ 4.59 Duke Energy Indiana FTRs 22 RTO auction pricing FTR price – per MWh (2.07 ) – 8.27 Piedmont Natural gas contracts (141 ) Discounted cash flow Forward natural gas curves — price per MMBtu 1.87 – 2.95 Duke Energy Total Level 3 derivatives $ (113 ) December 31, 2017 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio FTRs $ 1 RTO auction pricing FTR price – per MWh $ 0.07 – $ 1.41 Duke Energy Indiana FTRs 27 RTO auction pricing FTR price – per MWh (0.77 ) – 7.44 Piedmont Natural gas contracts (142 ) Discounted cash flow Forward natural gas curves — price per MMBtu 2.10 – 2.88 Duke Energy Total Level 3 derivatives $ (114 )
Schedule of Long-term debt Fair Value	The fair value and book value of long-term debt, including current maturities, is summarized in the following table. Estimates determined are not necessarily indicative of amounts that could have been settled in current markets. Fair value of long-term debt uses Level 2 measurements. December 31, 2018 December 31, 2017 (in millions) Book Value Fair Value Book Value Fair Value Duke Energy (a) $ 54,529 $ 54,534 $ 52,279 $ 55,331 Duke Energy Carolinas 10,939 11,471 10,103 11,372 Progress Energy 18,911 19,885 17,837 20,000 Duke Energy Progress 8,204 8,300 7,357 7,992 Duke Energy Florida 7,321 7,742 7,095 7,953 Duke Energy Ohio 2,165 2,239 2,067 2,249 Duke Energy Indiana 3,782 4,158 3,783 4,464 Piedmont 2,138 2,180 2,037 2,209 (a) Book value of long-term debt includes $1.6 billion as of December 31, 2018 , and $1.7 billion as of December 31, 2017 , of unamortized debt discount and premium, net in purchase accounting adjustments related to the mergers with Progress Energy and Piedmont that are excluded from fair value of long-term debt.
Duke Energy Carolinas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 (in millions) Total Fair Value Level 1 Level 2 Not Categorized NDTF equity securities $ 2,484 $ 2,419 $ — $ 65 NDTF debt securities 1,069 149 920 — Derivative assets 3 — 3 — Total assets 3,556 2,568 923 65 Derivative liabilities (33 ) — (33 ) — Net assets $ 3,523 $ 2,568 $ 890 $ 65 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Not Categorized NDTF equity securities $ 2,692 $ 2,618 $ — $ 74 NDTF debt securities 1,066 204 862 — Derivative assets 2 — 2 — Total assets 3,760 2,822 864 74 Derivative liabilities (35 ) (1 ) (34 ) — Net assets $ 3,725 $ 2,821 $ 830 $ 74
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following table provides reconciliations of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Investments Year Ended December 31, (in millions) 2017 Balance at beginning of period $ 3 Total pretax realized or unrealized gains included in comprehensive income 1 Purchases, sales, issuances and settlements: Sales (4 ) Balance at end of period $ —
Progress Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Total Fair Value Level 1 Level 2 NDTF equity securities $ 1,991 $ 1,991 $ — $ 2,222 $ 2,222 $ — NDTF debt securities 1,162 427 735 1,108 431 677 Other debt securities 64 17 47 59 12 47 Derivative assets 4 — 4 3 1 2 Total assets 3,221 2,435 786 3,392 2,666 726 Derivative liabilities (44 ) — (44 ) (36 ) (1 ) (35 ) Net assets $ 3,177 $ 2,435 $ 742 $ 3,356 $ 2,665 $ 691
Duke Energy Progress [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Total Fair Value Level 1 Level 2 NDTF equity securities $ 1,588 $ 1,588 $ — $ 1,795 $ 1,795 $ — NDTF debt securities 906 294 612 796 243 553 Other debt securities 6 6 — 1 1 — Derivative assets 4 — 4 2 1 1 Total assets 2,504 1,888 616 2,594 2,040 554 Derivative liabilities (27 ) — (27 ) (18 ) (1 ) (17 ) Net assets $ 2,477 $ 1,888 $ 589 $ 2,576 $ 2,039 $ 537
Duke Energy Florida [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Total Fair Value Level 1 Level 2 NDTF equity securities $ 403 $ 403 $ — $ 427 $ 427 $ — NDTF debt securities 256 133 123 312 188 124 Other debt securities 48 1 47 48 1 47 Derivative assets — — — 1 — 1 Total assets 707 537 170 788 616 172 Derivative liabilities (9 ) — (9 ) (12 ) — (12 ) Net assets $ 698 $ 537 $ 161 $ 776 $ 616 $ 160
Duke Energy Ohio [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 2 Level 3 Total Fair Value Level 2 Level 3 Derivative assets $ 6 $ — $ 6 $ 1 $ — $ 1 Derivative liabilities (5 ) (5 ) — (5 ) (5 ) — Net assets (liabilities) $ 1 $ (5 ) $ 6 $ (4 ) $ (5 ) $ 1
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2018 2017 Balance at beginning of period $ 1 $ 5 Purchases, sales, issuances and settlements: Purchases 7 3 Settlements (4 ) (4 ) Total gains included on the Consolidated Balance Sheet 2 (3 ) Balance at end of period $ 6 $ 1
Duke Energy Indiana [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Total Fair Value Level 1 Level 2 Level 3 Other equity securities $ 67 $ 67 $ — $ — $ 97 $ 97 $ — $ — Other debt securities 41 — 41 — 31 — 31 — Derivative assets 23 1 — 22 27 — — 27 Total assets $ 131 $ 68 $ 41 $ 22 $ 155 $ 97 $ 31 $ 27
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2018 2017 Balance at beginning of period $ 27 $ 16 Purchases, sales, issuances and settlements: Purchases 50 52 Settlements (53 ) (43 ) Total (losses) gains included on the Consolidated Balance Sheet (2 ) 2 Balance at end of period $ 22 $ 27
Piedmont Natural Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following table provides recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. December 31, 2018 December 31, 2017 (in millions) Total Fair Value Level 1 Level 3 Total Fair Value Level 1 Level 3 Other debt securities $ — $ — $ — $ 1 $ 1 $ — Derivative assets 3 3 — 2 2 — Total assets 3 3 — 3 3 — Derivative liabilities (141 ) — (141 ) (142 ) — (142 ) Net (liabilities) assets $ (138 ) $ 3 $ (141 ) $ (139 ) $ 3 $ (142 )
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2018 2017 Balance at beginning of period $ (142 ) $ (187 ) Total gains and settlements 1 45 Balance at end of period $ (141 ) $ (142 )

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2018
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	The following table outlines amounts and expiration dates of the credit facilities described above. Duke Energy Duke Energy Duke Energy Duke Energy Carolinas Progress Florida CRC DERF DEPR DEFR Expiration date December 2020 December 2020 February 2021 April 2021 Credit facility amount (in millions) $ 325 $ 450 $ 300 $ 225 Amounts borrowed at December 31, 2018 325 450 300 225 Amounts borrowed at December 31, 2017 325 450 300 225 Restricted Receivables at December 31, 2018 564 699 547 357 Restricted Receivables at December 31, 2017 545 640 459 317
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	The following tables summarize the impact of non-consolidated VIEs on the Consolidated Balance Sheets. December 31, 2018 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Receivables from affiliated companies $ — $ — $ — $ — $ 93 $ 118 Investments in equity method unconsolidated affiliates 822 190 48 1,060 — — Total assets $ 822 $ 190 $ 48 $ 1,060 $ 93 $ 118 Taxes accrued (1 ) — — (1 ) — — Other current liabilities — — 4 4 — — Deferred income taxes 21 — — 21 — — Other noncurrent liabilities — — 12 12 — — Total liabilities $ 20 $ — $ 16 $ 36 $ — $ — Net assets $ 802 $ 190 $ 32 $ 1,024 $ 93 $ 118 December 31, 2017 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Receivables from affiliated companies $ — $ — $ — $ — $ 87 $ 106 Investments in equity method unconsolidated affiliates 697 180 42 919 — — Other noncurrent assets 17 — — 17 — — Total assets $ 714 $ 180 $ 42 $ 936 $ 87 $ 106 Taxes accrued (29 ) — — (29 ) — — Other current liabilities — — 4 4 — — Deferred income taxes 42 — — 42 — — Other noncurrent liabilities — — 12 12 — — Total liabilities $ 13 $ — $ 16 $ 29 $ — $ — Net assets $ 701 $ 180 $ 26 $ 907 $ 87 $ 106
DEFPF [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	The following table summarizes the impact of DEFPF on Duke Energy Florida's Consolidated Balance Sheets. (in millions) December 31, 2018 December 31, 2017 Receivables of VIEs $ 5 $ 4 Regulatory Assets: Current 52 51 Current Assets: Other 39 40 Other Noncurrent Assets: Regulatory assets 1,041 1,091 Current Liabilities: Other 10 10 Current maturities of long-term debt 53 53 Long-Term Debt 1,111 1,164
Commercial Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	The table below presents material balances reported on Duke Energy's Consolidated Balance Sheets related to renewables VIEs. (in millions) December 31, 2018 December 31, 2017 Current Assets: Other $ 123 $ 174 Property, plant and equipment, cost 4,007 3,923 Accumulated depreciation and amortization (698 ) (591 ) Other Noncurrent Assets: Other 261 50 Current maturities of long-term debt 174 170 Long-Term Debt 1,587 1,700 Other Noncurrent Liabilities: Deferred income taxes — (148 ) Other Noncurrent Liabilities: Asset Retirement Obligations 106 83 Other Noncurrent Liabilities: Other 212 241
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	The table below presents Duke Energy's ownership interest and investment balance in these joint ventures. Investment Amount (in millions) Ownership December 31, December 31, Entity Name Interest 2018 2017 ACP 47 % $ 797 $ 397 Sabal Trail (a) 7.5 % — 219 Constitution (b) 24 % 25 81 Total $ 822 $ 697 (a) At December 31, 2017 , Sabal Trail was considered a VIE due to having insufficient equity to finance their own activities without subordinated financial support. However, Sabal Trail is now a fully operational, well capitalized entity. As a result, Sabal Trail has sufficient equity to finance its own activities, and therefore, is no longer considered a VIE. Duke Energy's investment in Sabal Trail was $112 million at December 31, 2018 . (b) During the year ended December 31, 2018 , Duke Energy recorded an OTTI of $55 million related to Constitution within Equity in earnings of unconsolidated affiliates on Duke Energy's Consolidated Statements of Income. See Note 4 for additional information.
Cinergy Receivables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	Key assumptions used in estimating fair value are detailed in the following table. Duke Energy Ohio Duke Energy Indiana 2018 2017 2018 2017 Anticipated credit loss ratio 0.5 % 0.5 % 0.3 % 0.3 % Discount rate 3.0 % 2.1 % 3.0 % 2.1 % Receivable turnover rate 13.5 % 13.5 % 11.0 % 10.7 % The following table shows the gross and net receivables sold. Duke Energy Ohio Duke Energy Indiana (in millions) 2018 2017 2018 2017 Receivables sold $ 269 $ 273 $ 336 $ 312 Less: Retained interests 93 87 118 106 Net receivables sold $ 176 $ 186 $ 218 $ 206 The following table shows sales and cash flows related to receivables sold. Duke Energy Ohio Duke Energy Indiana Years Ended December 31, Years Ended December 31, (in millions) 2018 2017 2016 2018 2017 2016 Sales Receivables sold $ 1,987 $ 1,879 $ 1,926 $ 2,842 $ 2,711 $ 2,635 Loss recognized on sale 13 10 9 16 12 11 Cash Flows Cash proceeds from receivables sold 1,967 1,865 1,882 2,815 2,694 2,583 Collection fees received 1 1 1 1 1 1 Return received on retained interests 6 3 2 9 7 5

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction	Supplemental requirements contracts that include contracted blocks of energy and capacity at contractually fixed prices have the following estimated remaining performance obligations: Remaining Performance Obligations (in millions) 2019 2020 2021 2022 2023 Thereafter Total Progress Energy $ 112 $ 121 $ 80 $ 82 $ 39 $ 42 $ 476 Duke Energy Progress 9 9 9 9 9 9 54 Duke Energy Florida 103 112 71 73 30 33 422 Duke Energy Indiana 9 10 5 — — — 24 Estimated remaining performance obligations are as follows: Remaining Performance Obligations (in millions) 2019 2020 2021 2022 2023 Thereafter Total Piedmont $ 70 $ 68 $ 63 $ 63 $ 60 $ 430 $ 754
Disaggregation of Revenue	Disaggregated revenues are presented as follows: Year Ended December 31, 2018 Duke Duke Duke Duke Duke (in millions) Duke Energy Progress Energy Energy Energy Energy By market or type of customer Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Electric Utilities and Infrastructure Residential $ 9,587 $ 2,981 $ 4,785 $ 2,019 $ 2,766 $ 743 $ 1,076 $ — General 6,127 2,119 2,809 1,280 1,529 422 778 — Industrial 2,974 1,180 904 642 262 131 760 — Wholesale 2,324 508 1,462 1,303 159 57 298 — Other revenues 717 320 502 320 182 73 91 — Total Electric Utilities and Infrastructure revenue from contracts with customers $ 21,729 $ 7,108 $ 10,462 $ 5,564 $ 4,898 $ 1,426 $ 3,003 $ — Gas Utilities and Infrastructure Residential $ 1,000 $ — $ — $ — $ — $ 331 $ — $ 669 Commercial 514 — — — — 135 — 378 Industrial 147 — — — — 18 — 128 Power Generation — — — — — — — 54 Other revenues 139 — — — — 19 — 120 Total Gas Utilities and Infrastructure revenue from contracts with customers $ 1,800 $ — $ — $ — $ — $ 503 $ — $ 1,349 Commercial Renewables Revenue from contracts with customers $ 209 $ — $ — $ — $ — $ — $ — $ — Other Revenue from contracts with customers $ 19 $ — $ — $ — $ — $ 1 $ — $ — Total revenue from contracts with customers $ 23,757 $ 7,108 $ 10,462 $ 5,564 $ 4,898 $ 1,930 $ 3,003 $ 1,349 Other revenue sources (a) $ 764 $ 192 $ 266 $ 135 $ 123 $ 27 $ 56 $ 26 Total revenues $ 24,521 $ 7,300 $ 10,728 $ 5,699 $ 5,021 $ 1,957 $ 3,059 $ 1,375 (a) Other revenue sources include revenues from leases, derivatives and alternative revenue programs that are not considered revenues from contracts with customers. Alternative revenue programs in certain jurisdictions include regulatory mechanisms that periodically adjust for over or under collection of related revenues.
Schedule Of Unbilled Revenues With Restricted Receivables	These receivables for unbilled revenues are shown in the table below. December 31, (in millions) 2018 2017 Duke Energy Ohio $ 86 $ 104 Duke Energy Indiana 128 132 Unbilled revenues are included within Receivables and Receivables of VIEs on the Consolidated Balance Sheets as shown in the following table. December 31, (in millions) 2018 2017 Duke Energy $ 896 $ 944 Duke Energy Carolinas 313 342 Progress Energy 244 228 Duke Energy Progress 148 143 Duke Energy Florida 96 85 Duke Energy Ohio 2 4 Duke Energy Indiana 23 21 Piedmont 73 86

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Schedule Of Earnings Per Share	The following table presents Duke Energy’s basic and diluted EPS calculations and reconciles the weighted average number of common stock outstanding to the diluted weighted average number of common stock outstanding. Years Ended December 31, (in millions, except per share amounts) 2018 2017 2016 Income from continuing operations attributable to Duke Energy common stockholders excluding impact of participating securities $ 2,642 $ 3,059 $ 2,567 Weighted average shares outstanding – basic 708 700 691 Weighted average shares outstanding – diluted 708 700 691 Earnings per share from continuing operations attributable to Duke Energy common stockholders Basic $ 3.73 $ 4.37 $ 3.71 Diluted $ 3.73 $ 4.37 $ 3.71 Potentially dilutive items excluded from the calculation (a) 2 2 2 Dividends declared per common share $ 3.64 $ 3.49 $ 3.36 (a) Performance stock awards were not included in the dilutive securities calculation because the performance measures related to the awards had not been met.

Severance (Tables)

Severance (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Schedule of Severance Expense	The following table presents the direct and allocated severance and related charges recorded by the Duke Energy Registrants. Amounts are included within Operation, maintenance and other on the Consolidated Statements of Operations. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont (a) Year Ended December 31, 2018 $ 187 $ 102 $ 69 $ 52 $ 17 $ 6 $ 7 $ 2 Year Ended December 31, 2017 15 2 2 1 1 — 1 9 Year Ended December 31, 2016 118 39 40 23 17 3 7 (a) Piedmont severance benefit charges were $3 million for the two months ended December 31, 2016, and $19 million for the year ended October 31, 2016.
Schedule of Severance Liability	The table below presents the severance liability for past and ongoing severance plans including the plans described above. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at December 31, 2017 $ 19 $ 5 $ 2 $ 1 $ — $ — $ — $ 5 Provision/Adjustments 200 98 50 40 10 2 2 — Cash Reductions (14 ) (3 ) (1 ) — (1 ) — — (5 ) Balance at December 31, 2018 $ 205 $ 100 $ 51 $ 41 $ 9 $ 2 $ 2 $ —

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule Of Total Stock-Based Compensation Expense, net of tax	The following table summarizes the total expense recognized by the Duke Energy Registrants, net of tax, for stock-based compensation. Years Ended December 31, (in millions) 2018 2017 2016 Duke Energy $ 56 $ 43 $ 35 Duke Energy Carolinas 20 15 12 Progress Energy 21 16 12 Duke Energy Progress 13 10 7 Duke Energy Florida 8 6 5 Duke Energy Ohio 4 3 2 Duke Energy Indiana 5 4 3 Piedmont (a) 3 3 (a) Piedmont's stock-based compensation costs were not material for the two months ended December 31, 2016. See discussion below for information on Piedmont's pre-merger stock-based compensation plans.
Schedule Of Stock-Based Compensation Expense	Duke Energy's pretax stock-based compensation costs, the tax benefit associated with stock-based compensation expense and stock-based compensation costs capitalized are included in the following table. Years Ended December 31, (in millions) 2018 2017 2016 Restricted stock unit awards $ 43 $ 41 $ 36 Performance awards 35 27 19 Pretax stock-based compensation cost $ 78 $ 68 $ 55 Stock-based compensation costs capitalized 5 4 2 Stock-based compensation expense $ 73 $ 64 $ 53 Tax benefit associated with stock-based compensation expense $ 17 $ 25 $ 20
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The following table includes information related to RSU awards. Years Ended December 31, 2018 2017 2016 Shares awarded (in thousands) 649 583 684 Fair value (in millions) $ 49 $ 47 $ 52 The following table summarizes information about RSU awards outstanding. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2017 1,121 $ 78 Granted 649 76 Vested (545 ) 78 Forfeited (72 ) 77 Outstanding at December 31, 2018 1,153 77 Restricted stock unit awards expected to vest 1,101 77
Schedule of Performance Awards	The following table includes information related to stock-based performance awards. Years Ended December 31, 2018 2017 2016 Shares granted assuming target performance (in thousands) 372 461 338 Fair value (in millions) $ 27 $ 37 $ 25
Schedule of Nonvested Performance-based Units Activity	The following table summarizes information about stock-based performance awards outstanding and assumes payout at the target level. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2017 1,065 $ 79 Granted 372 73 Vested (155 ) 81 Forfeited (165 ) 80 Outstanding at December 31, 2018 1,117 77 Stock-based performance awards expected to vest 1,086 77
Piedmont Natural Gas [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule Of Stock-Based Compensation Expense	Piedmont's stock-based compensation costs and the tax benefit associated with stock-based compensation expense are included in the following table. (in millions) Year Ended October 31, 2016 Pretax stock-based compensation cost $ 16 Tax benefit associated with stock-based compensation expense 6 Net of tax stock-based compensation cost $ 10

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Contributions	Duke Energy’s policy is to fund amounts on an actuarial basis to provide assets sufficient to meet benefit payments to be paid to plan participants. Duke Energy does not anticipate making any contributions in 2019. The following table includes information related to the Duke Energy Registrants’ contributions to its qualified defined benefit pension plans. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont (a) Contributions Made: 2018 $ 141 $ 46 $ 45 $ 25 $ 20 $ — $ 8 $ — 2017 19 — — — — 4 — 11 2016 155 43 43 24 20 5 9 (a) Piedmont contributed $10 million to its U.S. qualified defined benefit pension plan during the two months ended December 31, 2016, and $10 million for the year ended October 31, 2016.
Fair Value and Allocation of Plan Assets	The following tables provide the fair value measurement amounts for VEBA trust assets. December 31, 2018 Total Fair (in millions) Value Level 2 Cash and cash equivalents $ 3 $ 3 Real estate 1 1 Equity securities 25 25 Debt securities 20 20 Total assets $ 49 $ 49 December 31, 2017 Total Fair (in millions) Value Level 2 Cash and cash equivalents $ 8 $ 8 Real estate 1 1 Equity securities 28 28 Debt securities 21 21 Total assets $ 58 $ 58 The following tables provide the fair value measurement amounts for the Duke Energy Master Retirement Trust qualified pension and other post-retirement assets. December 31, 2018 Total Fair Not (in millions) Value Level 1 Level 2 Level 3 Categorized (b) Equity securities $ 2,373 $ 1,751 $ — $ — $ 622 Corporate debt securities 4,054 — 4,054 — — Short-term investment funds 363 279 84 — — Partnership interests 120 — — — 120 Hedge funds 226 — — — 226 Real estate limited partnerships 144 — — — 144 U.S. government securities 961 — 961 — — Guaranteed investment contracts 27 — — 27 — Governments bonds – foreign 30 — 30 — — Cash 28 28 — — — Net pending transactions and other investments (2 ) (6 ) 4 — — Total assets (a) $ 8,324 $ 2,052 $ 5,133 $ 27 $ 1,112 (a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana, and Piedmont were allocated approximately 27 percent , 31 percent , 15 percent , 16 percent , 5 percent , 7 percent , and 4 percent , respectively, of the Duke Energy Master Retirement Trust at December 31, 2018 . Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages. (b) Certain investments that are measured at fair value using the net asset value per share practical expedient have not been categorized in the fair value hierarchy. December 31, 2017 Total Fair Not (in millions) Value Level 1 Level 2 Level 3 Categorized (b) Equity securities $ 2,823 $ 1,976 $ — $ — $ 847 Corporate debt securities 4,694 — 4,694 — — Short-term investment funds 246 192 54 — — Partnership interests 137 — — — 137 Hedge funds 226 — — — 226 Real estate limited partnerships 135 — — — 135 U.S. government securities 762 — 762 — — Guaranteed investment contracts 28 — — 28 — Governments bonds – foreign 38 — 38 — — Cash 6 6 — — — Government and commercial mortgage backed securities 2 — 2 — — Net pending transactions and other investments 17 15 2 — — Total assets (a) $ 9,114 $ 2,189 $ 5,552 $ 28 $ 1,345 (a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana, and Piedmont were allocated approximately 27 percent , 30 percent , 15 percent , 15 percent , 5 percent , 8 percent , and 4 percent , respectively, of the Duke Energy Master Retirement Trust and Piedmont's Pension assets at December 31, 2017 . Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages. (b) Certain investments that are measured at fair value using the net asset value per share practical expedient have not been categorized in the fair value hierarchy. The following table presents target and actual asset allocations for the VEBA trusts at December 31, 2018 . Actual Allocation at Target December 31, Allocation 2018 2017 U.S. equity securities 32 % 43 % 41 % Non-U.S. equity securities 6 % 8 % 8 % Real estate 2 % 2 % 2 % Debt securities 45 % 40 % 36 % Cash 15 % 7 % 13 % Total 100 % 100 % 100 % The following table includes the target asset allocations by asset class at December 31, 2018 , and the actual asset allocations for the Duke Energy Master Retirement Trust. Actual Allocation at Target December 31, Allocation 2018 2017 U.S. equity securities 10 % 11 % 11 % Non-U.S. equity securities 8 % 8 % 8 % Global equity securities 10 % 10 % 10 % Global private equity securities 3 % 2 % 2 % Debt securities 63 % 63 % 63 % Hedge funds 2 % 2 % 2 % Real estate and cash 2 % 2 % 2 % Other global securities 2 % 2 % 2 % Total 100 % 100 % 100 %
Master Trust Level 3 Rollforward	The following table provides a reconciliation of beginning and ending balances of Duke Energy Master Retirement Trust qualified pension and other post-retirement assets at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3). (in millions) 2018 2017 (a) Balance at January 1 $ 28 $ 38 Sales (1 ) (2 ) Total gains and other, net — 1 Transfer of Level 3 assets to other classifications — (9 ) Balance at December 31 $ 27 $ 28 (a) Balance at January 1 includes $9 million associated with Piedmont pension assets.
Employee Savings Plan Matching Contributions	The following table includes pretax employer matching contributions made by Duke Energy and expensed by the Subsidiary Registrants. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont (a) Years ended December 31, 2018 $ 213 $ 68 $ 58 $ 40 $ 19 $ 4 $ 10 $ 12 2017 179 61 53 37 16 3 9 7 2016 169 57 50 35 15 3 8 (a) Piedmont's pretax employer matching contributions were $1 million and $7 million during the two months ended December 31, 2016, and for the year ended October 31, 2016, respectively.
Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Components of Net Periodic Pension Costs Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 182 $ 58 $ 51 $ 29 $ 22 $ 5 $ 11 $ 7 Interest cost on projected benefit obligation 299 72 94 43 50 17 23 11 Expected return on plan assets (559 ) (147 ) (178 ) (85 ) (91 ) (28 ) (42 ) (22 ) Amortization of actuarial loss 132 29 44 21 23 5 10 11 Amortization of prior service credit (32 ) (8 ) (3 ) (2 ) (1 ) — (2 ) (10 ) Net periodic pension costs (a)(b) $ 22 $ 4 $ 8 $ 6 $ 3 $ (1 ) $ — $ (3 ) Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 159 $ 48 $ 45 $ 26 $ 19 $ 4 $ 9 $ 10 Interest cost on projected benefit obligation 328 79 100 47 53 18 26 14 Expected return on plan assets (545 ) (142 ) (167 ) (82 ) (85 ) (27 ) (42 ) (24 ) Amortization of actuarial loss 146 31 52 23 29 5 12 11 Amortization of prior service credit (24 ) (8 ) (3 ) (2 ) (1 ) (1 ) (2 ) (2 ) Settlement charge 12 — — — — — — 12 Other 8 2 2 1 1 — 1 1 Net periodic pension costs (a)(b) $ 84 $ 10 $ 29 $ 13 $ 16 $ (1 ) $ 4 $ 22 Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 147 $ 48 $ 42 $ 24 $ 19 $ 4 $ 9 Interest cost on projected benefit obligation 335 86 106 49 55 19 28 Expected return on plan assets (519 ) (142 ) (168 ) (82 ) (84 ) (27 ) (42 ) Amortization of actuarial loss 134 33 51 23 29 4 11 Amortization of prior service credit (17 ) (8 ) (3 ) (2 ) (1 ) — (1 ) Settlement charge 3 — — — — — — Other 8 2 3 1 1 1 1 Net periodic pension costs (a)(b) $ 91 $ 19 $ 31 $ 13 $ 19 $ 1 $ 6 (a) Duke Energy amounts exclude $5 million , $7 million and $8 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $2 million , $3 million and $4 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.
Amounts Recognized in AOCI and Regulatory Assets and Liabilities	Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net increase (decrease) $ 298 $ 170 $ 40 $ 31 $ 9 $ 10 $ 30 $ 8 Accumulated other comprehensive loss (income) Deferred income tax expense $ (2 ) — 1 — — — — — Amortization of prior year service credit 1 — — — — — — — Amortization of prior year actuarial losses 10 — (4 ) — — — — — Net amount recognized in accumulated other comprehensive income $ 9 $ — $ (3 ) $ — $ — $ — $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net (decrease) increase $ (212 ) $ (70 ) $ (49 ) $ (37 ) $ (11 ) $ 9 $ (19 ) $ (64 ) Accumulated other comprehensive (income) loss Deferred income tax expense $ — $ — $ 3 $ — $ — $ — $ — $ — Prior year service credit arising during the year 1 — — — — — — — Amortization of prior year actuarial losses (7 ) — (7 ) — — — — — Net amount recognized in accumulated other comprehensive income $ (6 ) $ — $ (4 ) $ — $ — $ — $ — $ — Piedmont's regulatory asset net increase was $34 million and $35 million for the two months ended December 31, 2016, and for the year ended October 31, 2016, respectively.
Reconciliation of Funded Status to Net Amount Recognized	Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 8,448 $ 2,029 $ 2,637 $ 1,211 $ 1,410 $ 479 $ 669 $ 313 Service cost 174 56 49 28 21 5 10 7 Interest cost 299 72 94 43 50 17 23 11 Actuarial gain (485 ) (44 ) (204 ) (87 ) (114 ) (29 ) (29 ) (18 ) Transfers — — — — — — — (16 ) Benefits paid (567 ) (159 ) (143 ) (70 ) (72 ) (37 ) (55 ) (33 ) Obligation at measurement date $ 7,869 $ 1,954 $ 2,433 $ 1,125 $ 1,295 $ 435 $ 618 $ 264 Accumulated Benefit Obligation at measurement date $ 7,818 $ 1,954 $ 2,404 $ 1,125 $ 1,265 $ 425 $ 614 $ 264 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 9,003 $ 2,372 $ 2,814 $ 1,366 $ 1,429 $ 458 $ 684 $ 368 Employer contributions 141 46 45 25 20 — 8 — Actual return on plan assets (344 ) (91 ) (110 ) (53 ) (55 ) (16 ) (26 ) (14 ) Benefits paid (567 ) (159 ) (143 ) (70 ) (72 ) (37 ) (55 ) (33 ) Transfers — — — — — — — (16 ) Plan assets at measurement date $ 8,233 $ 2,168 $ 2,606 $ 1,268 $ 1,322 $ 405 $ 611 $ 305 Funded status of plan $ 364 $ 214 $ 173 $ 143 $ 27 $ (30 ) $ (7 ) $ 41 Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 8,131 $ 1,952 $ 2,512 $ 1,158 $ 1,323 $ 447 $ 658 $ 344 Service cost 159 48 45 26 19 4 9 10 Interest cost 328 79 100 47 53 18 26 14 Actuarial loss 455 68 158 57 99 35 26 38 Transfers — 27 (32 ) (2 ) (15 ) 12 — — Plan amendments (61 ) — — — — — — (61 ) Benefits paid (537 ) (145 ) (146 ) (75 ) (69 ) (37 ) (50 ) (5 ) Benefits paid — settlements (27 ) — — — — — — (27 ) Obligation at measurement date $ 8,448 $ 2,029 $ 2,637 $ 1,211 $ 1,410 $ 479 $ 669 $ 313 Accumulated Benefit Obligation at measurement date $ 8,369 $ 2,029 $ 2,601 $ 1,211 $ 1,375 $ 468 $ 652 $ 313 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 8,531 $ 2,225 $ 2,675 $ 1,290 $ 1,352 $ 428 $ 657 $ 346 Employer contributions 19 — — — — 4 — 11 Actual return on plan assets 1,017 265 317 153 161 51 77 43 Benefits paid (537 ) (145 ) (146 ) (75 ) (69 ) (37 ) (50 ) (5 ) Benefits paid — settlements (27 ) — — — — — — (27 ) Transfers — 27 (32 ) (2 ) (15 ) 12 — — Plan assets at measurement date $ 9,003 $ 2,372 $ 2,814 $ 1,366 $ 1,429 $ 458 $ 684 $ 368 Funded status of plan $ 555 $ 343 $ 177 $ 155 $ 19 $ (21 ) $ 15 $ 55
Amounts Recognized in the Consolidated Balance Sheet	Amounts Recognized in the Consolidated Balance Sheets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Prefunded pension (a) $ 433 $ 214 $ 242 $ 143 $ 96 $ 24 $ 39 $ 41 Noncurrent pension liability (b) $ 69 $ — $ 69 $ — $ 69 $ 54 $ 46 $ — Net asset (liability) recognized $ 364 $ 214 $ 173 $ 143 $ 27 $ (30 ) $ (7 ) $ 41 Regulatory assets $ 2,184 $ 576 $ 796 $ 372 $ 424 $ 100 $ 182 $ 81 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (43 ) $ — $ (2 ) $ — $ — $ — $ — $ — Prior service credit (4 ) — — — — — — — Net actuarial loss 126 — 5 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 79 $ — $ 3 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension costs in the next year Unrecognized net actuarial loss $ 97 $ 22 $ 37 $ 13 $ 24 $ 3 $ 5 $ 7 Unrecognized prior service credit (32 ) (8 ) (3 ) (2 ) (1 ) — (2 ) (9 ) December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Prefunded pension (a) $ 680 $ 343 $ 245 $ 155 $ 87 $ 8 $ 16 $ 55 Noncurrent pension liability (b) $ 125 $ — $ 68 $ — $ 68 $ 29 $ 1 $ — Net asset recognized $ 555 $ 343 $ 177 $ 155 $ 19 $ (21 ) $ 15 $ 55 Regulatory assets $ 1,886 $ 406 $ 756 $ 341 $ 415 $ 90 $ 152 $ 73 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (41 ) $ — $ (3 ) $ — $ — $ — $ — $ — Prior service credit (5 ) — — — — — — — Net actuarial loss 116 — 9 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 70 $ — $ 6 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension costs in the next year Unrecognized net actuarial loss $ 132 $ 29 $ 44 $ 21 $ 23 $ 5 $ 7 $ 11 Unrecognized prior service credit $ (32 ) $ (8 ) $ (3 ) $ (2 ) $ (1 ) $ — $ (2 ) $ (9 ) (a) Included in Other within Other Noncurrent Assets on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.
Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets	Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2018 Duke Duke Duke Duke Progress Energy Energy Energy (in millions) Energy Energy Florida Ohio Indiana Projected benefit obligation $ 679 $ 679 $ 679 $ 123 $ 203 Accumulated benefit obligation 651 651 651 115 199 Fair value of plan assets 610 610 610 69 159 December 31, 2017 Duke Duke Duke Progress Energy Energy (in millions) Energy Energy Florida Ohio Projected benefit obligation $ 1,386 $ 718 $ 718 $ 337 Accumulated benefit obligation 1,326 683 683 326 Fair value of plan assets 1,260 650 650 308
Assumptions Used for Pension Benefits Accounting	The following tables present the assumptions or range of assumptions used for pension benefit accounting. December 31, 2018 2017 2016 Benefit Obligations Discount rate 4.30% 3.60% 4.10% Salary increase 3.50 % – 4.00% 3.50 % – 4.00% 4.00 % – 4.50% Net Periodic Benefit Cost Discount rate 3.60% 4.10% 4.40% Salary increase 3.50 % – 4.00% 4.00 % – 4.50% 4.00 % – 4.40% Expected long-term rate of return on plan assets 6.50% 6.50 % – 6.75% 6.50 % – 6.75%
Expected Benefit Payments	Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Years ending December 31, 2019 $ 662 $ 210 $ 179 $ 105 $ 73 $ 33 $ 47 $ 20 2020 651 177 171 90 80 37 51 24 2021 663 182 177 95 81 37 51 23 2022 662 189 179 94 84 37 49 22 2023 655 185 181 95 85 35 47 22 2024-2028 2,993 794 902 451 447 158 217 96
Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Components of Net Periodic Pension Costs Year Ended December 31, 2018 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Service cost $ 2 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 12 — 4 1 2 Amortization of actuarial loss 8 — 2 1 1 Amortization of prior service credit (2 ) — — — — Net periodic pension costs $ 20 $ 1 $ 6 $ 2 $ 3 Year Ended December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Service cost $ 2 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 13 1 5 1 2 Amortization of actuarial loss 8 — 2 1 1 Amortization of prior service credit (2 ) — — — — Net periodic pension costs $ 21 $ 2 $ 7 $ 2 $ 3 Year Ended December 31, 2016 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Service cost $ 2 $ — $ — $ — $ — Interest cost on projected benefit obligation 14 1 5 1 2 Amortization of actuarial loss 8 1 1 1 1 Amortization of prior service credit (1 ) — — — — Net periodic pension costs $ 23 $ 2 $ 6 $ 2 $ 3
Amounts Recognized in AOCI and Regulatory Assets and Liabilities	Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2018 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Regulatory assets, net (decrease) increase $ (16 ) $ 1 $ (6 ) $ (3 ) $ (3 ) Accumulated other comprehensive (income) loss Deferred income tax benefit $ 1 $ — $ 1 $ — $ — Actuarial gain arising during the year (4 ) — (3 ) — — Net amount recognized in accumulated other comprehensive loss (income) $ (3 ) $ — $ (2 ) $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Regulatory assets, net increase (decrease) $ 5 $ (1 ) $ 3 $ 1 $ 2 Accumulated other comprehensive (income) loss Prior service credit arising during the year $ (1 ) $ — $ — $ — $ — Actuarial loss arising during the year 2 — — — — Net amount recognized in accumulated other comprehensive loss (income) $ 1 $ — $ — $ — $ —
Reconciliation of Funded Status to Net Amount Recognized	Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Service cost 2 1 — — — — — — Interest cost 12 — 4 1 2 — — — Actuarial gain (17 ) — (6 ) (2 ) (3 ) (1 ) — (1 ) Benefits paid (24 ) (1 ) (8 ) (3 ) (3 ) — — — Obligation at measurement date $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Accumulated Benefit Obligation at measurement date $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Change in Fair Value of Plan Assets Benefits paid $ (24 ) $ (1 ) $ (8 ) $ (3 ) $ (3 ) $ — $ — $ — Employer contributions 24 1 8 3 3 — — — Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Obligation at prior measurement date $ 332 $ 14 $ 114 $ 33 $ 46 $ 4 $ 3 $ 4 Service cost 2 1 — — — — — — Interest cost 13 1 5 1 2 — — — Actuarial loss (gain) 15 — 5 4 2 — — — Benefits paid (31 ) (2 ) (8 ) (3 ) (3 ) — — — Obligation at measurement date $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Accumulated Benefit Obligation at measurement date $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Change in Fair Value of Plan Assets Benefits paid $ (31 ) $ (2 ) $ (8 ) $ (3 ) $ (3 ) $ — $ — $ — Employer contributions 31 2 8 3 3 — — — Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — $ —
Amounts Recognized in the Consolidated Balance Sheet	Amounts Recognized in the Consolidated Balance Sheets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current pension liability (a) $ 21 $ 2 $ 8 $ 3 $ 3 $ — $ — $ — Noncurrent pension liability (b) 283 12 98 28 40 3 3 3 Total accrued pension liability $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Regulatory assets $ 62 $ 5 $ 15 $ 5 $ 10 $ 1 $ — $ 1 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (3 ) $ — $ (2 ) $ — $ — $ — $ — $ — Prior service credit (1 ) — — — — — — — Net actuarial loss 8 — 6 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 4 $ — $ 4 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss $ 6 $ — $ 2 $ 1 $ 1 $ — $ — $ — Unrecognized prior service credit (2 ) — — — — — — — December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current pension liability (a) $ 23 $ 2 $ 8 $ 3 $ 3 $ — $ — $ — Noncurrent pension liability (b) 308 12 108 32 44 4 3 4 Total accrued pension liability $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Regulatory assets $ 78 $ 4 $ 21 $ 8 $ 13 $ 1 $ — $ 1 Accumulated other comprehensive (income) loss Deferred income tax benefit $ (4 ) $ — $ (3 ) $ — $ — $ — $ — $ — Prior service credit (1 ) — — — — — — — Net actuarial loss 12 — 9 — — — — — Net amounts recognized in accumulated other comprehensive loss $ 7 $ — $ 6 $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss $ 8 $ — $ 2 $ 1 $ 1 $ — $ — $ — Unrecognized prior service credit $ (2 ) $ — $ — $ — $ — $ — $ — $ — (a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.
Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets	Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Projected benefit obligation $ 304 $ 14 $ 106 $ 31 $ 43 $ 3 $ 3 $ 3 Accumulated benefit obligation 304 14 106 31 43 3 3 3 December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Projected benefit obligation $ 331 $ 14 $ 116 $ 35 $ 47 $ 4 $ 3 $ 4 Accumulated benefit obligation 331 14 116 35 47 4 3 4
Assumptions Used for Pension Benefits Accounting	The following tables present the assumptions used for pension benefit accounting. December 31, 2018 2017 2016 Benefit Obligations Discount rate 4.30 % 3.60 % 4.10 % Salary increase 3.50 % – 4.00 % 3.50 % – 4.00 % 4.40 % Net Periodic Benefit Cost Discount rate 3.60 % 4.10 % 4.40 % Salary increase 3.50 % – 4.00 % 4.40 % 4.40 % Piedmont Two Months Ended Year Ended December 31, 2016 October 31, 2016 Benefit Obligations Discount rate 4.10 % 3.80 % Net Periodic Benefit Cost Discount rate 3.80 % 3.85 %
Expected Benefit Payments	Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Years ending December 31, 2019 $ 22 $ 2 $ 8 $ 3 $ 3 $ — $ — $ — 2020 21 1 8 2 3 — — — 2021 23 1 8 2 3 — — — 2022 25 1 8 2 3 — — — 2023 25 3 7 2 3 — — — 2024-2028 125 10 37 11 15 1 1 2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Components of Net Periodic Other Post-Retirement Benefit Costs Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 6 $ 1 $ 1 $ — $ 1 $ 1 $ 1 $ 1 Interest cost on accumulated post-retirement benefit obligation 28 7 12 6 6 1 3 1 Expected return on plan assets (13 ) (8 ) — — — — — (2 ) Amortization of actuarial loss 6 3 1 1 — — 4 — Amortization of prior service credit (19 ) (5 ) (8 ) (1 ) (7 ) (1 ) (1 ) (2 ) Net periodic post-retirement benefit costs (a)(b) $ 8 $ (2 ) $ 6 $ 6 $ — $ 1 $ 7 $ (2 ) Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 4 $ 1 $ — $ — $ — $ — $ — $ 1 Interest cost on accumulated post-retirement benefit obligation 34 8 13 7 6 1 3 1 Expected return on plan assets (14 ) (8 ) — — — — (1 ) (2 ) Amortization of actuarial loss (gain) 10 (2 ) 21 12 9 (2 ) (1 ) 1 Amortization of prior service credit (115 ) (10 ) (84 ) (54 ) (30 ) — (1 ) — Curtailment credit (c) (30 ) (4 ) (16 ) — (16 ) (2 ) (2 ) — Net periodic post-retirement benefit costs (a)(b) $ (111 ) $ (15 ) $ (66 ) $ (35 ) $ (31 ) $ (3 ) $ (2 ) $ 1 Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ 1 $ 1 $ — $ 1 $ — $ — Interest cost on accumulated post-retirement benefit obligation 35 8 15 8 7 1 4 Expected return on plan assets (12 ) (8 ) — — — — (1 ) Amortization of actuarial loss (gain) 6 (3 ) 22 13 9 (2 ) (1 ) Amortization of prior service credit (141 ) (14 ) (103 ) (68 ) (35 ) — (1 ) Net periodic post-retirement benefit costs (a)(b) $ (109 ) $ (16 ) $ (65 ) $ (47 ) $ (18 ) $ (1 ) $ 1 (a) Duke Energy amounts exclude $7 million , $7 million and $8 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $2 million , $2 million and $2 million for the years ended December 2018 , 2017 and 2016 , respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (c) Curtailment credit resulted from a reduction in average future service of plan participants due to a plan amendment.
Amounts Recognized in AOCI and Regulatory Assets and Liabilities	Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net increase (decrease) $ 137 $ — $ 133 $ 84 $ 49 $ — $ (5 ) $ 4 Regulatory liabilities, net increase (decrease) $ 154 $ (6 ) $ 149 $ 93 $ 56 $ 2 $ 3 $ — Accumulated other comprehensive (income) loss Deferred income tax benefit $ (1 ) $ — $ — $ — $ — $ — $ — $ — Amortization of prior year actuarial gain 1 — — — — — — — Net amount recognized in accumulated other comprehensive income $ — $ — $ — $ — $ — $ — $ — $ — Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Regulatory assets, net increase (decrease) $ 71 $ — $ 81 $ 42 $ 39 $ — $ (5 ) $ (11 ) Regulatory liabilities, net increase (decrease) $ (27 ) $ (2 ) $ — $ — $ — $ (3 ) $ (7 ) $ — Accumulated other comprehensive (income) loss Deferred income tax benefit $ (1 ) $ — $ — $ — $ — $ — $ — $ — Amortization of prior year prior service credit 3 — — — — — — — Net amount recognized in accumulated other comprehensive income $ 2 $ — $ — $ — $ — $ — $ — $ — Piedmont's regulatory assets net decreased $1 million for the two months ended December 31, 2016, and increased $2 million for the year ended October 31, 2016.
Reconciliation of Funded Status to Net Amount Recognized	Reconciliation of Funded Status to Accrued Other Post-Retirement Benefit Costs Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 813 $ 189 $ 342 $ 184 $ 156 $ 30 $ 78 $ 32 Service cost 6 1 1 — 1 1 1 1 Interest cost 28 7 12 6 6 1 3 1 Plan participants' contributions 18 3 6 4 3 1 2 — Actuarial gains (51 ) (8 ) (23 ) (9 ) (13 ) (2 ) (5 ) (1 ) Transfers — — — — — — — (1 ) Benefits paid (86 ) (18 ) (35 ) (19 ) (16 ) (2 ) (12 ) (2 ) Accumulated post-retirement benefit obligation at measurement date $ 728 $ 174 $ 303 $ 166 $ 137 $ 29 $ 67 $ 30 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 225 $ 133 $ — $ — $ — $ 7 $ 11 $ 31 Actual return on plan assets (8 ) (5 ) — — — — — (1 ) Benefits paid (86 ) (18 ) (35 ) (19 ) (16 ) (2 ) (12 ) (2 ) Employer contributions 46 2 29 15 13 2 4 1 Plan participants' contributions 18 3 6 4 3 1 2 — Plan assets at measurement date $ 195 $ 115 $ — $ — $ — $ 8 $ 5 $ 29 Funded status of plan $ (533 ) $ (59 ) $ (303 ) $ (166 ) $ (137 ) $ (21 ) $ (62 ) $ (1 ) Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 868 $ 201 $ 357 $ 191 $ 164 $ 32 $ 83 $ 39 Service cost 4 1 — — — — — 1 Interest cost 34 8 13 7 6 1 3 1 Plan participants' contributions 17 3 6 3 3 1 2 — Actuarial losses (gains) 4 (3 ) 4 1 3 — 3 1 Transfers — 2 (1 ) — (1 ) 1 — — Plan amendments (28 ) (5 ) (3 ) (1 ) (2 ) (2 ) (2 ) (9 ) Benefits paid (86 ) (18 ) (34 ) (17 ) (17 ) (3 ) (11 ) (1 ) Accumulated post-retirement benefit obligation at measurement date $ 813 $ 189 $ 342 $ 184 $ 156 $ 30 $ 78 $ 32 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 244 $ 137 $ 1 $ — $ — $ 7 $ 22 $ 29 Actual return on plan assets 25 15 1 — — 2 1 3 Benefits paid (86 ) (18 ) (34 ) (17 ) (17 ) (3 ) (11 ) (1 ) Employer contributions (reimbursements) 25 (4 ) 26 14 14 — (3 ) — Plan participants' contributions 17 3 6 3 3 1 2 — Plan assets at measurement date $ 225 $ 133 $ — $ — $ — $ 7 $ 11 $ 31 Funded status of plan $ (588 ) $ (56 ) $ (342 ) $ (184 ) $ (156 ) $ (23 ) $ (67 ) $ (1 )
Amounts Recognized in the Consolidated Balance Sheet	Amounts Recognized in the Consolidated Balance Sheets December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current post-retirement liability (a) $ 8 $ — $ 5 $ 3 $ 2 $ 2 $ — $ — Noncurrent post-retirement liability (b) 525 59 298 163 135 19 62 1 Total accrued post-retirement liability $ 533 $ 59 $ 303 $ 166 $ 137 $ 21 $ 62 $ 1 Regulatory assets $ 262 $ — $ 262 $ 164 $ 98 $ — $ 41 $ — Regulatory liabilities $ 301 $ 38 $ 149 $ 93 $ 56 $ 18 $ 67 $ — Accumulated other comprehensive (income) loss Deferred income tax expense $ 3 $ — $ — $ — $ — $ — $ — $ — Prior service credit (2 ) — — — — — — — Net actuarial gain (9 ) — — — — — — — Net amounts recognized in accumulated other comprehensive income $ (8 ) $ — $ — $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss $ 4 $ 2 $ 1 $ — $ — $ — $ — $ — Unrecognized prior service credit (19 ) (5 ) (7 ) (1 ) (6 ) (1 ) (1 ) (2 ) December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current post-retirement liability (a) $ 36 $ — $ 29 $ 15 $ 14 $ 2 $ — $ — Noncurrent post-retirement liability (b) 552 56 313 169 142 21 67 1 Total accrued post-retirement liability $ 588 $ 56 $ 342 $ 184 $ 156 $ 23 $ 67 $ 1 Regulatory assets $ 125 $ — $ 129 $ 80 $ 49 $ — $ 46 $ (4 ) Regulatory liabilities $ 147 $ 44 $ — $ — $ — $ 16 $ 64 $ — Accumulated other comprehensive (income) loss Deferred income tax expense $ 4 $ — $ — $ — $ — $ — $ — $ — Prior service credit (2 ) — — — — — — — Net actuarial gain (10 ) — — — — — — — Net amounts recognized in accumulated other comprehensive income $ (8 ) $ — $ — $ — $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss (gain) $ 5 $ 3 $ 1 $ — $ 1 $ — $ — $ — Unrecognized prior service credit (19 ) (5 ) (7 ) (1 ) (6 ) (1 ) (1 ) (2 ) (a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.
Assumptions Used for Pension Benefits Accounting	The following tables present the assumptions used for other post-retirement benefits accounting. December 31, 2018 2017 2016 Benefit Obligations Discount rate 4.30 % 3.60 % 4.10 % Net Periodic Benefit Cost Discount rate 3.60 % 4.10 % 4.40 % Expected long-term rate of return on plan assets 6.50 % 6.50 % 6.50 % Assumed tax rate 35 % 35 % 35 % Piedmont Two Months Ended Year Ended December 31, 2016 October 31, 2016 Benefit Obligations Discount rate 4.10 % 3.80 % Net Periodic Benefit Cost Discount rate 3.80 % 4.38 % Expected long-term rate of return on plan assets 6.75 % 7.25 %
Assumed Health Care Cost Trend Rate	Assumed Health Care Cost Trend Rate December 31, 2018 2017 Health care cost trend rate assumed for next year 6.50 % 7.00 % Rate to which the cost trend is assumed to decline (the ultimate trend rate) 4.75 % 4.75 % Year that rate reaches ultimate trend 2024 2024
Sensitivity to Changes in Assumed Health Care Cost Trend Rates	Sensitivity to Changes in Assumed Health Care Cost Trend Rates Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont 1-Percentage Point Increase Effect on total service and interest costs $ 1 $ — $ 1 $ 1 $ — $ — $ — $ — Effect on post-retirement benefit obligation 22 5 9 5 4 1 2 1 1-Percentage Point Decrease Effect on total service and interest costs (1 ) — (1 ) (1 ) — — — — Effect on post-retirement benefit obligation (20 ) (5 ) (8 ) (5 ) (4 ) (1 ) (2 ) (1 )
Expected Benefit Payments	Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Years ending December 31, 2019 $ 81 $ 19 $ 30 $ 16 $ 14 $ 3 $ 9 $ 2 2020 75 18 29 15 13 3 8 2 2021 71 18 28 15 13 3 7 2 2022 68 17 27 14 12 3 7 3 2023 64 16 26 14 12 3 6 3 2024-2028 266 64 109 59 50 11 26 12
Piedmont Natural Gas [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Piedmont Two Months Ended Year Ended (in millions) December 31, 2016 October 31, 2016 Service cost $ 2 $ 11 Interest cost on projected benefit obligation 2 9 Expected return on plan assets (4 ) (24 ) Amortization of actuarial loss 2 8 Amortization of prior service credit (1 ) (2 ) Settlement charge 3 — Net periodic pension costs $ 4 $ 2
Assumptions Used for Pension Benefits Accounting	Piedmont Two Months Ended Year Ended December 31, 2016 October 31, 2016 Benefit Obligations Discount rate 4.10 % 3.80 % Salary increase 4.50 % 4.05 % Net Periodic Benefit Cost Discount rate 3.80 % 4.34 % Salary increase 4.05 % 4.07 % Expected long-term rate of return on plan assets 6.75 % 7.25 %
Piedmont Natural Gas [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Piedmont Year Ended (in millions) October 31, 2016 Amortization of prior service cost $ — Settlement charge 1 Net periodic pension costs $ 1
Assumptions Used for Pension Benefits Accounting	Piedmont Two Months Ended Year Ended December 31, 2016 October 31, 2016 Benefit Obligations Discount rate 4.10 % 3.80 % Net Periodic Benefit Cost Discount rate 3.80 % 3.85 %
Piedmont Natural Gas [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Piedmont Year Ended (in millions) October 31, 2016 Service cost $ 1 Interest cost on projected benefit obligation 1 Expected return on plan assets (2 ) Amortization of actuarial loss 1 Net periodic pension costs $ 1

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Schedule of Components of Income Tax Expense (Benefit)	Components of Income Tax Expense Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current income taxes Federal $ (647 ) $ (8 ) $ (135 ) $ (71 ) $ (49 ) $ 20 $ 29 $ 67 State (11 ) 6 (5 ) (5 ) (10 ) (1 ) 3 1 Foreign 3 — — — — — — — Total current income taxes (655 ) (2 ) (140 ) (76 ) (59 ) 19 32 68 Deferred income taxes Federal 1,064 299 341 256 115 21 74 (36 ) State 49 11 20 (17 ) 45 3 22 5 Total deferred income taxes (a)(b) 1,113 310 361 239 160 24 96 (31 ) Investment tax credit amortization (10 ) (5 ) (3 ) (3 ) — — — — Income tax expense from continuing operations 448 303 218 160 101 43 128 37 Tax benefit from discontinued operations (26 ) — — — — — — — Total income tax expense included in Consolidated Statements of Operations $ 422 $ 303 $ 218 $ 160 $ 101 $ 43 $ 128 $ 37 (a) Includes benefits of NOL carryforwards and tax credit carryforwards of $22 million at Duke Energy Carolinas, $293 million at Progress Energy, $59 million at Duke Energy Progress, $219 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $21 million at Duke Energy Indiana and $39 million at Piedmont. In addition, total deferred income taxes includes utilization of NOL carryforwards and tax credit carryforwards of $18 million at Duke Energy. (b) For the year ended December 31, 2018, the Company has revised the December 31, 2017, estimates of the income tax effects of the Tax Act, in accordance with SAB 118. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense. Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Current income taxes Federal $ (247 ) $ 221 $ (436 ) $ (95 ) $ (188 ) $ (37 ) $ 128 $ (90 ) State 4 20 (5 ) 2 (11 ) 2 21 (3 ) Foreign 3 — — — — — — — Total current income taxes (240 ) 241 (441 ) (93 ) (199 ) (35 ) 149 (93 ) Deferred income taxes Federal 1,344 381 664 378 194 99 138 147 State 102 35 44 10 51 (4 ) 14 8 Total deferred income taxes (a)(b) 1,446 416 708 388 245 95 152 155 Investment tax credit amortization (10 ) (5 ) (3 ) (3 ) — (1 ) — — Income tax expense from continuing operations 1,196 652 264 292 46 59 301 62 Tax benefit from discontinued operations (6 ) — — — — — — — Total income tax expense included in Consolidated Statements of Operations $ 1,190 $ 652 $ 264 $ 292 $ 46 $ 59 $ 301 $ 62 (a) Includes utilization of NOL carryforwards and tax credit carryforwards of $428 million at Duke Energy, $74 million at Progress Energy, $36 million at Duke Energy Florida, $17 million at Duke Energy Ohio, $42 million at Duke Energy Indiana and $79 million at Piedmont. In addition, total deferred income taxes includes benefits of NOL carryforwards and tax credit carryforwards of $10 million at Duke Energy Carolinas and $1 million at Duke Energy Progress. (b) As a result of the Tax Act, Duke Energy's deferred tax assets and liabilities were revalued as of December 31, 2017. See the Statutory Rate Reconciliation section below for additional information on the Tax Act's impact on income tax expense. Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ — $ 139 $ 15 $ (59 ) $ 76 $ (7 ) $ 7 State (15 ) 25 (19 ) (25 ) 22 (13 ) 6 Foreign 2 — — — — — — Total current income taxes (13 ) 164 (4 ) (84 ) 98 (20 ) 13 Deferred income taxes Federal 1,064 430 486 350 199 88 202 State 117 45 50 40 25 11 11 Total deferred income taxes (a) 1,181 475 536 390 224 99 213 Investment tax credit amortization (12 ) (5 ) (5 ) (5 ) — (1 ) (1 ) Income tax expense from continuing operations 1,156 634 527 301 322 78 225 Tax (benefit) expense from discontinued operations (30 ) — 1 — — (36 ) — Total income tax expense included in Consolidated Statements of Operations $ 1,126 $ 634 $ 528 $ 301 $ 322 $ 42 $ 225 (a) Includes benefits of NOL carryforwards and utilization of NOL and tax credit carryforwards of $648 million at Duke Energy, $4 million at Duke Energy Carolinas, $190 million at Progress Energy, $60 million at Duke Energy Progress, $49 million at Duke Energy Florida, $26 million at Duke Energy Ohio and $58 million at Duke Energy Indiana. Piedmont Two Months Ended Year Ended October 31, (in millions) December 31, 2016 2016 Current income taxes Federal $ 4 $ 27 State (2 ) 12 Total current income taxes 2 39 Deferred income taxes Federal 24 79 State 6 6 Total deferred income taxes (a) 30 85 Total income tax expense from continuing operations included in Consolidated Statements of Operations $ 32 $ 124
Schedule of Income before Income Tax, Domestic and Foreign	Duke Energy Income from Continuing Operations before Income Taxes Years Ended December 31, (in millions) 2018 2017 2016 Domestic (a) $ 3,018 $ 4,207 $ 3,689 Foreign 55 59 45 Income from continuing operations before income taxes $ 3,073 $ 4,266 $ 3,734 (a) Includes a $16 million expense in 2017 related to the Tax Act impact on equity earnings included within Equity in earnings (losses) of unconsolidated affiliates on the Consolidated Statement of Operations.
Summary of Effective Tax Rates	The following tables present a reconciliation of income tax expense at the U.S. federal statutory tax rate to the actual tax expense from continuing operations. Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Income tax expense, computed at the statutory rate of 21 percent $ 645 $ 288 $ 263 $ 174 $ 137 $ 46 $ 109 $ 35 State income tax, net of federal income tax effect 30 14 13 (17 ) 28 2 20 4 Amortization of excess deferred income tax (61 ) — (55 ) (1 ) (54 ) (3 ) (2 ) — AFUDC equity income (42 ) (15 ) (22 ) (12 ) (10 ) (2 ) (2 ) — AFUDC equity depreciation 31 18 9 5 4 1 4 — Renewable energy production tax credits (129 ) — — — — — — — Other tax credits (28 ) (7 ) (13 ) (5 ) (8 ) (1 ) (1 ) (3 ) Tax Act (a) 20 1 25 19 — 2 — — Other items, net (18 ) 4 (2 ) (3 ) 4 (2 ) — 1 Income tax expense from continuing operations $ 448 $ 303 $ 218 $ 160 $ 101 $ 43 $ 128 $ 37 Effective tax rate 14.6 % 22.1 % 17.4 % 19.3 % 15.4 % 19.6 % 24.6 % 22.3 % (a) For the year ended December 31, 2018, the Company revised the December 31, 2017 estimates of the income tax effects of the Tax Act, in accordance with SAB 118. Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits. Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Income tax expense, computed at the statutory rate of 35 percent $ 1,493 $ 653 $ 536 $ 353 $ 265 $ 88 $ 229 $ 70 State income tax, net of federal income tax effect 69 36 25 8 26 (1 ) 23 3 AFUDC equity income (81 ) (37 ) (32 ) (17 ) (16 ) (4 ) (8 ) — Renewable energy production tax credits (132 ) — — — — — — — Tax Act (a) (112 ) 15 (246 ) (40 ) (226 ) (23 ) 55 (12 ) Tax true up (52 ) (24 ) (19 ) (13 ) (7 ) (5 ) (6 ) — Other items, net 11 9 — 1 4 4 8 1 Income tax expense from continuing operations $ 1,196 $ 652 $ 264 $ 292 $ 46 $ 59 $ 301 $ 62 Effective tax rate 28.0 % 34.9 % 17.2 % 29.0 % 6.1 % 23.4 % 46.0 % 30.8 % (a) Amounts primarily include but are not limited to items that are excluded for ratemaking purposes related to abandoned or impaired assets, certain wholesale fixed rate contracts, remeasurement of nonregulated net deferred tax liabilities, Federal net operating losses, and valuation allowance on foreign tax credits. Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,307 $ 630 $ 548 $ 315 $ 306 $ 95 $ 212 State income tax, net of federal income tax effect 64 46 20 10 30 (2 ) 11 AFUDC equity income (70 ) (36 ) (26 ) (17 ) (9 ) (2 ) (6 ) Renewable energy production tax credits (97 ) — — — — — — Audit adjustment 5 3 — — — — — Tax true up (14 ) (14 ) (11 ) (3 ) (9 ) (16 ) 2 Other items, net (39 ) 5 (4 ) (4 ) 4 3 6 Income tax expense from continuing operations $ 1,156 $ 634 $ 527 $ 301 $ 322 $ 78 $ 225 Effective tax rate 31.0 % 35.2 % 33.7 % 33.4 % 36.9 % 28.9 % 37.1 %
Schedule of Deferred Tax Assets and Liabilities	December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Deferred credits and other liabilities $ 143 $ 33 $ 78 $ 23 $ 49 $ 11 $ 6 $ (5 ) Capital lease obligations 49 14 — — — — 2 — Pension, post-retirement and other employee benefits 295 (17 ) 111 44 60 14 18 (4 ) Progress Energy merger purchase accounting adjustments (a) 536 — — — — — — — Tax credits and NOL carryforwards 4,527 234 402 156 143 25 216 70 Regulatory liabilities and deferred credits — 222 — — — 65 — 61 Investments and other assets — — — — — — 1 18 Other 73 10 1 4 — — — — Valuation allowance (519 ) — (14 ) — — — — — Total deferred income tax assets 5,104 496 578 227 252 115 243 140 Investments and other assets (1,419 ) (849 ) (470 ) (289 ) (187 ) — (14 ) — Accelerated depreciation rates (9,216 ) (3,060 ) (2,803 ) (1,583 ) (1,257 ) (896 ) (966 ) (697 ) Regulatory assets and deferred debits, net (1,090 ) — (807 ) (238 ) (569 ) — (188 ) — Other — — — — — — — (7 ) Total deferred income tax liabilities (11,725 ) (3,909 ) (4,080 ) (2,110 ) (2,013 ) (896 ) (1,168 ) (704 ) Net deferred income tax liabilities $ (6,621 ) $ (3,413 ) $ (3,502 ) $ (1,883 ) $ (1,761 ) $ (781 ) $ (925 ) $ (564 ) (a) Primarily related to capital lease obligations and debt fair value adjustments. Net Deferred Income Tax Liability Components December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Deferred credits and other liabilities $ 164 $ 64 $ 35 $ 53 $ — $ 17 $ 6 $ 17 Capital lease obligations 60 26 — — — — 2 — Pension, post-retirement and other employee benefits 347 24 110 47 58 16 24 (1 ) Progress Energy merger purchase accounting adjustments (a) 483 — — — — — — — Tax credits and NOL carryforwards 4,580 257 693 215 363 42 237 110 Regulatory liabilities and deferred credits — — — — — 56 — 48 Investments and other assets — — — — — 18 — 16 Other 25 6 5 5 — 1 (1 ) — Valuation allowance (484 ) — — — — — — — Total deferred income tax assets 5,175 377 843 320 421 150 268 190 Investments and other assets (1,317 ) (795 ) (430 ) (272 ) (163 ) — (5 ) — Accelerated depreciation rates (10,124 ) (3,207 ) (3,369 ) (1,735 ) (1,670 ) (967 ) (1,081 ) (733 ) Regulatory assets and deferred debits, net (1,540 ) (64 ) (985 ) (432 ) (574 ) — (191 ) — Other — — — — — — — (8 ) Total deferred income tax liabilities (12,981 ) (4,066 ) (4,784 ) (2,439 ) (2,407 ) (967 ) (1,277 ) (741 ) Net deferred income tax liabilities $ (7,806 ) $ (3,689 ) $ (3,941 ) $ (2,119 ) $ (1,986 ) $ (817 ) $ (1,009 ) $ (551 ) (a) Primarily related to capital lease obligations and debt fair value adjustments.
Summary of Tax Credit Carryforwards	The following table presents the expiration of tax credits and NOL carryforwards. December 31, 2018 (in millions) Amount Expiration Year Investment tax credits $ 1,614 2024 — 2038 Alternative minimum tax credits 574 Refundable by 2021 Federal NOL carryforwards (a)(e) 788 2022 — Indefinite State NOL carryforwards and credits (b)(e) 301 2019 — Indefinite Foreign NOL carryforwards (c) 12 2027 — 2037 Foreign Tax Credits (d) 1,271 2024 — 2027 Charitable contribution carryforwards 20 2019 — 2023 Total tax credits and NOL carryforwards $ 4,580 (a) A valuation allowance of $4 million has been recorded on the Federal NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (b) A valuation allowance of $85 million has been recorded on the state NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (c) A valuation allowance of $12 million has been recorded on the foreign NOL carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (d) A valuation allowance of $383 million has been recorded on the foreign tax credits, as presented in the Net Deferred Income Tax Liability Components table. (e) Indefinite carryforward for Federal NOLs, and NOLs for states that have adopted the Tax Act's NOL provisions, generated in tax years beginning after December 31, 2017. December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Deferred credits and other liabilities $ 143 $ 33 $ 78 $ 23 $ 49 $ 11 $ 6 $ (5 ) Capital lease obligations 49 14 — — — — 2 — Pension, post-retirement and other employee benefits 295 (17 ) 111 44 60 14 18 (4 ) Progress Energy merger purchase accounting adjustments (a) 536 — — — — — — — Tax credits and NOL carryforwards 4,527 234 402 156 143 25 216 70 Regulatory liabilities and deferred credits — 222 — — — 65 — 61 Investments and other assets — — — — — — 1 18 Other 73 10 1 4 — — — — Valuation allowance (519 ) — (14 ) — — — — — Total deferred income tax assets 5,104 496 578 227 252 115 243 140 Investments and other assets (1,419 ) (849 ) (470 ) (289 ) (187 ) — (14 ) — Accelerated depreciation rates (9,216 ) (3,060 ) (2,803 ) (1,583 ) (1,257 ) (896 ) (966 ) (697 ) Regulatory assets and deferred debits, net (1,090 ) — (807 ) (238 ) (569 ) — (188 ) — Other — — — — — — — (7 ) Total deferred income tax liabilities (11,725 ) (3,909 ) (4,080 ) (2,110 ) (2,013 ) (896 ) (1,168 ) (704 ) Net deferred income tax liabilities $ (6,621 ) $ (3,413 ) $ (3,502 ) $ (1,883 ) $ (1,761 ) $ (781 ) $ (925 ) $ (564 )
Schedule of Unrecognized Tax Benefits Roll Forward	The following tables present changes to unrecognized tax benefits. Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unrecognized tax benefits – January 1 $ 25 $ 5 $ 5 $ 5 $ 5 $ 1 $ 1 $ 3 Unrecognized tax benefits increases (decreases) Gross decreases – tax positions in prior periods (2 ) (1 ) — — (4 ) — — — Gross increases – current period tax positions 7 2 4 1 2 — — 1 Decreases due to settlements (6 ) — — — — — — — Total changes (1 ) 1 4 1 (2 ) — — 1 Unrecognized tax benefits – December 31 $ 24 $ 6 $ 9 $ 6 $ 3 $ 1 $ 1 $ 4 Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Unrecognized tax benefits – January 1 $ 17 $ 1 $ 2 $ 2 $ 4 $ 4 $ — $ — Unrecognized tax benefits increases (decreases) Gross increases – tax positions in prior periods 12 4 3 3 1 1 1 3 Gross decreases – tax positions in prior periods (4 ) — — — — (4 ) — — Total changes 8 4 3 3 1 (3 ) 1 3 Unrecognized tax benefits – December 31 $ 25 $ 5 $ 5 $ 5 $ 5 $ 1 $ 1 $ 3 Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Unrecognized tax benefits – January 1 $ 88 $ 72 $ 1 $ 3 $ — $ — $ 1 Unrecognized tax benefits increases (decreases) Gross increases – tax positions in prior periods — — — — 4 4 — Gross decreases – tax positions in prior periods (4 ) (4 ) (1 ) (1 ) — — — Decreases due to settlements (68 ) (67 ) — — — — (1 ) Reduction due to lapse of statute of limitations 1 — 2 — — — — Total changes (71 ) (71 ) 1 (1 ) 4 4 (1 ) Unrecognized tax benefits – December 31 $ 17 $ 1 $ 2 $ 2 $ 4 $ 4 $ —
Summary of Income Tax Contingencies	The following table includes additional information regarding the Duke Energy Registrants' unrecognized tax benefits at December 31, 2018 . All Duke Energy Registrants do not anticipate a material increase or decrease in unrecognized tax benefits within the next 12 months. December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Amount that if recognized, would affect the effective tax rate or regulatory liability (a) $ 21 $ 6 $ 9 $ 6 $ 3 $ 1 $ 1 $ 4 Amount that if recognized, would be recorded as a component of discontinued operations 2 — — — — — — — (a) Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, Duke Energy Indiana and Piedmont are unable to estimate the specific amounts that would affect the effective tax rate versus the regulatory liability. The following tables include interest recognized in the Consolidated Statements of Operations and the Consolidated Balance Sheets. Year Ended December 31, 2018 Duke Duke Progress Energy (in millions) Energy Energy Progress Net interest income recognized related to income taxes $ 2 $ — $ — Interest payable related to income taxes 3 1 1 Year Ended December 31, 2017 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Net interest income recognized related to income taxes $ — $ — $ 1 $ — $ 1 Net interest expense recognized related to income taxes — 2 — — — Interest payable related to income taxes 5 25 1 1 — Year Ended December 31, 2016 Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Net interest income recognized related to income taxes $ — $ — $ 1 $ — $ 2 Net interest expense recognized related to income taxes — 7 — — — Interest payable related to income taxes 4 23 1 1 —
Piedmont Natural Gas [Member]
Income Tax Disclosure [Line Items]
Schedule of Components of Income Tax Expense (Benefit)	Piedmont Two Months Ended Year Ended October 31, (in millions) December 31, 2016 2016 Current income taxes Federal $ 4 $ 27 State (2 ) 12 Total current income taxes 2 39 Deferred income taxes Federal 24 79 State 6 6 Total deferred income taxes (a) 30 85 Total income tax expense from continuing operations included in Consolidated Statements of Operations $ 32 $ 124 (a) Includes benefits of NOL and tax carryforwards of $17 million and $91 million for the two months ended December 31, 2016, and the year ended October 31, 2016, respectively.
Summary of Effective Tax Rates	Piedmont Two Months Ended Year Ended October 31, (in millions) December 31, 2016 2016 Income tax expense, computed at the statutory rate of 35 percent $ 30 $ 111 State income tax, net of federal income tax effect 1 11 Other items, net 1 2 Income tax expense from continuing operations $ 32 $ 124 Effective tax rate 37.2 % 39.1 %

Other Income and Expenses, Net

Other Income and Expenses, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Component Of Other Income Expense Nonoperating [Line Items]
Schedule of Other Income and Expenses, Net	The components of Other income and expenses, net on the Consolidated Statements of Operations are as follows. Year Ended December 31, 2018 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Interest income $ 20 $ 1 $ 18 $ 1 $ 18 $ 7 $ 9 $ 1 AFUDC equity 221 73 104 57 47 11 32 — Post in-service equity returns 15 9 5 5 — 1 — — Nonoperating income, other 143 70 38 24 21 4 4 13 Other income and expense, net $ 399 $ 153 $ 165 $ 87 $ 86 $ 23 $ 45 $ 14 Year Ended December 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Interest income $ 13 $ 2 $ 6 $ 2 $ 5 $ 6 $ 8 $ — AFUDC equity 237 106 92 47 45 11 28 — Post in-service equity returns 40 28 12 12 — — — — Nonoperating income, other 218 63 99 54 46 6 11 (11 ) Other income and expense, net $ 508 $ 199 $ 209 $ 115 $ 96 $ 23 $ 47 $ (11 ) Year Ended December 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 21 $ 4 $ 4 $ 3 $ 2 $ 5 $ 6 AFUDC equity 200 102 76 50 26 6 16 Post in-service equity returns 67 55 12 12 — — — Nonoperating income, other 175 53 94 67 35 — 4 Other income and expense, net (a) $ 463 $ 214 $ 186 $ 132 $ 63 $ 11 $ 26 (a) Amounts for Piedmont for the two months ended December 31, 2016, and for the year ended October 31, 2016, were not material.

Quarterly Financial Data (Una_2

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	Quarterly EPS amounts may not sum to the full-year total due to changes in the weighted average number of common shares outstanding and rounding. First Second Third Fourth (in millions, except per share data) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 6,135 $ 5,643 $ 6,628 $ 6,115 $ 24,521 Operating income 1,256 979 1,579 871 4,685 Income from continuing operations 622 507 1,062 434 2,625 (Loss) Income from discontinued operations, net of tax — (5 ) 4 20 19 Net income 622 502 1,066 454 2,644 Net income attributable to Duke Energy Corporation 620 500 1,082 464 2,666 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 0.88 $ 0.72 $ 1.51 $ 0.62 $ 3.73 Diluted $ 0.88 $ 0.72 $ 1.51 $ 0.62 $ 3.73 (Loss) Income from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ — $ (0.01 ) $ — $ 0.03 $ 0.03 Diluted $ — $ (0.01 ) $ — $ 0.03 $ 0.03 Net income attributable to Duke Energy Corporation common stockholders Basic $ 0.88 $ 0.71 $ 1.51 $ 0.65 $ 3.76 Diluted $ 0.88 $ 0.71 $ 1.51 $ 0.65 $ 3.76 2017 Operating revenues $ 5,729 $ 5,555 $ 6,482 $ 5,799 $ 23,565 Operating income 1,402 1,353 1,661 1,209 5,625 Income from continuing operations 717 691 957 705 3,070 Loss from discontinued operations, net of tax — (2 ) (2 ) (2 ) (6 ) Net income 717 689 955 703 3,064 Net income attributable to Duke Energy Corporation 716 686 954 703 3,059 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.37 Diluted $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.37 Loss from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ — $ — $ — $ — $ (0.01 ) Diluted $ — $ — $ — $ — $ (0.01 ) Net income attributable to Duke Energy Corporation common stockholders Basic $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.36 Diluted $ 1.02 $ 0.98 $ 1.36 $ 1.00 $ 4.36
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (17 ) $ (20 ) $ (16 ) $ (31 ) $ (84 ) Regulatory and Legislative Impacts (see Note 4) (86 ) (179 ) — — (265 ) Sale of Retired Plant (see Note 3) (107 ) — — — (107 ) Impairment Charges (see Notes 4, 11 and 12) (55 ) — (93 ) (60 ) (208 ) Severance Charges (see Note 20) — — — (187 ) (187 ) Impacts of the Tax Act (see Note 23) (76 ) — 3 53 (20 ) Total $ (341 ) $ (199 ) $ (106 ) $ (225 ) $ (871 ) 2017 Costs to Achieve Mergers (see Note 2) $ (16 ) $ (30 ) $ (23 ) $ (34 ) $ (103 ) Regulatory Settlements (see Note 4) — — (135 ) (23 ) (158 ) Commercial Renewables Impairments (see Notes 10 and 11) — — (84 ) (18 ) (102 ) Impacts of the Tax Act (see Note 23) — — — 102 102 Total $ (16 ) $ (30 ) $ (242 ) $ 27 $ (261 )
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY CAROLINAS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 1,763 $ 1,672 $ 2,090 $ 1,775 $ 7,300 Operating income 482 224 713 241 1,660 Net income 323 117 496 135 1,071 2017 Operating revenues $ 1,716 $ 1,729 $ 2,136 $ 1,721 $ 7,302 Operating income 471 471 763 384 2,089 Net income 270 273 466 205 1,214
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (2 ) $ (2 ) $ (1 ) $ (9 ) Regulatory and Legislative Impacts (see Note 4) (19 ) (179 ) — — (198 ) Severance Charges (see Note 20) — — — (102 ) (102 ) Impacts of the Tax Act (see Note 23) — — (1 ) — (1 ) Total $ (23 ) $ (181 ) $ (3 ) $ (103 ) $ (310 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (6 ) $ (5 ) $ (5 ) $ (20 ) Impacts of the Tax Act (see Note 23) — — — (15 ) (15 ) Total $ (4 ) $ (6 ) $ (5 ) $ (20 ) $ (35 )
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	PROGRESS ENERGY First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 2,576 $ 2,498 $ 3,045 $ 2,609 $ 10,728 Operating income 447 484 663 334 1,928 Net income 237 267 406 123 1,033 Net income attributable to Parent 235 265 404 123 1,027 2017 Operating revenues $ 2,179 $ 2,392 $ 2,864 $ 2,348 $ 9,783 Operating income 471 576 641 459 2,147 Net income 201 277 343 447 1,268 Net income attributable to Parent 199 274 341 444 1,258
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (3 ) $ (1 ) $ (2 ) $ (10 ) Regulatory and Legislative Impacts (see Note 4) (67 ) — — — (67 ) Impairment Charges (see Note 4) — — — (60 ) (60 ) Severance Charges (see Note 20) — — — (69 ) (69 ) Impacts of the Tax Act (see Note 23) (1 ) — (5 ) (19 ) (25 ) Total $ (72 ) $ (3 ) $ (6 ) $ (150 ) $ (231 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (4 ) $ (7 ) $ (6 ) $ (6 ) $ (23 ) Regulatory Settlements (see Note 4) — — (135 ) (23 ) (158 ) Impacts of the Tax Act (see Note 23) — — — 246 246 Total $ (4 ) $ (7 ) $ (141 ) $ 217 $ 65
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY PROGRESS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 1,460 $ 1,291 $ 1,582 $ 1,366 $ 5,699 Operating income 269 233 330 227 1,059 Net income 177 139 216 135 667 2017 Operating revenues $ 1,219 $ 1,199 $ 1,460 $ 1,251 $ 5,129 Operating income 274 270 398 243 1,185 Net income 147 154 246 168 715
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (2 ) $ (1 ) $ (1 ) $ (6 ) Regulatory and Legislative Impacts (see Note 4) (67 ) — — — (67 ) Severance Charges (see Note 20) — — — (52 ) (52 ) Impacts of the Tax Act (see Note 23) — — (4 ) (15 ) (19 ) Total $ (69 ) $ (2 ) $ (5 ) $ (68 ) $ (144 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (4 ) $ (4 ) $ (4 ) $ (14 ) Regulatory Settlements (see Note 4) — — — (23 ) (23 ) Impacts of the Tax Act (see Note 23) — — — 40 40 Total $ (2 ) $ (4 ) $ (4 ) $ 13 $ 3
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY FLORIDA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 1,115 $ 1,203 $ 1,462 $ 1,241 $ 5,021 Operating income 173 245 331 107 856 Net income 103 168 243 40 554 2017 Operating revenues $ 959 $ 1,191 $ 1,401 $ 1,095 $ 4,646 Operating income 192 301 236 212 941 Net income 90 158 120 344 712
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (1 ) $ — $ (1 ) $ (4 ) Impairment Charges (see Note 4) — — — (60 ) (60 ) Severance Charges (see Note 20) — — — (17 ) (17 ) Impacts of the Tax Act (see Note 23) — — (2 ) 2 — Total $ (2 ) $ (1 ) $ (2 ) $ (76 ) $ (81 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (2 ) $ (3 ) $ (2 ) $ (2 ) $ (9 ) Regulatory Settlements (see Note 4) — — (135 ) — (135 ) Impacts of the Tax Act (see Note 23) — — — 226 226 Total $ (2 ) $ (3 ) $ (137 ) $ 224 $ 82
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY OHIO First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 524 $ 459 $ 469 $ 505 $ 1,957 Operating (loss) income (21 ) 77 139 93 288 Net (loss) income (25 ) 46 100 55 176 2017 Operating revenues $ 518 $ 437 $ 471 $ 497 $ 1,923 Operating income 82 64 101 73 320 Loss from discontinued operations, net of tax — — (1 ) — (1 ) Net income 42 30 55 65 192
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (3 ) $ (5 ) $ — $ (6 ) $ (14 ) Sale of Retired Plant (see Note 3) (107 ) — — — (107 ) Severance Charges (see Note 20) — — — (6 ) (6 ) Impacts of the Tax Act (see Note 23) — — — (2 ) (2 ) Total $ (110 ) $ (5 ) $ — $ (14 ) $ (129 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (1 ) $ (1 ) $ (2 ) $ (2 ) $ (6 ) Impacts of the Tax Act (see Note 23) — — — 23 23 Total $ (1 ) $ (1 ) $ (2 ) $ 21 $ 17
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY INDIANA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 731 $ 738 $ 819 $ 771 $ 3,059 Operating income 168 169 173 133 643 Net income 100 98 119 76 393 2017 Operating revenues $ 758 $ 742 $ 802 $ 745 $ 3,047 Operating income 184 208 228 166 786 Net income 91 106 121 36 354
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ — $ — $ (2 ) $ — $ (2 ) Severance Charges (see Note 20) — — — (7 ) (7 ) Total $ — $ — $ (2 ) $ (7 ) $ (9 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (1 ) $ (2 ) $ (2 ) $ (1 ) $ (6 ) Impacts of the Tax Act (see Note 23) — — — (55 ) (55 ) Total $ (1 ) $ (2 ) $ (2 ) $ (56 ) $ (61 )
Piedmont Natural Gas [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Operating revenues $ 553 $ 215 $ 172 $ 435 $ 1,375 Operating income (loss) 161 5 (19 ) 79 226 Net income (loss) 110 (8 ) (21 ) 48 129 2017 Operating revenues $ 500 $ 201 $ 183 $ 444 $ 1,328 Operating income (loss) 170 5 (4 ) 126 297 Net income (loss) 95 (8 ) (11 ) 63 139
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2018 Costs to Achieve Piedmont Merger (see Note 2) $ (6 ) $ (9 ) $ (11 ) $ (22 ) $ (48 ) Severance Charges (see Note 20) — — — (2 ) (2 ) Total $ (6 ) $ (9 ) $ (11 ) $ (24 ) $ (50 ) 2017 Costs to Achieve Piedmont Merger (see Note 2) $ (6 ) $ (13 ) $ (8 ) $ (19 ) $ (46 ) Impacts of the Tax Act (see Note 23) — — — 2 2 Total $ (6 ) $ (13 ) $ (8 ) $ (17 ) $ (44 )

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Narrative) (Details) - Accounting Standards Update 2017-07 [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Nonoperating Income (Expense) [Member]
Organization And Basis Of Presentation [Line Items]
New accounting pronouncement, quantified affect	$ 156	$ 139
Operating Expense [Member]
Organization And Basis Of Presentation [Line Items]
New accounting pronouncement, quantified affect	$ 156	$ 139

(Other Assets and Liabilities)

(Other Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	$ 729	$ 330
Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	793	757
Duke Energy Carolinas [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	251	252
Progress Energy [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	66	278
Progress Energy [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	345	338
Duke Energy Progress [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	137	129
Accrued compensation	130	132
Duke Energy Florida [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	208	208
Accrued compensation	85	16
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	13	36
Duke Energy Ohio [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	44	46
Duke Energy Indiana [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	47	45
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	$ 11	$ 43

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Amounts Attributable to Controlling Interests) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Net Income Attributable to Noncontrolling Interest	$ (22)	$ 5	$ 18
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interests	$ (22)	$ 5	7
Income (Loss) from Discontinued Operations Attributable to Noncontrolling Interest, net of tax			$ 11

Summary of Significant Accoun_6

Summary of Significant Accounting Policies (Schedule of Cash and Cash Equivalents) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Assets
Cash and cash equivalents	$ 442	$ 358
Other	141	138
Other Noncurrent Assets
Other	8	9
Total cash, cash equivalents and restricted cash	591	505	$ 541	$ 481
Progress Energy [Member]
Current Assets
Cash and cash equivalents	67	40
Other	39	40
Other Noncurrent Assets
Other	6	7
Total cash, cash equivalents and restricted cash	112	87	110	55
Duke Energy Florida [Member]
Current Assets
Cash and cash equivalents	36	13
Other	39	40
Other Noncurrent Assets
Total cash, cash equivalents and restricted cash	$ 75	$ 53	$ 69	$ 8

Summary of Significant Accoun_7

Summary of Significant Accounting Policies (Inventory) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Public Utilities, Inventory [Line Items]
Materials and supplies	$ 2,238	$ 2,293
Coal	491	603
Natural gas, oil, other	355	354
Total inventory	3,084	3,250
Duke Energy Carolinas [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	731	744
Coal	175	192
Natural gas, oil, other	42	35
Total inventory	948	971
Progress Energy [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	1,049	1,118
Coal	192	255
Natural gas, oil, other	218	219
Total inventory	1,459	1,592
Duke Energy Progress [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	734	774
Coal	106	139
Natural gas, oil, other	114	104
Total inventory	954	1,017
Duke Energy Florida [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	315	343
Coal	86	116
Natural gas, oil, other	103	115
Total inventory	504	574
Duke Energy Ohio [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	84	82
Coal	14	17
Natural gas, oil, other	28	34
Total inventory	126	133
Duke Energy Indiana [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	312	309
Coal	109	139
Natural gas, oil, other	1	2
Total inventory	422	450
Piedmont Natural Gas [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	2	2
Natural gas, oil, other	68	64
Total inventory	$ 70	$ 66

Summary of Significant Accoun_8

Summary of Significant Accounting Policies (Property, Plant and Equipment) (Details)	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate		3.00%	2.80%	2.80%
Duke Energy Carolinas [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate		2.80%	2.80%	2.80%
Progress Energy [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate		2.90%	2.60%	2.70%
Duke Energy Progress [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate		2.90%	2.60%	2.60%
Duke Energy Florida [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate		3.00%	2.80%	2.80%
Duke Energy Ohio [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate		2.80%	2.80%	2.60%
Duke Energy Indiana [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate		3.30%	3.00%	3.10%
Piedmont Natural Gas [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.40%	2.50%	2.30%		2.40%

Summary of Significant Accoun_9

Summary of Significant Accounting Policies (Excise Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 405	$ 376	$ 362
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	35	36	31
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	241	220	213
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	19	19	18
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	222	201	195
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	105	98	100
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	22	20	$ 17
Piedmont Natural Gas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 2	$ 2		$ 2

Summary of Significant Accou_10

Summary of Significant Accounting Policies (Right of Use Assets and Operating Lease Liabilities) (Details) - Scenario, Forecast [Member] - Accounting Standards Update 2016-02 [Member] $ in Millions	Jan. 01, 2019USD ($)
Lessee, Lease, Description [Line Items]
Operating lease liability	$ 1,700
Right of use assets	1,700
Duke Energy Carolinas [Member]
Lessee, Lease, Description [Line Items]
Operating lease liability	150
Right of use assets	150
Progress Energy [Member]
Lessee, Lease, Description [Line Items]
Operating lease liability	850
Right of use assets	850
Duke Energy Progress [Member]
Lessee, Lease, Description [Line Items]
Operating lease liability	400
Right of use assets	400
Duke Energy Florida [Member]
Lessee, Lease, Description [Line Items]
Operating lease liability	450
Right of use assets	450
Duke Energy Ohio [Member]
Lessee, Lease, Description [Line Items]
Operating lease liability	25
Right of use assets	25
Duke Energy Indiana [Member]
Lessee, Lease, Description [Line Items]
Operating lease liability	60
Right of use assets	60
Piedmont Natural Gas [Member]
Lessee, Lease, Description [Line Items]
Operating lease liability	30
Right of use assets	$ 30

Acquisitions and Dispositions_2

Acquisitions and Dispositions (Acquisitions Narrative) (Details) - USD ($) $ in Millions	Oct. 03, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Business Combination, Integration Related Costs		$ 31	$ 16	$ 20	$ 17	$ 34	$ 23	$ 30	$ 16	$ 84	$ 103
Asset Impairment Charges										402	282	$ 18
Net Income (Loss) Attributable to Parent		$ 464	$ 1,082	$ 500	$ 620	$ 703	$ 954	$ 686	$ 716	2,666	3,059	2,152
Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 5,000
Long-term debt assumed	$ 2,000
Business Combination, Integration Related Costs										84	103	439
Asset Impairment Charges											7
Business Combination, After Tax Integration Related Costs												279
Revenues												367
Net Income (Loss) Attributable to Parent												20
Interest Rate Contract [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Loss on Interest Rate Derivative Instruments Not Designated as Hedging Instruments												190
Sales [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs												10
Operating Expense [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs											64	101
Operating Income (Loss) [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs												46
Interest Expense [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs												234
Other Expense [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs												104
Other Expense [Member] | Operating Expense [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs												94
Other Expense [Member] | Operating Income (Loss) [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs												$ 10
System Integration Costs [Member] | Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs										$ 78	$ 71

Acquisitions and Dispositions_3

Acquisitions and Dispositions (Dispositions Narrative) (Details) $ in Millions	Dec. 29, 2016USD ($)MW	Dec. 20, 2016USD ($)MW	Dec. 31, 2016USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Divestiture of Businesses			$ 1,900
DEI Latin American [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Owned Plant Capacity | MW		2,230
Enterprise Value		$ 1,200
DEI Brazil Holdings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Owned Plant Capacity | MW	2,090
Enterprise Value	$ 1,200
Obligations [Member] | International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Tax obligations				$ 54	$ 78

Acquisitions and Dispositions_4

Acquisitions and Dispositions (Pro Forma Information) (Details) - Piedmont Natural Gas [Member] $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Revenues	$ 23,504
Net income attributable to Duke Energy Corporation	$ 2,442

Acquisitions and Dispositions_5

Acquisitions and Dispositions (Duke Energy Discontinued Operations) (Details) - USD ($) $ in Millions	3 Months Ended						12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) From Discontinued Operations, net of tax	$ 20	$ 4	$ (5)	$ (2)	$ (2)	$ (2)	$ 19	$ (6)	$ (408)
International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) From Discontinued Operations, net of tax									(534)
Other Disposal Groups [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) From Discontinued Operations, net of tax									$ 126

Acquisitions and Dispositions_6

Acquisitions and Dispositions (International Energy Discontinued Operations) (Details) - USD ($) $ in Millions	3 Months Ended						12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)							$ (26)	$ (6)	$ (30)
Income (Loss) From Discontinued Operations, net of tax	$ 20	$ 4	$ (5)	$ (2)	$ (2)	$ (2)	19	(6)	(408)
Asset Impairment Charges							$ 402	282	18
International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) From Discontinued Operations, net of tax									(534)
Asset Impairment Charges									194
Cumulative foreign currency translation losses									620
Income (Loss) from Discontinued Operation, before Income Tax, Attributable to Parent									(445)
Income tax expense on disposal									126
After-tax loss on disposal									640
Previously Remitted Earnings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)								$ (95)
Previously Remitted Earnings [Member] | International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Foreign Income Tax Expense (Benefit), Continuing Operations									(95)
Discontinued Operations, Disposed of by Sale [Member] | International Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Revenues									988
Fuel used in electric generation and purchased power									227
Cost of natural gas									43
Operation, maintenance and other									341
Depreciation and amortization									62
Property and other taxes									15
Impairment charges									194
(Loss) Gains on Sales of Other Assets and Other, net									(3)
Other income and expenses, net									58
Interest Expense									82
Pretax loss on disposal									514
(Loss) Income before income taxes									(435)
Income tax expense (benefit)									$ 99

Acquisitions and Dispositions_7

Acquisitions and Dispositions (Cash Flow Statement) (Details) - International Energy [Member] $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Activities	$ 204
Investing Activities	$ (434)

Business Segments (Narrative) (

Business Segments (Narrative) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Loss on sale									$ 89	$ (28)	$ (27)
Operation, maintenance and other									6,463	5,944	6,224
Revenues	$ 6,115	$ 6,628	$ 5,643	$ 6,135	$ 5,799	$ 6,482	$ 5,555	$ 5,729	$ 24,521	23,565	22,743
Duke Energy Progress [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment									1
Loss on sale									$ (9)	(4)	(3)
Operation, maintenance and other									1,578	1,439	1,565
Revenues	1,366	1,582	1,291	1,460	1,251	1,460	1,199	1,219	$ 5,699	5,129	5,277
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment									2
Loss on sale									$ 106	(1)	(2)
Operation, maintenance and other									480	530	514
Revenues	$ 505	$ 469	$ 459	$ 524	$ 497	$ 471	$ 437	$ 518	1,957	$ 1,923	$ 1,944
Beckjord [Member]
Segment Reporting Information [Line Items]
Loss on sale									106
Operation, maintenance and other									1
Revenue [Member] | Customer Concentration Risk [Member] | Duke Energy Progress [Member]
Segment Reporting Information [Line Items]
Revenues									$ 633

Business Segments (Business Seg

Business Segments (Business Segment Data) (Details) - USD ($) $ in Millions	Oct. 03, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues		$ 6,115	$ 6,628	$ 5,643	$ 6,135	$ 5,799	$ 6,482	$ 5,555	$ 5,729	$ 24,521	$ 23,565	$ 22,743
Interest expense										2,094	1,986	1,916
Depreciation and amortization										4,074	3,527	3,294
Equity in earnings (losses) of unconsolidated affiliates										83	119	(15)
Income tax expense (benefit) from continuing operations										448	1,196	1,156
Segment income (loss)										2,647	3,065	2,571
Add back noncontrolling interests component										(22)	5	7
Income (Loss) From Discontinued Operations, net of tax		20	4	(5)		(2)	(2)	(2)		19	(6)	(408)
Net income (loss)		454	1,066	502	622	703	955	689	717	2,644	3,064	2,170
Net Income (Loss) Attributable to Parent		464	1,082	500	620	703	954	686	716	2,666	3,059	2,152
Tax Act										20	(112)
After-tax severance charges		187								187	15	118
After-tax loss on sale and retirement					(107)					(107)
Asset Impairment Charges										402	282	18
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										9,668	8,198	13,215
Segment assets		145,392				137,914				145,392	137,914	132,761
Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues		505	469	459	524	497	471	437	518	1,957	1,923	1,944
Interest expense										92	91	86
Depreciation and amortization										268	261	233
Income tax expense (benefit) from continuing operations										43	59	78
Segment income (loss)										176	193	192
Income (Loss) From Discontinued Operations, net of tax							(1)				(1)	36
Net Income (Loss) Attributable to Parent		55	$ 100	46	(25)	65	55	$ 30	$ 42	176	192	228
Tax Act		2				(23)				2	(23)
After-tax severance charges		6								6		3
After-tax loss on sale and retirement					107					107
Asset Impairment Charges											1
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										827	686	476
Segment assets		8,555				7,875				8,555	7,875	7,528
Piedmont Natural Gas [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net Income (Loss) Attributable to Parent												20
Asset Impairment Charges											7
Segment Reporting Information Assets [Abstract]
Payments to Acquire Businesses, Gross	$ 5,000
International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Income (Loss) From Discontinued Operations, net of tax												(534)
Asset Impairment Charges												194
Regulatory settlements [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Regulatory settlement charges				$ 179	$ 86	23	$ 135			265	158
Electric Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										22,242	21,300	21,336
Equity in earnings (losses) of unconsolidated affiliates										6	5	5
Tax Act										24	231
Electric Utilities and Infrastructure [Member] | Regulatory settlements [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Regulatory settlement charges										202	98
Electric Utilities and Infrastructure [Member] | After-tax impairment charge [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Asset Impairment Charges, net of tax										46
Gas Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,783	1,743	875
Equity in earnings (losses) of unconsolidated affiliates										27	62	19
Tax Act										1	26
Gas Utilities and Infrastructure [Member] | Piedmont Natural Gas [Member]
Segment Reporting Information Assets [Abstract]
Payments to Acquire Businesses, Gross	$ 5,000
Gas Utilities and Infrastructure [Member] | After-tax impairment charge [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Asset Impairment Charges, net of tax										42
Commercial Renewables [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										477	460	484
Equity in earnings (losses) of unconsolidated affiliates										(1)	(5)	(82)
Tax Act										3	442
Asset Impairment Charges, net of tax										91	74
Asset Impairment Charges												71
Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										19	62	48
Tax Act										2	597
After-tax severance charges										144
After-tax loss on sale and retirement										82
Costs to achieve mergers, acquisition costs										65	64	329
Cost Savings Initiative, Net of tax												57
Other Segments [Member] | International Energy [Member]
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions												26
Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										24,502	23,503	22,695
Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										22,273	21,331	21,366
Interest expense										1,288	1,240	1,136
Depreciation and amortization										3,523	3,010	2,897
Equity in earnings (losses) of unconsolidated affiliates										5	5	5
Income tax expense (benefit) from continuing operations										799	1,355	1,672
Segment income (loss)										3,058	3,210	3,040
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										8,086	7,024	6,649
Segment assets		125,364				119,423				125,364	119,423	114,993
Operating Segments [Member] | Electric Utilities and Infrastructure [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,450	1,373	1,410
Interest expense										67	62	58
Depreciation and amortization										183	178	151
Income tax expense (benefit) from continuing operations										47	40	55
Segment income (loss)										186	138	154
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										655	491	322
Segment assets		5,643				5,066				5,643	5,066	4,782
Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,881	1,836	901
Interest expense										106	105	46
Depreciation and amortization										245	231	115
Equity in earnings (losses) of unconsolidated affiliates										27	62	19
Income tax expense (benefit) from continuing operations										78	116	90
Segment income (loss)										274	319	152
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										1,133	907	5,519
Segment assets		12,361				11,462				12,361	11,462	10,760
Operating Segments [Member] | Gas Utilities and Infrastructure [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										506	508	503
Interest expense										24	28	27
Depreciation and amortization										85	83	80
Income tax expense (benefit) from continuing operations										24	39	44
Segment income (loss)										93	85	77
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										172	195	154
Segment assets		2,874				2,758				2,874	2,758	2,696
Operating Segments [Member] | Commercial Renewables [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										477	460	484
Interest expense										88	87	53
Depreciation and amortization										155	155	130
Equity in earnings (losses) of unconsolidated affiliates										(1)	(5)	(82)
Income tax expense (benefit) from continuing operations										(147)	(628)	(160)
Segment income (loss)										9	441	23
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										193	92	857
Segment assets		4,204				4,156				4,204	4,156	4,377
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										24,631	23,627	22,751
Interest expense										1,482	1,432	1,235
Depreciation and amortization										3,923	3,396	3,142
Equity in earnings (losses) of unconsolidated affiliates										31	62	(58)
Income tax expense (benefit) from continuing operations										730	843	1,602
Segment income (loss)										3,341	3,970	3,215
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										9,412	8,023	13,025
Segment assets		141,929				135,041				141,929	135,041	130,130
Operating Segments [Member] | Total Reportable Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1,956	1,881	1,913
Interest expense										91	90	85
Depreciation and amortization										268	261	231
Income tax expense (benefit) from continuing operations										71	79	99
Segment income (loss)										279	223	231
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										827	686	476
Segment assets		8,517				7,824				8,517	7,824	7,478
Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										(199)	(200)	(125)
Interest expense										(45)	(20)	(12)
Depreciation and amortization										(1)
Segment income (loss)												1
Segment Reporting Information Assets [Abstract]
Segment assets		188				188				188	188	188
Intersegment Eliminations [Member] | Duke Energy Ohio [Member]
Segment Reporting Information Assets [Abstract]
Segment assets						(15)					(15)	(12)
Intersegment Eliminations [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										31	31	30
Intersegment Eliminations [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										98	93	26
Intersegment Eliminations [Member] | Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										70	76	69
Intersegment Eliminations [Member] | Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										129	124	56
Corporate, Non-Segment [Member] | Other Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										89	138	117
Interest expense										657	574	693
Depreciation and amortization										152	131	152
Equity in earnings (losses) of unconsolidated affiliates										52	57	43
Income tax expense (benefit) from continuing operations										(282)	353	(446)
Segment income (loss)										(694)	(905)	(645)
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										256	175	190
Segment assets		3,275				2,685				3,275	2,685	2,443
Corporate, Non-Segment [Member] | Other Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Revenues										1	42	31
Interest expense										1	1	1
Depreciation and amortization												2
Income tax expense (benefit) from continuing operations										(28)	(20)	(21)
Segment income (loss)										(103)	(30)	(39)
Segment Reporting Information Assets [Abstract]
Segment assets		$ 38				$ 66				38	66	62
Noncontrolling Interest [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Net income (loss)										(22)	$ 5	$ 18
Noncontrolling Interest [Member] | Commercial Renewables [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Asset Impairment Charges, net of tax										$ 2

Business Segments (Major Custom

Business Segments (Major Customer Disclosure) (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Revenue, Major Customer [Line Items]
Revenues	$ 6,115	$ 6,628	$ 5,643	$ 6,135	$ 5,799	$ 6,482	$ 5,555	$ 5,729	$ 24,521	$ 23,565	$ 22,743
Duke Energy Progress [Member]
Revenue, Major Customer [Line Items]
Revenues	$ 1,366	$ 1,582	$ 1,291	$ 1,460	$ 1,251	$ 1,460	$ 1,199	$ 1,219	$ 5,699	$ 5,129	$ 5,277
Number of Reportable Segments | segment									1

Business Segments (Schedule of

Business Segments (Schedule of Revenue, By Products and Services) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 6,115	$ 6,628	$ 5,643	$ 6,135	$ 5,799	$ 6,482	$ 5,555	$ 5,729	$ 24,521	$ 23,565	$ 22,743
Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									22,242	21,300	21,336
Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									1,783	1,743	875
Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Revenues									477	460	484
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Revenues									24,502	23,503	22,695
Retail Electric [Member]
Segment Reporting Information [Line Items]
Revenues									19,013	18,177	18,338
Retail Electric [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									19,013	18,177	18,338
Wholesale Electric [Member]
Segment Reporting Information [Line Items]
Revenues									2,720	2,479	2,398
Wholesale Electric [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									2,345	2,104	2,095
Wholesale Electric [Member] | Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Revenues									375	375	303
Retail Natural Gas [Member]
Segment Reporting Information [Line Items]
Revenues									1,817	1,732	871
Retail Natural Gas [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									1,817	1,732	871
Other Revenues [Member]
Segment Reporting Information [Line Items]
Revenues									1,081	1,239	1,144
Other Revenues [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									915	1,050	933
Other Revenues [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									64	104	30
Other Revenues [Member] | Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Revenues									102	85	181
Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									22,273	21,331	21,366
Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenues									1,881	1,836	901
Operating Segments [Member] | Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Revenues									477	460	484
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Revenues									$ 24,631	$ 23,627	$ 22,751

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) $ in Millions	Jan. 30, 2019USD ($)	Dec. 27, 2018USD ($)	Nov. 08, 2018USD ($)	Oct. 03, 2018	Sep. 20, 2018USD ($)	Aug. 31, 2018USD ($)	Jul. 31, 2018USD ($)	Jul. 25, 2018USD ($)	Jul. 10, 2018USD ($)	Jun. 27, 2018USD ($)	Jun. 22, 2018USD ($)	Jun. 08, 2018USD ($)	May 31, 2018USD ($)	Apr. 13, 2018USD ($)	Apr. 01, 2018USD ($)	Feb. 15, 2018USD ($)	Sep. 27, 2017USD ($)	Sep. 26, 2017USD ($)	Sep. 01, 2017USD ($)	Aug. 25, 2017USD ($)	Jun. 30, 2017USD ($)	Jun. 01, 2017USD ($)	Jun. 30, 2016	Dec. 22, 2015	May 04, 2015USD ($)	Jan. 05, 2015	Sep. 02, 2014	Jan. 31, 2019USD ($)	Dec. 31, 2018USD ($)customer	Nov. 30, 2018USD ($)	Oct. 31, 2018USD ($)customer	Sep. 30, 2018USD ($)customer	Jul. 31, 2018USD ($)	Jun. 30, 2018USD ($)	May 31, 2018USD ($)	Feb. 28, 2018USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2018USD ($)customer	Sep. 30, 2018USD ($)customer	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)customerMW	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Oct. 31, 2016USD ($)	Jan. 29, 2019USD ($)	Sep. 30, 2017USD ($)	Oct. 02, 2014USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net																													$ 91,694											$ 91,694				$ 91,694	$ 86,391
Regulatory assets, noncurrent																													13,617											13,617				13,617	12,442
Net property, plant and equipment																													91,694											91,694				91,694	86,391
Operation, maintenance and other																																												6,463	5,944	$ 6,224
Regulatory assets																													15,622											15,622				15,622	13,879
Total income (loss) from continuing operations before income taxes																																												(3,073)	(4,266)	(3,734)
Impairment charges																																												402	282	18
Regulated Revenue																																												22,097	21,177	21,221
Asset Impairment Charges																																												402	282	18
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment																													$ 283											$ 283				$ 283
Capacity (in MW) | MW																																												865
Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																											47.00%
Long-term Purchase Commitment, Period																											20 years
Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																									7.50%
Estimated capital cost																									$ 3,200
Long-term Purchase Commitment, Period																									25 years
Constitution Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																													24.00%											24.00%				24.00%
Estimated Contributions																													$ 229											$ 229				$ 229
Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													4,255											4,255				4,255	4,025
Regulatory Clause Revenues, under-recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													24											24				24	64
Accrued Pension And Post Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													2,654											2,654				2,654	2,249
Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													445											445				445	480
NCEMPA deferrals [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													50											50				50	53
Nuclear asset securitized balance, net [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													1,093											1,093				1,093	1,142
Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													133											133				133	119
Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													1,117											1,117				1,117	531
Minimum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost																													7,000											7,000				7,000
Maximum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost																													$ 7,800											$ 7,800				$ 7,800
Dominion Resources [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																											48.00%
Southern Company Gas [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																											5.00%
Enbridge Inc. [Member] | Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																									50.00%
NextEra Energy [Member] | Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																									42.50%
Williams Partners L.P. [Member] | Constitution Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage																													41.00%											41.00%				41.00%
Hurricane Florence Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Customers Experiencing Outages | customer																																2,000,000									2,000,000
Operation, maintenance and other																																$ 500
Estimated capital cost																																90									$ 90
Hurricane Michael Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Customers Experiencing Outages | customer																															1,000,000
Operation, maintenance and other																															$ 100
Estimated capital cost																															21
Winter Storm Diego Damage [Member]
Public Utilities, General Disclosures [Line Items]
Customers Experiencing Outages | customer																													800,000											800,000				800,000
Operation, maintenance and other																													$ 85
Estimated capital cost																													9											$ 9				$ 9
Progress Energy Merger FERC Mitigation [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Penalty assessed												$ 3.5
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net																													29,245											29,245				29,245	27,876
Regulatory assets, noncurrent																													3,457											3,457				3,457	2,853
Net property, plant and equipment																													29,245											29,245				29,245	27,876
Operation, maintenance and other																																												2,130	2,021	2,158
Regulatory assets																													3,977											3,977				3,977	3,152
Total income (loss) from continuing operations before income taxes																																												(1,374)	(1,866)	(1,800)
Impairment charges																																												192		1
Asset Impairment Charges																																												192		1
Duke Energy Carolinas [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Long-term Purchase Commitment, Period																											20 years
Duke Energy Carolinas [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													1,725											1,725				1,725	1,645
Duke Energy Carolinas [Member] | Accrued Pension And Post Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													581											581				581	410
Duke Energy Carolinas [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													21											21				21	29
Duke Energy Carolinas [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													87											87				87	84
Duke Energy Carolinas [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													160											160				160
Duke Energy Carolinas [Member] | William States Lee Combined Cycle Facility [Member] | NCEMC [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC																													$ 650											$ 650				$ 650
Joint owner ownership percentage																													13.00%											13.00%				13.00%
Approved rate increase (decrease) amount by state commission																																												$ 600
Duke Energy Carolinas [Member] | Hurricane Florence Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																70
Estimated capital cost																																5									5
Duke Energy Carolinas [Member] | Hurricane Michael Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																															75
Estimated capital cost																															12
Duke Energy Carolinas [Member] | Winter Storm Diego Damage [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																													$ 60
Estimated capital cost																													7											$ 7				7
Duke Energy Carolinas [Member] | 2017 NC Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																				$ 647
Requested Rate Increase (Decrease), Percentage																				13.60%
Requested Return on Equity, Percentage																																				9.90%
Public Utilities, Requested Equity Capital Structure, Percentage																																				52.00%
Public Utilities, Requested Debt Capital Structure, Percentage																																				48.00%
Operation, maintenance and other																																				$ 4
Total income (loss) from continuing operations before income taxes																																											$ 14
Penalty assessed											$ 70
Estimated future coal ash costs											201
Utilities Operating Expense											150
Duke Energy Carolinas [Member] | 2017 NC Rate Case [Member] | NCUC [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets											$ 554
Regulatory Noncurrent Asset, Amortization Period											5 years
Duke Energy Carolinas [Member] | 2017 NC Rate Case [Member] | NCUC [Member] | Deferred Project Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets											$ 347
Regulatory Noncurrent Asset, Amortization Period											12 years
Duke Energy Carolinas [Member] | 2017 NC Rate Case [Member] | William State Lee III Nuclear Station [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Utilities Operating Expense																																										$ 29
Duke Energy Carolinas [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount			$ 168
Requested Rate Increase (Decrease), Percentage			10.00%
Tax benefit from change in enacted tax rates			$ 66
Tax benefits from Tax Act			46
Duke Energy Carolinas [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets			$ 242
Regulatory Noncurrent Asset, Amortization Period			5 years
Duke Energy Carolinas [Member] | FERC Formula Rate Matter [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Customer Refundable Fees, Refund Payments																$ 25
Duke Energy Carolinas [Member] | 2018 PSCSC Petitions [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission								$ 33
Duke Energy Carolinas [Member] | 2018 Sale of Hydro Plants [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Estimated loss on Asset Sale																																			$ 40
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net																													20,398											20,398				20,398	19,101
Regulatory assets, noncurrent																													4,111											4,111				4,111	3,507
Net property, plant and equipment																													20,398											20,398				20,398	19,101
Operation, maintenance and other																																												1,578	1,439	1,565
Regulatory assets																													4,814											4,814				4,814	3,859
Total income (loss) from continuing operations before income taxes																																												(827)	(1,007)	(900)
Impairment charges																																												33	19	1
Asset Impairment Charges																																												33	19	1
Duke Energy Progress [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Long-term Purchase Commitment, Period																											20 years
Duke Energy Progress [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													2,051											2,051				2,051	1,975
Duke Energy Progress [Member] | Accrued Pension And Post Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													542											542				542	430
Duke Energy Progress [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													148											148				148	170
Duke Energy Progress [Member] | NCEMPA deferrals [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													50											50				50	53
Duke Energy Progress [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													46											46				46	35
Duke Energy Progress [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													571											571				571	150
Duke Energy Progress [Member] | Asheville Plant [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment																													327											327				$ 327	385
Capacity (in MW) | MW																																												376
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent																													43											43				$ 43
Wholesale Debt Return Amortization Period																																												15 years
Regulatory Noncurrent Asset, Amortization Period																																												8 years
Duke Energy Progress [Member] | Hurricane Florence Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																																430
Estimated capital cost																																$ 85									85
Duke Energy Progress [Member] | Hurricane Michael Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																															25
Estimated capital cost																															$ 9
Duke Energy Progress [Member] | Winter Storm Diego Damage [Member]
Public Utilities, General Disclosures [Line Items]
Operation, maintenance and other																													25
Estimated capital cost																													2											2				$ 2
Duke Energy Progress [Member] | 2017 NC Rate Case [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																						$ 477
Requested Rate Increase (Decrease), Percentage																						14.90%
Requested Rate Increase (Decrease), Amended, Amount																						$ 420
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage																						13.00%
Requested Return on Equity, Percentage																																												9.90%
Public Utilities, Requested Equity Capital Structure, Percentage																																												52.00%
Public Utilities, Requested Debt Capital Structure, Percentage																																												48.00%
Utilities Operating Expense, Impairments																																													25
Estimated Storm Costs - Capital and Operation Maintenance																																																	$ 116
Total income (loss) from continuing operations before income taxes																																											$ 68
Penalty assessed																																												$ 30
Estimated future coal ash costs																													129											129				129
Duke Energy Progress [Member] | 2017 NC Rate Case [Member] | NCUC [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													234											234				$ 234
Regulatory Noncurrent Asset, Amortization Period																																												5 years
Excluded Deferred Coal Ash Costs																													10											10				$ 10
Duke Energy Progress [Member] | 2017 NC Rate Case [Member] | NCUC [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																																												80
Approved rate increase (decrease) amount by state commission																																												$ 51
Regulatory Noncurrent Asset, Amortization Period																																												5 years
Duke Energy Progress [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount			$ 59
Requested Rate Increase (Decrease), Percentage			10.30%
Tax benefit from change in enacted tax rates			$ 15
Tax benefits from Tax Act			10
Duke Energy Progress [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets			$ 51
Regulatory Noncurrent Asset, Amortization Period			5 years
Duke Energy Progress [Member] | 2016 South Carolina Rate Case Settlement [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																																												$ 56
Approved return on equity percentage amount by state commission																																												10.10%
Regulatory Noncurrent Asset, Amortization Period																																												15 years
Duke Energy Progress [Member] | 2016 South Carolina Rate Case Settlement Year 1 Increase [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																																												$ 38
Duke Energy Progress [Member] | 2016 South Carolina Rate Case Settlement Year 2 Increase [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																																												$ 19
Duke Energy Progress [Member] | 2016 South Carolina Rate Case Settlement Year 2 Offset [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																																													(19)
Duke Energy Progress [Member] | Western Carolinas Modernization Plan [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period																																												10 years
Estimated capital cost																													893											893				$ 893
Duke Energy Progress [Member] | 2018 PSCSC Petitions [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																																	$ 20
Duke Energy Progress [Member] | FERC Form 1 Reporting Matter [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Customer Refundable Fees, Refund Payments																																												14
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net																													13,824											13,824				13,824	12,783
Regulatory assets, noncurrent																													2,454											2,454				2,454	2,503
Net property, plant and equipment																													13,824											13,824				13,824	12,783
Operation, maintenance and other																																												1,025	853	884
Regulatory assets																													2,888											2,888				2,888	2,892
Total income (loss) from continuing operations before income taxes																																												(655)	(758)	(873)
Impairment charges																																												54	138	6
Asset Impairment Charges																																												54	138	6
Duke Energy Florida [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													10											10				10	9
Duke Energy Florida [Member] | Accrued Pension And Post Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													532											532				532	476
Duke Energy Florida [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													219											219				219	216
Duke Energy Florida [Member] | Nuclear asset securitized balance, net [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													1,093											1,093				1,093	1,142
Duke Energy Florida [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													382											382				382	376
Duke Energy Florida [Member] | Citrus County Combined Cycle Facility [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC																																																		$ 1,500
Impairment charges																																								60
Asset Impairment Charges																																								60
Duke Energy Florida [Member] | Citrus County Combined Cycle Facility [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC																												$ 1,600
Duke Energy Florida [Member] | Hurricane Michael Storm Damage [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment																													35											35				35
Customers Experiencing Outages | customer																															72,000
Estimated Storm Costs - Capital and Operation Maintenance																													165		$ 200									165				165
Duke Energy Florida [Member] | Hurricane Michael Storm Damage [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													$ 165											$ 165				$ 165
Duke Energy Florida [Member] | Storm Restoration Cost Recovery [Member]
Public Utilities, General Disclosures [Line Items]
Customers Experiencing Outages																													1,000,000											1,000,000				1,000,000
Estimated Storm Costs - Capital and Operation Maintenance																													$ 510											$ 510				$ 510
Regulatory assets																													217											217				217
Allowed Storm Reserve																													$ 132											$ 132				$ 132
Duke Energy Florida [Member] | Storm Restoration Cost Recovery [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Estimated Storm Costs - Capital and Operation Maintenance																																																$ 508
Duke Energy Florida [Member] | Federal Tax Act Impacts [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Tax Act Annual Tax Savings Requested Rate Decrease, Amount		$ 4											$ 134
Tax Act Excess Deferred Tax Amortization Requested Rate Decrease, Amount		67											67
Duke Energy Florida [Member] | Federal Tax Act Impacts Revenue Requirement [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount		$ 71											201
Duke Energy Florida [Member] | Federal Tax Act Impacts Revenue Requirement [Member] | FPSC [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets													151																						151
Duke Energy Florida [Member] | Federal Tax Act Impacts Revenue Requirement [Member] | Crystal River Units 3 and 4 [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net													$ 50																						$ 50
Duke Energy Florida [Member] | Citrus County Combined Cycle Facility [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission									$ 200
Duke Energy Florida [Member] | Second Revised And Restated Stipulation And Settlement Agreement 2017 [Member] | Hamilton Project [Member] | Subsequent Event [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																												$ (15)
Duke Energy Florida [Member] | Second Revised And Restated Stipulation And Settlement Agreement 2017 [Member] | Columbia Project [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount							$ (14)
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Limit of Total Capital																													30.00%											30.00%				30.00%
Public Utilities, Property, Plant and Equipment, Net																													$ 6,643											$ 6,643				$ 6,643	6,041
Regulatory assets, noncurrent																													531											531				531	445
Net property, plant and equipment																													6,643											6,643				6,643	6,041
Operation, maintenance and other																																												480	530	514
Regulatory assets																													564											564				564	494
Total income (loss) from continuing operations before income taxes																																												(219)	(252)	(270)
Impairment charges																																													1
Regulated Revenue																																												1,450	1,373	1,410
Asset Impairment Charges																																													1
Duke Energy Ohio [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													20											20				20	17
Duke Energy Ohio [Member] | Accrued Pension And Post Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													146											146				146	139
Duke Energy Ohio [Member] | Storm Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													4											4				4	5
Duke Energy Ohio [Member] | RTO Realignment [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													43											43				43	50
Duke Energy Ohio [Member] | Electric Base Rate Case [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																																					$ 15
Requested Rate Increase (Decrease), Amended, Amount														$ (19)
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage														9.84%
Requested Return on Equity, Percentage																																					10.40%
Public Utilities, Requested Equity Capital Structure, Percentage														50.75%
Public Utilities, Requested Debt Capital Structure, Percentage														49.25%
Approved rate increase (decrease) amount by state commission															$ (20)
Duke Energy Ohio [Member] | Electric Base Rate Case [Member] | PUCO [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																		$ (18)
Requested Return on Equity, Percentage																		9.22%
Duke Energy Ohio [Member] | Electric Base Rate Case [Member] | PUCO [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																		$ (29)
Requested Return on Equity, Percentage																		10.24%
Requested Rider Revenue Increase														$ 10
Duke Energy Ohio [Member] | Natural Gas Pipeline Extension [Member] | Ohio Power Siting Board [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated Capital Cost Excluding AFUDC																													163											163				163
Duke Energy Ohio [Member] | Natural Gas Pipeline Extension [Member] | Ohio Power Siting Board [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated Capital Cost Excluding AFUDC																													245											245				245
Duke Energy Ohio [Member] | Energy Efficiency Cost Recovery Program [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																																													56
Regulated Revenue																																						$ 20
Duke Energy Ohio [Member] | Energy Efficiency Cost Recovery Program [Member] | PUCO [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																	$ 38
Duke Energy Ohio [Member] | Mgp Remediation [Member] | East End Site [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													24											24				24
Duke Energy Ohio [Member] | Mgp Remediation [Member] | West End Site [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													$ 23											$ 23				23
Duke Energy Ohio [Member] | FERC 494 Refund Of Regional Transmission Enhancement Projects [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Customer Refundable Fees, Refund Payments																																												$ 47
Duke Energy Kentucky [Member]
Public Utilities, General Disclosures [Line Items]
Required Equity Capital Structure Percent																													35.00%											35.00%				35.00%
Duke Energy Kentucky [Member] | Duke Energy Kentucky Electric Rate Case [Member] | KPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																			$ 49
Requested Rate Increase (Decrease), Percentage																			15.00%
Requested Rate Increase (Decrease), Amended, Amount																			$ (30.1)
Public Utilities, Requested Rate Increase (Decrease), Amended, Percentage																			9.00%
Approved rate increase (decrease) amount by state commission														$ 8
Approved return on equity percentage amount by state commission														9.725%
Public Utilities, Approved Equity Capital Structure, Percentage														49.00%
Total Allocable Capitalization														$ 650
Incremental Rider Revenue														$ 13
Duke Energy Kentucky [Member] | Duke Energy Kentucky Gas Base Rate Case [Member] | KPSC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount						$ 11
Requested Rate Increase (Decrease), Percentage						11.10%
Requested Rate Increase (Decrease), Amended, Amount						$ (5)
Duke Energy Kentucky [Member] | Duke Energy Kentucky Gas Base Rate Case [Member] | Subsequent Event [Member] | KPSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission	$ 7
Duke Energy Kentucky [Member] | FERC 494 Refund Of Regional Transmission Enhancement Projects [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Customer Refundable Fees, Refund Payments																																												$ 47
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net																													$ 10,529											$ 10,529				10,529	10,286
Regulatory assets, noncurrent																													982											982				982	978
Net property, plant and equipment																													10,529											10,529				10,529	10,286
Operation, maintenance and other																																												788	743	727
Regulatory assets																													1,157											1,157				1,157	1,143
Total income (loss) from continuing operations before income taxes																																												(521)	(655)	(606)
Impairment charges																																												30	18	8
Asset Impairment Charges																																												30	18	$ 8
Duke Energy Indiana [Member] | Asset retirement obligations - coal ash [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													450											450				450	380
Duke Energy Indiana [Member] | Accrued Pension And Post Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													222											222				222	197
Duke Energy Indiana [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													57											57				$ 57	65
Duke Energy Indiana [Member] | Edwardsport Integrated Gasification Combined Cycle Plant [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission					$ (10)
Impairment charges																																									32
Regulatory assets, net increase (decrease)					$ (30)
Asset Impairment Charges																																									$ 32
Duke Energy Indiana [Member] | Benton County Wind Farm Dispute [Member]
Public Utilities, General Disclosures [Line Items]
Litigation Settlement, Amount Awarded to Other Party																					$ 29
Duke Energy Indiana [Member] | FERC Transmission Rates [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission																																												12.38%
Approved Return on Equity Percentage Adder																										0.50%
Duke Energy Indiana [Member] | FERC Complaint [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Requested Return on Equity, Percentage																																												8.67%
Duke Energy Indiana [Member] | FERC Complaint 1 [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission																								10.32%
Duke Energy Indiana [Member] | FERC Complaint 2 [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Requested Return on Equity, Percentage																							9.70%
Duke Energy Indiana [Member] | Federal Tax Act Impacts Tranche 1 [Member] | IURC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount										$ (7)
Duke Energy Indiana [Member] | Federal Tax Act Impacts Tranche 2 [Member] | IURC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount										$ (35)
Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net																													5,911											5,911				$ 5,911	5,246
Regulatory assets, noncurrent																													303											303				303	283
Net property, plant and equipment																													5,911											5,911				5,911	5,246
Operation, maintenance and other																																							$ 50					357	304		$ 353
Regulatory assets																													357											357				357	378
Total income (loss) from continuing operations before income taxes																																							$ (86)					(166)	(201)		$ (317)
Impairment charges																																													7
Asset Impairment Charges																																													7
Piedmont Natural Gas [Member] | Regulatory Clause Revenues, under-recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													24											24				24	64
Piedmont Natural Gas [Member] | Accrued Pension And Post Retirement [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets																													$ 99											$ 99				$ 99	$ 91
Piedmont Natural Gas [Member] | South Carolina Rate Stabilization Adjustment Filing [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission				10.20%
Piedmont Natural Gas [Member] | NCUC IMR Petition Filed October 2017 [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount																															$ 10
Piedmont Natural Gas [Member] | NCUC IMR Petition Filed May 2017 [Member] | NCUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																																		$ 6
Piedmont Natural Gas [Member] | Tennessee Integrity Management Rider Filing November 2018 [Member] | TPUC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission																														$ 3
North Carolina Department of Revenue [Member] | Duke Energy Progress [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Tax benefits from Tax Act			$ 17
North Carolina Department of Revenue [Member] | State [Member] | Duke Energy Carolinas [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Tax benefit from reduction in state taxes			(17)
North Carolina Department of Revenue [Member] | State [Member] | Duke Energy Progress [Member] | South Carolina Rate Case 2018 [Member] | PSCSC [Member]
Public Utilities, General Disclosures [Line Items]
Tax benefit from reduction in state taxes			$ (12)

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Regulatory Assets Liabilities [Line Items]
Regulatory assets	$ 15,622	$ 13,879
Regulatory Assets, Current	2,005	1,437
Regulatory assets, noncurrent	13,617	12,442
Regulatory Liabilities	15,432	15,732
Regulatory Liability, Current	598	402
Regulatory Liability, Noncurrent	14,834	15,330
Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	5,421	5,968
Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	538	806
Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	8,058	8,113
Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	34	10
Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		20
Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	301	146
Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	16	47
Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1,064	622
Deferred Asset - Lee COLA [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	383
Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	4,255	4,025
Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	772	852
Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,654	2,249
Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	445	480
Debt Fair Value Adjustment [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,099	1,197
Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,117	531
Nuclear asset securitized balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,093	1,142
Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	204	234
Derivatives - natural gas supply contracts [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	141	142
Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	449	530
Grid Modernization [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	31	39
Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	213	213
Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	838	507
Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	133	119
Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	320	366
Transmission Expansion Obligation [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	39	46
Manufactured Gas Plant [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	99	91
Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	367	362
NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	50	53
East Bend deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	47	45
Deferred pipeline integrity [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	65	54
Amounts due from customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	24	64
Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	784	538
Duke Energy Carolinas [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	3,977	3,152
Regulatory Assets, Current	520	299
Regulatory assets, noncurrent	3,457	2,853
Regulatory Liabilities	6,198	6,357
Regulatory Liability, Current	199	126
Regulatory Liability, Noncurrent	5,999	6,231
Duke Energy Carolinas [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1,968	2,054
Duke Energy Carolinas [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	538	806
Duke Energy Carolinas [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	3,082	3,028
Duke Energy Carolinas [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		20
Duke Energy Carolinas [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	38	44
Duke Energy Carolinas [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		46
Duke Energy Carolinas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	572	359
Duke Energy Carolinas [Member] | Deferred Asset - Lee COLA [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	383
Duke Energy Carolinas [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,725	1,645
Duke Energy Carolinas [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	581	410
Duke Energy Carolinas [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21	29
Duke Energy Carolinas [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	160
Duke Energy Carolinas [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	101	109
Duke Energy Carolinas [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	169	210
Duke Energy Carolinas [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	78	83
Duke Energy Carolinas [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	196	140
Duke Energy Carolinas [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	87	84
Duke Energy Carolinas [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	34	35
Duke Energy Carolinas [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	176	185
Duke Energy Carolinas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	266	222
Progress Energy [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	7,701	6,751
Regulatory Assets, Current	1,137	741
Regulatory assets, noncurrent	6,564	6,010
Regulatory Liabilities	5,329	5,519
Regulatory Liability, Current	280	213
Regulatory Liability, Noncurrent	5,049	5,306
Progress Energy [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	2,135	2,537
Progress Energy [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	2,710	2,802
Progress Energy [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	149
Progress Energy [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	16	1
Progress Energy [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	319	179
Progress Energy [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,061	1,984
Progress Energy [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	601	655
Progress Energy [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,074	906
Progress Energy [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	367	386
Progress Energy [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	953	526
Progress Energy [Member] | Nuclear asset securitized balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,093	1,142
Progress Energy [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	74	94
Progress Energy [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	256	281
Progress Energy [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	41	42
Progress Energy [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	600	349
Progress Energy [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	46	35
Progress Energy [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	36	38
Progress Energy [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	127	150
Progress Energy [Member] | NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	50	53
Progress Energy [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	322	110
Duke Energy Progress [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	4,814	3,859
Regulatory Assets, Current	703	352
Regulatory assets, noncurrent	4,111	3,507
Regulatory Liabilities	4,133	4,138
Regulatory Liability, Current	178	139
Regulatory Liability, Noncurrent	3,955	3,999
Duke Energy Progress [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1,878	2,122
Duke Energy Progress [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1,863	1,854
Duke Energy Progress [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	93
Duke Energy Progress [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities		1
Duke Energy Progress [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	299	161
Duke Energy Progress [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,051	1,975
Duke Energy Progress [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	429	359
Duke Energy Progress [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	542	430
Duke Energy Progress [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	148	170
Duke Energy Progress [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	571	150
Duke Energy Progress [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	54	64
Duke Energy Progress [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	235	264
Duke Energy Progress [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	41	42
Duke Energy Progress [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	397	130
Duke Energy Progress [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	46	35
Duke Energy Progress [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	36	38
Duke Energy Progress [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	67	75
Duke Energy Progress [Member] | NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	50	53
Duke Energy Progress [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	147	74
Duke Energy Florida [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,888	2,892
Regulatory Assets, Current	434	389
Regulatory assets, noncurrent	2,454	2,503
Regulatory Liabilities	1,196	1,381
Regulatory Liability, Current	102	74
Regulatory Liability, Noncurrent	1,094	1,307
Duke Energy Florida [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	257	415
Duke Energy Florida [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	847	948
Duke Energy Florida [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	56
Duke Energy Florida [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	16
Duke Energy Florida [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	20	18
Duke Energy Florida [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	10	9
Duke Energy Florida [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	172	296
Duke Energy Florida [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	532	476
Duke Energy Florida [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	219	216
Duke Energy Florida [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	382	376
Duke Energy Florida [Member] | Nuclear asset securitized balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,093	1,142
Duke Energy Florida [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	20	30
Duke Energy Florida [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21	17
Duke Energy Florida [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	203	219
Duke Energy Florida [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	60	75
Duke Energy Florida [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	176	36
Duke Energy Ohio [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	564	494
Regulatory Assets, Current	33	49
Regulatory assets, noncurrent	531	445
Regulatory Liabilities	897	927
Regulatory Liability, Current	57	36
Regulatory Liability, Noncurrent	840	891
Duke Energy Ohio [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	126	189
Duke Energy Ohio [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	678	688
Duke Energy Ohio [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	18	16
Duke Energy Ohio [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	75	34
Duke Energy Ohio [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	20	17
Duke Energy Ohio [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	146	139
Duke Energy Ohio [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	4	5
Duke Energy Ohio [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	5	6
Duke Energy Ohio [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	10	18
Duke Energy Ohio [Member] | Grid Modernization [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	31	39
Duke Energy Ohio [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	5	5
Duke Energy Ohio [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2
Duke Energy Ohio [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	17	19
Duke Energy Ohio [Member] | Transmission Expansion Obligation [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	43	50
Duke Energy Ohio [Member] | Manufactured Gas Plant [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	99	91
Duke Energy Ohio [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	46	6
Duke Energy Ohio [Member] | East Bend deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	47	45
Duke Energy Ohio [Member] | Deferred pipeline integrity [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	14	12
Duke Energy Ohio [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	75	42
Duke Energy Indiana [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,157	1,143
Regulatory Assets, Current	175	165
Regulatory assets, noncurrent	982	978
Regulatory Liabilities	1,747	1,747
Regulatory Liability, Current	25	24
Regulatory Liability, Noncurrent	1,722	1,723
Duke Energy Indiana [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	628	644
Duke Energy Indiana [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1,009	998
Duke Energy Indiana [Member] | Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1	10
Duke Energy Indiana [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	67	64
Duke Energy Indiana [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	42	31
Duke Energy Indiana [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	450	380
Duke Energy Indiana [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	222	197
Duke Energy Indiana [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	57	65
Duke Energy Indiana [Member] | Hedge costs deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	24	25
Duke Energy Indiana [Member] | Demand Side Management And Energy Efficiency, Asset [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	14	21
Duke Energy Indiana [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	11	11
Duke Energy Indiana [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	40	18
Duke Energy Indiana [Member] | Post In Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	233	274
Duke Energy Indiana [Member] | Advanced Metering Infrastructure [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	18	21
Duke Energy Indiana [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	88	131
Piedmont Natural Gas [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	357	378
Regulatory Assets, Current	54	95
Regulatory assets, noncurrent	303	283
Regulatory Liabilities	1,218	1,144
Regulatory Liability, Current	37	3
Regulatory Liability, Noncurrent	1,181	1,141
Piedmont Natural Gas [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	564	544
Piedmont Natural Gas [Member] | Net regulatory liability related to income taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	579	597
Piedmont Natural Gas [Member] | Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	33
Piedmont Natural Gas [Member] | Accrued Pension And OPEB [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	1
Piedmont Natural Gas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory Liabilities	41	3
Piedmont Natural Gas [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	19	15
Piedmont Natural Gas [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	99	91
Piedmont Natural Gas [Member] | Derivatives - natural gas supply contracts [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	141	142
Piedmont Natural Gas [Member] | Vacation accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	12	10
Piedmont Natural Gas [Member] | Deferred pipeline integrity [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	51	42
Piedmont Natural Gas [Member] | Amounts due from customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	24	64
Piedmont Natural Gas [Member] | Other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	11	$ 14
Hurricane Michael Storm Damage [Member] | Duke Energy Florida [Member] | Storm cost deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	$ 165

Regulatory Matters (Schedule _2

Regulatory Matters (Schedule of MISO Exit fees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Balance, beginning of period	$ 19
Cash reductions	(14)
Balance, end of period	205
Total regulatory assets	15,622	$ 13,879
Duke Energy Ohio [Member]
Restructuring Reserve [Roll Forward]
Balance, end of period	2
Total regulatory assets	564	494
Duke Energy Ohio [Member] | RTO Realignment [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	66
Provisions/Adjustments	(4)
Cash reductions	(4)
Balance, end of period	58
Total regulatory assets	$ 43	$ 50

Regulatory Matters (Schedule _3

Regulatory Matters (Schedule of Net Carrying Value Of Facilities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)MW	Dec. 31, 2017USD ($)
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 91,694	$ 86,391
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	29,245	27,876
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	34,224	31,887
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	13,824	12,783
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	10,529	10,286
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	20,398	19,101
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 6,643	$ 6,041
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	865
Net property, plant and equipment	$ 283
Generation Facilities To Be Retired [Member] | Duke Energy Carolinas [Member] | Allen Steam Station Units 1-3 [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	585
Net property, plant and equipment	$ 162
Generation Facilities To Be Retired [Member] | Duke Energy Indiana [Member] | Gallagher Units 2 and 4 [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	280
Net property, plant and equipment	$ 121
Federal Energy Regulatory Commission [Member] | FERC 494 Refund Of Regional Transmission Enhancement Projects [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Customer Refundable Fees, Refund Payments	$ 47

Commitments and Contingencies_2

Commitments and Contingencies (Narrative) (Details)	1 Months Ended	2 Months Ended	12 Months Ended
	Jul. 31, 2018USD ($)	Feb. 28, 2019USD ($)	Dec. 31, 2018USD ($)plantreactorclaimT	Dec. 31, 2017USD ($)	Mar. 31, 2014USD ($)
Insurance [Abstract]
Insured public liability limit per nuclear incident			$ 14,100,000,000
Excess nuclear liability program coverage			13,600,000,000
Pro rata assessment for each reactor owned for each incident exceeding public liability insurance			$ 138,000,000
Number of licensed nuclear reactors | reactor			99
Annual payment limit to pro rata assessments			$ 20,500,000
Industry aggregate limit			3,200,000,000
Sublimit for non-nuclear terrorist events			$ 1,800,000,000
Insurance Coverage Percentage Initial Weeks			100.00%
Accidental Outage Insurance Coverage Initial Weeks			365 days
Insurance Coverage Percentage Additional Weeks			80.00%
Accidental Outage Insurance Coverage Additional Weeks			770 days
Weeks of Sublimits for Accidental Outage Coverage			728 days
Sublimit accidental outage recovery			$ 328,000,000
Maximum Magnitude of Retroactive Premiums			10
Maximum Period for Retroactive Premium Assessment			6 years
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			$ 65,000,000	$ 88,000,000
Coal Ash Insurance Coverage Litigation [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Number of NC and SC Plants with Ash Basins | plant			15
NCDEQ State Enforcement Actions [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Facilities with Ash Basins | plant			14
Number of Plants with No Disputed Facts | plant			7
Number of Plants with Disputed Facts | plant			7
Groundwater Contamination Claims [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Goodwill Payment			$ 5,000
Water Bill Stipend Period			25 years
Duke Energy Carolinas [Member]
Insurance [Abstract]
Primary nuclear liability program coverage			$ 450,000,000
Max Retroactive Premium Assessments			159,000,000
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			9,000,000	30,000,000
Duke Energy Carolinas [Member] | McGuire Nuclear Station [Member]
Insurance [Abstract]
Accidental outage insurance coverage policy limit			490,000,000
Duke Energy Carolinas [Member] | Catawba Nuclear Station [Member]
Insurance [Abstract]
Dedicated additional nuclear accident limit			1,250,000,000
Additional Non Nuclear Accident Limit			750,000,000
Accidental outage insurance coverage policy limit			$ 490,000,000
Potential Obligation percentage			100.00%
Duke Energy Carolinas [Member] | Oconee Nuclear Station [Member]
Insurance [Abstract]
Additional nuclear accident limit			$ 1,250,000,000
Additional Non Nuclear Accident Limit			750,000,000
Accidental outage insurance coverage policy limit			462,000,000
Duke Energy Carolinas [Member] | Harris Nuclear Plant [Member]
Insurance [Abstract]
Accidental outage insurance coverage policy limit			490,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Asbestos-related injuries and damages reserves			630,000,000	489,000,000
Reinsurance retention policy, excess retention, amount reinsured			764,000,000
Loss contingency, receivable, noncurrent			$ 739,000,000	585,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Non Malignant Asbestos Claim [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | claim			164
Asbestos-related injuries and damages reserves			$ 42,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Malignant Asbestos Claim [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | claim			87
Asbestos-related injuries and damages reserves			$ 21,000,000
Progress Energy [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			54,000,000	55,000,000
Duke Energy Progress [Member]
Insurance [Abstract]
Primary nuclear liability program coverage			450,000,000
Max Retroactive Premium Assessments			97,000,000
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			12,000,000	13,000,000
Duke Energy Progress [Member] | Robinson Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses			1,500,000,000
Accidental outage insurance coverage policy limit			392,000,000
Duke Energy Progress [Member] | Brunswick Nuclear Station [Member]
Insurance [Abstract]
Accidental outage insurance coverage policy limit			476,000,000
Duke Energy Progress [Member] | Spent Nuclear Fuels [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount			48,000,000
Litigation settlement, amount award from other party			$ 48,000,000
Duke Energy Progress [Member] | Gypsum Supply Agreements [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Minimum Amount of Gypsum To Be Supplied | T			50,000
Estimate of possible losses			$ 90,000,000
Settlement period			10 years
Loss contingency, damages paid, value			$ 3,000,000
Duke Energy Florida [Member]
Insurance [Abstract]
Primary nuclear liability program coverage			100,000,000
Max Retroactive Premium Assessments			1,000,000
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			24,000,000	24,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member]
Insurance [Abstract]
Sublimit property damage losses			50,000,000
Duke Energy Florida [Member] | Spent Nuclear Fuels [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount			25,000,000
Litigation settlement, amount award from other party			21,000,000
Duke Energy Florida [Member] | Westinghouse Electric Company Litigation [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount			54,000,000
Damages sough, original amount					$ 510,000,000
Damages awarded, value			30,000,000
Gain contingency, dismissed amount			54,000,000
Loss contingency, damages awarded and interest, value			34,000,000
Loss contingency, damages paid, value	$ 34,000,000
Duke Energy Florida [Member] | MGP Cost Recovery Action [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Loss contingency, damages sought, value			43,000,000
Piedmont Natural Gas [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			1,000,000	$ 2,000,000
Accounts Payable [Member] | Duke Energy Progress [Member] | Gypsum Supply Agreements [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			9,000,000
Other Noncurrent Liabilities [Member] | Duke Energy Progress [Member] | Gypsum Supply Agreements [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Reserves for legal matters			$ 63,000,000
Measurement Input, Discount Rate [Member] | Duke Energy Progress [Member] | Gypsum Supply Agreements [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Loss contingency, measurement input			0.04
Subsequent Event [Member] | Duke Energy Florida [Member] | Fluor Contract Litigation [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Loss contingency, damages sought, value		$ 110,000,000
Fluor Letter Of Credit [Member] | Subsequent Event [Member] | Duke Energy Florida [Member]
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Drawings on credit facility		$ 67,000,000

Commitments and Contingencies_3

Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016	Oct. 31, 2015
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	$ 81	$ 98	$ 94
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	81	98	94
Provision/adjustments	26	8	19
Cash reductions	(30)	(25)	(15)
Ending balance	77	81	98
Duke Energy Carolinas [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	10	10	10
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	10	10	10
Provision/adjustments	3	3	4
Cash reductions	(2)	(3)	(4)
Ending balance	11	10	10
Progress Energy [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	15	18	17
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	15	18	17
Provision/adjustments	2	3	7
Cash reductions	(6)	(6)	(6)
Ending balance	11	15	18
Duke Energy Progress [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	3	3	3
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	3	3	3
Provision/adjustments	3	2	2
Cash reductions	(2)	(2)	(2)
Ending balance	4	3	3
Duke Energy Florida [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	12	14	14
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	12	14	14
Provision/adjustments	(2)	2	4
Cash reductions	(4)	(4)	(4)
Ending balance	6	12	14
Duke Energy Ohio [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	47	59	54
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	47	59	54
Provision/adjustments	21	3	7
Cash reductions	(20)	(15)	(2)
Ending balance	48	47	59
Duke Energy Indiana [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	5	10	12
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5	10	12
Provision/adjustments	1	(4)	1
Cash reductions	(1)	(1)	(3)
Ending balance	5	5	10
Piedmont Natural Gas [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental reserve	2	1	1	$ 1	$ 1
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	2	1
Ending balance	2	$ 2	$ 1
Environmental Reserves [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	46
Environmental Reserves [Member] | Duke Energy Carolinas [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	17
Environmental Reserves [Member] | Duke Energy Ohio [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	19
Environmental Reserves [Member] | Piedmont Natural Gas [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	$ 2

Commitments and Contingencies_4

Commitments and Contingencies (Schedule of Legal Reserves) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Legal Reserves Details [Line Items]
Reserves for legal matters	$ 65	$ 88
Duke Energy Carolinas [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	9	30
Progress Energy [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	54	55
Duke Energy Progress [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	12	13
Duke Energy Florida [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	24	24
Piedmont Natural Gas [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	$ 1	$ 2

(PurchPower) (Details)

(PurchPower) (Details) - Public Utilities Purchased Power [Member] $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Duke Energy Progress [Member]
Unconditional Purchase Obligations [Abstract]
2,019	$ 51
2,020	52
2,021	53
2,022	30
2,023	25
Thereafter	215
Total	$ 426
Duke Energy Progress [Member] | Minimum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	2,022
Duke Energy Progress [Member] | Maximum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	2,031
Long-term Contract for Purchase of Electric Power, Share of Plant Output Being Purchased	100.00%
Duke Energy Florida [Member]
Unconditional Purchase Obligations [Abstract]
2,019	$ 363
2,020	380
2,021	365
2,022	363
2,023	382
Thereafter	361
Total	$ 2,214
Duke Energy Florida [Member] | Minimum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	2,021
Long-term Contract for Purchase of Electric Power, Share of Plant Output Being Purchased	81.00%
Duke Energy Florida [Member] | Maximum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	2,025
Long-term Contract for Purchase of Electric Power, Share of Plant Output Being Purchased	100.00%
Duke Energy Ohio [Member]
Unconditional Purchase Obligations [Abstract]
2,019	$ 146
2,020	117
2,021	53
2,022	11
Total	$ 327
Duke Energy Ohio [Member] | Minimum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	2,020
Long-term Contract for Purchase of Electric Power, Share of Plant Output Being Purchased	1.00%
Duke Energy Ohio [Member] | Maximum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term Contract for Purchase of Electric Power, Date of Contract Expiration	2,022
Long-term Contract for Purchase of Electric Power, Share of Plant Output Being Purchased	8.00%

Commitments and Contingencies_5

Commitments and Contingencies (Gas Supply Contracts) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Natural Gas Supply and Capacity Contracts [Member]
Long-term Purchase Commitment [Line Items]
2,019	$ 314
2,020	287
2,021	255
2,022	225
2,023	148
Thereafter	1,067
Total	$ 2,296
Maximum [Member] | Pipeline and Storage Capacity Contracts [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	16 years
Maximum [Member] | Natural Gas Supply Contract Fixed Payments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	7 years
Maximum [Member] | Natural Gas Supply Contract Commitment [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	12 years
Duke Energy Ohio [Member] | Natural Gas Supply and Capacity Contracts [Member]
Long-term Purchase Commitment [Line Items]
2,019	$ 38
2,020	30
2,021	29
2,022	11
2,023	4
Thereafter	0
Total	$ 112
Duke Energy Ohio [Member] | Maximum [Member] | Pipeline and Storage Capacity Contracts [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	16 years
Duke Energy Ohio [Member] | Maximum [Member] | Natural Gas Supply Contract Fixed Payments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	7 years
Duke Energy Ohio [Member] | Maximum [Member] | Natural Gas Supply Contract Commitment [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	12 years
Piedmont Natural Gas [Member] | Natural Gas Supply and Capacity Contracts [Member]
Long-term Purchase Commitment [Line Items]
2,019	$ 276
2,020	257
2,021	226
2,022	214
2,023	144
Thereafter	1,067
Total	$ 2,184
Piedmont Natural Gas [Member] | Maximum [Member] | Pipeline and Storage Capacity Contracts [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	16 years
Piedmont Natural Gas [Member] | Maximum [Member] | Natural Gas Supply Contract Fixed Payments [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	7 years
Piedmont Natural Gas [Member] | Maximum [Member] | Natural Gas Supply Contract Commitment [Member]
Long-term Purchase Commitment [Line Items]
Long-term Purchase Commitment, Period	12 years

Commitments and Contingencies_6

Commitments and Contingencies (Future Minimum Payments for Operating and Capital Leases) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Operating Leased Assets
Rental expense on operating leases		$ 268	$ 241	$ 242
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		239
2,020		219
2,021		186
2,022		170
2,023		160
Thereafter		1,017
Total future minimum lease payments		1,991
Capital Leases, Future Minimum Payments Due [Abstract]
2,019		170
2,020		174
2,021		177
2,022		165
2,023		165
Thereafter		577
Minimum annual payments		1,428
Less amount representing interest		(487)
Total		941
Duke Energy Carolinas [Member]
Operating Leased Assets
Rental expense on operating leases		49	44	45
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		33
2,020		29
2,021		19
2,022		19
2,023		17
Thereafter		68
Total future minimum lease payments		185
Capital Leases, Future Minimum Payments Due [Abstract]
2,019		20
2,020		20
2,021		15
2,022		15
2,023		15
Thereafter		204
Minimum annual payments		289
Less amount representing interest		(180)
Total		109
Progress Energy [Member]
Operating Leased Assets
Rental expense on operating leases		143	130	140
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		97
2,020		90
2,021		79
2,022		76
2,023		77
Thereafter		455
Total future minimum lease payments		874
Capital Leases, Future Minimum Payments Due [Abstract]
2,019		45
2,020		46
2,021		45
2,022		45
2,023		45
Thereafter		230
Minimum annual payments		456
Less amount representing interest		(205)
Total		251
Duke Energy Progress [Member]
Operating Leased Assets
Rental expense on operating leases		75	75	68
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		49
2,020		46
2,021		37
2,022		34
2,023		35
Thereafter		314
Total future minimum lease payments		515
Capital Leases, Future Minimum Payments Due [Abstract]
2,019		20
2,020		21
2,021		20
2,022		21
2,023		21
Thereafter		209
Minimum annual payments		312
Less amount representing interest		(175)
Total		137
Duke Energy Florida [Member]
Operating Leased Assets
Rental expense on operating leases		68	55	72
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		48
2,020		44
2,021		42
2,022		42
2,023		42
Thereafter		141
Total future minimum lease payments		359
Capital Leases, Future Minimum Payments Due [Abstract]
2,019		25
2,020		25
2,021		25
2,022		24
2,023		24
Thereafter		21
Minimum annual payments		144
Less amount representing interest		(30)
Total		114
Duke Energy Ohio [Member]
Operating Leased Assets
Rental expense on operating leases		13	15	16
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		2
2,020		2
2,021		2
2,022		2
2,023		2
Thereafter		23
Total future minimum lease payments		33
Capital Leases, Future Minimum Payments Due [Abstract]
2,019		2
Minimum annual payments		2
Total		2
Duke Energy Indiana [Member]
Operating Leased Assets
Rental expense on operating leases		21	23	$ 23
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		6
2,020		5
2,021		4
2,022		4
2,023		5
Thereafter		66
Total future minimum lease payments		90
Capital Leases, Future Minimum Payments Due [Abstract]
2,019		1
2,020		1
2,021		1
2,022		1
2,023		1
Thereafter		27
Minimum annual payments		32
Less amount representing interest		(22)
Total		10
Piedmont Natural Gas [Member]
Operating Leased Assets
Rental expense on operating leases	$ 1	11	$ 7		$ 5
Operating Leases, Future Minimum Payments Due [Abstract]
2,019		5
2,020		5
2,021		5
2,022		5
2,023		6
Thereafter		11
Total future minimum lease payments		$ 37

Debt and Credit Facilities (Nar

Debt and Credit Facilities (Narrative) (Details)	1 Months Ended	2 Months Ended	12 Months Ended
	Jan. 31, 2019USD ($)	Feb. 28, 2019USD ($)	Dec. 31, 2018USD ($)	Aug. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Debt issuances			$ 5,050,000,000		$ 6,070,000,000
Other Debt Matters [Abstract]
Demand notes, maximum amount available for sale			3,000,000,000
Demand notes, maximum amount outstanding			1,500,000,000
Principal amount of demand notes			1,010,000,000		986,000,000
Other Loans [Abstract]
Other loans outstanding against cash surrender value of life insurance policies			$ 741,000,000		701,000,000
Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.65
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 8,000,000,000
Line of credit facility, expiration date			Mar. 16, 2023
June 2017 Three Year Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 1,000,000,000
Debt Instrument, Term			3 years
Long-term Line of Credit			$ 500,000,000
Term Loan Proceeds			500,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Debt issuances			$ 2,000,000,000		550,000,000
Duke Energy Carolinas [Member] | Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.65
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 1,750,000,000
Progress Energy [Member] | Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.65
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Debt issuances			$ 800,000,000		800,000,000
Other Loans [Abstract]
Other loans outstanding against cash surrender value of life insurance policies			$ 37,000,000		38,000,000
Duke Energy Progress [Member] | Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.65
Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 1,400,000,000
Duke Energy Progress [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 700,000,000
Debt Instrument, Term			2 years
Long-term Line of Credit			$ 50,000,000
Term Loan Proceeds			50,000,000
Duke Energy Progress [Member] | Subsequent Event [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Drawings on credit facility		$ 650,000,000
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Debt issuances			$ 1,000,000,000		1,300,000,000
Duke Energy Florida [Member] | Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.65
Duke Energy Florida [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 650,000,000
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Debt issuances					$ 100,000,000
Duke Energy Ohio [Member] | Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.65
Duke Energy Ohio [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 450,000,000
Duke Energy Indiana [Member] | Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.65
Duke Energy Indiana [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 600,000,000
Piedmont Natural Gas [Member] | Maximum [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower			0.7
Piedmont Natural Gas [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility Size			$ 500,000,000
Piedmont Natural Gas [Member] | June 2017 Piedmont Term Loan Facility [Member]
Debt Instrument [Line Items]
Facility Size			350,000,000	$ 250,000,000
Long-term Line of Credit			350,000,000
Term Loan Proceeds			350,000,000
USDOJ [Member] | North Carolina Ash Basins [Member] | Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Minimum Master Credit Facility Balance required			250,000,000
USDOJ [Member] | North Carolina Ash Basins [Member] | Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Minimum Master Credit Facility Balance required			$ 250,000,000
January 2019 First Mortgage Bonds [Member] | Duke Energy Ohio [Member] | Subsequent Event [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Debt issuances	$ 800,000,000
Restrictive Debt Covenants [Abstract]
Proceeds from Issuance of First Mortgage Bond	$ 450,000,000
January 2019 First Mortgage Bonds, 3.65% Interest [Member] | Duke Energy Ohio [Member] | Subsequent Event [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Interest rate	3.65%
Debt issuances	$ 400,000,000
Debt Instrument, Term	10 years
January 2019 First Mortgage Bonds, 4.30% Interest [Member] | Duke Energy Ohio [Member] | Subsequent Event [Member] | First Mortgage [Member]
Debt Instrument [Line Items]
Interest rate	4.30%
Debt issuances	$ 400,000,000
Debt Instrument, Term	30 years

Debt and Credit Facilities (Sum

Debt and Credit Facilities (Summary of Debt and Related Terms) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unsecured Debt	$ 20,955,000,000	$ 20,409,000,000
Secured Debt	4,297,000,000	4,458,000,000
First mortgage bonds	25,628,000,000	23,529,000,000
Capital leases	941,000,000	1,000,000,000
Tax exempt bonds	941,000,000	941,000,000
Notes payable and commercial paper	4,035,000,000	2,788,000,000
Fair value hedge carrying value adjustment	5,000,000	6,000,000
Unamortized debt discount and premium, net	1,434,000,000	1,582,000,000
Unamortized debt issuance costs	(297,000,000)	(271,000,000)
Total debt	57,939,000,000	54,442,000,000
Short-term notes payable and commercial paper	(3,410,000,000)	(2,163,000,000)
Current maturities of long-term debt	(3,406,000,000)	(3,244,000,000)
Total long-term debt	$ 51,123,000,000	$ 49,035,000,000
Weighted-average rate	4.13%	4.09%
Short term obligations classified as long-term debt	$ 937,000,000	$ 937,000,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument, Maturity Date Range, End	Dec. 31, 2078	Dec. 31, 2073
Weighted-average rate	4.26%	4.17%
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2020	Dec. 31, 2018
Debt Instrument, Maturity Date Range, End	Dec. 31, 2037	Dec. 31, 2037
Weighted-average rate	3.69%	3.15%
First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument, Maturity Date Range, End	Dec. 31, 2048	Dec. 31, 2047
Weighted-average rate	4.32%	4.51%
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument, Maturity Date Range, End	Dec. 31, 2051	Dec. 31, 2051
Weighted-average rate	5.06%	4.55%
Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2019	Dec. 31, 2019
Debt Instrument, Maturity Date Range, End	Dec. 31, 2041	Dec. 31, 2041
Weighted-average rate	3.40%	3.23%
Short term obligations classified as long-term debt	$ 312,000,000	$ 312,000,000
Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	$ 625,000,000	$ 625,000,000
Notes Payable And Commercial Paper [Member]
Debt Instrument [Line Items]
Weighted-average rate	2.73%	1.57%
Short term obligations classified as long-term debt	$ 625,000,000	$ 625,000,000
Weighted Average Days to Maturity	16 days	14 days
Parent Company [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 41,000,000	$ 47,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Unsecured Debt	1,150,000,000	1,150,000,000
Secured Debt	450,000,000	450,000,000
First mortgage bonds	8,759,000,000	7,959,000,000
Capital leases	109,000,000	61,000,000
Tax exempt bonds	243,000,000	243,000,000
Money pool borrowings	739,000,000	404,000,000
Fair value hedge carrying value adjustment	5,000,000	6,000,000
Unamortized debt discount and premium, net	(23,000,000)	(19,000,000)
Unamortized debt issuance costs	(54,000,000)	(47,000,000)
Total debt	11,378,000,000	10,207,000,000
Short-term money pool borrowings	(439,000,000)	(104,000,000)
Current maturities of long-term debt	(6,000,000)	(1,205,000,000)
Total long-term debt	10,933,000,000	8,898,000,000
Short term obligations classified as long-term debt	300,000,000	300,000,000
Duke Energy Carolinas [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	300,000,000	300,000,000
Progress Energy [Member]
Debt Instrument [Line Items]
Unsecured Debt	3,800,000,000	3,950,000,000
Secured Debt	1,703,000,000	1,757,000,000
First mortgage bonds	13,100,000,000	11,801,000,000
Capital leases	251,000,000	269,000,000
Tax exempt bonds	48,000,000	48,000,000
Money pool borrowings	1,385,000,000	955,000,000
Unamortized debt discount and premium, net	(29,000,000)	(30,000,000)
Unamortized debt issuance costs	(112,000,000)	(108,000,000)
Total debt	20,146,000,000	18,642,000,000
Short-term money pool borrowings	(1,235,000,000)	(805,000,000)
Current maturities of long-term debt	(1,672,000,000)	(771,000,000)
Total long-term debt	17,239,000,000	17,066,000,000
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Unsecured Debt	50,000,000
Secured Debt	300,000,000	300,000,000
First mortgage bonds	7,574,000,000	6,776,000,000
Capital leases	137,000,000	139,000,000
Tax exempt bonds	48,000,000	48,000,000
Money pool borrowings	444,000,000	390,000,000
Unamortized debt discount and premium, net	(15,000,000)	(16,000,000)
Unamortized debt issuance costs	(40,000,000)	(40,000,000)
Total debt	8,498,000,000	7,597,000,000
Short-term money pool borrowings	(294,000,000)	(240,000,000)
Current maturities of long-term debt	(603,000,000)	(3,000,000)
Total long-term debt	7,601,000,000	7,354,000,000
Short term obligations classified as long-term debt	150,000,000	150,000,000
Duke Energy Progress [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150,000,000	150,000,000
Duke Energy Progress [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Capital leases	63,000,000	81,000,000
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Unsecured Debt	350,000,000	550,000,000
Secured Debt	1,403,000,000	1,457,000,000
First mortgage bonds	5,526,000,000	5,025,000,000
Capital leases	114,000,000	129,000,000
Money pool borrowings	108,000,000
Unamortized debt discount and premium, net	(11,000,000)	(10,000,000)
Unamortized debt issuance costs	(61,000,000)	(56,000,000)
Total debt	7,429,000,000	7,095,000,000
Short-term money pool borrowings	(108,000,000)
Current maturities of long-term debt	(270,000,000)	(768,000,000)
Total long-term debt	7,051,000,000	6,327,000,000
Duke Energy Florida [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Capital leases	531,000,000	603,000,000
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Unsecured Debt	1,000,000,000	900,000,000
First mortgage bonds	1,099,000,000	1,100,000,000
Capital leases	2,000,000	5,000,000
Tax exempt bonds	77,000,000	77,000,000
Money pool borrowings	299,000,000	54,000,000
Unamortized debt discount and premium, net	(31,000,000)	(33,000,000)
Unamortized debt issuance costs	(7,000,000)	(7,000,000)
Total debt	2,439,000,000	2,096,000,000
Short-term money pool borrowings	(274,000,000)	(29,000,000)
Current maturities of long-term debt	(551,000,000)	(3,000,000)
Total long-term debt	1,614,000,000	2,064,000,000
Short term obligations classified as long-term debt	52,000,000	52,000,000
Duke Energy Ohio [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	27,000,000	27,000,000
Duke Energy Ohio [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	25,000,000	25,000,000
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Unsecured Debt	408,000,000	411,000,000
First mortgage bonds	2,670,000,000	2,669,000,000
Capital leases	10,000,000	11,000,000
Tax exempt bonds	572,000,000	572,000,000
Money pool borrowings	317,000,000	311,000,000
Unamortized debt discount and premium, net	(8,000,000)	(9,000,000)
Unamortized debt issuance costs	(20,000,000)	(21,000,000)
Total debt	3,949,000,000	3,944,000,000
Short-term money pool borrowings	(167,000,000)	(161,000,000)
Current maturities of long-term debt	(63,000,000)	(3,000,000)
Total long-term debt	3,719,000,000	3,780,000,000
Short term obligations classified as long-term debt	435,000,000	435,000,000
Duke Energy Indiana [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	285,000,000	285,000,000
Duke Energy Indiana [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150,000,000	150,000,000
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Unsecured Debt	2,150,000,000	2,050,000,000
Money pool borrowings	198,000,000	364,000,000
Unamortized debt discount and premium, net	(1,000,000)	(1,000,000)
Unamortized debt issuance costs	(11,000,000)	(12,000,000)
Total debt	2,336,000,000	2,401,000,000
Short-term money pool borrowings	(198,000,000)	(364,000,000)
Current maturities of long-term debt	(350,000,000)	(250,000,000)
Total long-term debt	1,788,000,000	1,787,000,000
Piedmont Natural Gas [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Unamortized debt discount and premium, net	156,000,000	176,000,000
Progress Energy [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Unamortized debt discount and premium, net	$ 1,380,000,000	$ 1,509,000,000
June 2017 Three Year Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt Instrument, Term	3 years
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Tax exempt bonds	$ 81,000,000
Revolving Credit Facility [Member] | Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Tax exempt bonds	$ 81,000,000
Line of Credit [Member] | Revolving Credit Facility [Member] | Duke Energy Progress [Member]
Debt Instrument [Line Items]
Debt Instrument, Term	2 years

Debt and Credit Facilities (S_2

Debt and Credit Facilities (Summary of Debt Issuances) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt issuances	$ 5,050,000,000	$ 6,070,000,000
January 2017 Issuance Maturing January 2027 [Member]
Debt Instrument [Line Items]
Interest rate		3.20%
January 2017 Issuance Maturing January 2027 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 650,000,000
April 2017 Issuance Maturing April 2025 [Member]
Debt Instrument [Line Items]
Interest rate		3.364%
April 2017 Issuance Maturing April 2025 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 420,000,000
June 2017 Issuance Maturing June 2020 [Member]
Debt Instrument [Line Items]
Interest rate		2.10%
June 2017 Issuance Maturing June 2020 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 330,000,000
August 2017 Issuance Maturing August 2022 [Member]
Debt Instrument [Line Items]
Interest rate		2.40%
August 2017 Issuance Maturing August 2022 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
August 2017 Issuance Maturing August 2027 [Member]
Debt Instrument [Line Items]
Interest rate		3.15%
August 2017 Issuance Maturing August 2027 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 750,000,000
August 2017 Issuance Maturing August 2047 [Member]
Debt Instrument [Line Items]
Interest rate		3.95%
August 2017 Issuance Maturing August 2047 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
December 2017 Issuance Maturing December 2019 [Member]
Debt Instrument [Line Items]
Interest rate		2.10%
December 2017 Issuance Maturing December 2019 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 400,000,000
February 2017 Issuance Maturing June 2034 [Member]
Debt Instrument [Line Items]
Interest rate		4.12%
February 2017 Issuance Maturing June 2034 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 587,000,000
March 2018 Debt Issuance 3.950% Coupon Due 2025 [Member]
Debt Instrument [Line Items]
Interest rate	3.95%
March 2018 Debt Issuance 3.950% Coupon Due 2025 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	$ 250,000,000
May 2018 Debt Issuance 2.819% Coupon Due 2021 [Member]
Debt Instrument [Line Items]
Interest rate	3.114%
May 2018 Debt Issuance 2.819% Coupon Due 2021 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
September 2018 Debt Issuance 5.625% Coupon Due 2078 [Member]
Debt Instrument [Line Items]
Interest rate	5.625%
September 2018 Debt Issuance 5.625% Coupon Due 2078 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
June 2018 Debt Issuance 4.20 Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Interest rate	4.20%
June 2018 Debt Issuance 4.20 Coupon Due 2048 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 400,000,000
August 2018 Debt Issuance 3.375% Coupon Due 2023 [Member]
Debt Instrument [Line Items]
Interest rate	3.375%
August 2018 Debt Issuance 3.375% Coupon Due 2023 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 300,000,000
August 2018 Debt Issuance 3.700% Coupon Due 2028 [Member]
Debt Instrument [Line Items]
Interest rate	3.70%
August 2018 Debt Issuance 3.700% Coupon Due 2028 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
November 2018 Debt Issuance 3.350% Coupon Due 2022 [Member]
Debt Instrument [Line Items]
Interest rate	3.35%
November 2018 Debt Issuance 3.350% Coupon Due 2022 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 350,000,000
August 2017 Issuance Maturing December 2036 [Member]
Debt Instrument [Line Items]
Interest rate		4.11%
August 2017 Issuance Maturing December 2036 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 233,000,000
March 2018 Debt Issuance 3.050% Coupon Due 2023 [Member]
Debt Instrument [Line Items]
Interest rate	3.05%
March 2018 Debt Issuance 3.050% Coupon Due 2023 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
March 2018 Debt Issuance 3.950% Coupon Due 2048 [Member]
Debt Instrument [Line Items]
Interest rate	3.95%
March 2018 Debt Issuance 3.950% Coupon Due 2048 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500,000,000
June 2018 Debt issuance 3.80% coupon Due 2028 [Member]
Debt Instrument [Line Items]
Interest rate	3.80%
June 2018 Debt issuance 3.80% coupon Due 2028 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 600,000,000
January 2017 Issuance Maturing January 2020 [Member]
Debt Instrument [Line Items]
Interest rate		1.85%
January 2017 Issuance Maturing January 2020 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 250,000,000
March 2017 Issuance Maturing June 2046 [Member]
Debt Instrument [Line Items]
Interest rate		3.70%
March 2017 Issuance Maturing June 2046 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 100,000,000
September 2017 Issuance Maturing September 2020 [Member]
Debt Instrument [Line Items]
Interest rate		1.50%
September 2017 Issuance Maturing September 2020 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 300,000,000
November 2017 Issuance Maturing December 2047 [Member]
Debt Instrument [Line Items]
Interest rate		3.70%
November 2017 Issuance Maturing December 2047 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 550,000,000
November 2018 Debt Issuance 3.950% Coupon Due 2028 [Member]
Debt Instrument [Line Items]
Interest rate	3.95%
November 2018 Debt Issuance 3.950% Coupon Due 2028 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 650,000,000
September 2017 Issuance Maturing September 2047 [Member]
Debt Instrument [Line Items]
Interest rate		3.60%
September 2017 Issuance Maturing September 2047 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500,000,000
Parent Company [Member]
Debt Instrument [Line Items]
Debt issuances	1,250,000,000	2,500,000,000
Parent Company [Member] | April 2017 Issuance Maturing April 2025 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		420,000,000
Repayments of Debt		400,000,000
Parent Company [Member] | June 2017 Issuance Maturing June 2020 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		330,000,000
Repayments of Debt		700,000,000
Parent Company [Member] | August 2017 Issuance Maturing August 2022 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		500,000,000
Parent Company [Member] | August 2017 Issuance Maturing August 2027 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		750,000,000
Parent Company [Member] | August 2017 Issuance Maturing August 2047 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		500,000,000
Parent Company [Member] | March 2018 Debt Issuance 3.950% Coupon Due 2025 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	250,000,000
Parent Company [Member] | May 2018 Debt Issuance 2.819% Coupon Due 2021 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	500,000,000
Parent Company [Member] | September 2018 Debt Issuance 5.625% Coupon Due 2078 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	500,000,000
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Debt issuances	2,000,000,000	550,000,000
Duke Energy Carolinas [Member] | First Mortgage Bonds Maturing April 2018, 5.100% Coupon [Member]
Debt Instrument [Line Items]
Repayments of Debt	300,000,000
Duke Energy Carolinas [Member] | November 2018 Debt Issuance 3.350% Coupon Due 2022 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	350,000,000
Duke Energy Carolinas [Member] | March 2018 Debt Issuance 3.050% Coupon Due 2023 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	500,000,000
Duke Energy Carolinas [Member] | March 2018 Debt Issuance 3.950% Coupon Due 2048 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	500,000,000
Duke Energy Carolinas [Member] | November 2017 Issuance Maturing December 2047 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		550,000,000
Repayments of Debt		400,000,000
Duke Energy Carolinas [Member] | November 2018 Debt Issuance 3.950% Coupon Due 2028 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	650,000,000
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Debt issuances	800,000,000	800,000,000
Duke Energy Progress [Member] | August 2018 Debt Issuance 3.375% Coupon Due 2023 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	300,000,000
Duke Energy Progress [Member] | August 2018 Debt Issuance 3.700% Coupon Due 2028 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	500,000,000
Duke Energy Progress [Member] | September 2017 Issuance Maturing September 2020 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		300,000,000
Repayments of Debt		200,000,000
Duke Energy Progress [Member] | September 2017 Issuance Maturing September 2047 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		500,000,000
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Debt issuances	1,000,000,000	1,300,000,000
Duke Energy Florida [Member] | January 2017 Issuance Maturing January 2027 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		650,000,000
Duke Energy Florida [Member] | December 2017 Issuance Maturing December 2019 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		400,000,000
Duke Energy Florida [Member] | June 2018 Debt Issuance 4.20 Coupon Due 2048 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	400,000,000
Duke Energy Florida [Member] | June 2018 Debt issuance 3.80% coupon Due 2028 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 600,000,000
Duke Energy Florida [Member] | January 2017 Issuance Maturing January 2020 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		250,000,000
Repayments of Debt		250,000,000
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Debt issuances		100,000,000
Duke Energy Ohio [Member] | March 2017 Issuance Maturing June 2046 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 100,000,000

Debt and Credit Facilities (Ann

Debt and Credit Facilities (Annual Maturities) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	$ 3,406,000,000	$ 3,244,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	3,408,000,000
2,020	3,765,000,000
2,021	4,803,000,000
2,022	2,745,000,000
2,023	3,375,000,000
Thereafter	35,288,000,000
Total long-term debt, including current maturities	53,384,000,000
Purchase accounting adjustments	1,600,000,000	1,700,000,000
Other Debt Obligations [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	606,000,000
Purchase Accounting Adjustments [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Purchase accounting adjustments	$ (1,578,000,000)
Parent Company [Member] | Debt Maturing September 2019, 5.050% Coupon [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	5.05%
Current maturities of long-term debt	$ 500,000,000
Duke Energy Carolinas [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	6,000,000	1,205,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	6,000,000
2,020	907,000,000
2,021	503,000,000
2,022	353,000,000
2,023	1,303,000,000
Thereafter	7,940,000,000
Total long-term debt, including current maturities	11,012,000,000
Progress Energy [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	1,672,000,000	771,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	1,674,000,000
2,020	926,000,000
2,021	2,004,000,000
2,022	1,032,000,000
2,023	535,000,000
Thereafter	12,880,000,000
Total long-term debt, including current maturities	$ 19,051,000,000
Progress Energy [Member] | Debt Maturing March 2019, 7.050% Coupon [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	7.05%
Current maturities of long-term debt	$ 450,000,000
Duke Energy Progress [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	603,000,000	3,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	603,000,000
2,020	354,000,000
2,021	904,000,000
2,022	505,000,000
2,023	456,000,000
Thereafter	5,437,000,000
Total long-term debt, including current maturities	$ 8,259,000,000
Duke Energy Progress [Member] | Bonds Maturing January 2019, 5.300% Coupon [Member] | First Mortgage Bonds [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	5.30%
Current maturities of long-term debt	$ 600,000,000
Duke Energy Florida [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	270,000,000	768,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	270,000,000
2,020	572,000,000
2,021	600,000,000
2,022	77,000,000
2,023	79,000,000
Thereafter	5,793,000,000
Total long-term debt, including current maturities	7,391,000,000
Duke Energy Ohio [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	551,000,000	3,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	552,000,000
2,020	0
2,021	50,000,000
2,022	0
2,023	350,000,000
Thereafter	1,251,000,000
Total long-term debt, including current maturities	$ 2,203,000,000
Duke Energy Ohio [Member] | Bonds Maturing April 2019, 5.450% Coupon [Member] [Member] | First Mortgage Bonds [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	5.45%
Current maturities of long-term debt	$ 450,000,000
Duke Energy Indiana [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	63,000,000	3,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	63,000,000
2,020	503,000,000
2,021	70,000,000
2,022	94,000,000
2,023	153,000,000
Thereafter	2,925,000,000
Total long-term debt, including current maturities	3,808,000,000
Piedmont Natural Gas [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	350,000,000	$ 250,000,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	350,000,000
2,020	0
2,021	160,000,000
2,022	0
2,023	45,000,000
Thereafter	1,595,000,000
Total long-term debt, including current maturities	$ 2,150,000,000
Piedmont Natural Gas [Member] | Debt Maturing September 2019, 3.155% Coupon [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	3.155%
Current maturities of long-term debt	$ 350,000,000
Piedmont Natural Gas [Member] | Debt Maturing December 2019, 4.875% Coupon [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	4.875%
Current maturities of long-term debt	$ 350,000,000
Duke Energy Kentucky [Member] | Debt Maturing October 2019, 4.65% Coupon [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	4.65%
Current maturities of long-term debt	$ 100,000,000

Debt and Credit Facilities (Sch

Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Line of Credit Facility [Line Items]
Tax exempt bonds	$ (941,000,000)	$ (941,000,000)
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	8,000,000,000
Commercial Paper	(3,022,000,000)
Outstanding letters of credit	(53,000,000)
Tax exempt bonds	(81,000,000)
Coal ash set-aside	(500,000,000)
Available capacity	4,344,000,000
Parent Company [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	2,650,000,000
Commercial Paper	(917,000,000)
Outstanding letters of credit	(45,000,000)
Available capacity	1,688,000,000
Duke Energy Carolinas [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(243,000,000)	(243,000,000)
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	1,750,000,000
Commercial Paper	(739,000,000)
Outstanding letters of credit	(4,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	757,000,000
Duke Energy Progress [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(48,000,000)	(48,000,000)
Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	1,400,000,000
Commercial Paper	(444,000,000)
Outstanding letters of credit	(2,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	704,000,000
Duke Energy Florida [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	650,000,000
Commercial Paper	(108,000,000)
Outstanding letters of credit	0
Available capacity	542,000,000
Duke Energy Ohio [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(77,000,000)	(77,000,000)
Duke Energy Ohio [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	450,000,000
Commercial Paper	(299,000,000)
Available capacity	151,000,000
Duke Energy Indiana [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(572,000,000)	$ (572,000,000)
Duke Energy Indiana [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	600,000,000
Commercial Paper	(317,000,000)
Tax exempt bonds	(81,000,000)
Available capacity	202,000,000
Piedmont Natural Gas [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility Size	500,000,000
Commercial Paper	(198,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity	300,000,000
Proceeds Loaned To Subsidiary Registrants [Member] | Parent Company [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Commercial Paper	$ (625,000,000)

Guarantees and Indemnificatio_2

Guarantees and Indemnifications (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Oct. 31, 2017
Guarantor Obligations [Line Items]
Subsidiary debt guaranteed by parent	$ 650	$ 650
Unused letters of credit	60
Face value of guarantees	23	$ 21
Atlantic Coast Pipeline [Member]
Guarantor Obligations [Line Items]
Equity Method Investment Line Of Credit Facility Maximum Borrowing Capacity			$ 3,400
Surety Bond [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	63
Standby Letters Of Credit [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	454
Performance Guarantee [Member]
Guarantor Obligations [Line Items]
Maximum potential of future amounts associated with guarantees with expiration dates	248
Performance Guarantee [Member] | Less Than Wholly Owned Entity [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	11
Performance Guarantee [Member] | Third Parties, Unconsolidated Affiliates and Less Than Wholly Owned Consolidated Entities [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	296
Financial Guarantee [Member] | Atlantic Coast Pipeline [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	$ 677
Guarantee Obligations Maximum Exposure Percentage	47.00%
Spectra Capital [Member] | Performance Guarantee [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	$ 205

Joint Ownership of Generating_3

Joint Ownership of Generating and Transmission Facilities (Schedule Joint Ownership of Generating and Transmission Facilities) (Details) $ in Millions	Dec. 31, 2018USD ($)
Duke Energy Carolinas [Member] | Catawba (Units 1 and 2) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership interest	19.25%
Property, plant, and equipment	$ 989
Accumulated depreciation	483
Construction work in progress	$ 17
Duke Energy Carolinas [Member] | W.S. Lee CC [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership interest	86.67%
Property, plant, and equipment	$ 593
Accumulated depreciation	12
Construction work in progress	$ 4
Duke Energy Indiana [Member] | Gibson Station (Unit 5) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership interest	50.05%
Property, plant, and equipment	$ 390
Accumulated depreciation	173
Construction work in progress	$ 3
Duke Energy Indiana [Member] | Vermillion Generation Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Ownership interest	62.50%
Property, plant, and equipment	$ 168
Accumulated depreciation	135
Duke Energy Indiana [Member] | Transmission and local facilities [Member]
Jointly Owned Utility Plant Interests [Line Items]
Property, plant, and equipment	5,037
Accumulated depreciation	$ 1,769

Asset Retirement Obligations (R

Asset Retirement Obligations (Recorded on the Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	$ 10,467	$ 10,175	$ 10,611
Asset Retirement Obligation, Current	919	689
Asset Retirement Obligations, Noncurrent	9,548	9,486
Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	5,696
Closure of Ash Impoundments [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	4,446
Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	325
Duke Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	3,949	3,610	3,895
Asset Retirement Obligation, Current	290	337
Asset Retirement Obligations, Noncurrent	3,659	3,273
Duke Energy Carolinas [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,335
Duke Energy Carolinas [Member] | Closure of Ash Impoundments [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	1,568
Duke Energy Carolinas [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	46
Progress Energy [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	5,411	5,414	5,475
Asset Retirement Obligation, Current	514	295
Asset Retirement Obligations, Noncurrent	4,897	5,119
Progress Energy [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	3,209
Progress Energy [Member] | Closure of Ash Impoundments [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,123
Progress Energy [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	79
Duke Energy Progress [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	4,820	4,673	4,697
Asset Retirement Obligation, Current	509	295
Asset Retirement Obligations, Noncurrent	4,311	4,378
Duke Energy Progress [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,679
Duke Energy Progress [Member] | Closure of Ash Impoundments [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,103
Duke Energy Progress [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	38
Duke Energy Florida [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	591	742	778
Asset Retirement Obligation, Current	5
Asset Retirement Obligations, Noncurrent	586	742
Duke Energy Florida [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	530
Duke Energy Florida [Member] | Closure of Ash Impoundments [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	20
Duke Energy Florida [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	41
Duke Energy Ohio [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	93	84	77
Asset Retirement Obligation, Current	6	3
Asset Retirement Obligations, Noncurrent	87	81
Duke Energy Ohio [Member] | Closure of Ash Impoundments [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	52
Duke Energy Ohio [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	41
Duke Energy Indiana [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	722	781	866
Asset Retirement Obligation, Current	109	54
Asset Retirement Obligations, Noncurrent	613	727
Duke Energy Indiana [Member] | Closure of Ash Impoundments [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	702
Duke Energy Indiana [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	20
Piedmont Natural Gas [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	19	15	$ 14
Asset Retirement Obligations, Noncurrent	19	$ 15
Piedmont Natural Gas [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	$ 19

Asset Retirement Obligations (N

Asset Retirement Obligations (NDTF Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
NDTF Information [Abstract]
Annual funding requirement	$ 24
Decommissioning costs	8,737
Legally restricted NDTF investments, fair value	5,579	$ 5,864
Duke Energy Carolinas [Member]
NDTF Information [Abstract]
Decommissioning costs	4,291
Legally restricted NDTF investments, fair value	3,133	3,321
Progress Energy [Member]
NDTF Information [Abstract]
Annual funding requirement	24
Decommissioning costs	4,446
Legally restricted NDTF investments, fair value	2,446	2,543
Duke Energy Progress [Member]
NDTF Information [Abstract]
Annual funding requirement	24
Decommissioning costs	3,550
Legally restricted NDTF investments, fair value	2,446	$ 2,543
Duke Energy Florida [Member]
NDTF Information [Abstract]
Decommissioning costs	$ 896

Asset Retirement Obligations _2

Asset Retirement Obligations (Nuclear Operating Licenses) (Details)	12 Months Ended
	Dec. 31, 2018
Duke Energy Carolinas [Member] | Catawba Units 1 and 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,043
Duke Energy Carolinas [Member] | McGuire Unit 1 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,041
Duke Energy Carolinas [Member] | McGuire Unit 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,043
Duke Energy Carolinas [Member] | Oconee Units 1 and 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,033
Duke Energy Carolinas [Member] | Oconee Unit 3 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,034
Duke Energy Progress [Member] | Brunswick Unit 1 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,036
Duke Energy Progress [Member] | Brunswick Unit 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,034
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,046
Duke Energy Progress [Member] | Robinson Nuclear Station [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,030

Asset Retirement Obligations _3

Asset Retirement Obligations (Rollforward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligation [Line Items]
Beginning Balance	$ 10,175	$ 10,611
Accretion expense	427	435
Liabilities settled	(638)	(619)
Liabilities incurred in the current year	39	51
Revisions in estimates of cash flows	464	(303)
Ending Balance	10,467	10,175
Duke Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Beginning Balance	3,610	3,895
Accretion expense	179	184
Liabilities settled	(281)	(282)
Liabilities incurred in the current year	8	5
Revisions in estimates of cash flows	433	(192)
Ending Balance	3,949	3,610
Progress Energy [Member]
Asset Retirement Obligation [Line Items]
Beginning Balance	5,414	5,475
Accretion expense	225	228
Liabilities settled	(272)	(270)
Liabilities incurred in the current year	5
Revisions in estimates of cash flows	39	(19)
Ending Balance	5,411	5,414
Duke Energy Progress [Member]
Asset Retirement Obligation [Line Items]
Beginning Balance	4,673	4,697
Accretion expense	196	195
Liabilities settled	(227)	(204)
Revisions in estimates of cash flows	178	(15)
Ending Balance	4,820	4,673
Duke Energy Florida [Member]
Asset Retirement Obligation [Line Items]
Beginning Balance	742	778
Accretion expense	29	33
Liabilities settled	(45)	(65)
Liabilities incurred in the current year	5
Revisions in estimates of cash flows	(140)	(4)
Ending Balance	591	742
Duke Energy Ohio [Member]
Asset Retirement Obligation [Line Items]
Beginning Balance	84	77
Accretion expense	4	3
Liabilities settled	(5)	(7)
Liabilities incurred in the current year		7
Revisions in estimates of cash flows	10	4
Ending Balance	93	84
Duke Energy Indiana [Member]
Asset Retirement Obligation [Line Items]
Beginning Balance	781	866
Accretion expense	29	32
Liabilities settled	(79)	(49)
Liabilities incurred in the current year	25	29
Revisions in estimates of cash flows	(34)	(97)
Ending Balance	722	781
Piedmont Natural Gas [Member]
Asset Retirement Obligation [Line Items]
Beginning Balance	15	14
Accretion expense	1	1
Liabilities settled		(8)
Liabilities incurred in the current year		8
Revisions in estimates of cash flows	3
Ending Balance	$ 19	$ 15

Property, Plant and Equipment_2

Property, Plant and Equipment (Schedule Of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		$ 2,072	$ 1,559
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		4,675	4,498
Equipment		2,141	2,122
Construction in process		5,726	6,995
Total property, plant and equipment		134,458	127,507
Generation facilities to be retired, net		362	421
Total net property, plant and equipment		91,694	86,391
Asset Impairment Charges		402	282	$ 18
Capitalized leases		1,237	1,294
Accumulated amortization on capitalized leases		(61)	(57)
Capitalized Interest Costs [Abstract]
Capitalized interest		$ 161	$ 128	100
Commercial Renewables [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Asset Impairment Charges				71
Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Other, estimated useful life, in years		3 years	3 years
Equipment, estimated useful life, years		3 years	3 years
Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Other, estimated useful life, in years		40 years	40 years
Equipment, estimated useful life, years		55 years	55 years
Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Nuclear fuel		$ 3,460	$ 3,680
Accumulated depreciation and amortization		(1,947)	(2,113)
Variable Interest Entity, Primary Beneficiary [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment		4,007	3,941
Accumulated depreciation and amortization		(698)	(598)
Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(41,079)	(39,742)
Regulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		$ 100,706	$ 93,687
Regulated Operation [Member] | Electric Plant [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years		15 years	8 years
Regulated Operation [Member] | Electric Plant [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years		100 years	100 years
Regulated Operation [Member] | Natural Gas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		$ 8,808	$ 8,292
Regulated Operation [Member] | Natural Gas [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years		12 years	12 years
Regulated Operation [Member] | Natural Gas [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years		80 years	80 years
Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 1,966	$ 1,936
Regulated Operation [Member] | Other Buildings And Improvements [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Other, estimated useful life, in years		24 years	15 years
Regulated Operation [Member] | Other Buildings And Improvements [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Other, estimated useful life, in years		90 years	100 years
Nonregulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		$ (2,047)	$ (1,795)
Nonregulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		$ 4,410	$ 4,273
Nonregulated Operation [Member] | Electric Plant [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years		5 years	5 years
Nonregulated Operation [Member] | Electric Plant [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years		30 years	30 years
Nonregulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 494	$ 465
Nonregulated Operation [Member] | Other Buildings And Improvements [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Other, estimated useful life, in years		25 years	25 years
Nonregulated Operation [Member] | Other Buildings And Improvements [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Other, estimated useful life, in years		35 years	35 years
Duke Energy Carolinas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		$ 472	$ 467
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		1,077	1,032
Equipment		467	402
Construction in process		1,678	2,614
Total property, plant and equipment		44,741	42,939
Total net property, plant and equipment		29,245	27,876
Asset Impairment Charges		192		1
Capitalized leases		135	81
Accumulated amortization on capitalized leases		(12)	(11)
Capitalized Interest Costs [Abstract]
Capitalized interest		35	45	38
Duke Energy Carolinas [Member] | Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Nuclear fuel		1,898	2,120
Accumulated depreciation and amortization		(1,087)	(1,283)
Duke Energy Carolinas [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(15,496)	(15,063)
Duke Energy Carolinas [Member] | Regulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		38,468	35,657
Duke Energy Carolinas [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		681	647
Progress Energy [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		868	767
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		1,354	1,311
Equipment		565	555
Construction in process		2,515	3,059
Total property, plant and equipment		50,260	47,323
Generation facilities to be retired, net		362	421
Total net property, plant and equipment		34,224	31,887
Asset Impairment Charges		87	156	7
Capitalized leases net of accumulated amortization		257	272
Accumulated amortization on capitalized leases		(131)	(114)
Capitalized Interest Costs [Abstract]
Capitalized interest		51	45	31
Progress Energy [Member] | Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Nuclear fuel		1,562	1,560
Accumulated depreciation and amortization		(860)	(831)
Progress Energy [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(16,398)	(15,857)
Progress Energy [Member] | Regulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		42,760	39,419
Progress Energy [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		636	652
Duke Energy Progress [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		445	424
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		952	931
Equipment		399	416
Construction in process		1,659	1,434
Total property, plant and equipment		31,459	29,583
Generation facilities to be retired, net		362	421
Total net property, plant and equipment		20,398	19,101
Asset Impairment Charges		33	19	1
Capitalized leases net of accumulated amortization		137	139
Accumulated amortization on capitalized leases		(14)	(11)
Capitalized Interest Costs [Abstract]
Capitalized interest		26	21	17
Duke Energy Progress [Member] | Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Nuclear fuel		1,562	1,560
Accumulated depreciation and amortization		(860)	(831)
Duke Energy Progress [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(11,423)	(10,903)
Duke Energy Progress [Member] | Regulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		26,147	24,502
Duke Energy Progress [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		295	316
Duke Energy Florida [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		423	343
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		393	370
Equipment		166	139
Construction in process		856	1,625
Total property, plant and equipment		18,792	17,730
Total net property, plant and equipment		13,824	12,783
Asset Impairment Charges		54	138	6
Capitalized leases net of accumulated amortization		120	133
Accumulated amortization on capitalized leases		(117)	(103)
Capitalized Interest Costs [Abstract]
Capitalized interest		25	24	14
Duke Energy Florida [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(4,968)	(4,947)
Duke Energy Florida [Member] | Regulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		16,613	14,917
Duke Energy Florida [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		341	336
Duke Energy Ohio [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		136	134
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		257	228
Equipment		384	348
Construction in process		412	350
Total property, plant and equipment		9,360	8,732
Total net property, plant and equipment		6,643	6,041
Asset Impairment Charges			1
Capitalized leases		73	80
Accumulated amortization on capitalized leases		(20)	(21)
Capitalized Interest Costs [Abstract]
Capitalized interest		17	10	8
Duke Energy Ohio [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(2,717)	(2,691)
Duke Energy Ohio [Member] | Regulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		5,182	4,870
Duke Energy Ohio [Member] | Regulated Operation [Member] | Natural Gas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		2,719	2,559
Duke Energy Ohio [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		270	243
Duke Energy Indiana [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		116	111
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		279	271
Equipment		178	169
Construction in process		325	416
Total property, plant and equipment		15,443	14,948
Total net property, plant and equipment		10,529	10,286
Asset Impairment Charges		30	18	8
Capitalized leases		35	35
Accumulated amortization on capitalized leases		(10)	(9)
Capitalized Interest Costs [Abstract]
Capitalized interest		27	9	7
Duke Energy Indiana [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(4,914)	(4,662)
Duke Energy Indiana [Member] | Regulated Operation [Member] | Electric Plant [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		14,292	13,741
Duke Energy Indiana [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		253	240
Piedmont Natural Gas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land		448	41
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		300	300
Equipment		141	266
Construction in process		382	231
Total property, plant and equipment		7,486	6,725
Total net property, plant and equipment		5,911	5,246
Asset Impairment Charges			7
Capitalized Interest Costs [Abstract]
Capitalized interest	$ 12	17		$ 12	$ 2
Piedmont Natural Gas [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Accumulated depreciation and amortization		(1,575)	(1,479)
Piedmont Natural Gas [Member] | Regulated Operation [Member] | Natural Gas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution		6,089	5,733
Piedmont Natural Gas [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment		$ 126	154
Property, Plant and Equipment [Member] | Commercial Renewables [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Asset Impairment Charges			$ 58

Property, Plant and Equipment_3

Property, Plant and Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	$ 402	$ 282	$ 18
Commercial Renewables [Member]
Property, Plant and Equipment [Line Items]
Asset Impairment Charges			71
Property, Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	58
Finite-Lived Intangible Assets [Member]
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	11
Assets Leased to Others [Member] | Commercial Renewables [Member]
Property, Plant and Equipment [Line Items]
Contingent lease payments	268	$ 262	$ 216
Renewable energy projects	3,358
Accumulated depreciation and amortization	(602)
Wind Project [Member]
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	$ 69

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets (Goodwill By Reportable Operating Segment) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Gross		$ 19,425	$ 19,425
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		19,396
Goodwill, Impaired, Accumulated Impairment Loss		(122)	(29)
Goodwill, balance at end of period		19,303
Electric Utilities and Infrastructure [Member]
Goodwill [Line Items]
Goodwill, Gross		17,379	17,379
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		17,379
Goodwill, balance at end of period		17,379
Gas Utilities and Infrastructure [Member]
Goodwill [Line Items]
Goodwill, Gross		1,924	1,924
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		1,924
Goodwill, balance at end of period		1,924
Commercial Renewables [Member]
Goodwill [Line Items]
Goodwill, Gross		122	122
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		93
Goodwill, Impaired, Accumulated Impairment Loss		(122)	(29)
Goodwill, Impairment Loss	$ 93	29
Duke Energy Ohio [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		920
Goodwill, Impaired, Accumulated Impairment Loss		(216)	$ (216)
Goodwill, balance at end of period		920
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		596
Goodwill, balance at end of period		596
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		324
Goodwill, balance at end of period		324
Progress Energy [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		3,655
Goodwill, balance at end of period		3,655
Piedmont Natural Gas [Member]
Goodwill [Roll Forward]
Goodwill, balance at beginning of period		49
Goodwill, balance at end of period		$ 49

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	$ 300	$ 276
Accumulated amortization	(54)	(46)
Total intangible assets, net	246	230
Asset Impairment Charges	402	282	$ 18
Wind Project [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Asset Impairment Charges	69
Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	18	19
Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	168	148
Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	(20)	(19)
Renewable Operating and Development Projects [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	84	79
Accumulated amortization	(29)	(22)
Asset Impairment Charges		69
Renewable Operating and Development Projects [Member] | Property, Plant and Equipment [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Asset Impairment Charges		58
Renewable Operating and Development Projects [Member] | Finite-Lived Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Asset Impairment Charges		11
Renewable Operating and Development Projects [Member] | Wind Project [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount		18
Accumulated amortization		(7)
Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	6	6
Accumulated amortization	(5)	(5)
Duke Energy Carolinas [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	46	39
Total intangible assets, net	46	39
Asset Impairment Charges	192		1
Duke Energy Carolinas [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0	1
Duke Energy Carolinas [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	46	38
Progress Energy [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	125	112
Total intangible assets, net	125	112
Asset Impairment Charges	87	156	7
Progress Energy [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	5	5
Progress Energy [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	120	107
Duke Energy Progress [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	122	109
Total intangible assets, net	122	109
Asset Impairment Charges	33	19	1
Duke Energy Progress [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	2	2
Duke Energy Progress [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	120	107
Duke Energy Florida [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Total intangible assets, net	3	3
Asset Impairment Charges	54	138	6
Duke Energy Florida [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Duke Energy Ohio [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	2	3
Total intangible assets, net	2	3
Asset Impairment Charges		1
Duke Energy Ohio [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0	0
Duke Energy Ohio [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	2	3
Duke Energy Ohio [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	0	0
Accumulated amortization	0	0
Duke Energy Indiana [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	36	37
Accumulated amortization	(20)	(19)
Total intangible assets, net	16	18
Asset Impairment Charges	30	18	$ 8
Duke Energy Indiana [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	12	13
Duke Energy Indiana [Member] | Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	(20)	(19)
Piedmont Natural Gas [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Accumulated amortization	(3)	(3)
Asset Impairment Charges		7
Piedmont Natural Gas [Member] | Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	3	3
Accumulated amortization	$ (3)	$ (3)

Investments in Unconsolidated_3

Investments in Unconsolidated Affiliates (Narrative) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016	Oct. 03, 2016
Investments In Unconsolidated Affiliates [Line Items]
Distributions from equity investments		$ 108	$ 13	$ 31
Distributions from equity investments, return of capital		137	281	1
Income (Loss) from Equity Method Investments		83	119	(15)
Asset Impairment Charges		402	282	18
Atlantic Coast Pipeline [Member]
Investments In Unconsolidated Affiliates [Line Items]
Distributions from equity investments, return of capital		265
Electric Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Income (Loss) from Equity Method Investments		$ 6	5	5
Electric Utilities and Infrastructure [Member] | Duke American Transmission Co. [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage		50.00%
Electric Utilities and Infrastructure [Member] | Pioneer Transmission [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage		50.00%
Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Income (Loss) from Equity Method Investments		$ 27	62	19
Gas Utilities and Infrastructure [Member] | Atlantic Coast Pipeline [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage		47.00%
Gas Utilities and Infrastructure [Member] | Constitution Pipeline [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage		24.00%
Commercial Renewables [Member]
Investments In Unconsolidated Affiliates [Line Items]
Income (Loss) from Equity Method Investments		$ (1)	(5)	(82)
Asset Impairment Charges				71
Commercial Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Investments In Unconsolidated Affiliates [Line Items]
Asset Impairment Charges				71
Commercial Renewables [Member] | DS Cornerstone [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage		50.00%
Other [Member]
Investments In Unconsolidated Affiliates [Line Items]
Income (Loss) from Equity Method Investments		$ 51	$ 57	$ 43
Other [Member] | National Methanol Company [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage		17.50%	25.00%
Board representation and voting rights, ownership percentage		25.00%
Piedmont Natural Gas [Member]
Investments In Unconsolidated Affiliates [Line Items]
Distributions from equity investments	$ 1	$ 1	$ 4		$ 26
Distributions from equity investments, return of capital	1	3	2		18
Income (Loss) from Equity Method Investments	$ 2	$ 7	(6)		29
Asset Impairment Charges			$ 7
Piedmont Natural Gas [Member] | SouthStar [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity Method Investment Ownership Percentage Sold						15.00%
Proceeds from Sale of Equity Method Investments					160
Gain on Sale of Investments					81
Income (Loss) from Equity Method Investments					$ 19

Investments in Unconsolidated_4

Investments in Unconsolidated Affiliates (Investments in Equity Method Unconsolidated Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,409	$ 1,175	$ 925
Equity in earnings (losses) of unconsolidated affiliates	83	119	(15)
Electric Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	97	89	93
Equity in earnings (losses) of unconsolidated affiliates	6	5	5
Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	1,003	763	566
Equity in earnings (losses) of unconsolidated affiliates	27	62	19
Commercial Renewables [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	201	190	185
Equity in earnings (losses) of unconsolidated affiliates	(1)	(5)	(82)
Other [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	108	133	81
Equity in earnings (losses) of unconsolidated affiliates	$ 51	$ 57	$ 43

Investments in Unconsolidated_5

Investments in Unconsolidated Affiliates (Gas Utilities and Infrastructure Investments) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	$ 925	$ 1,409	$ 1,175	$ 925
Return of investment capital		137	281	1
Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates	566	1,003	763	$ 566
Atlantic Coast Pipeline [Member]
Investments In Unconsolidated Affiliates [Line Items]
Return of investment capital		$ 265
Atlantic Coast Pipeline [Member] | Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity Method Investment, Ownership Percentage		47.00%
Investments in equity method unconsolidated affiliates		$ 797	397
Sabal Trail Transmission Pipeline [Member] | Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity Method Investment, Ownership Percentage		7.50%
Investments in equity method unconsolidated affiliates		$ 112	219
Return of investment capital		$ 112
Constitution Pipeline [Member] | Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity Method Investment, Ownership Percentage		24.00%
Investments in equity method unconsolidated affiliates		$ 25	81
Piedmont Natural Gas [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in equity method unconsolidated affiliates		64	61
Return of investment capital	$ 1	$ 3	2		$ 18
Piedmont Natural Gas [Member] | Cardinal Pipeline Company, LLC [Member] | Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity Method Investment, Ownership Percentage		21.49%
Investments in equity method unconsolidated affiliates		$ 10	11
Piedmont Natural Gas [Member] | Pine Needle LNG Company, LLC [Member] | Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity Method Investment, Ownership Percentage		45.00%
Investments in equity method unconsolidated affiliates		$ 13	13
Piedmont Natural Gas [Member] | Hardy Storage Company, LLC [Member] | Gas Utilities and Infrastructure [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity Method Investment, Ownership Percentage		50.00%
Investments in equity method unconsolidated affiliates		$ 46	$ 42

Related Party Transactions (Oth

Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	12 Months Ended
	Oct. 31, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Duke Energy Carolinas [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			$ 985	$ 858	$ 831
Duke Energy Carolinas [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			22	23	22
Duke Energy Carolinas [Member] | Joint Dispatch Agreement (JDA) [Member] | Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party			84	49	38
Related party transaction, expenses from transactions with related party			207	145	156
Duke Energy Carolinas [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			15	9	2
Progress Energy [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			906	736	710
Progress Energy [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			34	38	35
Progress Energy [Member] | Joint Dispatch Agreement (JDA) [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party			207	145	156
Related party transaction, expenses from transactions with related party			84	49	38
Progress Energy [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			78	77	19
Duke Energy Progress [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			577	438	397
Duke Energy Progress [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			13	15	14
Duke Energy Progress [Member] | Joint Dispatch Agreement (JDA) [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party			207	145	156
Related party transaction, expenses from transactions with related party			84	49	38
Duke Energy Progress [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			78	77	19
Duke Energy Florida [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			329	298	313
Duke Energy Florida [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			21	23	21
Duke Energy Ohio [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			374	363	356
Duke Energy Ohio [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			5	5	5
Duke Energy Indiana [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			405	370	366
Duke Energy Indiana [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			7	8	$ 8
Piedmont Natural Gas [Member] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			170	50
Piedmont Natural Gas [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party			2	2
Piedmont Natural Gas [Member] | Intercompany Natural Gas Transactions [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	$ 7	$ 14				$ 74
Piedmont Natural Gas [Member] | Intercompany Natural Gas Transactions [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party			93	86
Piedmont Natural Gas [Member] | Natural Gas Storage And Transportation Costs [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party		$ 6	$ 25	$ 25		$ 29

Related Party Transactions (Int

Related Party Transactions (Intercompany Income Taxes) (Details) - Affiliated Entity [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Accrued Income Taxes, Current		$ 44
Income taxes receivable, current	$ 52
Progress Energy [Member]
Related Party Transaction [Line Items]
Income taxes receivable, current	47	168
Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Accrued Income Taxes, Current		21
Income taxes receivable, current	29
Duke Energy Florida [Member]
Related Party Transaction [Line Items]
Accrued Income Taxes, Current	16
Income taxes receivable, current		44
Duke Energy Ohio [Member]
Related Party Transaction [Line Items]
Accrued Income Taxes, Current	3
Income taxes receivable, current		22
Duke Energy Indiana [Member]
Related Party Transaction [Line Items]
Accrued Income Taxes, Current		35
Income taxes receivable, current	8
Piedmont Natural Gas [Member]
Related Party Transaction [Line Items]
Accrued Income Taxes, Current	$ 45
Income taxes receivable, current		$ 7

Derivatives and Hedging (Notion

Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)GWhMcf	Dec. 31, 2017USD ($)GWhMcf	Dec. 31, 2016USD ($)	Aug. 31, 2016USD ($)
Interest Rate Contract [Member]
Derivative [Line Items]
Notional Amount	$ 2,644	$ 1,587
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	923	660
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	$ 1,721	$ 927
Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	15,286	34
Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume in millions of decatherms | Mcf	739	770
Variable Interest Entity, Primary Beneficiary [Member] | Interest Rate Contract [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	$ 422	$ 660
Variable Interest Entity, Primary Beneficiary [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	194
Piedmont Natural Gas [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Loss on Interest Rate Derivative Instruments Not Designated as Hedging Instruments			$ 190
Piedmont Natural Gas [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount				$ 1,400
Duke Energy Carolinas [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional Amount	300	400
Duke Energy Carolinas [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	$ 300	$ 400
Duke Energy Carolinas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume in millions of decatherms | Mcf	121	105
Progress Energy [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional Amount	$ 1,200	$ 500
Progress Energy [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	$ 1,200	$ 500
Progress Energy [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume in millions of decatherms | Mcf	169	183
Duke Energy Progress [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional Amount	$ 650	$ 250
Duke Energy Progress [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	$ 650	$ 250
Duke Energy Progress [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume in millions of decatherms | Mcf	166	133
Duke Energy Florida [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional Amount	$ 550	$ 250
Duke Energy Florida [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	$ 550	$ 250
Duke Energy Florida [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume in millions of decatherms | Mcf	3	50
Duke Energy Ohio [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional Amount	$ 27	$ 27
Duke Energy Ohio [Member] | Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional Amount	$ 27	$ 27
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	1,786
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	13,500	34
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume in millions of decatherms | Mcf	1	2
Piedmont Natural Gas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume in millions of decatherms | Mcf	448	480

Derivatives and Hedging (Locati

Derivatives and Hedging (Location and Fair Value Amounts of Derivatives Reflected in the Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	$ 57	$ 51
Location and fair value amounts of derivatives (Liability)	242	230
Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	38	35
Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	19	16
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	68	66
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	174	164
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	39	35
Location and fair value amounts of derivatives (Liability)	191	182
Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	18	16
Location and fair value amounts of derivatives (Liability)	51	48
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	1
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	15
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	12	29
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	6
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	35	34
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	1
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	33	36
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	158	146
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	23	1
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	10	12
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Current [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Investments And Other Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12
Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	2
Location and fair value amounts of derivatives (Liability)	33	35
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	2
Duke Energy Carolinas [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1
Duke Energy Carolinas [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	23	31
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	10	4
Duke Energy Carolinas [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	2
Location and fair value amounts of derivatives (Liability)	24	10
Duke Energy Carolinas [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	9	25
Duke Energy Carolinas [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		25
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	2
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	14	6
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	10	4
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	9
Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	3
Location and fair value amounts of derivatives (Liability)	44	36
Progress Energy [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	2
Progress Energy [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	1
Progress Energy [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	23	19
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	21	17
Progress Energy [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	3
Location and fair value amounts of derivatives (Liability)	25	28
Progress Energy [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	19	8
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	2
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	1
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	10	18
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	15	10
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	13	1
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	7
Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	2
Location and fair value amounts of derivatives (Liability)	27	18
Duke Energy Progress [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	1
Duke Energy Progress [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	1
Duke Energy Progress [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	16	8
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	11	10
Duke Energy Progress [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4	2
Location and fair value amounts of derivatives (Liability)	11	12
Duke Energy Progress [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	16	6
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	1
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	1
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5	8
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	4
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	11
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5	6
Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Location and fair value amounts of derivatives (Liability)	9	12
Duke Energy Florida [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	8	10
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	2
Duke Energy Florida [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Location and fair value amounts of derivatives (Liability)	6	10
Duke Energy Florida [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	3	2
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	10
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	2
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	2
Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Location and fair value amounts of derivatives (Liability)	5	5
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Duke Energy Ohio [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	1
Duke Energy Ohio [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	4
Duke Energy Ohio [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Duke Energy Ohio [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5	5
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	1
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	1
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	4
Duke Energy Indiana [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	23	27
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	23	27
Duke Energy Indiana [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	23	27
Duke Energy Indiana [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	23	27
Piedmont Natural Gas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	2
Location and fair value amounts of derivatives (Liability)	141	142
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	2
Piedmont Natural Gas [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	8	11
Piedmont Natural Gas [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	133	131
Piedmont Natural Gas [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	2
Location and fair value amounts of derivatives (Liability)	141	142
Piedmont Natural Gas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	2
Piedmont Natural Gas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)
Piedmont Natural Gas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	8	11
Piedmont Natural Gas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	$ 133	$ 131

Derivatives and Hedging (Schedu

Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Offsetting Assets [Line Items]
Gross amounts recognized	$ 57	$ 51
Net amounts presented on Balance Sheets	57	51
Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	38	35
Gross amounts offset	(3)
Net amounts presented on Balance Sheets	35	35
Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	19	16
Gross amounts offset	(3)
Net amounts presented on Balance Sheets	16	16
Duke Energy Carolinas [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	3	2
Net amounts presented on Balance Sheets	3	2
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	2
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		2
Duke Energy Carolinas [Member] | Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	1
Gross amounts offset	(1)
Progress Energy [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	4	3
Net amounts presented on Balance Sheets	4	3
Progress Energy [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	2
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		2
Progress Energy [Member] | Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	1
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		1
Duke Energy Progress [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	4	2
Net amounts presented on Balance Sheets	4	2
Duke Energy Progress [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	1
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		1
Duke Energy Progress [Member] | Other Noncurrent Assets [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	2	1
Gross amounts offset	(2)
Net amounts presented on Balance Sheets		1
Duke Energy Florida [Member]
Offsetting Assets [Line Items]
Gross amounts recognized		1
Net amounts presented on Balance Sheets		1
Duke Energy Florida [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized		1
Net amounts presented on Balance Sheets		1
Duke Energy Ohio [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	6	1
Net amounts presented on Balance Sheets	6	1
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	6	1
Net amounts presented on Balance Sheets	6	1
Duke Energy Indiana [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	23	27
Net amounts presented on Balance Sheets	23	27
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	23	27
Net amounts presented on Balance Sheets	23	27
Piedmont Natural Gas [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	3	2
Net amounts presented on Balance Sheets	3	2
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Offsetting Assets [Line Items]
Gross amounts recognized	3	2
Net amounts presented on Balance Sheets	$ 3	$ 2

Derivatives and Hedging (Sche_2

Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Offsetting Liabilities [Line Items]
Gross amounts recognized	$ 242	$ 230
Net amounts presented on Balance Sheets	242	230
Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	68	66
Gross amounts offset	(4)	(3)
Net amounts presented on Balance Sheets	64	63
Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	174	164
Gross amounts offset	(3)	(1)
Net amounts presented on Balance Sheets	171	163
Duke Energy Carolinas [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	33	35
Net amounts presented on Balance Sheets	33	35
Duke Energy Carolinas [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	23	31
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	21	29
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	10	4
Gross amounts offset	(1)
Net amounts presented on Balance Sheets	9	4
Progress Energy [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	44	36
Net amounts presented on Balance Sheets	44	36
Progress Energy [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	23	19
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	21	17
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	21	17
Gross amounts offset	(2)	(1)
Net amounts presented on Balance Sheets	19	16
Duke Energy Progress [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	27	18
Net amounts presented on Balance Sheets	27	18
Duke Energy Progress [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	16	8
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	14	6
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	11	10
Gross amounts offset	(2)	(1)
Net amounts presented on Balance Sheets	9	9
Duke Energy Florida [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	9	12
Net amounts presented on Balance Sheets	9	12
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	8	10
Net amounts presented on Balance Sheets	8	10
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	2
Net amounts presented on Balance Sheets	1	2
Duke Energy Ohio [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	5	5
Net amounts presented on Balance Sheets	5	5
Duke Energy Ohio [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	1	1
Net amounts presented on Balance Sheets	1	1
Duke Energy Ohio [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	4	4
Net amounts presented on Balance Sheets	4	4
Piedmont Natural Gas [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	141	142
Net amounts presented on Balance Sheets	141	142
Piedmont Natural Gas [Member] | Other Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	8	11
Net amounts presented on Balance Sheets	8	11
Piedmont Natural Gas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross amounts recognized	133	131
Net amounts presented on Balance Sheets	$ 133	$ 131

Derivatives and Hedging (Deriva

Derivatives and Hedging (Derivative Instruments That Contain Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	$ 44	$ 59
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	44	59
Duke Energy Carolinas [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	19	35
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	19	35
Progress Energy [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	25	25
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	25	25
Duke Energy Progress [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	25	15
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	$ 25	15
Duke Energy Florida [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position		10
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered		$ 10

Investments in Debt and Equit_3

Investments in Debt and Equity Securities (Estimated Fair Value of Investments in Debt and Equity Securities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Available-for-sale Securities
Gross Unrealized Holding Gains		$ 2,899
Gross Unrealized Holding Losses		42
Estimated Fair Value		7,451
Debt Securities, Available-for-sale
Estimated Fair Value	$ 2,391
Total Investments
Unrealized Holding Gains	2,458
Unrealized Holding Losses	131
Estimated Fair Value	7,075
NDTF [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	88
Available-for-sale Securities
Gross Unrealized Holding Gains		2,837
Gross Unrealized Holding Losses		40
Estimated Fair Value		7,088
Equity Securities, FV-NI
Gross Unrealized Holding Gains	2,402
Gross Unrealized Holding Losses	95
Estimated Fair Value	4,475
Debt Securities, Available-for-sale
Estimated Fair Value	2,231
Total Investments
Unrealized Holding Gains	2,421
Unrealized Holding Losses	126
Estimated Fair Value	6,706
NDTF [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		115
NDTF [Member] | Equity Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		2,805
Gross Unrealized Holding Losses		27
Estimated Fair Value		4,914
NDTF [Member] | Corporate Debt Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		17
Gross Unrealized Holding Losses		2
Estimated Fair Value		570
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	4
Gross Unrealized Holding Losses	13
Estimated Fair Value	566
NDTF [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		4
Gross Unrealized Holding Losses		3
Estimated Fair Value		344
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1
Gross Unrealized Holding Losses	4
Estimated Fair Value	353
NDTF [Member] | US Treasury and Government [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		11
Gross Unrealized Holding Losses		7
Estimated Fair Value		1,027
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	14
Gross Unrealized Holding Losses	12
Estimated Fair Value	1,076
NDTF [Member] | Other Debt Obligations [Member]
Available-for-sale Securities
Gross Unrealized Holding Losses		1
Estimated Fair Value		118
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	2
Estimated Fair Value	148
Other Classification [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	22
Available-for-sale Securities
Gross Unrealized Holding Gains		62
Gross Unrealized Holding Losses		2
Estimated Fair Value		363
Equity Securities, FV-NI
Gross Unrealized Holding Gains	36
Gross Unrealized Holding Losses	1
Estimated Fair Value	99
Debt Securities, Available-for-sale
Estimated Fair Value	270
Total Investments
Unrealized Holding Gains	37
Unrealized Holding Losses	5
Estimated Fair Value	369
Other Classification [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		15
Other Classification [Member] | Equity Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		59
Estimated Fair Value		123
Other Classification [Member] | Corporate Debt Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		1
Estimated Fair Value		57
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	2
Estimated Fair Value	60
Other Classification [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		2
Gross Unrealized Holding Losses		1
Estimated Fair Value		83
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	1
Estimated Fair Value	85
Other Classification [Member] | US Treasury and Government [Member]
Available-for-sale Securities
Estimated Fair Value		41
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1
Estimated Fair Value	45
Other Classification [Member] | Other Debt Obligations [Member]
Available-for-sale Securities
Gross Unrealized Holding Losses		1
Estimated Fair Value		44
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	58
Duke Energy Carolinas [Member]
Debt Securities, Available-for-sale
Estimated Fair Value	1,040
Duke Energy Carolinas [Member] | NDTF [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	29
Available-for-sale Securities
Gross Unrealized Holding Gains		1,543
Gross Unrealized Holding Losses		20
Estimated Fair Value		3,758
Equity Securities, FV-NI
Gross Unrealized Holding Gains	1,309
Gross Unrealized Holding Losses	54
Estimated Fair Value	2,484
Debt Securities, Available-for-sale
Estimated Fair Value	1,069
Total Investments
Unrealized Holding Gains	1,316
Unrealized Holding Losses	74
Estimated Fair Value	3,553
Duke Energy Carolinas [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		32
Duke Energy Carolinas [Member] | NDTF [Member] | Equity Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		1,531
Gross Unrealized Holding Losses		12
Estimated Fair Value		2,692
Duke Energy Carolinas [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		9
Gross Unrealized Holding Losses		2
Estimated Fair Value		359
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2
Gross Unrealized Holding Losses	9
Estimated Fair Value	341
Duke Energy Carolinas [Member] | NDTF [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Losses		1
Estimated Fair Value		60
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	1
Estimated Fair Value	81
Duke Energy Carolinas [Member] | NDTF [Member] | US Treasury and Government [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses		4
Estimated Fair Value		503
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	5
Gross Unrealized Holding Losses	8
Estimated Fair Value	475
Duke Energy Carolinas [Member] | NDTF [Member] | Other Debt Obligations [Member]
Available-for-sale Securities
Gross Unrealized Holding Losses		1
Estimated Fair Value		112
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	2
Estimated Fair Value	143
Progress Energy [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		1,296
Gross Unrealized Holding Losses		20
Estimated Fair Value		3,389
Debt Securities, Available-for-sale
Estimated Fair Value	1,150
Total Investments
Unrealized Holding Gains	1,105
Unrealized Holding Losses	52
Estimated Fair Value	3,217
Progress Energy [Member] | NDTF [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	59
Available-for-sale Securities
Gross Unrealized Holding Gains		1,294
Gross Unrealized Holding Losses		20
Estimated Fair Value		3,330
Equity Securities, FV-NI
Gross Unrealized Holding Gains	1,093
Gross Unrealized Holding Losses	41
Estimated Fair Value	1,991
Debt Securities, Available-for-sale
Estimated Fair Value	1,162
Total Investments
Unrealized Holding Gains	1,105
Unrealized Holding Losses	52
Estimated Fair Value	3,153
Progress Energy [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		83
Progress Energy [Member] | NDTF [Member] | Equity Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		1,274
Gross Unrealized Holding Losses		15
Estimated Fair Value		2,222
Progress Energy [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		8
Estimated Fair Value		211
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2
Gross Unrealized Holding Losses	4
Estimated Fair Value	225
Progress Energy [Member] | NDTF [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		4
Gross Unrealized Holding Losses		2
Estimated Fair Value		284
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1
Gross Unrealized Holding Losses	3
Estimated Fair Value	272
Progress Energy [Member] | NDTF [Member] | US Treasury and Government [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		8
Gross Unrealized Holding Losses		3
Estimated Fair Value		524
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	9
Gross Unrealized Holding Losses	4
Estimated Fair Value	601
Progress Energy [Member] | NDTF [Member] | Other Debt Obligations [Member]
Available-for-sale Securities
Estimated Fair Value		6
Debt Securities, Available-for-sale
Estimated Fair Value	5
Progress Energy [Member] | Other Classification [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	17
Available-for-sale Securities
Gross Unrealized Holding Gains		2
Estimated Fair Value		59
Debt Securities, Available-for-sale
Estimated Fair Value	64
Total Investments
Unrealized Holding Gains	0
Estimated Fair Value	64
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		12
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		2
Estimated Fair Value		47
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Estimated Fair Value	47
Duke Energy Progress [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		995
Gross Unrealized Holding Losses		16
Estimated Fair Value		2,592
Debt Securities, Available-for-sale
Estimated Fair Value	860
Total Investments
Unrealized Holding Gains	842
Unrealized Holding Losses	39
Estimated Fair Value	2,500
Duke Energy Progress [Member] | NDTF [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	46
Available-for-sale Securities
Gross Unrealized Holding Gains		995
Gross Unrealized Holding Losses		16
Estimated Fair Value		2,591
Equity Securities, FV-NI
Gross Unrealized Holding Gains	833
Gross Unrealized Holding Losses	30
Estimated Fair Value	1,588
Debt Securities, Available-for-sale
Estimated Fair Value	906
Total Investments
Unrealized Holding Gains	842
Unrealized Holding Losses	39
Estimated Fair Value	2,494
Duke Energy Progress [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		50
Duke Energy Progress [Member] | NDTF [Member] | Equity Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		980
Gross Unrealized Holding Losses		12
Estimated Fair Value		1,795
Duke Energy Progress [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		6
Estimated Fair Value		149
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	2
Gross Unrealized Holding Losses	3
Estimated Fair Value	171
Duke Energy Progress [Member] | NDTF [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		4
Gross Unrealized Holding Losses		2
Estimated Fair Value		283
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	1
Gross Unrealized Holding Losses	3
Estimated Fair Value	271
Duke Energy Progress [Member] | NDTF [Member] | US Treasury and Government [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		5
Gross Unrealized Holding Losses		2
Estimated Fair Value		310
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	6
Gross Unrealized Holding Losses	3
Estimated Fair Value	415
Duke Energy Progress [Member] | NDTF [Member] | Other Debt Obligations [Member]
Available-for-sale Securities
Estimated Fair Value		4
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Estimated Fair Value	3
Duke Energy Progress [Member] | Other Classification [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	6
Available-for-sale Securities
Estimated Fair Value		1
Debt Securities, Available-for-sale
Estimated Fair Value	6
Total Investments
Estimated Fair Value	6
Duke Energy Progress [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		1
Duke Energy Florida [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		301
Gross Unrealized Holding Losses		4
Estimated Fair Value		787
Debt Securities, Available-for-sale
Estimated Fair Value	290
Total Investments
Unrealized Holding Gains	263
Unrealized Holding Losses	13
Estimated Fair Value	707
Duke Energy Florida [Member] | NDTF [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	13
Available-for-sale Securities
Gross Unrealized Holding Gains		299
Gross Unrealized Holding Losses		4
Estimated Fair Value		739
Equity Securities, FV-NI
Gross Unrealized Holding Gains	260
Gross Unrealized Holding Losses	11
Estimated Fair Value	403
Debt Securities, Available-for-sale
Estimated Fair Value	256
Total Investments
Unrealized Holding Gains	263
Unrealized Holding Losses	13
Estimated Fair Value	659
Duke Energy Florida [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		33
Duke Energy Florida [Member] | NDTF [Member] | Equity Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		294
Gross Unrealized Holding Losses		3
Estimated Fair Value		427
Duke Energy Florida [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		2
Estimated Fair Value		62
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	1
Estimated Fair Value	54
Duke Energy Florida [Member] | NDTF [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Estimated Fair Value		1
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Estimated Fair Value	1
Duke Energy Florida [Member] | NDTF [Member] | US Treasury and Government [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		3
Gross Unrealized Holding Losses		1
Estimated Fair Value		214
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	3
Gross Unrealized Holding Losses	1
Estimated Fair Value	186
Duke Energy Florida [Member] | NDTF [Member] | Other Debt Obligations [Member]
Available-for-sale Securities
Estimated Fair Value		2
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Gross Unrealized Holding Losses	0
Estimated Fair Value	2
Duke Energy Florida [Member] | Other Classification [Member]
Investment [Line Items]
Cash And Cash Equivalent Investments	1
Available-for-sale Securities
Gross Unrealized Holding Gains		2
Estimated Fair Value		48
Debt Securities, Available-for-sale
Estimated Fair Value	48
Total Investments
Estimated Fair Value	48
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Available-for-sale Securities
Estimated Fair Value		1
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		2
Estimated Fair Value		47
Debt Securities, Available-for-sale
Gross Unrealized Holding Gains	0
Estimated Fair Value	47
Duke Energy Indiana [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		49
Gross Unrealized Holding Losses		1
Estimated Fair Value		128
Equity Securities, FV-NI
Gross Unrealized Holding Gains	29
Estimated Fair Value	67
Debt Securities, Available-for-sale
Estimated Fair Value	41
Total Investments
Unrealized Holding Gains	29
Unrealized Holding Losses	1
Estimated Fair Value	108
Duke Energy Indiana [Member] | Equity Securities [Member]
Available-for-sale Securities
Gross Unrealized Holding Gains		49
Estimated Fair Value		97
Duke Energy Indiana [Member] | Corporate Debt Securities [Member]
Available-for-sale Securities
Estimated Fair Value		3
Debt Securities, Available-for-sale
Estimated Fair Value	8
Duke Energy Indiana [Member] | Municipal Bonds [Member]
Available-for-sale Securities
Gross Unrealized Holding Losses		1
Estimated Fair Value		$ 28
Debt Securities, Available-for-sale
Gross Unrealized Holding Losses	1
Estimated Fair Value	33
Duke Energy Indiana [Member] | Other Classification [Member]
Equity Securities, FV-NI
Estimated Fair Value	$ 67

Investments in Debt and Equit_4

Investments in Debt and Equity Securities (Maturities) (Details) $ in Millions	Dec. 31, 2018USD ($)
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	$ 98
Due after one through five years	501
Due after five through ten years	570
Due after ten years	1,222
Total	2,391
Duke Energy Carolinas [Member]
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	6
Due after one through five years	142
Due after five through ten years	303
Due after ten years	589
Total	1,040
Progress Energy [Member]
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	87
Due after one through five years	306
Due after five through ten years	216
Due after ten years	541
Total	1,150
Duke Energy Progress [Member]
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	49
Due after one through five years	231
Due after five through ten years	161
Due after ten years	419
Total	860
Duke Energy Florida [Member]
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	38
Due after one through five years	75
Due after five through ten years	55
Due after ten years	122
Total	290
Duke Energy Indiana [Member]
Debt Securities, Available-for-sale [Line Items]
Due in one year or less	3
Due after one through five years	20
Due after five through ten years	4
Due after ten years	14
Total	$ 41

Investments in Debt and Equit_5

Investments in Debt and Equity Securities (Realized Gains and Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
FV-NI:
Realized gains	$ 168
Realized losses	126
AFS:
Realized gains	22
Realized losses	51
Available-for-sale Securities, Realized Gain (Loss) [Abstract]
Realized gains		$ 202	$ 246
Realized losses		160	187
Duke Energy Carolinas [Member]
FV-NI:
Realized gains	89
Realized losses	73
AFS:
Realized gains	19
Realized losses	35
Available-for-sale Securities, Realized Gain (Loss) [Abstract]
Realized gains		135	157
Realized losses		103	121
Progress Energy [Member]
FV-NI:
Realized gains	79
Realized losses	53
AFS:
Realized gains	3
Realized losses	15
Available-for-sale Securities, Realized Gain (Loss) [Abstract]
Realized gains		65	84
Realized losses		56	64
Duke Energy Progress [Member]
FV-NI:
Realized gains	68
Realized losses	48
AFS:
Realized gains	2
Realized losses	10
Available-for-sale Securities, Realized Gain (Loss) [Abstract]
Realized gains		54	71
Realized losses		48	55
Duke Energy Florida [Member]
FV-NI:
Realized gains	11
Realized losses	5
AFS:
Realized gains	1
Realized losses	$ 5
Available-for-sale Securities, Realized Gain (Loss) [Abstract]
Realized gains		11	13
Realized losses		$ 8	$ 9

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Measurement Amounts for Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	$ 2,391
Derivative assets	57	$ 51
Total assets	7,132	7,503
Derivative liabilities	(242)	(230)
Net assets (liabilities)	6,890	7,273
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	4	3
Total assets	5,156	5,658
Derivative liabilities	(11)	(2)
Net assets (liabilities)	5,145	5,656
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	25	20
Total assets	1,883	1,743
Derivative liabilities	(90)	(86)
Net assets (liabilities)	1,793	1,657
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	28	28
Total assets	28	28
Derivative liabilities	(141)	(142)
Net assets (liabilities)	(113)	(114)
Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	65	74
Net assets (liabilities)	65	74
NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	4,475
Debt securities, available-for-sale	2,231
NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	4,410
Debt securities, available-for-sale	576
NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	1,655
NDTF [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	65
Investments		74
Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	99
Debt securities, available-for-sale	270
Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	99
Debt securities, available-for-sale	67
Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	203
Equity Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		4,914
Equity Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		4,840
Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		123
Equity Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		123
Debt Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		2,174
Debt Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		635
Debt Securities [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1,539
Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		241
Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		57
Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		184
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	1,040
Derivative assets	3	2
Total assets	3,556	3,760
Derivative liabilities	(33)	(35)
Net assets (liabilities)	3,523	3,725
Duke Energy Carolinas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	2,568	2,822
Derivative liabilities	0	(1)
Net assets (liabilities)	2,568	2,821
Duke Energy Carolinas [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	2
Total assets	923	864
Derivative liabilities	(33)	(34)
Net assets (liabilities)	890	830
Duke Energy Carolinas [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	65	74
Net assets (liabilities)	65	74
Duke Energy Carolinas [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	2,484
Debt securities, available-for-sale	1,069
Duke Energy Carolinas [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	2,419
Debt securities, available-for-sale	149
Duke Energy Carolinas [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	920
Duke Energy Carolinas [Member] | NDTF [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	65
Investments		74
Duke Energy Carolinas [Member] | Equity Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		2,692
Duke Energy Carolinas [Member] | Equity Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		2,618
Duke Energy Carolinas [Member] | Debt Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1,066
Duke Energy Carolinas [Member] | Debt Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		204
Duke Energy Carolinas [Member] | Debt Securities [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		862
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	1,150
Derivative assets	4	3
Total assets	3,221	3,392
Derivative liabilities	(44)	(36)
Net assets (liabilities)	3,177	3,356
Progress Energy [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	1
Total assets	2,435	2,666
Derivative liabilities	0	(1)
Net assets (liabilities)	2,435	2,665
Progress Energy [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	4	2
Total assets	786	726
Derivative liabilities	(44)	(35)
Net assets (liabilities)	742	691
Progress Energy [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	1,991
Debt securities, available-for-sale	1,162
Progress Energy [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	1,991
Debt securities, available-for-sale	427
Progress Energy [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	735
Progress Energy [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	64
Progress Energy [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	17
Progress Energy [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	47
Progress Energy [Member] | Equity Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		2,222
Progress Energy [Member] | Equity Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		2,222
Progress Energy [Member] | Debt Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1,108
Progress Energy [Member] | Debt Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		431
Progress Energy [Member] | Debt Securities [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		677
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		59
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		12
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		47
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	860
Derivative assets	4	2
Total assets	2,504	2,594
Derivative liabilities	(27)	(18)
Net assets (liabilities)	2,477	2,576
Duke Energy Progress [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	1
Total assets	1,888	2,040
Derivative liabilities	0	(1)
Net assets (liabilities)	1,888	2,039
Duke Energy Progress [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	4	1
Total assets	616	554
Derivative liabilities	(27)	(17)
Net assets (liabilities)	589	537
Duke Energy Progress [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	1,588
Debt securities, available-for-sale	906
Duke Energy Progress [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	1,588
Debt securities, available-for-sale	294
Duke Energy Progress [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	612
Duke Energy Progress [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	6
Duke Energy Progress [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	6
Duke Energy Progress [Member] | Equity Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1,795
Duke Energy Progress [Member] | Equity Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1,795
Duke Energy Progress [Member] | Debt Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		796
Duke Energy Progress [Member] | Debt Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		243
Duke Energy Progress [Member] | Debt Securities [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		553
Duke Energy Progress [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1
Duke Energy Progress [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	290
Derivative assets		1
Total assets	707	788
Derivative liabilities	(9)	(12)
Net assets (liabilities)	698	776
Duke Energy Florida [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	537	616
Net assets (liabilities)	537	616
Duke Energy Florida [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	1
Total assets	170	172
Derivative liabilities	(9)	(12)
Net assets (liabilities)	161	160
Duke Energy Florida [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	403
Debt securities, available-for-sale	256
Duke Energy Florida [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	403
Debt securities, available-for-sale	133
Duke Energy Florida [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	123
Duke Energy Florida [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	48
Duke Energy Florida [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	1
Duke Energy Florida [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	47
Duke Energy Florida [Member] | Equity Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		427
Duke Energy Florida [Member] | Equity Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		427
Duke Energy Florida [Member] | Debt Securities [Member] | NDTF [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		312
Duke Energy Florida [Member] | Debt Securities [Member] | NDTF [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		188
Duke Energy Florida [Member] | Debt Securities [Member] | NDTF [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		124
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		48
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		47
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	1
Derivative liabilities	(5)	(5)
Net assets (liabilities)	1	(4)
Duke Energy Ohio [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(5)	(5)
Net assets (liabilities)	(5)	(5)
Duke Energy Ohio [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	6	1
Net assets (liabilities)	6	1
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	67
Debt securities, available-for-sale	41
Derivative assets	23	27
Net assets (liabilities)	131	155
Duke Energy Indiana [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	1
Net assets (liabilities)	68	97
Duke Energy Indiana [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net assets (liabilities)	41	31
Duke Energy Indiana [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	22	27
Net assets (liabilities)	22	27
Duke Energy Indiana [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	67
Duke Energy Indiana [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities, FV-NI	67
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		97
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		97
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	41
Investments		31
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	41
Investments		31
Piedmont Natural Gas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	0
Derivative assets	3	2
Total assets	3	3
Derivative liabilities	(141)	(142)
Net assets (liabilities)	(138)	(139)
Piedmont Natural Gas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available-for-sale	0
Derivative assets	3	2
Total assets	3	3
Net assets (liabilities)	3	3
Piedmont Natural Gas [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(141)	(142)
Net assets (liabilities)	$ (141)	(142)
Piedmont Natural Gas [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		1
Piedmont Natural Gas [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		$ 1

Fair Value Measurements (Reconc

Fair Value Measurements (Reconciliation of Assets and Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs) (Details) - USD ($)	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Transfers Between Activity Levels		$ 0	$ 0	$ 0
Investments
Beginning balance			5,000,000
Total pretax realized and unrealized gains included in comprehensive income			1,000,000
Sales			(6,000,000)
Ending balance	$ 5,000,000			5,000,000
Derivatives (net)
Beginning balance		(114,000,000)	(166,000,000)
Purchases		57,000,000	55,000,000
Settlements		(57,000,000)	(47,000,000)
Total gains (losses) included on the Consolidated Balance Sheet		1,000,000	44,000,000
Ending balance	(166,000,000)	(113,000,000)	(114,000,000)	(166,000,000)
Investments and Derivatives, Net
Beginning balance		(114,000,000)	(161,000,000)
Total pretax realized or unrealized gains included in other comprehensive income			1,000,000
Purchases			55,000,000
Sales			(6,000,000)
Settlements			(47,000,000)
Total gains (losses) included on the Consolidated Balance Sheet			44,000,000
Ending balance	(161,000,000)		(114,000,000)	(161,000,000)
Duke Energy Carolinas [Member]
Investments
Beginning balance			3,000,000
Total pretax realized and unrealized gains included in comprehensive income			1,000,000
Sales			(4,000,000)
Ending balance	3,000,000			3,000,000
Duke Energy Ohio [Member]
Derivatives (net)
Beginning balance		1,000,000	5,000,000
Purchases		7,000,000	3,000,000
Settlements		(4,000,000)	(4,000,000)
Total gains (losses) included on the Consolidated Balance Sheet		2,000,000	(3,000,000)
Ending balance	5,000,000	6,000,000	1,000,000	5,000,000
Duke Energy Indiana [Member]
Derivatives (net)
Beginning balance		27,000,000	16,000,000
Purchases		50,000,000	52,000,000
Settlements		(53,000,000)	(43,000,000)
Total gains (losses) included on the Consolidated Balance Sheet		(2,000,000)	2,000,000
Ending balance	16,000,000	22,000,000	27,000,000	16,000,000
Piedmont Natural Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Measurement Transfers Between Activity Levels	0				$ 0
Derivatives (net)
Beginning balance		(142,000,000)	(187,000,000)
Total gains (losses) and settlements		1,000,000	45,000,000
Ending balance	$ (187,000,000)	$ (141,000,000)	$ (142,000,000)	$ (187,000,000)

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Level 3 Fair Value Disclosure - Assets) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)$ / MWh	Dec. 31, 2017USD ($)$ / MWh	Dec. 31, 2016USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	$ (113)	$ (114)	$ (166)
Duke Energy Ohio [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	6	1	5
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	$ 6	$ 1
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input Price Per Unit | $ / MWh	1.19	0.07
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input Price Per Unit | $ / MWh	4.59	1.41
Duke Energy Indiana [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	$ 22	$ 27	$ 16
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	$ 22	$ 27
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | Minimum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input Price Per Unit | $ / MWh	(2.07)	(0.77)
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | Maximum [Member] | Valuation, Market Approach [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input Price Per Unit | $ / MWh	8.27	7.44

Fair Value Measurements (Quan_2

Fair Value Measurements (Quantitative Level 3 Fair Value Disclosures - Liabilities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)$ / MMBTU	Dec. 31, 2017USD ($)$ / MMBTU	Dec. 31, 2016USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	$ (113)	$ (114)	$ (166)
Piedmont Natural Gas [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	(141)	(142)	$ (187)
Natural Gas, derivative liability [Member] | Valuation Technique, Discounted Cash Flow [Member] | Piedmont Natural Gas [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Net Derivative Asset (Liability)	$ (141)	$ (142)
Natural Gas, derivative liability [Member] | Minimum [Member] | Valuation Technique, Discounted Cash Flow [Member] | Piedmont Natural Gas [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input Price Per Unit | $ / MMBTU	1.87	2.10
Natural Gas, derivative liability [Member] | Maximum [Member] | Valuation Technique, Discounted Cash Flow [Member] | Piedmont Natural Gas [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair Value Input Price Per Unit | $ / MMBTU	2.95	2.88

Fair Value Measurements (Other

Fair Value Measurements (Other Fair Value Disclosures) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 54,534	$ 55,331
Long-term Debt	54,529	52,279
Unamortized debt discount and premium, net	1,600	1,700
Duke Energy Carolinas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	11,471	11,372
Long-term Debt	10,939	10,103
Progress Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	19,885	20,000
Long-term Debt	18,911	17,837
Duke Energy Progress [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	8,300	7,992
Long-term Debt	8,204	7,357
Duke Energy Florida [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	7,742	7,953
Long-term Debt	7,321	7,095
Duke Energy Ohio [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	2,239	2,249
Long-term Debt	2,165	2,067
Duke Energy Indiana [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	4,158	4,464
Long-term Debt	3,782	3,783
Piedmont Natural Gas [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	2,180	2,209
Long-term Debt	$ 2,138	$ 2,037

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Financial or Other Support, Amount	$ 0	$ 0	$ 0
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Percent of proceeds received as cash	75.00%
Percent of proceeds received as subordinated note	25.00%
Minimum Equity Balance required by Cinergy Receivables	$ 3,000,000
Pioneer Transmission [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Ownership Interest	50.00%
Duke Energy Ohio [Member] | Cinergy Receivables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%
Duke Energy Ohio [Member] | OVEC [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Ownership Interest	9.00%
Financial Guarantee [Member] | Atlantic Coast Pipeline [Member]
Variable Interest Entity [Line Items]
Maximum potential amount of future payments associated with guarantees	$ 677,000,000

Variable Interest Entities (Sch

Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Long-Term debt	$ 51,123	$ 49,035
Duke Energy Carolinas [Member]
Variable Interest Entity [Line Items]
Long-Term debt	10,633	8,598
Duke Energy Progress [Member]
Variable Interest Entity [Line Items]
Long-Term debt	7,451	7,204
Duke Energy Florida [Member]
Variable Interest Entity [Line Items]
Long-Term debt	$ 7,051	6,327
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Dec. 1, 2020
Facility Size	$ 325
Long-Term debt	325	325
Restricted Receivables	$ 564	545
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Dec. 1, 2020
Facility Size	$ 450
Long-Term debt	450	450
Restricted Receivables	$ 699	640
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Feb. 1, 2021
Facility Size	$ 300
Long-Term debt	300	300
Restricted Receivables	$ 547	459
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Line of credit facility, expiration date	Apr. 1, 2021
Facility Size	$ 225
Long-Term debt	225	225
Restricted Receivables	$ 357	$ 317

Variable Interest Entities (Con

Variable Interest Entities (Consolidated VIEs) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory Assets, Current	$ 2,005	$ 1,437
Other current assets	1,049	634
Property, plant and equipment, cost	134,458	127,507
Accumulated depreciation and amortization	(43,126)	(41,537)
Regulatory assets, noncurrent	13,617	12,442
Investments and other assets	2,935	2,960
Current maturities of long-term debt	3,406	3,244
Other current liabilities	2,085	1,865
Long-Term debt	51,123	49,035
Deferred income taxes	(7,806)	(6,621)
Asset retirement obligations	9,548	9,486
Other Liabilities	1,650	1,581
Duke Energy Carolinas [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory Assets, Current	520	299
Other current assets	72	19
Property, plant and equipment, cost	44,741	42,939
Accumulated depreciation and amortization	(15,496)	(15,063)
Regulatory assets, noncurrent	3,457	2,853
Investments and other assets	1,027	979
Current maturities of long-term debt	6	1,205
Other current liabilities	571	486
Long-Term debt	10,633	8,598
Deferred income taxes	(3,689)	(3,413)
Asset retirement obligations	3,659	3,273
Other Liabilities	671	566
Duke Energy Progress [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory Assets, Current	703	352
Other current assets	62	97
Property, plant and equipment, cost	31,459	29,583
Accumulated depreciation and amortization	(11,423)	(10,903)
Regulatory assets, noncurrent	4,111	3,507
Investments and other assets	612	599
Current maturities of long-term debt	603	3
Other current liabilities	408	376
Long-Term debt	7,451	7,204
Deferred income taxes	(2,119)	(1,883)
Asset retirement obligations	4,311	4,378
Other Liabilities	106	45
Duke Energy Florida [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Regulatory Assets, Current	434	389
Other current assets	46	86
Property, plant and equipment, cost	18,792	17,730
Accumulated depreciation and amortization	(4,968)	(4,947)
Regulatory assets, noncurrent	2,454	2,503
Investments and other assets	311	284
Current maturities of long-term debt	270	768
Other current liabilities	406	334
Long-Term debt	7,051	6,327
Deferred income taxes	(1,986)	(1,761)
Asset retirement obligations	586	742
Other Liabilities	93	108
DEFPF [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	5	4
Regulatory Assets, Current	52	51
Other current assets	39	40
Regulatory assets, noncurrent	1,041	1,091
Current maturities of long-term debt	53	53
Other current liabilities	10	10
Long-Term debt	1,111	1,164
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	699	640
Long-Term debt	450	450
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	547	459
Long-Term debt	300	300
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	357	317
Long-Term debt	225	225
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of VIEs	564	545
Long-Term debt	325	325
Commercial Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Other current assets	123	174
Property, plant and equipment, cost	4,007	3,923
Accumulated depreciation and amortization	(698)	(591)
Investments and other assets	261	50
Current maturities of long-term debt	174	170
Long-Term debt	1,587	1,700
Deferred income taxes		(148)
Asset retirement obligations	106	83
Other Liabilities	$ 212	$ 241

Variable Interest Entities (S_2

Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,409	$ 1,175	$ 925
Investments and other assets	2,935	2,960
Other current liabilities	2,085	1,865
Deferred income taxes	7,806	6,621
Other Liabilities	1,650	1,581
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	1,060	919
Investments and other assets		17
Total assets	1,060	936
Taxes accrued	(1)	(29)
Other current liabilities	4	4
Deferred income taxes	21	42
Other Liabilities	12	12
Total liabilities	36	29
Net assets of non-consolidated VIEs	1,024	907
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	822	697
Investments and other assets		17
Total assets	822	714
Taxes accrued	(1)	(29)
Deferred income taxes	21	42
Total liabilities	20	13
Net assets of non-consolidated VIEs	802	701
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	48	42
Total assets	48	42
Other current liabilities	4	4
Other Liabilities	12	12
Total liabilities	16	16
Net assets of non-consolidated VIEs	32	26
Commercial Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	190	180
Total assets	190	180
Net assets of non-consolidated VIEs	190	180
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	114	133
Investments and other assets	41	21
Other current liabilities	74	71
Deferred income taxes	817	781
Other Liabilities	93	108
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	93	87
Total assets	93	87
Net assets of non-consolidated VIEs	93	87
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	122	125
Investments and other assets	194	189
Other current liabilities	107	104
Deferred income taxes	1,009	925
Other Liabilities	16	18
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables from affiliated companies	118	106
Total assets	118	106
Net assets of non-consolidated VIEs	$ 118	$ 106

Variable Interest Entities (S_3

Variable Interest Entities (Schedule of Non-Consolidated VIE Pipeline Investments) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,409	$ 1,175	$ 925
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 1,060	919
Constitution Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	24.00%
Investments in equity method unconsolidated affiliates	$ 25	81
Sabal Trail Transmission Pipeline [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 112
Sabal Trail Transmission Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	7.50%
Investments in equity method unconsolidated affiliates		219
Atlantic Coast Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	47.00%
Investments in equity method unconsolidated affiliates	$ 797	397
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	822	697
Gas Utilities and Infrastructure [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	1,003	763	$ 566
Gas Utilities and Infrastructure [Member] | Constitution Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
OTTI impairment loss	55
Gas Utilities and Infrastructure [Member] | Sabal Trail Transmission Pipeline [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 112	$ 219

Variable Interest Entities (Fai

Variable Interest Entities (Fair Value Assumptions) (Details) - Cinergy Receivables [Member] - Variable Interest Entity, Not Primary Beneficiary [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Anticipated credit loss ratio	0.50%	0.50%
Discount rate	3.00%	2.10%
Receivable turnover rate	13.50%	13.50%
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Anticipated credit loss ratio	0.30%	0.30%
Discount rate	3.00%	2.10%
Receivable turnover rate	11.00%	10.70%

Variable Interest Entities (Rec

Variable Interest Entities (Receivables Sold) (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Cinergy Receivables [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Receivables sold	$ 269	$ 273
Less: retained interests	93	87
Net receivables sold	176	186
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Receivables sold	336	312
Less: retained interests	118	106
Net receivables sold	$ 218	$ 206

Variable Interest Entities (Sal

Variable Interest Entities (Sales and Cash Flows) (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Cinergy Receivables [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Receivables sold	$ 1,987	$ 1,879	$ 1,926
Loss recognized on sale	13	10	9
Cash proceeds from receivables sold	1,967	1,865	1,882
Collection fees received	1	1	1
Return received on retained interests	6	3	2
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Receivables sold	2,842	2,711	2,635
Loss recognized on sale	16	12	11
Cash proceeds from receivables sold	2,815	2,694	2,583
Collection fees received	1	1	1
Return received on retained interests	$ 9	$ 7	$ 5

Revenue (Remaining Performance

Revenue (Remaining Performance Obligations) (Details) $ in Millions	Dec. 31, 2018USD ($)
Progress Energy [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 112
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Progress Energy [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 121
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Progress Energy [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 80
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Progress Energy [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 82
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Progress Energy [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 39
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Progress Energy [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 42
Progress Energy [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	476
Duke Energy Progress [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 9
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Progress [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 9
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Progress [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 9
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Progress [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 9
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Progress [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 9
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Progress [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 9
Duke Energy Progress [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	54
Duke Energy Florida [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 103
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Florida [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 112
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Florida [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 71
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Florida [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 73
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Florida [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 30
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Florida [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 33
Duke Energy Florida [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	422
Duke Energy Indiana [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 9
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Indiana [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 10
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Indiana [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 5
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Indiana [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Indiana [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Duke Energy Indiana [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 24
Piedmont Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 70
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Piedmont Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 68
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Piedmont Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 63
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Piedmont Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 63
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Piedmont Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 60
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Piedmont Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 430
Piedmont Natural Gas [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, amount	$ 754

Revenue (Unbilled Revenues) (De

Revenue (Unbilled Revenues) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 896	$ 944
Duke Energy Carolinas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	313	342
Progress Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	244	228
Duke Energy Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	148	143
Duke Energy Florida [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	96	85
Duke Energy Ohio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	2	4
Duke Energy Indiana [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	23	21
Piedmont Natural Gas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	73	86
Cinergy Receivables [Member] | Duke Energy Ohio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables		104
Cinergy Receivables [Member] | Duke Energy Indiana [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables		$ 132
Cinergy Receivables [Member] | Duke Energy Ohio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	86
Cinergy Receivables [Member] | Duke Energy Indiana [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 128

Revenue (Disaggregation of Reve

Revenue (Disaggregation of Revenue) (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										$ 23,757
Revenue from sources other than contracts with customers										764
Total operating revenues		$ 6,115	$ 6,628	$ 5,643	$ 6,135	$ 5,799	$ 6,482	$ 5,555	$ 5,729	24,521	$ 23,565	$ 22,743
Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues										1,081	1,239	1,144
Electric Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										21,729
Total operating revenues										22,242	21,300	21,336
Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										9,587
Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | General [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										6,127
Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										2,974
Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										2,324
Electric Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										717
Total operating revenues										915	1,050	933
Gas Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,800
Total operating revenues										1,783	1,743	875
Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,000
Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										514
Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										147
Gas Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										139
Total operating revenues										64	104	30
Commercial Renewables [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										209
Total operating revenues										477	460	484
Commercial Renewables [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Total operating revenues										102	85	181
Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										19
Total operating revenues										19	62	48
Duke Energy Carolinas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										7,108
Revenue from sources other than contracts with customers										192
Total operating revenues		1,775	2,090	1,672	1,763	1,721	2,136	1,729	1,716	7,300	7,302	7,322
Duke Energy Carolinas [Member] | Electric Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										7,108
Duke Energy Carolinas [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										2,981
Duke Energy Carolinas [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | General [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										2,119
Duke Energy Carolinas [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,180
Duke Energy Carolinas [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										508
Duke Energy Carolinas [Member] | Electric Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										320
Progress Energy [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										10,462
Revenue from sources other than contracts with customers										266
Total operating revenues		2,609	3,045	2,498	2,576	2,348	2,864	2,392	2,179	10,728	9,783	9,853
Progress Energy [Member] | Electric Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										10,462
Progress Energy [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										4,785
Progress Energy [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | General [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										2,809
Progress Energy [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										904
Progress Energy [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,462
Progress Energy [Member] | Electric Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										502
Duke Energy Progress [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										5,564
Revenue from sources other than contracts with customers										135
Total operating revenues		1,366	1,582	1,291	1,460	1,251	1,460	1,199	1,219	5,699	5,129	5,277
Duke Energy Progress [Member] | Electric Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										5,564
Duke Energy Progress [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										2,019
Duke Energy Progress [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | General [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,280
Duke Energy Progress [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										642
Duke Energy Progress [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,303
Duke Energy Progress [Member] | Electric Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										320
Duke Energy Florida [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										4,898
Revenue from sources other than contracts with customers										123
Total operating revenues		1,241	1,462	1,203	1,115	1,095	1,401	1,191	959	5,021	4,646	4,568
Duke Energy Florida [Member] | Electric Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										4,898
Duke Energy Florida [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										2,766
Duke Energy Florida [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | General [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,529
Duke Energy Florida [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										262
Duke Energy Florida [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										159
Duke Energy Florida [Member] | Electric Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										182
Duke Energy Ohio [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,930
Revenue from sources other than contracts with customers										27
Total operating revenues		505	469	459	524	497	471	437	518	1,957	1,923	1,944
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,426
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										743
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | General [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										422
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										131
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										57
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										73
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										503
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										331
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										135
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										18
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										19
Duke Energy Ohio [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1
Duke Energy Indiana [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										3,003
Revenue from sources other than contracts with customers										56
Total operating revenues		771	819	738	731	745	802	742	758	3,059	3,047	$ 2,958
Duke Energy Indiana [Member] | Electric Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										3,003
Duke Energy Indiana [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,076
Duke Energy Indiana [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | General [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										778
Duke Energy Indiana [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										760
Duke Energy Indiana [Member] | Electric Utilities and Infrastructure [Member] | Electricity, US Regulated [Member] | Wholesale [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										298
Duke Energy Indiana [Member] | Electric Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										91
Piedmont Natural Gas [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,349
Revenue from sources other than contracts with customers										26
Total operating revenues	$ 322	$ 435	$ 172	$ 215	$ 553	$ 444	$ 183	$ 201	$ 500	1,375	$ 1,328		$ 1,149
Piedmont Natural Gas [Member] | Gas Utilities and Infrastructure [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										1,349
Piedmont Natural Gas [Member] | Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										669
Piedmont Natural Gas [Member] | Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										378
Piedmont Natural Gas [Member] | Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										128
Piedmont Natural Gas [Member] | Gas Utilities and Infrastructure [Member] | Natural Gas, US Regulated [Member] | Power Generation [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										54
Piedmont Natural Gas [Member] | Gas Utilities and Infrastructure [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers										$ 120

Common Stock (Earnings Per Shar

Common Stock (Earnings Per Share Data) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Income (Loss) from Continuing Operations, Net of Tax, Excluding Participating Securities									$ 2,642	$ 3,059	$ 2,567
Weighted Average Number of Shares Outstanding, Basic									708	700	691
Weighted Average Number of Shares Outstanding, Diluted									708	700	691
EPS, basic (usd per share)	$ 0.62	$ 1.51	$ 0.72	$ 0.88	$ 1	$ 1.36	$ 0.98	$ 1.02	$ 3.73	$ 4.37	$ 3.71
EPS, diluted (usd per share)	$ 0.62	$ 1.51	$ 0.72	$ 0.88	$ 1	$ 1.36	$ 0.98	$ 1.02	$ 3.73	$ 4.37	$ 3.71
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									2	2	2
Dividends declared per share (usd per share)									$ 3.6350	$ 3.49	$ 3.36

Common Stock (Equity Securities

Common Stock (Equity Securities Offering) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Feb. 20, 2018	Dec. 31, 2018	Jun. 30, 2018	Oct. 31, 2016	Mar. 31, 2018	Dec. 31, 2018	Mar. 31, 2016
Forward Contract Indexed to Issuer's Equity [Line Items]
Maximum value of shares to be issued under ATM program	$ 1,000
Stock Issued During Period, Shares, Dividend Reinvestment Plan						2.2
Stock Issued During Period, Value, Dividend Reinvestment Plan						$ 174
ATM [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Settlement Alternatives, Shares		2.6	2.6			2.6
Proceeds from Issuance or Sale of Equity		$ 195
Equity Forwards [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares offered					21.3
Sales price					$ 75
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share					$ 74.07
Settlement Alternatives, Shares					21.3
Shares, Issued		10.6	10.6			10.6
Proceeds from Issuance or Sale of Equity		$ 766	$ 781
Piedmont Natural Gas [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares offered							10.6
Settlement Alternatives, Shares							10.6
Common stock issuances, including dividend reinvestment and employee benefits (in shares)				10.6
Proceeds from Issuance or Sale of Equity				$ 723
Wells Fargo Bank [Member] | ATM [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares offered			1.3
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share			$ 72.02
Citibank [Member] | ATM [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share			$ 78.71

Severance (Narrative) (Details)

Severance (Narrative) (Details) - employee	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring and Related Activities [Abstract]
Number of eligible employees	1,900	100	600

Severance (Expenses) (Details)

Severance (Expenses) (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Restructuring Cost and Reserve [Line Items]
Severance expense		$ 187	$ 187	$ 15	$ 118
Duke Energy Carolinas [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		102	102	2	39
Progress Energy [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		69	69	2	40
Duke Energy Progress [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		52	52	1	23
Duke Energy Florida [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		17	17	1	17
Duke Energy Ohio [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		6	6		3
Duke Energy Indiana [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		7	7	1	$ 7
Piedmont Natural Gas [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 3	$ 2	$ 2	$ 9		$ 19

Severance (Rollforward) (Detail

Severance (Rollforward) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Restructuring Reserve [Roll Forward]
Balance, beginning of period	$ 19
Provision/adjustments	200
Cash reductions	(14)
Balance, end of period	205
Duke Energy Carolinas [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	5
Provision/adjustments	98
Cash reductions	(3)
Balance, end of period	100
Progress Energy [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	2
Provision/adjustments	50
Cash reductions	(1)
Balance, end of period	51
Duke Energy Progress [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	1
Provision/adjustments	40
Balance, end of period	41
Duke Energy Florida [Member]
Restructuring Reserve [Roll Forward]
Provision/adjustments	10
Cash reductions	(1)
Balance, end of period	9
Duke Energy Ohio [Member]
Restructuring Reserve [Roll Forward]
Provision/adjustments	2
Balance, end of period	2
Duke Energy Indiana [Member]
Restructuring Reserve [Roll Forward]
Provision/adjustments	2
Balance, end of period	2
Piedmont Natural Gas [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	5
Cash reductions	$ (5)

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for awards to employees and outside directors	10,000
Restricted Stock Units Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value	$ 49	$ 47	$ 52
Total grant date fair value of shares vested	43	42	38
Unrecognized compensation cost	$ 29
Unrecognized compensation cost, period of recognition, years	23 months
Restricted Stock Units Awards [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value	$ 27	37	25
Risk Free Interest Rate	2.40%
Expected Volatility Rate	16.00%
Total grant date fair value of shares vested	$ 13	$ 0	$ 25
Unrecognized compensation cost	$ 30
Unrecognized compensation cost, period of recognition, years	21 months
Piedmont Natural Gas [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued			194
Fair value			$ 11
Cash paid (in usd per share)			$ 60
Share price (in usd per share)			$ 56.85

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule of Stock-Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	$ 56	$ 43	$ 35
Pretax stock-based compensation cost	78	68	55
Stock-based compensation costs capitalized	5	4	2
Stock-based compensation expense	73	64	53
Tax benefit associated with stock-based compensation expense	17	25	20
Restricted Stock Units Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation cost	43	41	36
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation cost	35	27	19
Duke Energy Carolinas [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	20	15	12
Progress Energy [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	21	16	12
Duke Energy Progress [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	13	10	7
Duke Energy Florida [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	8	6	5
Duke Energy Ohio [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	4	3	2
Duke Energy Indiana [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	5	4	$ 3
Piedmont Natural Gas [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	$ 3	$ 3		$ 10
Pretax stock-based compensation cost				16
Tax benefit associated with stock-based compensation expense				$ 6

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary of Stock Awards Outstanding) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock Units Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period	1,121
Granted	649	583	684
Vested	(545)
Forfeited	(72)
Outstanding at end of period	1,153	1,121
Stock awards expected to vest	1,101
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average fair value at beginning of period	$ 78
Granted	76
Vested	78
Forfeited	77
Weighted average fair value at end of period	77	$ 78
Weighted average fair value of awards expected to vest	$ 77
Share Based Compensation Grants In Period Fair Value	$ 49	$ 47	$ 52
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period	1,065
Granted	372	461	338
Vested	(155)
Forfeited	(165)
Outstanding at end of period	1,117	1,065
Stock awards expected to vest	1,086
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average fair value at beginning of period	$ 79
Granted	73
Vested	81
Forfeited	80
Weighted average fair value at end of period	77	$ 79
Weighted average fair value of awards expected to vest	$ 77
Share Based Compensation Grants In Period Fair Value	$ 27	$ 37	$ 25
Piedmont Natural Gas [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures			194
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Share Based Compensation Grants In Period Fair Value			$ 11

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016	Jan. 01, 2019
Defined Benefit Plan Disclosure [Line Items]
Impact of plan conversion on next year's net periodic benefit cost		$ 33
Maximum years of participation		35 years
Additional contribution percentage for employees not participating in defined pension plans		4.00%
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation		100.00%
Expected long-term rate of return on plan assets		6.85%
Fair value of securities on loan		$ 154	$ 195
Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		13 years
Expected long-term rate of return on plan assets				6.75%
Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		10 years
Pension Plan [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage		98.00%
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		9 years
Expected long-term rate of return on plan assets		6.50%	6.50%	6.50%
Other Post-Retirement Benefit Plans [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage		2.00%
Duke Energy Carolinas [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		12 years
Duke Energy Carolinas [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		8 years
Duke Energy Carolinas [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		8 years
Progress Energy [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		12 years
Progress Energy [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		13 years
Progress Energy [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		6 years
Duke Energy Progress [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		13 years
Duke Energy Progress [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		11 years
Duke Energy Progress [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		6 years
Duke Energy Florida [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		12 years
Duke Energy Florida [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		15 years
Duke Energy Florida [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		7 years
Duke Energy Ohio [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		14 years
Duke Energy Ohio [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		8 years
Duke Energy Ohio [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		7 years
Duke Energy Indiana [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		14 years
Duke Energy Indiana [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		8 years
Duke Energy Indiana [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		6 years
Piedmont Natural Gas [Member]
Defined Benefit Plan Disclosure [Line Items]
Additional contribution percentage for employees not participating in defined pension plans		4.00%
Vesting period		3 years
Term		3 years
Piedmont Natural Gas [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		10 years
Expected long-term rate of return on plan assets	6.75%				7.25%
Piedmont Natural Gas [Member] | Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		8 years
Piedmont Natural Gas [Member] | Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years		7 years
Expected long-term rate of return on plan assets	6.75%				7.25%
Liability Hedging Assets [Member] | Subsequent Event [Member] | Pension Plan [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation						58.00%
Return Seeking Assets [Member] | Subsequent Event [Member] | Pension Plan [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Target allocation						42.00%
Minimum [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets			6.50%	6.50%
Minimum [Member] | Piedmont Natural Gas [Member]
Defined Benefit Plan Disclosure [Line Items]
Additional contribution percentage for employees not participating in defined pension plans		3.00%
Maximum [Member] | Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets		6.50%	6.75%
Maximum [Member] | Piedmont Natural Gas [Member]
Defined Benefit Plan Disclosure [Line Items]
Additional contribution percentage for employees not participating in defined pension plans		5.00%

Employee Benefit Plans (Contrib

Employee Benefit Plans (Contributions to Defined Benefit Pension Plans) (Details) - Pension Plan [Member] - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 141	$ 19	$ 155
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		46		43
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		45		43
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		25		24
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		20		20
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions			4	5
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions		$ 8		9
Piedmont Natural Gas [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 10		$ 11		$ 10

Employee Benefit Plans (Compone

Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of Regulatory Asset		$ 5	$ 7	$ 8
Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		182
Service cost		174	159	147
Interest cost		299	328	335
Expected return on plan assets		(559)	(545)	(519)
Amortization of actuarial loss (gain)		132	146	134
Amortization of prior service cost (credit)		(32)	(24)	(17)
Settlement charge			12	3
Other			8	8
Net periodic costs		22	84	91
Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		2	2	2
Interest cost		12	13	14
Amortization of actuarial loss (gain)		8	8	8
Amortization of prior service cost (credit)		(2)	(2)	(1)
Net periodic costs		20	21	23
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		58
Service cost		56	48	48
Interest cost		72	79	86
Expected return on plan assets		(147)	(142)	(142)
Amortization of actuarial loss (gain)		29	31	33
Amortization of prior service cost (credit)		(8)	(8)	(8)
Other			2	2
Net periodic costs		4	10	19
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1	1
Interest cost			1	1
Amortization of actuarial loss (gain)				1
Net periodic costs		1	2	2
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		51
Service cost		49	45	42
Interest cost		94	100	106
Expected return on plan assets		(178)	(167)	(168)
Amortization of actuarial loss (gain)		44	52	51
Amortization of prior service cost (credit)		(3)	(3)	(3)
Other			2	3
Net periodic costs		8	29	31
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		4	5	5
Amortization of actuarial loss (gain)		2	2	1
Net periodic costs		6	7	6
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		29
Service cost		28	26	24
Interest cost		43	47	49
Expected return on plan assets		(85)	(82)	(82)
Amortization of actuarial loss (gain)		21	23	23
Amortization of prior service cost (credit)		(2)	(2)	(2)
Other			1	1
Net periodic costs		6	13	13
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		1	1	1
Amortization of actuarial loss (gain)		1	1	1
Net periodic costs		2	2	2
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		22
Service cost		21	19	19
Interest cost		50	53	55
Expected return on plan assets		(91)	(85)	(84)
Amortization of actuarial loss (gain)		23	29	29
Amortization of prior service cost (credit)		(1)	(1)	(1)
Other			1	1
Net periodic costs		3	16	19
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		2	2	2
Amortization of actuarial loss (gain)		1	1	1
Net periodic costs		3	3	3
Pension Plan [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of Regulatory Asset		2	3	4
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		5
Service cost		5	4	4
Interest cost		17	18	19
Expected return on plan assets		(28)	(27)	(27)
Amortization of actuarial loss (gain)		5	5	4
Amortization of prior service cost (credit)			(1)
Other				1
Net periodic costs		(1)	(1)	1
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		11
Service cost		10	9	9
Interest cost		23	26	28
Expected return on plan assets		(42)	(42)	(42)
Amortization of actuarial loss (gain)		10	12	11
Amortization of prior service cost (credit)		(2)	(2)	(1)
Other			1	1
Net periodic costs		0	4	6
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		7
Service cost	$ 2	7	10		$ 11
Interest cost	2	11	14		9
Expected return on plan assets	(4)	(22)	(24)		(24)
Amortization of actuarial loss (gain)	2	11	11		8
Amortization of prior service cost (credit)	(1)	(10)	(2)		(2)
Settlement charge	3		12
Other			1
Net periodic costs	$ 4	(3)	22		2
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost			0
Interest cost			0
Settlement charge					1
Net periodic costs					1
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		6	4	3
Interest cost		28	34	35
Expected return on plan assets		(13)	(14)	(12)
Amortization of actuarial loss (gain)		6	10	6
Amortization of prior service cost (credit)		(19)	(115)	(141)
Curtailment credit			(30)
Net periodic costs		8	(111)	(109)
Amortization of Regulatory Asset		7	7	8
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1	1	1
Interest cost		7	8	8
Expected return on plan assets		(8)	(8)	(8)
Amortization of actuarial loss (gain)		3	(2)	(3)
Amortization of prior service cost (credit)		(5)	(10)	(14)
Curtailment credit			(4)
Net periodic costs		(2)	(15)	(16)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1		1
Interest cost		12	13	15
Amortization of actuarial loss (gain)		1	21	22
Amortization of prior service cost (credit)		(8)	(84)	(103)
Curtailment credit			(16)
Net periodic costs		6	(66)	(65)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Interest cost		6	7	8
Amortization of actuarial loss (gain)		1	12	13
Amortization of prior service cost (credit)		(1)	(54)	(68)
Net periodic costs		6	(35)	(47)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1		1
Interest cost		6	6	7
Amortization of actuarial loss (gain)			9	9
Amortization of prior service cost (credit)		(7)	(30)	(35)
Curtailment credit			(16)
Net periodic costs		0	(31)	(18)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1
Interest cost		1	1	1
Amortization of actuarial loss (gain)			(2)	(2)
Amortization of prior service cost (credit)		(1)
Curtailment credit			(2)
Net periodic costs		1	(3)	(1)
Amortization of Regulatory Asset		2	2	2
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1
Interest cost		3	3	4
Expected return on plan assets			(1)	(1)
Amortization of actuarial loss (gain)		4	(1)	(1)
Amortization of prior service cost (credit)		(1)	(1)	(1)
Curtailment credit			(2)
Net periodic costs		7	(2)	$ 1
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		1	1		1
Interest cost		1	1		1
Expected return on plan assets		(2)	(2)		(2)
Amortization of actuarial loss (gain)			1		1
Amortization of prior service cost (credit)		(2)	0
Net periodic costs		$ (2)	$ 1		$ 1

Employee Benefit Plans (Amounts

Employee Benefit Plans (Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		$ 6	$ (3)	$ 11
Progress Energy [Member]
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		(5)	(4)	$ (1)
Pension Plan [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		298	(212)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		(2)
Prior year service cost (credit) arising during the year		1	1
Amortization of prior year actuarial gains (losses)		10	(7)
Net amount recognized in accumulated other comprehensive (income) loss		9	(6)
Pension Plan [Member] | Nonqualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(16)	5
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		1
Actuarial (gains) losses arising during the year		(4)	2
Prior year service cost (credit) arising during the year			(1)
Net amount recognized in accumulated other comprehensive (income) loss		(3)	1
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		170	(70)
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		1	(1)
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		40	(49)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		1	3
Amortization of prior year actuarial gains (losses)		(4)	(7)
Net amount recognized in accumulated other comprehensive (income) loss		(3)	(4)
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(6)	3
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		1
Actuarial (gains) losses arising during the year		(3)
Net amount recognized in accumulated other comprehensive (income) loss		(2)
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		31	(37)
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(3)	1
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		9	(11)
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(3)	2
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		10	9
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		30	(19)
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)	$ 34	8	(64)		$ 35
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)			0
Prior year service cost (credit) arising during the year			0
Amortization of prior year actuarial gains (losses)			0
Net amount recognized in accumulated other comprehensive (income) loss			0
Other Post-Retirement Benefit Plans [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		137	71
Regulatory liabilities, net increase (decrease)		154	(27)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)		(1)	(1)
Amortization of prior year prior service cost		1	3
Net amount recognized in accumulated other comprehensive (income) loss			2
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory liabilities, net increase (decrease)		(6)	(2)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		133	81
Regulatory liabilities, net increase (decrease)		149
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		84	42
Regulatory liabilities, net increase (decrease)		93
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		49	39
Regulatory liabilities, net increase (decrease)		56
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory liabilities, net increase (decrease)		2	(3)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(5)	(5)
Regulatory liabilities, net increase (decrease)		3	(7)
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)	$ (1)	$ 4	(11)		$ 2
Regulatory liabilities, net increase (decrease)			0
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax expense (benefit)			0
Amortization of prior year prior service cost			0
Net amount recognized in accumulated other comprehensive (income) loss			$ 0

Employee Benefit Plans (Project

Employee Benefit Plans (Projected Benefit Obligations Reconciliation of Funded Status to Net Amount Recognized) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Pension Plan [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions		$ 141	$ 19	$ 155
Pension Plan [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		8,448	8,131
Service cost		174	159	147
Interest cost		299	328	335
Actuarial loss (gain)		(485)	455
Plan amendments			(61)
Benefits paid		(567)	(537)
Impact of settlements			(27)
Obligation at measurement date	$ 8,131	7,869	8,448	8,131
Accumulated benefit obligation at measurement date		7,818	8,369
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		9,003	8,531
Actual return on plan assets		(344)	1,017
Benefits paid		(567)	(537)
Impact of Settlements			(27)
Employer contributions		141	19
Plan assets at measurement date	8,531	8,233	9,003	8,531
Funded status of plan		364	555
Pension Plan [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		331	332
Service cost		2	2	2
Interest cost		12	13	14
Actuarial loss (gain)		(17)	15
Benefits paid		(24)	(31)
Obligation at measurement date	332	304	331	332
Accumulated benefit obligation at measurement date		304	331
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(24)	(31)
Employer contributions		24	31
Pension Plan [Member] | Duke Energy Carolinas [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions		46		43
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		2,029	1,952
Service cost		56	48	48
Interest cost		72	79	86
Actuarial loss (gain)		(44)	68
Transfers			27
Benefits paid		(159)	(145)
Obligation at measurement date	1,952	1,954	2,029	1,952
Accumulated benefit obligation at measurement date		1,954	2,029
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		2,372	2,225
Actual return on plan assets		(91)	265
Benefits paid		(159)	(145)
Transfer of plan assets			27
Employer contributions		46
Plan assets at measurement date	2,225	2,168	2,372	2,225
Funded status of plan		214	343
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		14	14
Service cost		1	1
Interest cost			1	1
Benefits paid		(1)	(2)
Obligation at measurement date	14	14	14	14
Accumulated benefit obligation at measurement date		14	14
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(1)	(2)
Employer contributions		1	2
Pension Plan [Member] | Progress Energy [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions		45		43
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		2,637	2,512
Service cost		49	45	42
Interest cost		94	100	106
Actuarial loss (gain)		(204)	158
Transfers			(32)
Benefits paid		(143)	(146)
Obligation at measurement date	2,512	2,433	2,637	2,512
Accumulated benefit obligation at measurement date		2,404	2,601
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		2,814	2,675
Actual return on plan assets		(110)	317
Benefits paid		(143)	(146)
Transfer of plan assets			(32)
Employer contributions		45
Plan assets at measurement date	2,675	2,606	2,814	2,675
Funded status of plan		173	177
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		116	114
Interest cost		4	5	5
Actuarial loss (gain)		(6)	5
Benefits paid		(8)	(8)
Obligation at measurement date	114	106	116	114
Accumulated benefit obligation at measurement date		106	116
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(8)	(8)
Employer contributions		8	8
Pension Plan [Member] | Duke Energy Progress [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions		25		24
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		1,211	1,158
Service cost		28	26	24
Interest cost		43	47	49
Actuarial loss (gain)		(87)	57
Transfers			(2)
Benefits paid		(70)	(75)
Obligation at measurement date	1,158	1,125	1,211	1,158
Accumulated benefit obligation at measurement date		1,125	1,211
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		1,366	1,290
Actual return on plan assets		(53)	153
Benefits paid		(70)	(75)
Transfer of plan assets			(2)
Employer contributions		25
Plan assets at measurement date	1,290	1,268	1,366	1,290
Funded status of plan		143	155
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		35	33
Interest cost		1	1	1
Actuarial loss (gain)		(2)	4
Benefits paid		(3)	(3)
Obligation at measurement date	33	31	35	33
Accumulated benefit obligation at measurement date		31	35
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(3)	(3)
Employer contributions		3	3
Pension Plan [Member] | Duke Energy Florida [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions		20		20
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		1,410	1,323
Service cost		21	19	19
Interest cost		50	53	55
Actuarial loss (gain)		(114)	99
Transfers			(15)
Benefits paid		(72)	(69)
Obligation at measurement date	1,323	1,295	1,410	1,323
Accumulated benefit obligation at measurement date		1,265	1,375
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		1,429	1,352
Actual return on plan assets		(55)	161
Benefits paid		(72)	(69)
Transfer of plan assets			(15)
Employer contributions		20
Plan assets at measurement date	1,352	1,322	1,429	1,352
Funded status of plan		27	19
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		47	46
Interest cost		2	2	2
Actuarial loss (gain)		(3)	2
Benefits paid		(3)	(3)
Obligation at measurement date	46	43	47	46
Accumulated benefit obligation at measurement date		43	47
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(3)	(3)
Employer contributions		3	3
Pension Plan [Member] | Duke Energy Ohio [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions			4	5
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		479	447
Service cost		5	4	4
Interest cost		17	18	19
Actuarial loss (gain)		(29)	35
Transfers			12
Benefits paid		(37)	(37)
Obligation at measurement date	447	435	479	447
Accumulated benefit obligation at measurement date		425	468
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		458	428
Actual return on plan assets		(16)	51
Benefits paid		(37)	(37)
Transfer of plan assets			12
Employer contributions			4
Plan assets at measurement date	428	405	458	428
Funded status of plan		(30)	(21)
Pension Plan [Member] | Duke Energy Ohio [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		4	4
Actuarial loss (gain)		(1)
Obligation at measurement date	4	3	4	4
Accumulated benefit obligation at measurement date		3	4
Pension Plan [Member] | Duke Energy Indiana [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions		8		9
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		669	658
Service cost		10	9	9
Interest cost		23	26	28
Actuarial loss (gain)		(29)	26
Benefits paid		(55)	(50)
Obligation at measurement date	658	618	669	658
Accumulated benefit obligation at measurement date		614	652
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		684	657
Actual return on plan assets		(26)	77
Benefits paid		(55)	(50)
Employer contributions		8
Plan assets at measurement date	657	611	684	657
Funded status of plan		(7)	15
Pension Plan [Member] | Duke Energy Indiana [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		3	3
Obligation at measurement date	3	3	3	3
Accumulated benefit obligation at measurement date		3	3
Pension Plan [Member] | Piedmont Natural Gas [Member]
Change in Fair Value of Plan Assets [Rollforward]
Employer contributions	10		11		$ 10
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		313	344
Service cost	2	7	10		11
Interest cost	2	11	14		9
Actuarial loss (gain)		(18)	(38)
Transfers		(16)	0
Plan amendments			(61)
Benefits paid		(33)	(5)
Impact of settlements			(27)
Obligation at measurement date	344	264	313	344
Accumulated benefit obligation at measurement date		264	313
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		368	346
Actual return on plan assets		(14)	43
Benefits paid		(33)	(5)
Impact of Settlements			(27)
Transfer of plan assets		(16)	0
Employer contributions			11
Plan assets at measurement date	346	305	368	346
Funded status of plan		41	55
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		4	4
Service cost			0
Interest cost			0
Actuarial loss (gain)		(1)	0
Benefits paid			0
Obligation at measurement date	4	3	4	4
Accumulated benefit obligation at measurement date		3	4
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid			0
Employer contributions			0
Other Post-Retirement Benefit Plans [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		813	868
Service cost		6	4	3
Interest cost		28	34	35
Plan participants' contributions		18	17
Actuarial loss (gain)		(51)	4
Plan amendments			(28)
Benefits paid		(86)	(86)
Obligation at measurement date	868	728	813	868
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		225	244
Actual return on plan assets		(8)	25
Benefits paid		(86)	(86)
Employer contributions (reimbursements)			25
Plan participants' contributions		18	17
Employer contributions		46
Plan assets at measurement date	244	195	225	244
Funded status of plan		(533)	(588)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		189	201
Service cost		1	1	1
Interest cost		7	8	8
Plan participants' contributions		3	3
Actuarial loss (gain)		(8)	(3)
Transfers			2
Plan amendments			(5)
Benefits paid		(18)	(18)
Obligation at measurement date	201	174	189	201
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		133	137
Actual return on plan assets		(5)	15
Benefits paid		(18)	(18)
Employer contributions (reimbursements)		2	(4)
Plan participants' contributions		3	3
Plan assets at measurement date	137	115	133	137
Funded status of plan		(59)	(56)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		342	357
Service cost		1		1
Interest cost		12	13	15
Plan participants' contributions		6	6
Actuarial loss (gain)		(23)	4
Transfers			(1)
Plan amendments			(3)
Benefits paid		(35)	(34)
Obligation at measurement date	357	303	342	357
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date			1
Actual return on plan assets			1
Benefits paid		(35)	(34)
Employer contributions (reimbursements)			26
Plan participants' contributions		6	6
Employer contributions		29
Plan assets at measurement date	1			1
Funded status of plan		(303)	(342)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		184	191
Interest cost		6	7	8
Plan participants' contributions		4	3
Actuarial loss (gain)		(9)	1
Plan amendments			(1)
Benefits paid		(19)	(17)
Obligation at measurement date	191	166	184	191
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(19)	(17)
Employer contributions (reimbursements)			14
Plan participants' contributions		4	3
Employer contributions		15
Funded status of plan		(166)	(184)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		156	164
Service cost		1		1
Interest cost		6	6	7
Plan participants' contributions		3	3
Actuarial loss (gain)		(13)	3
Transfers			(1)
Plan amendments			(2)
Benefits paid		(16)	(17)
Obligation at measurement date	164	137	156	164
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(16)	(17)
Employer contributions (reimbursements)			14
Plan participants' contributions		3	3
Employer contributions		13
Funded status of plan		(137)	(156)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		30	32
Service cost		1
Interest cost		1	1	1
Plan participants' contributions		1	1
Actuarial loss (gain)		(2)
Transfers			1
Plan amendments			(2)
Benefits paid		(2)	(3)
Obligation at measurement date	32	29	30	32
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		7	7
Actual return on plan assets			2
Benefits paid		(2)	(3)
Plan participants' contributions		1	1
Employer contributions		2
Plan assets at measurement date	7	8	7	7
Funded status of plan		(21)	(23)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		78	83
Service cost		1
Interest cost		3	3	4
Plan participants' contributions		2	2
Actuarial loss (gain)		(5)	3
Plan amendments			(2)
Benefits paid		(12)	(11)
Obligation at measurement date	83	67	78	83
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		11	22
Actual return on plan assets			1
Benefits paid		(12)	(11)
Employer contributions (reimbursements)		4	(3)
Plan participants' contributions		2	2
Plan assets at measurement date	22	5	11	22
Funded status of plan		(62)	(67)
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date		32	39
Service cost		1	1		1
Interest cost		1	1		$ 1
Plan participants' contributions			0
Actuarial loss (gain)		(1)	1
Transfers		(1)	0
Plan amendments			(9)
Benefits paid		(2)	(1)
Obligation at measurement date	39	30	32	39
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		31	29
Actual return on plan assets		(1)	3
Benefits paid		(2)	(1)
Employer contributions (reimbursements)			0
Plan participants' contributions			0
Employer contributions		1
Plan assets at measurement date	$ 29	29	31	$ 29
Funded status of plan		$ (1)	$ (1)

Employee Benefit Plans (Amoun_2

Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	$ 988	$ 1,103
Regulatory assets	15,622	13,879
Regulatory Liabilities	15,432	15,732
Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	99	95
Regulatory assets	3,977	3,152
Regulatory Liabilities	6,198	6,357
Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	521	545
Regulatory assets	7,701	6,751
Regulatory Liabilities	5,329	5,519
Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	237	248
Regulatory assets	4,814	3,859
Regulatory Liabilities	4,133	4,138
Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	254	264
Regulatory assets	2,888	2,892
Regulatory Liabilities	1,196	1,381
Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	79	59
Regulatory assets	564	494
Regulatory Liabilities	897	927
Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	115	76
Regulatory assets	1,157	1,143
Regulatory Liabilities	1,747	1,747
Piedmont Natural Gas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	4	5
Regulatory assets	357	378
Regulatory Liabilities	1,218	1,144
Pension Plan [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	433	680
Noncurrent pension liability	69	125
Net amount recognized	364	555
Regulatory assets	2,184	1,886
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(43)	(41)
Prior year service cost (credit) arising during the year	(4)	(5)
Net actuarial loss (gain)	126	116
Net amount recognized in accumulated other comprehensive income (loss)	79	70
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	97	132
Unrecognized prior service (credit) cost	(32)	(32)
Pension Plan [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	21	23
Noncurrent pension liability	283	308
Total accrued pension liability	304	331
Regulatory assets	62	78
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(3)	(4)
Prior year service cost (credit) arising during the year	(1)	(1)
Net actuarial loss (gain)	8	12
Net amount recognized in accumulated other comprehensive income (loss)	4	7
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	6	8
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	214	343
Net amount recognized	214	343
Regulatory assets	576	406
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	22	29
Unrecognized prior service (credit) cost	(8)	(8)
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	12	12
Total accrued pension liability	14	14
Regulatory assets	5	4
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	242	245
Noncurrent pension liability	69	68
Net amount recognized	173	177
Regulatory assets	796	756
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(2)	(3)
Net actuarial loss (gain)	5	9
Net amount recognized in accumulated other comprehensive income (loss)	3	6
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	37	44
Unrecognized prior service (credit) cost	(3)	(3)
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	8	8
Noncurrent pension liability	98	108
Total accrued pension liability	106	116
Regulatory assets	15	21
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(2)	(3)
Net actuarial loss (gain)	6	9
Net amount recognized in accumulated other comprehensive income (loss)	4	6
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	2	2
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	143	155
Net amount recognized	143	155
Regulatory assets	372	341
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	13	21
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	3
Noncurrent pension liability	28	32
Total accrued pension liability	31	35
Regulatory assets	5	8
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	1	1
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	96	87
Noncurrent pension liability	69	68
Net amount recognized	27	19
Regulatory assets	424	415
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	24	23
Unrecognized prior service (credit) cost	(1)	(1)
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	3
Noncurrent pension liability	40	44
Total accrued pension liability	43	47
Regulatory assets	10	13
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	1	1
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	24	8
Noncurrent pension liability	54	29
Net amount recognized	(30)	(21)
Regulatory assets	100	90
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	3	5
Pension Plan [Member] | Duke Energy Ohio [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	3	4
Total accrued pension liability	3	4
Regulatory assets	1	1
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	39	16
Noncurrent pension liability	46	1
Net amount recognized	(7)	15
Regulatory assets	182	152
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	5	7
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan [Member] | Duke Energy Indiana [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	3	3
Total accrued pension liability	3	3
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	41	55
Net amount recognized	41	55
Regulatory assets	81	73
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	7	11
Unrecognized prior service (credit) cost	(9)	(9)
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	3	4
Total accrued pension liability	3	4
Regulatory assets	1	1
Other Post-Retirement Benefit Plans [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	8	36
Noncurrent pension liability	525	552
Total accrued pension liability	533	588
Regulatory assets	262	125
Regulatory Liabilities	301	147
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	3	4
Prior year service cost (credit) arising during the year	(2)	(2)
Net actuarial loss (gain)	(9)	(10)
Net amount recognized in accumulated other comprehensive income (loss)	(8)	(8)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	4	5
Unrecognized prior service (credit) cost	(19)	(19)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	59	56
Total accrued pension liability	59	56
Regulatory Liabilities	38	44
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	2	3
Unrecognized prior service (credit) cost	(5)	(5)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	5	29
Noncurrent pension liability	298	313
Total accrued pension liability	303	342
Regulatory assets	262	129
Regulatory Liabilities	149
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	1	1
Unrecognized prior service (credit) cost	(7)	(7)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	15
Noncurrent pension liability	163	169
Total accrued pension liability	166	184
Regulatory assets	164	80
Regulatory Liabilities	93
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	14
Noncurrent pension liability	135	142
Total accrued pension liability	137	156
Regulatory assets	98	49
Regulatory Liabilities	56
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		1
Unrecognized prior service (credit) cost	(6)	(6)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	19	21
Total accrued pension liability	21	23
Regulatory Liabilities	18	16
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	62	67
Total accrued pension liability	62	67
Regulatory assets	41	46
Regulatory Liabilities	67	64
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	1	1
Total accrued pension liability	1	1
Regulatory assets		(4)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	$ (2)	$ (2)

Employee Benefit Plans (Informa

Employee Benefit Plans (Information For Plans with Accumulated Benefit Obligation in Excess of Plan Assets) (Details) - Pension Plan [Member] - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Qualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	$ 679	$ 1,386
Accumulated benefit obligation	651	1,326
Fair value of plan assets	610	1,260
Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	304	331
Accumulated benefit obligation	304	331
Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	14	14
Accumulated benefit obligation	14	14
Progress Energy [Member] | Qualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	679	718
Accumulated benefit obligation	651	683
Fair value of plan assets	610	650
Progress Energy [Member] | Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	106	116
Accumulated benefit obligation	106	116
Duke Energy Progress [Member] | Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	31	35
Accumulated benefit obligation	31	35
Duke Energy Florida [Member] | Qualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	679	718
Accumulated benefit obligation	651	683
Fair value of plan assets	610	650
Duke Energy Florida [Member] | Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	43	47
Accumulated benefit obligation	43	47
Duke Energy Ohio [Member] | Qualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	123	337
Accumulated benefit obligation	115	326
Fair value of plan assets	69	308
Duke Energy Ohio [Member] | Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	3	4
Accumulated benefit obligation	3	4
Duke Energy Indiana [Member] | Qualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	203
Accumulated benefit obligation	199
Fair value of plan assets	159
Duke Energy Indiana [Member] | Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	3	3
Accumulated benefit obligation	3	3
Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	3	4
Accumulated benefit obligation	$ 3	$ 4

Employee Benefit Plans (Assumpt

Employee Benefit Plans (Assumptions Used For Pension Benefits Accounting) (Details)	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Pension Plan [Member] | Qualified Plan [Member]
Benefit Obligations [Abstract]
Discount rate	4.10%	4.30%	3.60%	4.10%
Net Periodic Benefit Cost [Abstract]
Discount rate		3.60%	4.10%	4.40%
Expected long-term rate of return on plan assets				6.75%
Pension Plan [Member] | Nonqualified Plan [Member]
Benefit Obligations [Abstract]
Discount rate	4.10%	4.30%	3.60%	4.10%
Salary increase	4.40%			4.40%
Net Periodic Benefit Cost [Abstract]
Discount rate		3.60%	4.10%	4.40%
Salary increase			4.40%	4.40%
Pension Plan [Member] | Minimum [Member] | Qualified Plan [Member]
Benefit Obligations [Abstract]
Salary increase	4.00%	3.50%	3.50%	4.00%
Net Periodic Benefit Cost [Abstract]
Discount rate
Salary increase		3.50%	4.00%	4.00%
Expected long-term rate of return on plan assets			6.50%	6.50%
Pension Plan [Member] | Minimum [Member] | Nonqualified Plan [Member]
Benefit Obligations [Abstract]
Salary increase		3.50%	3.50%
Net Periodic Benefit Cost [Abstract]
Salary increase		3.50%
Pension Plan [Member] | Maximum [Member] | Qualified Plan [Member]
Benefit Obligations [Abstract]
Salary increase	4.50%	4.00%	4.00%	4.50%
Net Periodic Benefit Cost [Abstract]
Salary increase		4.00%	4.50%	4.40%
Expected long-term rate of return on plan assets		6.50%	6.75%
Pension Plan [Member] | Maximum [Member] | Nonqualified Plan [Member]
Benefit Obligations [Abstract]
Salary increase		4.00%	4.00%
Net Periodic Benefit Cost [Abstract]
Salary increase		4.00%
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Benefit Obligations [Abstract]
Discount rate	4.10%			4.10%	3.80%
Salary increase	4.50%			4.50%	4.05%
Net Periodic Benefit Cost [Abstract]
Discount rate	3.80%				4.34%
Salary increase	4.05%				4.07%
Expected long-term rate of return on plan assets	6.75%				7.25%
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Benefit Obligations [Abstract]
Discount rate	4.10%			4.10%	3.80%
Net Periodic Benefit Cost [Abstract]
Discount rate	3.80%				3.85%
Other Post-Retirement Benefit Plans [Member]
Benefit Obligations [Abstract]
Discount rate	4.10%	4.30%	3.60%	4.10%
Net Periodic Benefit Cost [Abstract]
Discount rate		3.60%	4.10%	4.40%
Expected long-term rate of return on plan assets		6.50%	6.50%	6.50%
Assumed tax rate		35.00%	35.00%	35.00%
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Benefit Obligations [Abstract]
Discount rate	4.10%			4.10%	3.80%
Net Periodic Benefit Cost [Abstract]
Discount rate	3.80%				4.38%
Expected long-term rate of return on plan assets	6.75%				7.25%

Employee Benefit Plans (Assumed

Employee Benefit Plans (Assumed Health Care Cost Trend Rates) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	6.50%	7.00%
Rate to which the cost trend is assumed to decline (the ultimate trend rate)	4.75%	4.75%
Year that the rate reaches the ultimate trend rate	2,024	2,024

Employee Benefit Plans (Sensiti

Employee Benefit Plans (Sensitivity to Changes in Assumed Health Care Cost Trend Rates) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest costs - 1 Percentage Point Increase	$ 1
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	22
Effect on total service and interest costs - 1 Percentage Point Decrease	(1)
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(20)
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	5
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(5)
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest costs - 1 Percentage Point Increase	1
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	9
Effect on total service and interest costs - 1 Percentage Point Decrease	(1)
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(8)
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest costs - 1 Percentage Point Increase	1
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	5
Effect on total service and interest costs - 1 Percentage Point Decrease	(1)
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(5)
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	4
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(4)
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	1
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(1)
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	2
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(2)
Piedmont Natural Gas [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	1
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	$ (1)

Employee Benefit Plans (Expecte

Employee Benefit Plans (Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2018USD ($)
Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	$ 662
2,020	651
2,021	663
2,022	662
2,023	655
2024-2028	2,993
Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	22
2,020	21
2,021	23
2,022	25
2,023	25
2024-2028	125
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	210
2,020	177
2,021	182
2,022	189
2,023	185
2024-2028	794
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	2
2,020	1
2,021	1
2,022	1
2,023	3
2024-2028	10
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	179
2,020	171
2,021	177
2,022	179
2,023	181
2024-2028	902
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	8
2,020	8
2,021	8
2,022	8
2,023	7
2024-2028	37
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	105
2,020	90
2,021	95
2,022	94
2,023	95
2024-2028	451
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	3
2,020	2
2,021	2
2,022	2
2,023	2
2024-2028	11
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	73
2,020	80
2,021	81
2,022	84
2,023	85
2024-2028	447
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	3
2,020	3
2,021	3
2,022	3
2,023	3
2024-2028	15
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	33
2,020	37
2,021	37
2,022	37
2,023	35
2024-2028	158
Pension Plan [Member] | Duke Energy Ohio [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2024-2028	1
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	47
2,020	51
2,021	51
2,022	49
2,023	47
2024-2028	217
Pension Plan [Member] | Duke Energy Indiana [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2024-2028	1
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	20
2,020	24
2,021	23
2,022	22
2,023	22
2024-2028	96
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2024-2028	2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	81
2,020	75
2,021	71
2,022	68
2,023	64
2024-2028	266
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	19
2,020	18
2,021	18
2,022	17
2,023	16
2024-2028	64
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	30
2,020	29
2,021	28
2,022	27
2,023	26
2024-2028	109
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	16
2,020	15
2,021	15
2,022	14
2,023	14
2024-2028	59
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	14
2,020	13
2,021	13
2,022	12
2,023	12
2024-2028	50
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	3
2,020	3
2,021	3
2,022	3
2,023	3
2024-2028	11
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	9
2,020	8
2,021	7
2,022	7
2,023	6
2024-2028	26
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	2
2,020	2
2,021	2
2,022	3
2,023	3
2024-2028	$ 12

Employee Benefit Plans (Target

Employee Benefit Plans (Target and Actual Asset Allocations) (Details)	Dec. 31, 2018	Dec. 31, 2017
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
Master Trust [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	11.00%	11.00%
Target allocation	10.00%
Master Trust [Member] | Non US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	8.00%	8.00%
Target allocation	8.00%
Master Trust [Member] | Global Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	10.00%	10.00%
Target allocation	10.00%
Master Trust [Member] | Global Private Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	3.00%
Master Trust [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	63.00%	63.00%
Target allocation	63.00%
Master Trust [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
Master Trust [Member] | Real Estate and Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
Master Trust [Member] | Other Global Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
OPEB [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	43.00%	41.00%
Target allocation	32.00%
OPEB [Member] | Non US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	8.00%	8.00%
Target allocation	6.00%
OPEB [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	40.00%	36.00%
Target allocation	45.00%
OPEB [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
OPEB [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	7.00%	13.00%
Target allocation	15.00%

Employee Benefit Plans (Fair Va

Employee Benefit Plans (Fair Value Measurements of Plan Assets - Master Retirement Trust) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	$ 27	$ 28	$ 38
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	8,324	9,114
Master Trust [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	2,052	2,189
Master Trust [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	5,133	5,552
Master Trust [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	27	28
Master Trust [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	1,112	1,345
Master Trust [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	2,373	2,823
Master Trust [Member] | Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	1,751	1,976
Master Trust [Member] | Equity Securities [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	622	847
Master Trust [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	4,054	4,694
Master Trust [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	4,054	4,694
Master Trust [Member] | Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	363	246
Master Trust [Member] | Short Term Investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	279	192
Master Trust [Member] | Short Term Investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	84	54
Master Trust [Member] | Partnership Interest [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	120	137
Master Trust [Member] | Partnership Interest [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	120	137
Master Trust [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	226	226
Master Trust [Member] | Hedge Funds [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	226	226
Master Trust [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	144	135
Master Trust [Member] | Real Estate [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	144	135
Master Trust [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	961	762
Master Trust [Member] | US Treasury and Government [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	961	762
Master Trust [Member] | Guaranteed Investment Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	27	28
Master Trust [Member] | Guaranteed Investment Contracts [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	27	28
Master Trust [Member] | Government Bonds - Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	30	38
Master Trust [Member] | Government Bonds - Foreign [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	30	38
Master Trust [Member] | Cash [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	28	6
Master Trust [Member] | Cash [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	28	6
Master Trust [Member] | Asset Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets		2
Master Trust [Member] | Asset Backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets		2
Master Trust [Member] | Miscellaneous Investments And Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	(2)	17
Master Trust [Member] | Miscellaneous Investments And Other [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	(6)	15
Master Trust [Member] | Miscellaneous Investments And Other [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	4	2
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	49	58
OPEB [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	49	58
OPEB [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	25	28
OPEB [Member] | Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	25	28
OPEB [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	1	1
OPEB [Member] | Real Estate [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	1	1
OPEB [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	3	8
OPEB [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	3	8
OPEB [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	20	21
OPEB [Member] | Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	$ 20	$ 21
Duke Energy Carolinas [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	27.00%	27.00%
Progress Energy [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	31.00%	30.00%
Duke Energy Progress [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	15.00%	15.00%
Duke Energy Florida [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	16.00%	15.00%
Duke Energy Ohio [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	5.00%	5.00%
Duke Energy Indiana [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	7.00%	8.00%
Piedmont Natural Gas [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets			$ 9
Piedmont Natural Gas [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	4.00%	4.00%

Employee Benefit Plans (Reconci

Employee Benefit Plans (Reconciliation of Assets Measured at Fair Value on a Recurring Basis) (Details) - Level 3 [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Plan assets at prior measurement date	$ 28	$ 38
Sales	(1)	(2)
Total gains (losses) and other, net	0	1
Transfer of Level 3 assets to other classifications	0	(9)
Plan assets at measurement date	$ 27	28
Piedmont Natural Gas [Member]
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Plan assets at prior measurement date		$ 9

Employee Benefit Plans (Employe

Employee Benefit Plans (Employee Savings Plans) (Details) - USD ($)	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Employee Savings Plans [Abstract]
Matching contribution percentage		100.00%
Eligible pay percentage		6.00%
Additional contribution percentage for employees not participating in defined pension plans		4.00%
Employer contributions		$ 213,000,000	$ 179,000,000	$ 169,000,000
Duke Energy Carolinas [Member]
Employee Savings Plans [Abstract]
Employer contributions		68,000,000	61,000,000	57,000,000
Progress Energy [Member]
Employee Savings Plans [Abstract]
Employer contributions		58,000,000	53,000,000	50,000,000
Duke Energy Progress [Member]
Employee Savings Plans [Abstract]
Employer contributions		40,000,000	37,000,000	35,000,000
Duke Energy Florida [Member]
Employee Savings Plans [Abstract]
Employer contributions		19,000,000	16,000,000	15,000,000
Duke Energy Ohio [Member]
Employee Savings Plans [Abstract]
Employer contributions		4,000,000	3,000,000	3,000,000
Duke Energy Indiana [Member]
Employee Savings Plans [Abstract]
Employer contributions		$ 10,000,000	9,000,000	8,000,000
Piedmont Natural Gas [Member]
Employee Savings Plans [Abstract]
Additional contribution percentage for employees not participating in defined pension plans		4.00%
Employer contributions			7,000,000
Piedmont Natural Gas [Member] | Pension Plan [Member]
Employee Savings Plans [Abstract]
Eligible pay percentage		4.00%
Employer contributions	$ 0		$ 2,000,000		$ 2,000,000
Piedmont Natural Gas [Member] | 401K [Member]
Employee Savings Plans [Abstract]
Employer contributions	$ 1,000,000	$ 12,000,000			$ 7,000,000

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Tax Act		$ 20	$ (112)
Analysis of Existing Regulatory Liability [Member]
Income Tax Disclosure [Line Items]
Measurement period adjustments		23
Bonus Depreciation [Member]
Income Tax Disclosure [Line Items]
Measurement period adjustments		10
Regulatory Liability [Member]
Income Tax Disclosure [Line Items]
Measurement period adjustments		83
Nondeductible Long-term Incentives [Member]
Income Tax Disclosure [Line Items]
Measurement period adjustments		7
Refundable AMT Credits [Member]
Income Tax Disclosure [Line Items]
Measurement period adjustments	$ 76
Reclassified AMT Credit Carryforwards [Member]
Income Tax Disclosure [Line Items]
Measurement period adjustments		$ 573

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		$ (647)	$ (247)
Current state taxes		(11)	4	$ (15)
Current foreign taxes		3	3	2
Total current income taxes		(655)	(240)	(13)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		1,064	1,344	1,064
Deferred state taxes		49	102	117
Total deferred income taxes		1,113	1,446	1,181
Investment tax credit amortization		(10)	(10)	(12)
Income tax expense (benefit) from continuing operations		448	1,196	1,156
Tax expense (benefit) from discontinued operations		(26)	(6)	(30)
Total income tax expense included in Consolidated Statements of Operations		422	1,190	1,126
Net operating loss carry forward		(18)	428	648
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Domestic		3,018	4,207	3,689
Foreign		55	59	45
Total income from continuing operations before income taxes		3,073	4,266	3,734
Equity in losses of unconsolidated affiliates		(83)	(119)	15
Tax Act [Member]
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Equity in losses of unconsolidated affiliates		16
Duke Energy Carolinas [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(8)	221	139
Current state taxes		6	20	25
Total current income taxes		(2)	241	164
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		299	381	430
Deferred state taxes		11	35	45
Total deferred income taxes		310	416	475
Investment tax credit amortization		(5)	(5)	(5)
Income tax expense (benefit) from continuing operations		303	652	634
Total income tax expense included in Consolidated Statements of Operations		303	652	634
Net operating loss carry forward		22	10	(4)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		1,374	1,866	1,800
Progress Energy [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(135)	(436)	15
Current state taxes		(5)	(5)	(19)
Total current income taxes		(140)	(441)	(4)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		341	664	486
Deferred state taxes		20	44	50
Total deferred income taxes		361	708	536
Investment tax credit amortization		(3)	(3)	(5)
Income tax expense (benefit) from continuing operations		218	264	527
Tax expense (benefit) from discontinued operations				1
Total income tax expense included in Consolidated Statements of Operations		218	264	528
Net operating loss carry forward		(293)	(74)	(190)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		1,251	1,532	1,566
Duke Energy Progress [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(71)	(95)	(59)
Current state taxes		(5)	2	(25)
Total current income taxes		(76)	(93)	(84)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		256	378	350
Deferred state taxes		(17)	10	40
Total deferred income taxes		239	388	390
Investment tax credit amortization		(3)	(3)	(5)
Income tax expense (benefit) from continuing operations		160	292	301
Total income tax expense included in Consolidated Statements of Operations		160	292	301
Net operating loss carry forward		59	1	(60)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		827	1,007	900
Duke Energy Florida [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(49)	(188)	76
Current state taxes		(10)	(11)	22
Total current income taxes		(59)	(199)	98
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		115	194	199
Deferred state taxes		45	51	25
Total deferred income taxes		160	245	224
Income tax expense (benefit) from continuing operations		101	46	322
Total income tax expense included in Consolidated Statements of Operations		101	46	322
Net operating loss carry forward		(219)	(36)	(49)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		655	758	873
Duke Energy Ohio [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		20	(37)	(7)
Current state taxes		(1)	2	(13)
Total current income taxes		19	(35)	(20)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		21	99	88
Deferred state taxes		3	(4)	11
Total deferred income taxes		24	95	99
Investment tax credit amortization			(1)	(1)
Income tax expense (benefit) from continuing operations		43	59	78
Tax expense (benefit) from discontinued operations				(36)
Total income tax expense included in Consolidated Statements of Operations		43	59	42
Net operating loss carry forward		(17)	(17)	(26)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		219	252	270
Duke Energy Indiana [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		29	128	7
Current state taxes		3	21	6
Total current income taxes		32	149	13
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		74	138	202
Deferred state taxes		22	14	11
Total deferred income taxes		96	152	213
Investment tax credit amortization				(1)
Income tax expense (benefit) from continuing operations		128	301	225
Total income tax expense included in Consolidated Statements of Operations		128	301	225
Net operating loss carry forward		(21)	(42)	(58)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		521	655	$ 606
Piedmont Natural Gas [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	$ 4	67	(90)		$ 27
Current state taxes	(2)	1	(3)		12
Total current income taxes	2	68	(93)		39
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	24	(36)	147		79
Deferred state taxes	6	5	8		6
Total deferred income taxes	30	(31)	155		85
Income tax expense (benefit) from continuing operations	32	37	62		124
Total income tax expense included in Consolidated Statements of Operations		37	62
Net operating loss carry forward	17	(39)	(79)		91
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	86	166	201		317
Equity in losses of unconsolidated affiliates	$ (2)	$ (7)	6		$ (29)
Previously Remitted Earnings [Member]
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Tax expense (benefit) from discontinued operations			$ (95)

Income Taxes (Effective Tax Rat

Income Taxes (Effective Tax Rates) (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended				12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate						$ 645	$ 1,493	$ 1,307
State income tax, net of federal income tax effect						30	69	64
Amortization of excess deferred income tax						(61)
AFUDC equity income						(42)	(81)	(70)
AFUDC equity depreciation						31
Renewable energy production tax credits						(129)	(132)	(97)
Other tax credits						(28)
Tax Act						20	(112)
Audit Adjustment								5
Tax true up							(52)	(14)
Other items, net						(18)	11	(39)
Income tax expense (benefit) from continuing operations						$ 448	$ 1,196	$ 1,156
Effective tax rate						14.60%	28.00%	31.00%
Duke Energy Carolinas [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate						$ 288	$ 653	$ 630
State income tax, net of federal income tax effect						14	36	46
AFUDC equity income						(15)	(37)	(36)
AFUDC equity depreciation						18
Other tax credits						(7)
Tax Act			$ 1		$ 15	1	15
Audit Adjustment								3
Tax true up							(24)	(14)
Other items, net						4	9	5
Income tax expense (benefit) from continuing operations						$ 303	$ 652	$ 634
Effective tax rate						22.10%	34.90%	35.20%
Progress Energy [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate						$ 263	$ 536	$ 548
State income tax, net of federal income tax effect						13	25	20
Amortization of excess deferred income tax						(55)
AFUDC equity income						(22)	(32)	(26)
AFUDC equity depreciation						9
Other tax credits						(13)
Tax Act		$ 19	5	$ 1	(246)	25	(246)
Tax true up							(19)	(11)
Other items, net						(2)		(4)
Income tax expense (benefit) from continuing operations						$ 218	$ 264	$ 527
Effective tax rate						17.40%	17.20%	33.70%
Duke Energy Progress [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate						$ 174	$ 353	$ 315
State income tax, net of federal income tax effect						(17)	8	10
Amortization of excess deferred income tax						(1)
AFUDC equity income						(12)	(17)	(17)
AFUDC equity depreciation						5
Other tax credits						(5)
Tax Act		15	4		(40)	19	(40)
Tax true up							(13)	(3)
Other items, net						(3)	1	(4)
Income tax expense (benefit) from continuing operations						$ 160	$ 292	$ 301
Effective tax rate						19.30%	29.00%	33.40%
Duke Energy Florida [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate						$ 137	$ 265	$ 306
State income tax, net of federal income tax effect						28	26	30
Amortization of excess deferred income tax						(54)
AFUDC equity income						(10)	(16)	(9)
AFUDC equity depreciation						4
Other tax credits						(8)
Tax Act		(2)	$ 2		(226)		(226)
Tax true up							(7)	(9)
Other items, net						4	4	4
Income tax expense (benefit) from continuing operations						$ 101	$ 46	$ 322
Effective tax rate						15.40%	6.10%	36.90%
Duke Energy Ohio [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate						$ 46	$ 88	$ 95
State income tax, net of federal income tax effect						2	(1)	(2)
Amortization of excess deferred income tax						(3)
AFUDC equity income						(2)	(4)	(2)
AFUDC equity depreciation						1
Other tax credits						(1)
Tax Act		$ 2			(23)	2	(23)
Tax true up							(5)	(16)
Other items, net						(2)	4	3
Income tax expense (benefit) from continuing operations						$ 43	$ 59	$ 78
Effective tax rate						19.60%	23.40%	28.90%
Duke Energy Indiana [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate						$ 109	$ 229	$ 212
State income tax, net of federal income tax effect						20	23	11
Amortization of excess deferred income tax						(2)
AFUDC equity income						(2)	(8)	(6)
AFUDC equity depreciation						4
Other tax credits						(1)
Tax Act					$ 55		55
Tax true up							(6)	2
Other items, net							8	6
Income tax expense (benefit) from continuing operations						$ 128	$ 301	$ 225
Effective tax rate						24.60%	46.00%	37.10%
Piedmont Natural Gas [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 30					$ 35	$ 70		$ 111
State income tax, net of federal income tax effect	1					4	3		11
Other tax credits						(3)
Tax Act							(12)
Other items, net	1					1	1		2
Income tax expense (benefit) from continuing operations	$ 32					$ 37	$ 62		$ 124
Effective tax rate	37.20%					22.30%	30.80%		39.10%

Income Taxes (Deferred Income T

Income Taxes (Deferred Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		$ 164	$ 143
Capital lease obligations		60	49
Pension, postretirement and other employee benefits		347	295
Progress Energy merger purchase accounting adjustments		483	536
Tax credits and NOL carryforwards		4,580	4,527
Other		25	73
Valuation allowance		(484)	(519)
Total deferred income tax assets		5,175	5,104
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(1,317)	(1,419)
Accelerated depreciation rates		(10,124)	(9,216)
Regulatory assets and deferred debits, net		(1,540)	(1,090)
Total deferred income tax liabilities		(12,981)	(11,725)
Net deferred income tax liabilities		(7,806)	(6,621)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		4,580	4,527
Valuation allowance		(484)	(519)
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		$ (7,806)	(6,621)
State [Member] | Tax Year 2019 [Member] | North Carolina Department of Revenue [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate		2.50%
Net reduction in deferred tax liability	$ 55
Investment Tax Credits [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		$ 1,614
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		1,614
Alternative Minimum Tax Credit [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		574
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		574
NOL Carryforwards [Member] | Federal [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		788
Valuation allowance		(4)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		788
Valuation allowance		(4)
NOL Carryforwards [Member] | State [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		301
Valuation allowance		(85)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		301
Valuation allowance		(85)
NOL Carryforwards [Member] | Foreign Jurisdictions [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		12
Valuation allowance		(12)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		12
Valuation allowance		(12)
Foreign Tax Credit [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		1,271
Valuation allowance		(383)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		1,271
Valuation allowance		(383)
Charitable contribution carryforwards [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		20
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		20
Duke Energy Carolinas [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		64	33
Capital lease obligations		26	14
Pension, postretirement and other employee benefits		24	(17)
Tax credits and NOL carryforwards		257	234
Regulatory liabilities and deferred credits			222
Other		6	10
Total deferred income tax assets		377	496
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(795)	(849)
Accelerated depreciation rates		(3,207)	(3,060)
Regulatory assets and deferred debits, net		(64)
Total deferred income tax liabilities		(4,066)	(3,909)
Net deferred income tax liabilities		(3,689)	(3,413)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		257	234
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		(3,689)	(3,413)
Progress Energy [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		35	78
Pension, postretirement and other employee benefits		110	111
Tax credits and NOL carryforwards		693	402
Other		5	1
Valuation allowance			(14)
Total deferred income tax assets		843	578
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(430)	(470)
Accelerated depreciation rates		(3,369)	(2,803)
Regulatory assets and deferred debits, net		(985)	(807)
Total deferred income tax liabilities		(4,784)	(4,080)
Net deferred income tax liabilities		(3,941)	(3,502)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		693	402
Valuation allowance			(14)
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		(3,941)	(3,502)
Duke Energy Progress [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		53	23
Pension, postretirement and other employee benefits		47	44
Tax credits and NOL carryforwards		215	156
Other		5	4
Total deferred income tax assets		320	227
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(272)	(289)
Accelerated depreciation rates		(1,735)	(1,583)
Regulatory assets and deferred debits, net		(432)	(238)
Total deferred income tax liabilities		(2,439)	(2,110)
Net deferred income tax liabilities		(2,119)	(1,883)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		215	156
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		(2,119)	(1,883)
Duke Energy Florida [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities			49
Pension, postretirement and other employee benefits		58	60
Tax credits and NOL carryforwards		363	143
Total deferred income tax assets		421	252
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(163)	(187)
Accelerated depreciation rates		(1,670)	(1,257)
Regulatory assets and deferred debits, net		(574)	(569)
Total deferred income tax liabilities		(2,407)	(2,013)
Net deferred income tax liabilities		(1,986)	(1,761)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		363	143
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		(1,986)	(1,761)
Duke Energy Ohio [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		17	11
Pension, postretirement and other employee benefits		16	14
Tax credits and NOL carryforwards		42	25
Regulatory liabilities and deferred credits		56	65
Investments and other assets		18
Other		1
Total deferred income tax assets		150	115
Deferred Tax Liabilities, Gross [Abstract]
Accelerated depreciation rates		(967)	(896)
Total deferred income tax liabilities		(967)	(896)
Net deferred income tax liabilities		(817)	(781)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		42	25
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		(817)	(781)
Duke Energy Indiana [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		6	6
Capital lease obligations		2	2
Pension, postretirement and other employee benefits		24	18
Tax credits and NOL carryforwards		237	216
Investments and other assets			1
Other		(1)
Total deferred income tax assets		268	243
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(5)	(14)
Accelerated depreciation rates		(1,081)	(966)
Regulatory assets and deferred debits, net		(191)	(188)
Total deferred income tax liabilities		(1,277)	(1,168)
Net deferred income tax liabilities		(1,009)	(925)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		237	216
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		(1,009)	(925)
Piedmont Natural Gas [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		17	(5)
Pension, postretirement and other employee benefits		(1)	(4)
Tax credits and NOL carryforwards		110	70
Regulatory liabilities and deferred credits		48	61
Investments and other assets		16	18
Total deferred income tax assets		190	140
Deferred Tax Liabilities, Gross [Abstract]
Accelerated depreciation rates		(733)	(697)
Other		(8)	(7)
Total deferred income tax liabilities		(741)	(704)
Net deferred income tax liabilities		(551)	(564)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		110	70
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Net deferred income tax liabilities		$ (551)	$ (564)

Income Taxes (Other Disclosures

Income Taxes (Other Disclosures) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	$ 25	$ 17	$ 88
Gross increases-tax positions in prior periods		12
Gross decreases-tax positions in prior periods	(2)	(4)	(4)
Gross increases-current period tax positions	7
Decreases due to settlements	(6)		(68)
Reduction due to lapse of statute of limitations			1
Total changes	(1)	8	(71)
Unrecognized Tax Benefits - December 31	24	25	17
Amount that if recognized, would affect the effective tax rate or regulatory liability	21
Amount that if recognized, would be recorded as a component of discontinued operations	2
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	2
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	3	5	4
Duke Energy Carolinas [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	1	72
Gross increases-tax positions in prior periods		4
Gross decreases-tax positions in prior periods	(1)		(4)
Gross increases-current period tax positions	2
Decreases due to settlements			(67)
Total changes	1	4	(71)
Unrecognized Tax Benefits - December 31	6	5	1
Amount that if recognized, would affect the effective tax rate or regulatory liability	6
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest expense recognized related to income taxes		2	7
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes		25	23
Progress Energy [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	2	1
Gross increases-tax positions in prior periods		3
Gross decreases-tax positions in prior periods			(1)
Gross increases-current period tax positions	4
Reduction due to lapse of statute of limitations			2
Total changes	4	3	1
Unrecognized Tax Benefits - December 31	9	5	2
Amount that if recognized, would affect the effective tax rate or regulatory liability	9
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes		1	1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	1	1	1
Duke Energy Progress [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	2	3
Gross increases-tax positions in prior periods		3
Gross decreases-tax positions in prior periods			(1)
Gross increases-current period tax positions	1
Total changes	1	3	(1)
Unrecognized Tax Benefits - December 31	6	5	2
Amount that if recognized, would affect the effective tax rate or regulatory liability	6
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	1	1	1
Duke Energy Florida [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	5	4
Gross increases-tax positions in prior periods		1	4
Gross decreases-tax positions in prior periods	(4)
Gross increases-current period tax positions	2
Total changes	(2)	1	4
Unrecognized Tax Benefits - December 31	3	5	4
Amount that if recognized, would affect the effective tax rate or regulatory liability	3
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes		1	2
Duke Energy Ohio [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	1	4
Gross increases-tax positions in prior periods		1	4
Gross decreases-tax positions in prior periods		(4)
Total changes		(3)	4
Unrecognized Tax Benefits - December 31	1	1	4
Amount that if recognized, would affect the effective tax rate or regulatory liability	1
Duke Energy Indiana [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	1		1
Gross increases-tax positions in prior periods		1
Decreases due to settlements			(1)
Total changes		1	$ (1)
Unrecognized Tax Benefits - December 31	1	1
Amount that if recognized, would affect the effective tax rate or regulatory liability	1
Piedmont Natural Gas [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	3
Gross increases-tax positions in prior periods		3
Gross increases-current period tax positions	1
Total changes	1	3
Unrecognized Tax Benefits - December 31	4	$ 3
Amount that if recognized, would affect the effective tax rate or regulatory liability	$ 4
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes				$ 1

Other Income and Expenses, Ne_2

Other Income and Expenses, Net (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		$ 20	$ 13	$ 21
AFUDC equity		221	237	200
Post in-service equity returns		15	40	67
Nonoperating income (expense), other		143	218	175
Other income and expenses, net		399	508	463
Duke Energy Carolinas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		1	2	4
AFUDC equity		73	106	102
Post in-service equity returns		9	28	55
Nonoperating income (expense), other		70	63	53
Other income and expenses, net		153	199	214
Progress Energy [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		18	6	4
AFUDC equity		104	92	76
Post in-service equity returns		5	12	12
Nonoperating income (expense), other		38	99	94
Other income and expenses, net		165	209	186
Duke Energy Progress [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		1	2	3
AFUDC equity		57	47	50
Post in-service equity returns		5	12	12
Nonoperating income (expense), other		24	54	67
Other income and expenses, net		87	115	132
Duke Energy Florida [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		18	5	2
AFUDC equity		47	45	26
Nonoperating income (expense), other		21	46	35
Other income and expenses, net		86	96	63
Duke Energy Ohio [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		7	6	5
AFUDC equity		11	11	6
Post in-service equity returns		1
Nonoperating income (expense), other		4	6
Other income and expenses, net		23	23	11
Duke Energy Indiana [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		9	8	6
AFUDC equity		32	28	16
Nonoperating income (expense), other		4	11	4
Other income and expenses, net		45	47	$ 26
Piedmont Natural Gas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income		1
Nonoperating income (expense), other		13	(11)
Other income and expenses, net	$ (2)	$ 14	$ (11)		$ (1)

Quarterly Financial Data (Una_3

Quarterly Financial Data (Unaudited) (Schedule of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Millions	2 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Quarterly Financial Information Disclosure [Line Items]
Operating revenues		$ 6,115	$ 6,628	$ 5,643	$ 6,135	$ 5,799	$ 6,482	$ 5,555	$ 5,729	$ 24,521	$ 23,565	$ 22,743
Operating income (loss)		871	1,579	979	1,256	1,209	1,661	1,353	1,402	4,685	5,625	5,202
Income (loss) from continuing operations		434	1,062	507	622	705	957	691	717	2,625	3,070	2,578
Income (Loss) From Discontinued Operations, net of tax		20	4	(5)		(2)	(2)	(2)		19	(6)	(408)
Net income (loss)		454	1,066	502	622	703	955	689	717	2,644	3,064	2,170
Net Income (Loss) Attributable to Parent		$ 464	$ 1,082	$ 500	$ 620	$ 703	$ 954	$ 686	$ 716	$ 2,666	$ 3,059	$ 2,152
Income (loss) from continuing operations attributable to Duke Energy Corporation common shareholders [Abstract]
Basic (in usd per share)		$ 0.62	$ 1.51	$ 0.72	$ 0.88	$ 1	$ 1.36	$ 0.98	$ 1.02	$ 3.73	$ 4.37	$ 3.71
Diluted (in usd per share)		0.62	1.51	0.72	0.88	1	1.36	0.98	1.02	3.73	4.37	3.71
Income (loss) from discontinued operations attributable to Duke Energy Corporation common shareholders [Abstract]
Basic (in usd per share)		0.03		(0.01)						0.03	(0.01)	(0.60)
Diluted (in usd per share)		0.03		(0.01)						0.03	(0.01)	(0.60)
Net income attributable to Duke Energy Corporation common stockholders
Basic (in usd per share)		0.65	1.51	0.71	0.88	1	1.36	0.98	1.02	3.76	4.36	3.11
Diluted (in usd per share)		$ 0.65	$ 1.51	$ 0.71	$ 0.88	$ 1	$ 1.36	$ 0.98	$ 1.02	$ 3.76	$ 4.36	$ 3.11
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues		$ 1,775	$ 2,090	$ 1,672	$ 1,763	$ 1,721	$ 2,136	$ 1,729	$ 1,716	$ 7,300	$ 7,302	$ 7,322
Operating income (loss)		241	713	224	482	384	763	471	471	1,660	2,089	2,010
Net Income (Loss) Attributable to Parent		135	496	117	323	205	466	273	270	1,071	1,214	1,166
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues		2,609	3,045	2,498	2,576	2,348	2,864	2,392	2,179	10,728	9,783	9,853
Operating income (loss)		334	663	484	447	459	641	576	471	1,928	2,147	2,069
Income (loss) from continuing operations										1,033	1,268	1,039
Income (Loss) From Discontinued Operations, net of tax												2
Net income (loss)		123	406	267	237	447	343	277	201	1,033	1,268	1,041
Net Income (Loss) Attributable to Parent		123	404	265	235	444	341	274	199	1,027	1,258	1,031
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues		1,366	1,582	1,291	1,460	1,251	1,460	1,199	1,219	5,699	5,129	5,277
Operating income (loss)		227	330	233	269	243	398	270	274	1,059	1,185	1,025
Net Income (Loss) Attributable to Parent		135	216	139	177	168	246	154	147	667	715	599
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues		1,241	1,462	1,203	1,115	1,095	1,401	1,191	959	5,021	4,646	4,568
Operating income (loss)		107	331	245	173	212	236	301	192	856	941	1,022
Net Income (Loss) Attributable to Parent		40	243	168	103	344	120	158	90	554	712	551
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues		505	469	459	524	497	471	437	518	1,957	1,923	1,944
Operating income (loss)		93	139	77	(21)	73	101	64	82	288	320	345
Income (loss) from continuing operations										176	193	192
Income (Loss) From Discontinued Operations, net of tax							(1)				(1)	36
Net Income (Loss) Attributable to Parent		55	100	46	(25)	65	55	30	42	176	192	228
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues		771	819	738	731	745	802	742	758	3,059	3,047	2,958
Operating income (loss)		133	173	169	168	166	228	208	184	643	786	761
Net Income (Loss) Attributable to Parent		76	119	98	100	36	121	106	91	393	354	$ 381
Piedmont Natural Gas [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	$ 322	435	172	215	553	444	183	201	500	1,375	1,328		$ 1,149
Operating income (loss)	98	79	(19)	5	161	126	(4)	5	170	226	297		225
Net Income (Loss) Attributable to Parent	$ 54	$ 48	$ (21)	$ (8)	$ 110	$ 63	$ (11)	$ (8)	$ 95	$ 129	$ 139		$ 193

Quarterly Financial Data (Una_4

Quarterly Financial Data (Unaudited) (Unusual or Infrequently Occurring Items) (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		$ (31)	$ (16)	$ (20)	$ (17)	$ (34)	$ (23)	$ (30)	$ (16)	$ (84)	$ (103)
Asset Impairment Charges										(402)	(282)	$ (18)
Sale of Retired Plant					107					107
Severance Costs		(187)								(187)	(15)	(118)
Income (Loss) From Discontinued Operations, net of tax		20	4	(5)		(2)	(2)	(2)		19	(6)	(408)
Tax Act										(20)	112
Total		(225)	(106)	(199)	(341)	27	(242)	(30)	(16)	(871)	(261)
Regulatory Impairments [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges		(60)	(93)		(55)					(208)
Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Utilities Operating Expense, Impairments				(179)	(86)	(23)	(135)			(265)	(158)
Commercial Renewables Impairment [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges						(18)	(84)				(102)
Impacts of the Tax Act [Member]
Quarterly Financial Information Disclosure [Line Items]
Tax Act		53	3		(76)	102				(20)	102
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(1)	(2)	(2)	(4)	(5)	(5)	(6)	(4)	(9)	(20)
Asset Impairment Charges										(192)		(1)
Severance Costs		(102)								(102)	(2)	(39)
Tax Act			(1)			(15)				(1)	(15)
Total		(103)	(3)	(181)	(23)	(20)	(5)	(6)	(4)	(310)	(35)
Duke Energy Carolinas [Member] | Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Utilities Operating Expense, Impairments				(179)	(19)					(198)
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(2)	(1)	(3)	(4)	(6)	(6)	(7)	(4)	(10)	(23)
Asset Impairment Charges										(87)	(156)	(7)
Severance Costs		(69)								(69)	(2)	(40)
Income (Loss) From Discontinued Operations, net of tax												2
Tax Act		(19)	(5)		(1)	246				(25)	246
Total		(150)	(6)	(3)	(72)	217	(141)	(7)	(4)	(231)	65
Progress Energy [Member] | Regulatory Impairments [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges		(60)								(60)
Progress Energy [Member] | Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Utilities Operating Expense, Impairments					(67)	(23)	(135)			(67)	(158)
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(1)	(1)	(2)	(2)	(4)	(4)	(4)	(2)	(6)	(14)
Asset Impairment Charges										(33)	(19)	(1)
Severance Costs		(52)								(52)	(1)	(23)
Tax Act		(15)	(4)			40				(19)	40
Total		(68)	(5)	(2)	(69)	13	(4)	(4)	(2)	(144)	3
Duke Energy Progress [Member] | Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Utilities Operating Expense, Impairments					(67)	(23)				(67)	(23)
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(1)		(1)	(2)	(2)	(2)	(3)	(2)	(4)	(9)
Asset Impairment Charges										(54)	(138)	(6)
Severance Costs		(17)								(17)	(1)	(17)
Tax Act		2	(2)			226					226
Total		(76)	(2)	(1)	(2)	224	(137)	(3)	(2)	(81)	82
Duke Energy Florida [Member] | Regulatory Impairments [Member]
Quarterly Financial Information Disclosure [Line Items]
Asset Impairment Charges		(60)								(60)
Duke Energy Florida [Member] | Regulatory settlements [Member]
Quarterly Financial Information Disclosure [Line Items]
Utilities Operating Expense, Impairments							(135)				(135)
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(6)		(5)	(3)	(2)	(2)	(1)	(1)	(14)	(6)
Asset Impairment Charges											(1)
Sale of Retired Plant					(107)					(107)
Severance Costs		(6)								(6)		(3)
Income (Loss) From Discontinued Operations, net of tax							(1)				(1)	36
Tax Act		(2)				23				(2)	23
Total		(14)		(5)	(110)	21	(2)	(1)	(1)	(129)	17
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs			(2)			(1)	(2)	(2)	(1)	(2)	(6)
Asset Impairment Charges										(30)	(18)	(8)
Severance Costs		(7)								(7)	(1)	$ (7)
Tax Act						(55)					(55)
Total		(7)	(2)			(56)	(2)	(2)	(1)	(9)	(61)
Piedmont Natural Gas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers, integration costs		(22)	(11)	(9)	(6)	(19)	(8)	(13)	(6)	(48)	(46)
Asset Impairment Charges											(7)
Severance Costs	$ (3)	(2)								(2)	(9)		$ (19)
Tax Act											12
Total		$ (24)	$ (11)	$ (9)	$ (6)	(17)	$ (8)	$ (13)	$ (6)	$ (50)	(44)
Piedmont Natural Gas [Member] | Impacts of the Tax Act [Member]
Quarterly Financial Information Disclosure [Line Items]
Tax Act						$ 2					$ 2