Duke Energy (DUK) 10-Q 9 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2017shares
Document Information [Line Items]
Entity Registrant Name	Duke Energy Corporation
Entity Central Index Key	1,326,160
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding	699,883,528
Trading Symbol	DUK
Duke Energy Carolinas [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Carolinas, LLC
Entity Central Index Key	30,371
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Progress Energy [Member]
Document Information [Line Items]
Entity Registrant Name	Progress Energy, Inc
Entity Central Index Key	1,094,093
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Duke Energy Progress [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Progress, LLC
Entity Central Index Key	17,797
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Duke Energy Florida [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Florida, LLC
Entity Central Index Key	37,637
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Duke Energy Ohio [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Ohio, Inc.
Entity Central Index Key	20,290
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Duke Energy Indiana [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Indiana, LLC
Entity Central Index Key	81,020
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Piedmont Natural Gas [Member]
Document Information [Line Items]
Entity Registrant Name	Piedmont Natural Gas Company, Inc.
Entity Central Index Key	78,460
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating Revenues
Regulated electric	$ 4,913	$ 5,053
Regulated natural gas	646	169
Nonregulated electric and other	170	155
Total operating revenues	5,729	5,377
Operating Expenses
Fuel used in electric generation and purchased power	1,449	1,588
Cost of natural gas	258	49
Operation, maintenance and other	1,433	1,416
Depreciation and amortization	859	793
Property and other taxes	304	295
Impairment charges		3
Total operating expenses	4,303	4,144
Gains on Sales of Other Assets and Other, net	11	7
Operating Income	1,437	1,240
Other Income and Expenses
Equity in earnings of unconsolidated affiliates	29	8
Other income and expenses, net	86	70
Total other income and expenses	115	78
Interest Expense	491	489
Income From Continuing Operations Before Income Taxes	1,061	829
Income Tax Expense from Continuing Operations	344	252
Income from Continuing Operations	717	577
Income From Discontinued Operations, net of tax		122
Net income	717	699
Less: Net Income Attributable to Noncontrolling Interests	1	5
Net Income Attributable to Parent	716	694
Other Comprehensive Income (Loss), net of tax
Pension and OPEB adjustments	1
Reclassification into earnings from cash flow hedges	1	2
Unrealized gains on available-for-sale securities	4	4
Other Comprehensive Income, net of tax	8	41
Comprehensive Income	725	740
Less: Comprehensive Income Attributable to Noncontrolling Interests	1	6
Comprehensive Income Attributable to Parent	$ 724	$ 734
Income from continuing operations attributable to Duke Energy Corporation common stockholders
Basic (usd per share)	$ 1.02	$ 0.83
Diluted (usd per share)	1.02	0.83
Income from discontinued operations attributable to Duke Energy Corporation common stockholders
Basic (usd per share)		0.18
Diluted (usd per share)		0.18
Net income attributable to Duke Energy Corporation common stockholders
Basic (usd per share)	1.02	1.01
Diluted (usd per share)	$ 1.02	$ 1.01
Weighted average shares outstanding
Basic (shares)	700	689
Diluted (shares)	700	689
Duke Energy Carolinas [Member]
Operating Revenues
Total operating revenues	$ 1,716	$ 1,740
Operating Expenses
Fuel used in electric generation and purchased power	428	421
Operation, maintenance and other	482	512
Depreciation and amortization	254	259
Property and other taxes	68	67
Total operating expenses	1,232	1,259
Operating Income	484	481
Other Income and Expenses
Other income and expenses, net	37	37
Interest Expense	103	107
Income From Continuing Operations Before Income Taxes	418	411
Income Tax Expense from Continuing Operations	148	140
Net Income Attributable to Parent	270	271
Other Comprehensive Income (Loss), net of tax
Reclassification into earnings from cash flow hedges		1
Other Comprehensive Income, net of tax		1
Comprehensive Income Attributable to Parent	270	272
Progress Energy [Member]
Operating Revenues
Total operating revenues	2,179	2,332
Operating Expenses
Fuel used in electric generation and purchased power	726	860
Operation, maintenance and other	544	592
Depreciation and amortization	313	290
Property and other taxes	117	119
Impairment charges		2
Total operating expenses	1,700	1,863
Gains on Sales of Other Assets and Other, net	8	6
Operating Income	487	475
Other Income and Expenses
Other income and expenses, net	24	20
Interest Expense	206	160
Income From Continuing Operations Before Income Taxes	305	335
Income Tax Expense from Continuing Operations	104	123
Net income	201	212
Less: Net Income Attributable to Noncontrolling Interests	2	3
Net Income Attributable to Parent	199	209
Other Comprehensive Income (Loss), net of tax
Pension and OPEB adjustments	1	1
Reclassification into earnings from cash flow hedges	1	1
Unrealized gains on available-for-sale securities	1	1
Other Comprehensive Income, net of tax	3	3
Comprehensive Income	204	215
Less: Comprehensive Income Attributable to Noncontrolling Interests	2	3
Comprehensive Income Attributable to Parent	202	212
Duke Energy Progress [Member]
Operating Revenues
Total operating revenues	1,219	1,307
Operating Expenses
Fuel used in electric generation and purchased power	364	448
Operation, maintenance and other	350	386
Depreciation and amortization	181	175
Property and other taxes	40	41
Total operating expenses	935	1,050
Gains on Sales of Other Assets and Other, net	2	1
Operating Income	286	258
Other Income and Expenses
Other income and expenses, net	19	17
Interest Expense	82	63
Income From Continuing Operations Before Income Taxes	223	212
Income Tax Expense from Continuing Operations	76	75
Net Income Attributable to Parent	147	137
Other Comprehensive Income (Loss), net of tax
Comprehensive Income Attributable to Parent	147	137
Duke Energy Florida [Member]
Operating Revenues
Total operating revenues	959	1,024
Operating Expenses
Fuel used in electric generation and purchased power	362	412
Operation, maintenance and other	191	205
Depreciation and amortization	132	114
Property and other taxes	77	78
Impairment charges	1	2
Total operating expenses	763	811
Operating Income	196	213
Other Income and Expenses
Other income and expenses, net	16	5
Interest Expense	70	41
Income From Continuing Operations Before Income Taxes	142	177
Income Tax Expense from Continuing Operations	52	67
Net Income Attributable to Parent	90	110
Other Comprehensive Income (Loss), net of tax
Unrealized gains on available-for-sale securities	1	1
Other Comprehensive Income, net of tax	1	1
Comprehensive Income Attributable to Parent	91	111
Duke Energy Ohio [Member]
Operating Revenues
Regulated electric	337	340
Regulated natural gas	170	170
Nonregulated electric and other	11	6
Total operating revenues	518	516
Operating Expenses
Fuel used in electric generation and purchased power	97	111
Fuel used in electric generation and purchased power – nonregulated	15	10
Cost of natural gas	54	49
Operation, maintenance and other	130	119
Depreciation and amortization	67	61
Property and other taxes	72	71
Total operating expenses	435	421
Gains on Sales of Other Assets and Other, net		1
Operating Income	83	96
Other Income and Expenses
Other income and expenses, net	4	2
Interest Expense	22	20
Income From Continuing Operations Before Income Taxes	65	78
Income Tax Expense from Continuing Operations	23	21
Income from Continuing Operations	42	57
Income From Discontinued Operations, net of tax		2
Net Income Attributable to Parent	42	59
Other Comprehensive Income (Loss), net of tax
Comprehensive Income Attributable to Parent	42	59
Duke Energy Indiana [Member]
Operating Revenues
Total operating revenues	758	714
Operating Expenses
Fuel used in electric generation and purchased power	251	228
Operation, maintenance and other	174	162
Depreciation and amortization	125	125
Property and other taxes	22	23
Total operating expenses	572	538
Operating Income	186	176
Other Income and Expenses
Other income and expenses, net	8	4
Interest Expense	44	44
Income From Continuing Operations Before Income Taxes	150	136
Income Tax Expense from Continuing Operations	59	41
Net Income Attributable to Parent	91	95
Other Comprehensive Income (Loss), net of tax
Reclassification into earnings from cash flow hedges		(1)
Other Comprehensive Income, net of tax		(1)
Comprehensive Income Attributable to Parent	91	94
Piedmont Natural Gas [Member]
Operating Revenues
Regulated natural gas	498	481
Nonregulated electric and other	2	2
Total operating revenues	500	483
Operating Expenses
Cost of natural gas	205	197
Operation, maintenance and other	77	74
Depreciation and amortization	35	34
Property and other taxes	13	11
Total operating expenses	330	316
Operating Income	170	167
Other Income and Expenses
Equity in earnings of unconsolidated affiliates	3	16
Interest Expense	20	17
Income From Continuing Operations Before Income Taxes	153	166
Income Tax Expense from Continuing Operations	58	63
Net Income Attributable to Parent	95	103
Other Comprehensive Income (Loss), net of tax
Comprehensive Income Attributable to Parent	$ 95	$ 103

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Net income	$ 717	$ 699
Other Comprehensive (Loss) Income, net of tax
Foreign currency translation adjustments		49
Pension and OPEB adjustments	1
Net unrealized gains (losses) on cash flow hedges	2	(14)
Reclassification into earnings from cash flow hedges	1	2
Unrealized gains on available-for-sale securities	4	4
Other Comprehensive Income, net of tax	8	41
Comprehensive Income	725	740
Less: Comprehensive Income (Loss) Attributable to Noncontrolling Interests	1	6
Comprehensive Income Attributable to Parent	$ 724	$ 734

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 878	$ 392
Receivables (net of allowance for doubtful accounts)	623	751
Receivables of VIEs (net of allowance for doubtful accounts)	1,682	1,893
Inventory	3,366	3,522
Regulatory assets	1,031	1,023
Other	425	458
Total current assets	8,005	8,039
Property, Plant and Equipment
Cost	123,301	121,397
Accumulated depreciation and amortization	(40,293)	(39,406)
Generation facilities to be retired, net	508	529
Net property, plant and equipment	83,516	82,520
Other Noncurrent Assets
Goodwill	19,425	19,425
Regulatory assets	12,838	12,878
Nuclear decommissioning trust funds	6,448	6,205
Investments in equity method unconsolidated affiliates	1,122	925
Other	2,754	2,769
Total other noncurrent assets	42,587	42,202
Total Assets	134,108	132,761
Current Liabilities
Accounts payable	2,203	2,994
Notes payable and commercial paper	3,558	2,487
Taxes accrued	363	384
Interest accrued	526	503
Current maturities of long-term debt	1,977	2,319
Asset retirement obligation	404	411
Regulatory liabilities	340	409
Other	1,570	2,044
Total current liabilities	10,941	11,551
Long-Term Debt	47,021	45,576
Other Noncurrent Liabilities
Deferred income taxes	14,443	14,155
Asset retirement obligations	10,186	10,200
Regulatory liabilities	6,972	6,881
Accrued pension and other post-retirement benefit costs	1,115	1,111
Investment tax credits	537	493
Other	1,707	1,753
Total other noncurrent liabilities	34,960	34,593
Commitments and Contingencies
Equity
Common stock	1	1
Additional paid-in capital	38,742	38,741
Retained earnings	2,521	2,384
Accumulated other comprehensive income (loss)	(85)	(93)
Total Parent stockholders' equity	41,179	41,033
Noncontrolling interests	7	8
Total equity	41,186	41,041
Total Liabilities and Equity	134,108	132,761
Duke Energy Carolinas [Member]
Current Assets
Cash and cash equivalents	11	14
Receivables (net of allowance for doubtful accounts)	166	160
Receivables of VIEs (net of allowance for doubtful accounts)	563	645
Receivables from affiliated companies	109	163
Notes receivable from affiliated companies		66
Inventory	1,051	1,055
Regulatory assets	233	238
Other	65	37
Total current assets	2,198	2,378
Property, Plant and Equipment
Cost	41,600	41,127
Accumulated depreciation and amortization	(14,649)	(14,365)
Net property, plant and equipment	26,951	26,762
Other Noncurrent Assets
Regulatory assets	3,098	3,159
Nuclear decommissioning trust funds	3,406	3,273
Other	926	943
Total other noncurrent assets	7,430	7,375
Total Assets	36,579	36,515
Current Liabilities
Accounts payable	602	833
Accounts payable to affiliated companies	250	247
Notes payable to affiliated companies	337
Taxes accrued	90	143
Interest accrued	134	102
Current maturities of long-term debt	404	116
Asset retirement obligation	224	222
Regulatory liabilities	118	161
Other	345	468
Total current liabilities	2,504	2,292
Long-Term Debt	8,787	9,187
Long-Term Debt Payable to Affiliated Companies	300	300
Other Noncurrent Liabilities
Deferred income taxes	6,668	6,544
Asset retirement obligations	3,658	3,673
Regulatory liabilities	2,860	2,840
Accrued pension and other post-retirement benefit costs	103	97
Investment tax credits	237	203
Other	595	607
Total other noncurrent liabilities	14,121	13,964
Commitments and Contingencies
Equity
Member's equity	10,876	10,781
Accumulated other comprehensive income (loss)	(9)	(9)
Total member's equity	10,867	10,772
Total Liabilities and Equity	36,579	36,515
Progress Energy [Member]
Current Assets
Cash and cash equivalents	38	46
Receivables (net of allowance for doubtful accounts)	80	114
Receivables of VIEs (net of allowance for doubtful accounts)	612	692
Receivables from affiliated companies	2	106
Notes receivable from affiliated companies	184	80
Inventory	1,652	1,717
Regulatory assets	447	401
Other	252	148
Total current assets	3,267	3,304
Property, Plant and Equipment
Cost	45,902	44,864
Accumulated depreciation and amortization	(15,618)	(15,212)
Generation facilities to be retired, net	508	529
Net property, plant and equipment	30,792	30,181
Other Noncurrent Assets
Goodwill	3,655	3,655
Regulatory assets	5,815	5,722
Nuclear decommissioning trust funds	3,041	2,932
Other	851	856
Total other noncurrent assets	13,362	13,165
Total Assets	47,421	46,650
Current Liabilities
Accounts payable	678	1,003
Accounts payable to affiliated companies	316	348
Notes payable to affiliated companies	866	729
Taxes accrued	96	83
Interest accrued	224	201
Current maturities of long-term debt	521	778
Asset retirement obligation	180	189
Regulatory liabilities	157	189
Other	627	745
Total current liabilities	3,665	4,265
Long-Term Debt	16,454	15,590
Long-Term Debt Payable to Affiliated Companies	1,173	1,173
Other Noncurrent Liabilities
Deferred income taxes	5,484	5,246
Asset retirement obligations	5,289	5,286
Regulatory liabilities	2,472	2,395
Accrued pension and other post-retirement benefit costs	540	547
Other	332	341
Total other noncurrent liabilities	14,117	13,815
Commitments and Contingencies
Equity
Additional paid-in capital	8,094	8,094
Retained earnings	3,963	3,764
Accumulated other comprehensive income (loss)	(35)	(38)
Total Parent stockholders' equity	12,022	11,820
Noncontrolling interests	(10)	(13)
Total equity	12,012	11,807
Total Liabilities and Equity	47,421	46,650
Duke Energy Progress [Member]
Current Assets
Cash and cash equivalents	11	11
Receivables (net of allowance for doubtful accounts)	28	51
Receivables of VIEs (net of allowance for doubtful accounts)	364	404
Receivables from affiliated companies	6	5
Notes receivable from affiliated companies		165
Inventory	1,053	1,076
Regulatory assets	187	188
Other	102	57
Total current assets	1,751	1,957
Property, Plant and Equipment
Cost	28,769	28,419
Accumulated depreciation and amortization	(10,716)	(10,561)
Generation facilities to be retired, net	508	529
Net property, plant and equipment	18,561	18,387
Other Noncurrent Assets
Regulatory assets	3,338	3,243
Nuclear decommissioning trust funds	2,315	2,217
Other	535	525
Total other noncurrent assets	6,188	5,985
Total Assets	26,500	26,329
Current Liabilities
Accounts payable	317	589
Accounts payable to affiliated companies	244	227
Notes payable to affiliated companies	502
Taxes accrued	35	104
Interest accrued	90	102
Current maturities of long-term debt	202	452
Asset retirement obligation	180	189
Regulatory liabilities	149	158
Other	294	365
Total current liabilities	2,013	2,186
Long-Term Debt	6,409	6,409
Long-Term Debt Payable to Affiliated Companies	150	150
Other Noncurrent Liabilities
Deferred income taxes	3,453	3,323
Asset retirement obligations	4,516	4,508
Regulatory liabilities	2,012	1,946
Accrued pension and other post-retirement benefit costs	247	252
Investment tax credits	146	146
Other	49	51
Total other noncurrent liabilities	10,423	10,226
Commitments and Contingencies
Equity
Total member's equity	7,505	7,358
Total Liabilities and Equity	26,500	26,329
Duke Energy Florida [Member]
Current Assets
Cash and cash equivalents	7	16
Receivables (net of allowance for doubtful accounts)	50	61
Receivables of VIEs (net of allowance for doubtful accounts)	248	288
Receivables from affiliated companies	2	5
Notes receivable from affiliated companies	293
Inventory	599	641
Regulatory assets	260	213
Other	104	125
Total current assets	1,563	1,349
Property, Plant and Equipment
Cost	17,122	16,434
Accumulated depreciation and amortization	(4,894)	(4,644)
Net property, plant and equipment	12,228	11,790
Other Noncurrent Assets
Regulatory assets	2,476	2,480
Nuclear decommissioning trust funds	726	715
Other	268	278
Total other noncurrent assets	3,470	3,473
Total Assets	17,261	16,612
Current Liabilities
Accounts payable	361	413
Accounts payable to affiliated companies	77	125
Notes payable to affiliated companies		297
Taxes accrued	62	33
Interest accrued	76	49
Current maturities of long-term debt	319	326
Regulatory liabilities	7	31
Other	309	352
Total current liabilities	1,211	1,626
Long-Term Debt	6,662	5,799
Other Noncurrent Liabilities
Deferred income taxes	2,800	2,694
Asset retirement obligations	773	778
Regulatory liabilities	459	448
Accrued pension and other post-retirement benefit costs	261	262
Other	104	105
Total other noncurrent liabilities	4,397	4,287
Commitments and Contingencies
Equity
Member's equity	4,989	4,899
Accumulated other comprehensive income (loss)	2	1
Total member's equity	4,991	4,900
Total Liabilities and Equity	17,261	16,612
Duke Energy Ohio [Member]
Current Assets
Cash and cash equivalents	13	13
Receivables (net of allowance for doubtful accounts)	63	71
Receivables from affiliated companies	88	129
Notes receivable from affiliated companies	179	94
Inventory	118	137
Regulatory assets	21	37
Other	34	37
Total current assets	516	518
Property, Plant and Equipment
Cost	8,236	8,126
Accumulated depreciation and amortization	(2,611)	(2,579)
Net property, plant and equipment	5,625	5,547
Other Noncurrent Assets
Goodwill	920	920
Regulatory assets	525	520
Other	23	23
Total other noncurrent assets	1,468	1,463
Total Assets	7,609	7,528
Current Liabilities
Accounts payable	252	282
Accounts payable to affiliated companies	64	63
Notes payable to affiliated companies	8	16
Taxes accrued	127	178
Interest accrued	33	19
Current maturities of long-term debt	1	1
Regulatory liabilities	21	21
Other	83	91
Total current liabilities	589	671
Long-Term Debt	1,951	1,858
Long-Term Debt Payable to Affiliated Companies	25	25
Other Noncurrent Liabilities
Deferred income taxes	1,472	1,443
Asset retirement obligations	76	77
Regulatory liabilities	236	236
Accrued pension and other post-retirement benefit costs	56	56
Other	166	166
Total other noncurrent liabilities	2,006	1,978
Commitments and Contingencies
Equity
Common stock	762	762
Additional paid-in capital	2,695	2,695
Retained earnings	(419)	(461)
Total Parent stockholders' equity	3,038	2,996
Total Liabilities and Equity	7,609	7,528
Duke Energy Indiana [Member]
Current Assets
Cash and cash equivalents	15	17
Receivables (net of allowance for doubtful accounts)	72	105
Receivables from affiliated companies	88	114
Notes receivable from affiliated companies	199	86
Inventory	478	504
Regulatory assets	156	149
Other	35	45
Total current assets	1,043	1,020
Property, Plant and Equipment
Cost	14,411	14,241
Accumulated depreciation and amortization	(4,426)	(4,317)
Net property, plant and equipment	9,985	9,924
Other Noncurrent Assets
Regulatory assets	1,066	1,073
Other	156	147
Total other noncurrent assets	1,222	1,220
Total Assets	12,250	12,164
Current Liabilities
Accounts payable	210	263
Accounts payable to affiliated companies	75	74
Taxes accrued	72	31
Interest accrued	52	61
Current maturities of long-term debt	3	3
Regulatory liabilities	44	40
Other	75	93
Total current liabilities	531	565
Long-Term Debt	3,631	3,633
Long-Term Debt Payable to Affiliated Companies	150	150
Other Noncurrent Liabilities
Deferred income taxes	1,921	1,900
Asset retirement obligations	867	866
Regulatory liabilities	743	748
Accrued pension and other post-retirement benefit costs	77	71
Investment tax credits	148	137
Other	24	27
Total other noncurrent liabilities	3,780	3,749
Commitments and Contingencies
Equity
Total member's equity	4,158	4,067
Total Liabilities and Equity	12,250	12,164
Piedmont Natural Gas [Member]
Current Assets
Cash and cash equivalents	15	25
Receivables (net of allowance for doubtful accounts)	193	232
Receivables from affiliated companies	7	7
Inventory	29	66
Regulatory assets	98	124
Other	21	21
Total current assets	363	475
Property, Plant and Equipment
Cost	6,297	6,174
Accumulated depreciation and amortization	(1,390)	(1,360)
Net property, plant and equipment	4,907	4,814
Other Noncurrent Assets
Goodwill	49	49
Regulatory assets	350	373
Investments in equity method unconsolidated affiliates	225	212
Other	19	21
Total other noncurrent assets	643	655
Total Assets	5,913	5,944
Current Liabilities
Accounts payable	104	155
Accounts payable to affiliated companies	3	8
Notes payable and commercial paper		330
Notes payable to affiliated companies	261
Taxes accrued	69	67
Interest accrued	27	33
Current maturities of long-term debt	35	35
Other	70	102
Total current liabilities	569	730
Long-Term Debt	1,786	1,786
Other Noncurrent Liabilities
Deferred income taxes	981	931
Asset retirement obligations	14	14
Regulatory liabilities	613	608
Accrued pension and other post-retirement benefit costs	14	14
Other	169	189
Total other noncurrent liabilities	1,791	1,756
Commitments and Contingencies
Equity
Common stock	860	860
Retained earnings	907	812
Total Parent stockholders' equity	1,767	1,672
Total Liabilities and Equity	$ 5,913	$ 5,944

Condensed Consolidated Balance5

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts and Other Receivables, Current	$ 13	$ 14
Regulatory assets	1,031	1,023
Current Assets: Other	425	458
Regulatory assets	12,838	12,878
Current maturities of long-term debt	1,977	2,319
Long-term Debt of VIEs	$ 47,021	$ 45,576
Common stock, par or stated value	$ 0.001	$ 0.001
Common stock, shares authorized	2,000,000,000	2,000,000,000
Common stock, shares outstanding	700,000,000	700,000,000
Variable Interest Entity [Member]
Allowance for Doubtful Accounts Receivable, Current	$ 57	$ 54
Regulatory assets	53	50
Regulatory assets	1,131	1,142
Current maturities of long-term debt	281	260
Long-term Debt of VIEs	4,108	3,587
Duke Energy Carolinas [Member]
Allowance for Doubtful Accounts and Other Receivables, Current	2	2
Regulatory assets	233	238
Current Assets: Other	65	37
Regulatory assets	3,098	3,159
Current maturities of long-term debt	404	116
Long-term Debt of VIEs	8,787	9,187
Duke Energy Carolinas [Member] | Variable Interest Entity [Member]
Allowance for Doubtful Accounts Receivable, Current	7	7
Progress Energy [Member]
Allowance for Doubtful Accounts and Other Receivables, Current	3	6
Regulatory assets	447	401
Current Assets: Other	252	148
Regulatory assets	5,815	5,722
Current maturities of long-term debt	521	778
Long-term Debt of VIEs	$ 16,454	$ 15,590
Common stock, par or stated value	$ 0.01	$ 0.01
Common stock, shares authorized	100	100
Common stock, shares outstanding	100	100
Progress Energy [Member] | Variable Interest Entity [Member]
Allowance for Doubtful Accounts Receivable, Current	$ 7	$ 7
Regulatory assets	53	50
Regulatory assets	1,131	1,142
Current maturities of long-term debt	55	62
Long-term Debt of VIEs	1,713	1,741
Duke Energy Progress [Member]
Allowance for Doubtful Accounts and Other Receivables, Current	1	4
Regulatory assets	187	188
Current Assets: Other	102	57
Regulatory assets	3,338	3,243
Current maturities of long-term debt	202	452
Long-term Debt of VIEs	6,409	6,409
Duke Energy Progress [Member] | Variable Interest Entity [Member]
Allowance for Doubtful Accounts Receivable, Current	5	5
Duke Energy Florida [Member]
Allowance for Doubtful Accounts and Other Receivables, Current	2	2
Regulatory assets	260	213
Current Assets: Other	104	125
Regulatory assets	2,476	2,480
Current maturities of long-term debt	319	326
Long-term Debt of VIEs	6,662	5,799
Duke Energy Florida [Member] | Variable Interest Entity [Member]
Allowance for Doubtful Accounts Receivable, Current	2	2
Regulatory assets	53	50
Current Assets: Other	14	53
Regulatory assets	1,131	1,142
Current maturities of long-term debt	55	62
Long-term Debt of VIEs	1,414	1,442
Duke Energy Ohio [Member]
Allowance for Doubtful Accounts and Other Receivables, Current	2	2
Regulatory assets	21	37
Current Assets: Other	34	37
Regulatory assets	525	520
Current maturities of long-term debt	1	1
Long-term Debt of VIEs	$ 1,951	$ 1,858
Common stock, par or stated value	$ 8.50	$ 8.50
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares outstanding	89,663,086	89,663,086
Duke Energy Indiana [Member]
Allowance for Doubtful Accounts and Other Receivables, Current	$ 1	$ 1
Regulatory assets	156	149
Current Assets: Other	35	45
Regulatory assets	1,066	1,073
Current maturities of long-term debt	3	3
Long-term Debt of VIEs	3,631	3,633
Piedmont Natural Gas [Member]
Allowance for Doubtful Accounts and Other Receivables, Current	5	3
Regulatory assets	98	124
Current Assets: Other	21	21
Regulatory assets	350	373
Current maturities of long-term debt	35	35
Long-term Debt of VIEs	$ 1,786	$ 1,786
Common stock, par or stated value	$ 0	$ 0
Common stock, shares authorized	100	100
Common stock, shares outstanding	100	100

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 717	$ 699
Net income (attributable to parent)	716	694
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	991	931
Equity component of AFUDC	(62)	(42)
Gains on sales of other assets	(11)	(9)
Impairment charges		3
Deferred income taxes	342	181
Equity in earnings of unconsolidated affiliates	(29)	(8)
Accrued pension and other post-retirement benefit costs	6	4
Payments for asset retirement obligations	(134)	(112)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(38)	102
Receivables	343	139
Inventory	155	89
Other current assets	16	13
Increase (decrease) in
Accounts payable	(463)	(210)
Taxes accrued	(28)	40
Other current liabilities	(478)	(81)
Other assets	(40)	45
Other liabilities	2	(102)
Net cash provided by operating activities	1,289	1,682
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(2,160)	(1,645)
Contributions to equity method investments	(175)	(59)
Purchases of available-for-sale securities	(1,386)	(1,347)
Proceeds from sales and maturities of available-for-sale securities	1,405	1,362
Change in restricted cash	(34)	(32)
Other	(49)	(37)
Net cash used in investing activities	(2,399)	(1,758)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	1,563	1,140
Proceeds from the issuance of common stock related to employee benefit plans		7
Payments for the redemption of long-term debt	(408)	(389)
Proceeds from issuance of short-term debt with original maturities greater than 90 days	25
Payments for the redemption of short-term debt with original maturities greater than 90 days	(7)	(92)
Notes payable and commercial paper	1,045	(66)
Change in bank overdrafts	5
Dividends paid	(600)	(570)
Other	(27)	(33)
Net cash provided by (used in) financing activities	1,596	(3)
Change in cash and cash equivalents associated with assets held for sale		30
Net increase (decrease) in cash and cash equivalents	486	(49)
Cash and cash equivalents at beginning of period	392	383
Cash and cash equivalents at end of period	878	334
Significant non-cash transactions:
Accrued capital expenditures	575	576
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	270	271
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	339	330
Equity component of AFUDC	(30)	(23)
Deferred income taxes	162	145
Accrued pension and other post-retirement benefit costs		1
Payments for asset retirement obligations	(65)	(52)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	3	3
Receivables	66	2
Receivable from affiliated companies	54	33
Inventory	4	40
Other current assets	(26)	102
Increase (decrease) in
Accounts payable	(131)	(165)
Accounts payable to affiliated companies	3	21
Taxes accrued	(53)	52
Other current liabilities	(125)	21
Other assets	(3)	26
Other liabilities	(2)	(26)
Net cash provided by operating activities	466	781
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(563)	(459)
Purchases of available-for-sale securities	(722)	(785)
Proceeds from sales and maturities of available-for-sale securities	722	785
Notes receivable from affiliated companies	66
Notes receivable from affiliated companies		(691)
Other	(20)	(18)
Net cash used in investing activities	(517)	(1,168)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		992
Payments for the redemption of long-term debt	(113)	(1)
Notes payable to affiliated companies	337
Distributions to parent	(175)	(600)
Other	(1)
Net cash provided by (used in) financing activities	48	391
Net increase (decrease) in cash and cash equivalents	(3)	4
Cash and cash equivalents at beginning of period	14	13
Cash and cash equivalents at end of period	11	17
Significant non-cash transactions:
Accrued capital expenditures	164	179
Progress Energy [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	201	212
Net income (attributable to parent)	199	209
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	365	342
Equity component of AFUDC	(24)	(14)
Gains on sales of other assets	(9)	(7)
Impairment charges		2
Deferred income taxes	220	182
Accrued pension and other post-retirement benefit costs	(3)	(6)
Payments for asset retirement obligations	(60)	(54)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(2)	6
Receivables	115	70
Receivable from affiliated companies	100	295
Inventory	65	3
Other current assets	(173)	(76)
Increase (decrease) in
Accounts payable	(228)	9
Accounts payable to affiliated companies	(32)	(55)
Taxes accrued	12	42
Other current liabilities	(121)	(64)
Other assets	(53)	(46)
Other liabilities	(14)	(7)
Net cash provided by operating activities	359	834
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(1,011)	(750)
Purchases of available-for-sale securities	(629)	(533)
Proceeds from sales and maturities of available-for-sale securities	635	548
Proceeds from Insurance	4	43
Notes receivable from affiliated companies	(104)
Change in restricted cash	5
Other	(4)	(15)
Net cash used in investing activities	(1,104)	(707)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	892	53
Payments for the redemption of long-term debt	(288)	(310)
Notes payable to affiliated companies	137	128
Distributions to noncontrolling interests	(1)	(1)
Other	(3)
Net cash provided by (used in) financing activities	737	(130)
Net increase (decrease) in cash and cash equivalents	(8)	(3)
Cash and cash equivalents at beginning of period	46	44
Cash and cash equivalents at end of period	38	41
Significant non-cash transactions:
Accrued capital expenditures	219	228
Duke Energy Progress [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	147	137
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	228	223
Equity component of AFUDC	(13)	(10)
Gains on sales of other assets	(3)	(2)
Deferred income taxes	120	100
Accrued pension and other post-retirement benefit costs	(5)	(8)
Payments for asset retirement obligations	(47)	(42)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(2)	(1)
Receivables	65	18
Receivable from affiliated companies	(1)	10
Inventory	23	15
Other current assets	(60)	83
Increase (decrease) in
Accounts payable	(192)	(16)
Accounts payable to affiliated companies	17	(14)
Taxes accrued	(68)	18
Other current liabilities	(81)	(39)
Other assets	(44)	(17)
Other liabilities	(10)	(4)
Net cash provided by operating activities	74	451
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(474)	(379)
Purchases of available-for-sale securities	(476)	(390)
Proceeds from sales and maturities of available-for-sale securities	470	384
Notes receivable from affiliated companies	165
Other	(9)	(13)
Net cash used in investing activities	(324)	(398)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt		53
Payments for the redemption of long-term debt	(250)	(8)
Notes payable to affiliated companies	502	(101)
Other	(2)	(1)
Net cash provided by (used in) financing activities	250	(57)
Net increase (decrease) in cash and cash equivalents		(4)
Cash and cash equivalents at beginning of period	11	15
Cash and cash equivalents at end of period	11	11
Significant non-cash transactions:
Accrued capital expenditures	66	55
Duke Energy Florida [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	90	110
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	134	116
Equity component of AFUDC	(11)	(4)
Impairment charges	1	2
Deferred income taxes	100	83
Accrued pension and other post-retirement benefit costs	1	1
Payments for asset retirement obligations	(14)	(12)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions		7
Receivables	51	52
Receivable from affiliated companies	(1)	14
Inventory	42	(12)
Other current assets	(33)	(44)
Increase (decrease) in
Accounts payable	(35)	25
Accounts payable to affiliated companies	(48)	(40)
Taxes accrued	29	(70)
Other current liabilities	(47)	(14)
Other assets	(13)	(30)
Other liabilities	(5)	(6)
Net cash provided by operating activities	241	178
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(538)	(370)
Purchases of available-for-sale securities	(153)	(143)
Proceeds from sales and maturities of available-for-sale securities	165	164
Proceeds from Insurance	4	43
Notes receivable from affiliated companies	(293)
Other	9	(1)
Net cash used in investing activities	(806)	(307)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	892
Payments for the redemption of long-term debt	(38)	(2)
Notes payable to affiliated companies	(297)	135
Other	(1)
Net cash provided by (used in) financing activities	556	133
Net increase (decrease) in cash and cash equivalents	(9)	4
Cash and cash equivalents at beginning of period	16	8
Cash and cash equivalents at end of period	7	12
Significant non-cash transactions:
Accrued capital expenditures	153	173
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	42	59
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	68	62
Equity component of AFUDC	(2)	(1)
Gains on sales of other assets		(1)
Deferred income taxes	30	11
Accrued pension and other post-retirement benefit costs	1	1
Payments for asset retirement obligations	(2)	(1)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	1	2
Receivables	7	(18)
Receivable from affiliated companies	41	(9)
Inventory	19	1
Other current assets	9	78
Increase (decrease) in
Accounts payable	(10)	(1)
Accounts payable to affiliated companies	1
Taxes accrued	(52)	(31)
Other current liabilities	9	14
Other assets	(6)	(2)
Other liabilities	(3)
Net cash provided by operating activities	153	164
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(143)	(85)
Notes receivable from affiliated companies	(85)	(19)
Other	(8)	(4)
Net cash used in investing activities	(236)	(108)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of long-term debt	93	95
Payments for the redemption of long-term debt	(1)	(51)
Notes payable to affiliated companies	(8)	(95)
Other	(1)
Net cash provided by (used in) financing activities	83	(51)
Net increase (decrease) in cash and cash equivalents		5
Cash and cash equivalents at beginning of period	13	14
Cash and cash equivalents at end of period	13	19
Significant non-cash transactions:
Accrued capital expenditures	57	31
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	91	95
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	126	127
Equity component of AFUDC	(6)	(3)
Deferred income taxes	37	(16)
Accrued pension and other post-retirement benefit costs	1	2
Payments for asset retirement obligations	(7)	(5)
(Increase) decrease in
Receivables	44	16
Receivable from affiliated companies	26	7
Inventory	26	45
Other current assets	(2)	(19)
Increase (decrease) in
Accounts payable	(32)	(44)
Accounts payable to affiliated companies	1	(22)
Taxes accrued	41	30
Other current liabilities	(15)	(18)
Other assets	(11)	(4)
Other liabilities	(3)	(11)
Net cash provided by operating activities	317	180
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(189)	(151)
Purchases of available-for-sale securities	(4)	(5)
Proceeds from sales and maturities of available-for-sale securities	2	4
Notes receivable from affiliated companies	(113)	(19)
Other	(12)	(1)
Net cash used in investing activities	(316)	(172)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments for the redemption of long-term debt	(2)
Other	(1)
Net cash provided by (used in) financing activities	(3)
Net increase (decrease) in cash and cash equivalents	(2)	8
Cash and cash equivalents at beginning of period	17	9
Cash and cash equivalents at end of period	15	17
Significant non-cash transactions:
Accrued capital expenditures	84	42
Piedmont Natural Gas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (attributable to parent)	95	103
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion (including amortization of nuclear fuel)	37	37
Deferred income taxes	50	68
Equity in earnings of unconsolidated affiliates	(3)	(16)
Accrued pension and other post-retirement benefit costs	3	1
Payments for asset retirement obligations		(1)
(Increase) decrease in
Net realized and unrealized mark-to-market and hedging transactions	(41)
Receivables	40	(14)
Inventory	37	49
Other current assets	24	20
Increase (decrease) in
Accounts payable	(31)	(21)
Accounts payable to affiliated companies	(5)
Taxes accrued	2	3
Other current liabilities	(17)	(9)
Other assets	25	23
Other liabilities	(1)	(20)
Net cash provided by operating activities	215	223
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(141)	(132)
Contributions to equity method investments	(12)	(9)
Other	(3)	(1)
Net cash used in investing activities	(156)	(142)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of common stock related to employee benefit plans		7
Notes payable and commercial paper	(330)	(80)
Notes payable to affiliated companies	261
Dividends paid		(27)
Net cash provided by (used in) financing activities	(69)	(100)
Net increase (decrease) in cash and cash equivalents	(10)	(19)
Cash and cash equivalents at beginning of period	25	33
Cash and cash equivalents at end of period	15	14
Significant non-cash transactions:
Accrued capital expenditures	$ 24	$ 43

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Changes in 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 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]	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 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 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 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 Balance, in shares at Dec. 31, 2015			688,000,000
Beginning Balance (member's equity) at Dec. 31, 2015														$ 11,606	$ 11,617	$ (11)									$ 7,059	$ 5,121	$ 5,121
Beginning Balance (parent) at Dec. 31, 2015																													$ 2,784	$ 762	$ 2,720	$ (698)	$ 3,836	$ 1	$ 1,384	$ 2,450		$ 1	$ 1,458	$ 728	$ 731	$ (1)
Net income	699				694						694		5				212		209				209	3
Net income (attributable to parent)	694													271	271		209								137	110	110		59			59	95				$ 95		103		103
Other comprehensive income (loss)	41						48	(12)	4		40		1	1		1	3			1	$ 1	1	3			1		$ 1					(1)					$ (1)
Common stock issuances, including dividend reinvestment and employee benefits, shares			1,000,000
Common stock issuances, including dividend reinvestment and employee benefits	1			1							1																												7	7
Common stock dividends	(570)				(570)						(570)																												(27)		(27)
Distributions to parent														(600)	(600)
Distributions to noncontrolling interest in subsidiaries	(1)												(1)				(1)							(1)
Other																																		$ (1)	$ (1,384)	$ (2,450)	3,835
Ending Balance at Mar. 31, 2016	39,941		$ 1	37,969	2,688		$ (644)	(62)	1	(61)	39,892		49				13,067	8,092	5,040	(30)	1	(16)	13,087	(20)
Ending Balance, in shares at Mar. 31, 2016			689,000,000
Ending Balance (member's equity) at Mar. 31, 2016														11,278	11,288	(10)									7,196	5,232	5,231	1					3,930				3,930
Ending Balance (parent) at Mar. 31, 2016																													$ 2,843	762	2,720	(639)							$ 1,541	735	807	$ (1)
Beginning Balance 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)
Beginning Balance, in shares at Dec. 31, 2016	700,000,000		700,000,000														100												89,663,086										100
Beginning Balance (member's equity) at Dec. 31, 2016														10,772	10,781	(9)									7,358	4,900	4,899	1					4,067				4,067
Beginning Balance (parent) at Dec. 31, 2016	$ 41,033																$ 11,820												$ 2,996	762	2,695	(461)							$ 1,672	860	812
Net income	717				716						716		1				201		199				199	2
Net income (attributable to parent)	716													270	270		199								147	90	90		$ 42			42	91				91		$ 95		95
Other comprehensive income (loss)	8							3	4	1	8						3			1	1	1	3			1		1
Common stock issuances, including dividend reinvestment and employee benefits	1			1							1
Common stock dividends	(600)				(600)						(600)
Distributions to parent														(175)	(175)
Distributions to noncontrolling interest in subsidiaries	(2)												(2)
Other	21	[1]			21	[1]					21	[1]					1							1
Ending Balance at Mar. 31, 2017	$ 41,186		$ 1	$ 38,742	$ 2,521			$ (17)	$ 3	$ (71)	$ 41,179		$ 7				$ 12,012	$ 8,094	$ 3,963	$ (22)	$ 2	$ (15)	$ 12,022	$ (10)
Ending Balance, in shares at Mar. 31, 2017	700,000,000		700,000,000														100												89,663,086										100
Ending Balance (member's equity) at Mar. 31, 2017														$ 10,867	$ 10,876	$ (9)									$ 7,505	$ 4,991	$ 4,989	$ 2					$ 4,158				$ 4,158
Ending Balance (parent) at Mar. 31, 2017	$ 41,179																$ 12,022												$ 3,038	$ 762	$ 2,695	$ (419)							$ 1,767	$ 860	$ 907
[1]	Cumulative-effect adjustment due to implementation of a new accounting standard related to stock-based compensation and the associated income taxes. See Note 1 for more information.

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Organization and Basis of Presentation	Index to Combined Notes to Condensed Consolidated Financial Statements The unaudited notes to the condensed consolidated financial statements that follow are a combined presentation. The following list indicates the registrants to which the footnotes apply. Applicable Notes Registrant 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Duke Energy Corporation • • • • • • • • • • • • • • • • Duke Energy Carolinas, LLC • • • • • • • • • • • • • Progress Energy, Inc. • • • • • • • • • • • • • • Duke Energy Progress, LLC • • • • • • • • • • • • • Duke Energy Florida, LLC • • • • • • • • • • • • • Duke Energy Ohio, Inc. • • • • • • • • • • • • • Duke Energy Indiana, LLC • • • • • • • • • • • • • Piedmont Natural Gas Company, Inc. • • • • • • • • • • • • • • • • 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, (ii) subsidiaries that are not registrants but included in the consolidated Duke Energy balances and (iii) the Piedmont registrant not included in the consolidated Duke Energy results for the three months ended March 31, 2016, as Piedmont results were not consolidated by Duke Energy until after the acquisition date of October 3, 2016. ORGANIZATION AND BASIS OF PRESENTATION NATURE OF OPERATIONS AND BASIS OF CONSOLIDATION Duke Energy Corporation (collectively with its subsidiaries, Duke Energy) is an energy company headquartered in Charlotte, North Carolina, subject to regulation by the Federal Energy Regulatory Commission (FERC). Duke Energy operates in the United States (U.S.) primarily through its direct and indirect subsidiaries. Certain Duke Energy subsidiaries are also subsidiary registrants, including Duke Energy Carolinas, LLC (Duke Energy Carolinas); Progress Energy, Inc. (Progress Energy); Duke Energy Progress, LLC (Duke Energy Progress); Duke Energy Florida, LLC (Duke Energy Florida); Duke Energy Ohio, Inc. (Duke Energy Ohio), Duke Energy Indiana, LLC (Duke Energy Indiana) and Piedmont Natural Gas Company, Inc. (Piedmont). When discussing Duke Energy’s consolidated financial information, it necessarily includes the results of its separate subsidiary registrants (collectively referred to as the Subsidiary Registrants), which, along with Duke Energy, are collectively referred to as the Duke Energy Registrants. On October 3, 2016, Duke Energy completed the acquisition of Piedmont. Piedmont's results of operations and cash flows are included in the accompanying condensed consolidated financial statements of Duke Energy for the three months ended March 31, 2017 , but not for the three months ended March 31, 2016, as Piedmont's earnings and cash flows are only included in Duke Energy's consolidated results subsequent to the acquisition date. 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 National Methanol Company (NMC), was completed through two transactions including a sale of assets in Brazil to China Three Gorges (Luxembourg) Energy S.à.r.l. (China Three Gorges) and a sale of Duke Energy's remaining Latin American assets in Peru, Chile, Ecuador, Guatemala, El Salvador and Argentina to ISQ Enerlam Aggregator, L.P. and Enerlam (UK) Holding Ltd. (I Squared Capital) (collectively, the International Disposal Group). See Note 2 for additional information on the sale of International Energy. The results of operations of the International Disposal Group have been classified as Discontinued Operations on the Condensed 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 Condensed Consolidated Financial Statements exclude amounts related to discontinued operations. See Note 2 for additional information. These Condensed Consolidated Financial Statements include, after eliminating intercompany transactions and balances, the accounts of the Duke Energy Registrants and subsidiaries where the respective Duke Energy Registrants have control. These Condensed Consolidated Financial Statements also reflect the Duke Energy Registrants’ proportionate share of certain jointly owned generation and transmission facilities. 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 North Carolina Utilities Commission (NCUC), Public Service Commission of South Carolina (PSCSC), U.S. Nuclear Regulatory Commission (NRC) and FERC. Progress Energy is a public utility holding company headquartered in Raleigh, North Carolina, subject to regulation by FERC. Progress Energy conducts operations through its wholly owned subsidiaries, Duke Energy Progress and Duke Energy Florida. 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 Florida Public Service Commission (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 Condensed Consolidated Statements of Operations and Comprehensive Income. Operations in Kentucky are conducted through its wholly owned subsidiary, Duke Energy Kentucky, Inc. (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 Public Utilities Commission of Ohio (PUCO), Kentucky Public Service Commission (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 Indiana Utility Regulatory Commission (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 also invested in joint venture, energy-related businesses, including regulated interstate natural gas transportation and storage and intrastate natural gas transportation businesses. Piedmont is subject to the regulatory provisions of the NCUC, PSCSC, Tennessee Public Utility Commission (formerly the Tennessee Regulatory Authority) (TPUC) and FERC. BASIS OF PRESENTATION These Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles (GAAP) in the U.S. for interim financial information and with the instructions to Form 10-Q and Regulation S-X. Accordingly, these Condensed Consolidated Financial Statements do not include all information and notes required by GAAP in the U.S. for annual financial statements. Since the interim Condensed Consolidated Financial Statements and Notes do not include all information and notes required by GAAP in the U.S. for annual financial statements, the Condensed Consolidated Financial Statements and other information included in this quarterly report should be read in conjunction with the Consolidated Financial Statements and Notes in the Duke Energy Registrants’ combined Annual Report on Form 10-K for the year ended December 31, 2016 , and the Consolidated Financial Statements and Notes in the Piedmont Annual Report on Form 10-K for the year ended October 31, 2016. 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) as of December 31, 2016, for the transition period from November 1, 2016 to December 31, 2016. The information in these combined notes relates to each of the Duke Energy Registrants as noted in the Index to Combined Notes to Condensed Consolidated Financial Statements. However, none of the registrants make any representations as to information related solely to Duke Energy or the subsidiaries of Duke Energy other than itself. These Condensed Consolidated Financial Statements, in the opinion of the respective companies’ management, reflect all normal recurring adjustments necessary to fairly present the financial position and results of operations of each of the Duke Energy Registrants. Amounts reported in Duke Energy’s interim Condensed Consolidated Statements of Operations and each of the Subsidiary Registrants’ interim Condensed Consolidated Statements of Operations and Comprehensive Income are not necessarily indicative of amounts expected for the respective annual periods due to effects of seasonal temperature variations on energy consumption, regulatory rulings, timing of maintenance on electric generating units, changes in mark-to-market valuations, changing commodity prices and other factors. In preparing financial statements that conform to GAAP, management 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. Certain prior year amounts have been reclassified to conform to the current year presentation. UNBILLED REVENUE Revenues on sales of electricity and natural gas are recognized when service is provided or the product is delivered. Unbilled revenues are recognized by applying customer billing rates to the estimated volumes of energy and 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, meter reading schedules, and the impact of weather normalization or margin decoupling mechanisms. Unbilled revenues are included within Receivables and Receivables of variable interest entities (VIEs) on the Condensed Consolidated Balance Sheets as shown in the following table. (in millions) March 31, 2017 December 31, 2016 Duke Energy $ 724 $ 831 Duke Energy Carolinas 296 313 Progress Energy 151 161 Duke Energy Progress 84 102 Duke Energy Florida 67 59 Duke Energy Ohio 2 2 Duke Energy Indiana 27 32 Piedmont 38 77 Additionally, Duke Energy Ohio and Duke Energy Indiana sell nearly all of their retail accounts receivable to an affiliate, Cinergy Receivables Company, LLC (CRC), on a revolving basis. These transfers of receivables are accounted for as sales and include receivables for unbilled revenues. Accordingly, the receivables sold are not reflected on the Condensed Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana. See Note 12 for further information. These receivables for unbilled revenues are shown in the table below. (in millions) March 31, 2017 December 31, 2016 Duke Energy Ohio $ 69 $ 97 Duke Energy Indiana 106 123 AMOUNTS ATTRIBUTABLE TO CONTROLLING INTERESTS Duke Energy's amount of Income from Discontinued Operations, net of tax presented on the Condensed Consolidated Statements of Operations for the three months ended March 31, 2016 , includes amounts attributable to noncontrolling interest. The following table presents Net Income Attributable to Duke Energy Corporation for continuing operations and discontinued operations. Three Months Ended (in millions) March 31, 2016 Income from Continuing Operations $ 577 Income from Continuing Operations Attributable to Noncontrolling Interests 3 Income from Continuing Operations Attributable to Duke Energy Corporation $ 574 Income from Discontinued Operations, net of tax $ 122 Income from Discontinued Operations Attributable to Noncontrolling Interests, net of tax 2 Income from Discontinued Operations Attributable to Duke Energy Corporation, net of tax $ 120 Net Income $ 699 Net Income Attributable to Noncontrolling Interests 5 Net Income Attributable to Duke Energy Corporation $ 694 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 for the three months ended March 31, 2017 and December 31, 2016 . The components of inventory are presented in the tables below. March 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 $ 2,328 $ 766 $ 1,122 $ 780 $ 341 $ 85 $ 315 $ 2 Coal 724 248 297 162 135 17 161 — Natural gas, oil and other fuel 314 37 233 111 123 16 2 27 Total inventory $ 3,366 $ 1,051 $ 1,652 $ 1,053 $ 599 $ 118 $ 478 $ 29 December 31, 2016 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 $ 2,374 $ 767 $ 1,167 $ 813 $ 354 $ 84 $ 312 $ 1 Coal 774 251 314 148 166 19 190 — Natural gas, oil and other fuel 374 37 236 115 121 34 2 65 Total inventory $ 3,522 $ 1,055 $ 1,717 $ 1,076 $ 641 $ 137 $ 504 $ 66 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, excise taxes are accounted for net. Excise taxes accounted for on a gross basis as both operating revenues and property and other taxes on the Condensed Consolidated Statements of Operations were as follows. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy $ 91 $ 91 Duke Energy Carolinas 9 8 Progress Energy 46 47 Duke Energy Progress 5 5 Duke Energy Florida 41 42 Duke Energy Ohio 28 28 Duke Energy Indiana 7 8 Piedmont 1 1 NEW ACCOUNTING STANDARDS The new accounting standards adopted for 2017 and 2016 had no material impact on the presentation or results of operations, cash flows or financial position of the Duke Energy Registrants. While immaterial, adoption of the following accounting standard had the most significant impact on the Duke Energy results of operations, cash flows and financial position for the three months ended March 31, 2017. Stock-Based Compensation and Income Taxes. In March 2017, Duke Energy adopted Financial Accounting Standards Board (FASB) guidance, which revised the accounting for stock-based compensation and the associated income taxes. The adopted guidance changes certain aspects of accounting for stock-based payment awards to employees including the accounting for income taxes and classification on the Condensed Consolidated Statements of Cash Flows. The primary impact to Duke Energy as a result of implementing this guidance was a cumulative-effect adjustment to retained earnings for tax benefits not previously recognized and higher income tax expense for the three months ended March 31, 2017. See the Duke Energy Condensed Consolidated Statements of Changes in Equity and Note 16 for further information. The following new Accounting Standards Updates (ASUs) have been issued, but have not yet been adopted by Duke Energy, as of March 31, 2017 . Retirement Benefits. In March 2017, the FASB issued revised accounting guidance for the presentation of net periodic costs related to benefit plans. Current GAAP permits the aggregation of all the components of net periodic costs on the income statement and does not require the disclosure of the location of net periodic costs on the Condensed Consolidated Statement of Operations. Under the amended guidance, the service cost component of net periodic costs must be included within Operating income within the same line as other compensation expenses. All other components of net periodic costs must be 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 current GAAP, which permits all components of net periodic costs to be capitalized. The guidance allows for a practical expedient that permits a company to use amounts disclosed in prior-period financial statements as the estimation basis for applying the retrospective presentation requirements. For Duke Energy, this guidance is effective for interim and annual periods beginning January 1, 2018. These amendments should be applied retrospectively for the presentation of the various components of net periodic costs and prospectively for the change in eligible costs to be capitalized. Duke Energy currently presents all of the components of net periodic costs that are not capitalized within Operation, maintenance and other on the Condensed Consolidated Statement of Operations. Under this updated guidance, Duke Energy will retrospectively move all the components of net periodic costs except for the service cost component to below Operating income. However, Duke Energy will continue to present the service cost component not capitalized within Operation, maintenance and other as this line item includes other compensation expense. Duke Energy is currently evaluating the financial statement impact, if any, of adopting this standard and whether or not the practical expedient will be utilized. Goodwill Impairment. In January 2017, the FASB issued revised guidance for subsequent measurement of goodwill. Under the guidance, a company will recognize an impairment to goodwill for the amount by which a reporting unit's carrying value exceeds the reporting unit's fair value, not to exceed the amount of goodwill allocated to that reporting unit. For Duke Energy, this guidance is effective for interim and annual periods beginning January 1, 2020. However, Duke Energy expects to early adopt this guidance on a prospective basis for the next interim or annual goodwill impairment test. Duke Energy does not expect adopting this guidance will have a material impact to its results of operations or financial position. 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 to which the entity expects to be entitled in exchange for those goods or services. The amendments in this update also require 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. Most of Duke Energy’s revenue is expected to be in scope of the new guidance. The majority of our sales, including energy provided to residential customers, are from tariff offerings that provide natural gas or electricity without a defined contractual term (‘at-will’). For such arrangements, Duke Energy expects that the revenue from contracts with customers will be equivalent to the electricity or natural gas supplied and billed in that period (including estimated billings). As such, Duke Energy does not expect that there will be a significant shift in the timing or pattern of revenue recognition for such sales. The evaluation of other revenue streams is ongoing, including long-term contracts with industrial customers and long-term purchase power agreements (PPA). Duke Energy continues to evaluate what information would be most useful for users of the financial statements, including information already provided in disclosures outside of the financial statement footnotes. These additional disclosures could include the disaggregation of revenues by geographic location, type of service, customer class or by duration of contract (‘at-will’ versus contracted revenue). Revenues from contracts with customers, revenue recognized under regulated operations accounting and revenue from lease accounting will also be disclosed. Duke Energy intends to use the modified retrospective method of adoption effective January 1, 2018. This method results in a cumulative-effect adjustment that will be recorded to retained earnings as of January 1, 2018, as if the standard had always been in effect. Disclosures for 2018 will include a comparison to what would have been reported for 2018 under the current revenue recognition rules in order to assist financial statement users in understanding how revenue recognition has changed as a result of this standard and to facilitate comparability with prior year reported results, which are not restated under the modified retrospective approach. 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, although it can be early adopted. The guidance is applied using a modified retrospective approach. Duke Energy is currently evaluating the financial statement impact of adopting this standard. Other than an expected increase in assets and liabilities, the ultimate impact of the new standard has not yet been determined. Significant system enhancements may be required to facilitate the identification, tracking and reporting of potential leases based upon requirements of the new lease standard. 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 statement of cash flows. Under the updated guidance, restricted cash and restricted cash equivalents will be included within beginning-of-period and end-of-period cash and cash equivalents on the statement of cash flows. For Duke Energy, this guidance is effective for the interim and annual periods beginning January 1, 2018, although it can be early adopted. The guidance will be applied using a retrospective transition method to each period presented. Upon adoption by Duke Energy, the revised guidance will result in a change to the amount of cash and cash equivalents and restricted cash explained when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. Prior to adoption, the Duke Energy Registrants reflect changes in restricted cash within Cash Flows from Investing Activities on the Condensed Consolidated Statement of Cash Flows. Financial Instruments Classification and Measurement. In January 2016, the FASB issued revised accounting guidance for the classification and measurement of financial instruments. Changes in the fair value of all equity securities will be required to be recorded in net income. Current GAAP allows some changes in fair value for available-for-sale equity securities to be recorded in Accumulated other comprehensive income (AOCI). Additional disclosures will be required to present separately the financial assets and financial liabilities by measurement category and form of financial asset. 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. For Duke Energy, the revised accounting guidance is effective for interim and annual periods beginning January 1, 2018, by recording a cumulative-effect adjustment to retained earnings as of January 1, 2018. This guidance is expected to have minimal impact on the Duke Energy Registrant's Condensed Consolidated Statements of Operations and Comprehensive Income as changes in the fair value of most of the Duke Energy Registrants' available-for-sale equity securities are deferred as regulatory assets or liabilities pursuant to accounting guidance for regulated operations.

Acquisitions and Dispositions

Acquisitions and Dispositions	3 Months Ended
	Mar. 31, 2017
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. 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. Purchase Price Allocation The purchase price allocation of the Piedmont acquisition is as follows: (in millions) Current assets $ 497 Property, plant and equipment, net 4,714 Goodwill 3,353 Other long-term assets 804 Total assets 9,368 Current liabilities, including current maturities of long-term debt 576 Long-term liabilities 1,790 Long-term debt 2,002 Total liabilities 4,368 Total purchase price $ 5,000 The fair value of Piedmont's assets and liabilities were determined based on significant estimates and assumptions that are judgmental in nature, including projected future cash flows (including timing), discount rates reflecting risk inherent in the future cash flows and market prices of long-term debt. The majority of Piedmont’s operations are subject to the rate-setting authority of the NCUC, the PSCSC and the TPUC and are accounted for pursuant to accounting guidance for regulated operations. The rate-setting and cost recovery provisions currently in place for Piedmont’s regulated operations provide revenues derived from costs, including a return on investment of assets and liabilities included in rate base. Thus, the fair value of Piedmont's assets and liabilities subject to these rate-setting provisions approximates the pre-acquisition carrying value and does not reflect any net valuation adjustments. The significant assets and liabilities for which valuation adjustments were reflected within the purchase price allocation include the acquired equity method investments and long-term debt. The difference between the fair value and the pre-acquisition carrying value of long-term debt for regulated operations was recorded as a regulatory asset. The excess of the purchase price over the fair value of Piedmont's assets and liabilities on the acquisition date was recorded as goodwill. The goodwill reflects the value paid by Duke Energy primarily for establishing a broader, long-term strategic natural gas infrastructure platform, an improved risk profile and expected synergies resulting from the combined entities. Under Securities and Exchange Commission (SEC) regulations, Duke Energy elected not to apply push down accounting to the stand-alone Piedmont financial statements. Accounting Charges Related to the Acquisition Duke Energy incurred pretax nonrecurring transaction and integration costs associated with the acquisition of $16 million and $101 million for the three months ended March 31, 2017 and 2016, respectively. The 2016 amount includes $100 million of Interest Expense, which was driven by $93 million of unrealized losses on forward-starting interest rate swaps related to the acquisition financing. See Note 9 for additional information on the swaps. 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, 2016. The pro forma financial information excludes potential cost savings, intercompany revenues, Piedmont’s earnings from the equity method investment in SouthStar sold immediately prior to the merger, and after-tax nonrecurring transaction and integration costs incurred by Duke Energy and Piedmont of $63 million . See Note 3 for additional information on Piedmont's sale of SouthStar. 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. Three Months Ended (in millions) March 31, 2016 Operating Revenues $ 5,840 Net Income Attributable to Duke Energy Corporation 832 DISPOSITIONS Sale of International Energy In December 2016, Duke Energy sold its International Energy businesses, excluding the equity method investment in NMC (the International Disposal Group), in two separate transactions. Duke Energy sold its Brazilian business to China Three Gorges for approximately $1.2 billion , including the assumption of debt, and its remaining Central and South American businesses to I Squared Capital in a deal also valued at approximately $1.2 billion , including the assumption of debt. The transactions generated cash proceeds of $1.9 billion , excluding transaction costs, which were primarily used to reduce Duke Energy holding company debt. The following table presents the results of the International Disposal Group, which are included in Income from Discontinued Operations, net of tax in Duke Energy's Condensed Consolidated Statements of Operations. 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. Three Months Ended (in millions) March 31, 2016 Operating Revenues $ 246 Fuel used in electric generation and purchased power 47 Cost of natural gas 11 Operation, maintenance and other 71 Depreciation and amortization 22 Property and other taxes 3 Other Income and Expenses, net 10 Interest Expense 22 Income before income taxes 80 Income tax benefit (a) (39 ) Income from discontinued operations of the International Disposal Group 119 Income from discontinued operations of other businesses 3 Income from Discontinued Operations, net of tax $ 122 (a) Includes an income tax benefit of $95 million related to historical undistributed foreign earnings. See Note 16 for additional information. Duke Energy has elected not to separately disclose discontinued operations on the Condensed Consolidated Statements of Cash Flows. The following table summarizes Duke Energy's cash flows from discontinued operations related to the International Disposal Group. Three Months Ended (in millions) March 31, 2016 Cash flows provided by (used in): Operating activities $ 85 Investing activities (9 ) Other Sale Related Matters Duke Energy will provide certain transition services to China Three Gorges and I Squared Capital for a period not to extend beyond November 2017 and December 2017, respectively. Cash flows related to providing the transition services are not material. In addition, Duke Energy will reimburse China Three Gorges and I Squared Capital for all tax obligations arising from the period preceding consummation on the transactions, totaling approximately $78 million . Duke Energy has not recorded any other liabilities, contingent liabilities or indemnifications related to the International Disposal Group.

Business Segments

Business Segments	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS Operating 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 includes intercompany revenues and expenses that are eliminated in the Condensed Consolidated Financial Statements. Products and services are sold between affiliate companies and reportable segments of Duke Energy at cost. Duke Energy Due to the Piedmont acquisition and the sale of International Energy in the fourth quarter of 2016, Duke Energy's segment structure has been realigned to include the following segments: Electric Utilities and Infrastructure, Gas Utilities and Infrastructure and Commercial Renewables. Prior period information has been recast to conform to the current segment structure. See Note 2 for further information on the Piedmont and International Energy transactions. 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 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 mid-stream pipeline investments. Gas Utilities and Infrastructure's operations are substantially all regulated and, accordingly, qualify for regulatory accounting treatment. Commercial Renewables 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 unallocated corporate interest expense, unallocated corporate costs, contributions to the Duke Energy Foundation and the operations of Duke Energy’s wholly owned captive insurance subsidiary, Bison Insurance Company Limited (Bison). Other also includes Duke Energy's 25 percent interest in NMC, a large regional producer of methyl tertiary butyl ether (MTBE) located in Saudi Arabia. The investment in NMC is accounted for under the equity method of accounting. Business segment information is presented in the following tables. Segment assets presented exclude intercompany assets. Three Months Ended March 31, 2017 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Consolidated Unaffiliated revenues $ 4,939 $ 648 $ 128 $ 5,715 $ 14 $ — $ 5,729 Intersegment revenues 8 22 — 30 19 (49 ) — Total revenues $ 4,947 $ 670 $ 128 $ 5,745 $ 33 $ (49 ) $ 5,729 Segment income (loss) $ 635 $ 133 $ 25 $ 793 $ (77 ) $ — $ 716 Add back noncontrolling interests 1 Net income $ 717 Segment assets $ 115,766 $ 10,866 $ 4,400 $ 131,032 $ 2,898 $ 178 $ 134,108 Three Months Ended March 31, 2016 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Consolidated Unaffiliated revenues $ 5,081 $ 169 $ 114 $ 5,364 $ 13 $ — $ 5,377 Intersegment revenues 8 1 — 9 16 (25 ) — Total revenues $ 5,089 $ 170 $ 114 $ 5,373 $ 29 $ (25 ) $ 5,377 Segment income (loss) (a) $ 664 $ 32 $ 26 $ 722 $ (148 ) $ — $ 574 Add back noncontrolling interests 3 Income from discontinued operations, net of tax 122 Net income $ 699 (a) Other includes $74 million of after-tax costs to achieve mergers, including losses on forward-starting interest rate swaps related to the Piedmont acquisition financing. See Note 9 for additional information. Duke Energy Ohio Duke Energy Ohio has two reportable operating 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 Kentucky. Gas Utilities and Infrastructure transports and sells natural gas in portions of Ohio and northern Kentucky. It conducts operations primarily through Duke Energy Ohio and its wholly owned subsidiary, Duke Energy Kentucky. Other is primarily comprised of governance costs allocated by its parent, Duke Energy, and revenues and expenses related to Duke Energy Ohio's contractual arrangement to buy power from the Ohio Valley Electric Corporation's (OVEC) power plants. See Note 8 for additional information on related party transactions. Three Months Ended March 31, 2017 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Consolidated Total revenues $ 337 $ 170 $ 507 $ 11 $ — $ 518 Segment income (loss)/Net Income 24 26 50 (8 ) — 42 Segment assets 4,856 2,696 7,552 71 (14 ) 7,609 Three Months Ended March 31, 2016 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Consolidated Total revenues $ 340 $ 170 $ 510 $ 6 $ — $ 516 Segment income (loss) $ 36 $ 31 $ 67 $ (9 ) $ (1 ) $ 57 Income from discontinued operations, net of tax 2 Net income $ 59 DUKE ENERGY CAROLINAS, PROGRESS ENERGY, DUKE ENERGY PROGRESS, DUKE ENERGY FLORIDA, DUKE ENERGY INDIANA AND PIEDMONT Piedmont has one reportable segment, Gas Utilities and Infrastructure, which transports and sells natural gas. The remainder of Piedmont's operations is classified as Other. While not considered a reportable segment, Other primarily consists of certain unallocated corporate costs, including acquisition-related expenses, and Piedmont's equity method investment in SouthStar Energy Services, LLC (SouthStar) prior to its sale. Piedmont sold its 15 percent membership interest in SouthStar on October 3, 2016. Piedmont's income, net of tax, from SouthStar for the three months ended March 31, 2016 was $7 million . The remaining Subsidiary Registrants each have one reportable operating segment, Electric Utilities and Infrastructure, which generates, transmits, distributes and sells electricity. The remainder of each company's operations is classified as Other. While not considered a reportable segment for any of these companies, Other consists of certain unallocated corporate costs. Other for Progress Energy also includes interest expense on corporate debt instruments of $55 million and $56 million for the three months ended March 31, 2017 and 2016, respectively. The following table summarizes the net loss of Other for each of these entities. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas $ (6 ) $ (17 ) Progress Energy (43 ) (49 ) Duke Energy Progress (3 ) (8 ) Duke Energy Florida (2 ) (4 ) Duke Energy Indiana (2 ) (2 ) Piedmont (4 ) 6 The assets at Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida and Duke Energy Indiana are substantially all included within the Electric Utilities and Infrastructure segment at March 31, 2017 . The assets at Piedmont are substantially all included within the Gas Utilities and Infrastructure segment at March 31, 2017 .

Regulatory Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2017
Regulated Operations [Abstract]
Regulatory Matters	REGULATORY MATTERS 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 Ash Basin Closure Costs Deferral On December 30, 2016, Duke Energy Carolinas and Duke Energy Progress filed a joint petition with the NCUC seeking an accounting order authorizing deferral of certain costs incurred in connection with federal and state environmental remediation requirements related to the permanent closure of ash basins and other ash storage units at coal-fired generating facilities that have provided or are providing generation to customers located in North Carolina. Initial comments were received in March 2017, and reply comments were filed on April 19, 2017. Duke Energy Carolinas and Duke Energy Progress cannot predict the outcome of this matter. Duke Energy Carolinas William States Lee Combined Cycle Facility On April 9, 2014, the PSCSC granted Duke Energy Carolinas and North Carolina Electric Membership Corporation (NCEMC) a Certificate of Environmental Compatibility and Public Convenience and Necessity (CECPCN) for the construction and operation of a 750-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 estimates a cost to build of $600 million for its share of the facility, including AFUDC. The project is expected to be commercially available in late 2017. NCEMC will own approximately 13 percent of the project. On July 3, 2014, the South Carolina Coastal Conservation League (SCCL) and Southern Alliance for Clean Energy (SACE) jointly filed a Notice of Appeal with the Court of Appeals of South Carolina (S.C. Court of Appeals) seeking the court's review of the PSCSC's decision, claiming the PSCSC did not properly consider a request related to a proposed solar facility prior to granting approval of the CECPCN. The S.C. Court of Appeals affirmed the PSCSC's decision on February 10, 2016, and on March 24, 2016, denied a request for rehearing filed by SCCL and SACE. On April 21, 2016, SCCL and SACE petitioned the South Carolina Supreme Court for review of the S.C. Court of Appeals decision. On March 24, 2017, the South Carolina Supreme Court denied the request for review, thus concluding the matter. William States Lee III Nuclear Station In December 2007, Duke Energy Carolinas applied to the NRC for combined operating licenses (COLs) for two Westinghouse Electric Company (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 have concurred with the prudency of Duke Energy Carolinas decisions to incur 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. On March 29, 2017, Westinghouse filed for voluntary Chapter 11 bankruptcy in the U.S. Bankruptcy Court for the Southern District of New York. Duke Energy Carolinas is monitoring the bankruptcy proceedings to assess the impact it will have on the future construction of nuclear plants. Duke Energy Progress Storm Cost Deferral Filing On December 16, 2016, Duke Energy Progress filed a petition with the NCUC requesting an accounting order to defer certain costs incurred in connection with response to Hurricane Matthew and other significant storms in 2016. Duke Energy Progress proposed in the filing to true-up the total costs quarterly through August 2017. The current estimate of incremental operation and maintenance and capital costs is $116 million . On March 15, 2017, the Public Staff filed comments supporting deferral of a portion of Duke Energy Progress’ requested amount. Duke Energy Progress filed reply comments on April 12, 2017. Duke Energy Progress cannot predict the outcome of this matter. Western Carolinas Modernization Plan On November 4, 2015, Duke Energy Progress announced a Western Carolinas Modernization Plan, which included retirement of the existing Asheville coal-fired plant, the construction of two 280‑MW combined-cycle natural gas plants having dual fuel capability, with the option to build a third natural gas simple cycle unit in 2023 based upon the outcome of initiatives to reduce the region's power demand. The plan also included upgrades to existing transmission lines and substations, installation of solar generation and a pilot battery storage project. These investments will be made within the next seven years. Duke Energy Progress is also working with the local natural gas distribution company to upgrade an existing natural gas pipeline to serve the natural gas plant. On March 28, 2016, the NCUC issued an order approving a Certificate of Public Convenience and Necessity (CPCN) for the new combined-cycle natural gas plants, but denying the CPCN for the contingent simple cycle unit without prejudice to Duke Energy Progress to refile for approval in the future. On March 28, 2017, Duke Energy Progress filed an annual progress report for the construction of the combined-cycle plants with the NCUC, with an estimated cost of $893 million . Site preparation activities for the combined-cycle plants are underway and construction of these plants is scheduled to begin in fall 2017, with an expected in-service date in late 2019. Duke Energy Progress plans to file for future approvals related to the proposed solar generation and pilot battery storage project. The carrying value of the 376 -MW Asheville coal-fired plant, including associated ash basin closure costs, of $471 million and $492 million are included in Generation facilities to be retired, net on Duke Energy Progress' Condensed Consolidated Balance Sheet as of March 31, 2017 and December 31, 2016 , respectively. Duke Energy Florida Hines Chiller Uprate Project On February 2, 2017, Duke Energy Florida filed a petition seeking approval to include in base rates the revenue requirement for a Chiller Uprate Project (Uprate Project) at the Hines Energy Complex. The Uprate Project was placed into service in March 2017 at a cost of approximately $150 million . The retail revenue requirement is approximately $19 million . On March 28, 2017, the FPSC issued an order approving the revenue requirement which were included in base rates for the first billing cycle of April 2017. Levy Nuclear Project On July 28, 2008, Duke Energy Florida applied to the NRC for COLs for two Westinghouse AP1000 reactors at Levy. In 2008, the FPSC granted Duke Energy Florida’s petition for an affirmative Determination of Need and related orders requesting cost recovery under Florida’s nuclear cost-recovery rule, together with the associated facilities, including transmission lines and substation facilities. In October 2016, the NRC issued COLs for the proposed Levy Nuclear Plant Units 1 and 2. Duke Energy Florida is not required to build the nuclear reactors as a result of the COLs being issued. On January 28, 2014, Duke Energy Florida terminated the Levy engineering, procurement and construction agreement (EPC). Duke Energy Florida may be required to pay for work performed under the EPC. Duke Energy Florida recorded an exit obligation in 2014 for the termination of the EPC. This liability was recorded within Other in Deferred Credits and Other Liabilities with an offset primarily to Regulatory assets on the Condensed Consolidated Balance Sheets. Duke Energy Florida is allowed to recover reasonable and prudent EPC cancellation costs from its retail customers. On May 1, 2017, Duke Energy Florida filed a request with the FPSC to recover approximately $82 million of Levy Nuclear Project costs from retail customers in 2018. A hearing is scheduled in August 2017. Duke Energy Florida cannot predict the outcome of this matter. On March 29, 2017, Westinghouse filed for voluntary Chapter 11 bankruptcy in the U.S. Bankruptcy Court for the Southern District of New York. Duke Energy Florida is monitoring the bankruptcy proceedings to assess the impact it will have on the future construction of nuclear plants. Duke Energy Ohio Ohio Valley Electric Corporation On March 31, 2017, Duke Energy Ohio filed for approval to adjust its existing price stabilization rider (Rider PSR) to pass through net costs related to its contractual entitlement to capacity and energy from the generating assets owned by OVEC. The PUCO approved Rider PSR, but set it at zero dollars in connection with the most recent electric security plan. The application seeks to adjust Rider PSR as of April 1, 2017. Duke Energy Ohio is seeking deferral authority for net costs incurred from April 1, 2017, until the new rates under Rider PSR are put into effect. See Note 12 for additional discussion of Duke Energy Ohio's ownership interest in OVEC. Duke Energy Ohio cannot predict the outcome of this proceeding. East Bend Coal Ash Basin Filing On December 2, 2016, Duke Energy Kentucky filed with the KPSC a request for a CPCN for construction projects necessary to close and repurpose an ash basin at the East Bend facility as a result of current and proposed U.S. Environmental Protection Agency (EPA) regulations. Duke Energy Kentucky estimated a total cost of approximately $93 million in the filing and expects in-service date in the fourth quarter of 2018. Duke Energy Kentucky expects the KPSC to issue an order in the second quarter of 2017. Base Rate Case Duke Energy Ohio filed with the PUCO an electric distribution base rate case application and supporting testimony in March 2017. Duke Energy Ohio has requested an estimated annual increase of approximately $15 million and a return on equity of 10.4 percent . The application also includes requests to continue certain current riders and establish new riders related to LED Outdoor Lighting Service and regulatory mandates. Duke Energy Ohio cannot predict the outcome of this matter. Natural Gas Pipeline Extension Duke Energy Ohio is proposing to install a new natural gas pipeline in its Ohio service territory to increase system reliability and enable the retirement of older infrastructure. On January 20, 2017, Duke Energy Ohio filed an amended application with the Ohio Power Siting Board for approval of one of two proposed routes. If approved, construction of the pipeline extension is expected to be completed before the 2019/2020 winter season. A public hearing is scheduled for June 15, 2017, and an adjudicatory hearing is scheduled to begin July 12, 2017. The proposed project involves the installation of a natural gas line and is estimated to cost between $86 million and $110 million , excluding AFUDC. Advanced Metering Infrastructure On April 25, 2016, Duke Energy Kentucky filed with the KPSC an application for approval of a CPCN for the construction of advanced metering infrastructure. Duke Energy Kentucky estimates the $49 million project, if approved, will take two years to complete. Duke Energy Kentucky also requested approval to establish a regulatory asset of approximately $10 million for the remaining book value of existing meter equipment and inventory to be replaced. Duke Energy Kentucky and the Kentucky Attorney General entered into a stipulation to settle matters related to the application. An evidentiary hearing on the application and stipulation was held on December 8, 2016. Duke Energy Kentucky cannot predict the outcome of this matter. Accelerated Natural Gas Service Line Replacement Rider On January 20, 2015, Duke Energy Ohio filed an application for approval of an accelerated natural gas service line replacement program (ASRP). Under the ASRP, Duke Energy Ohio proposed to replace certain natural gas service lines on an accelerated basis over a 10-year period. Duke Energy Ohio also proposed to complete preliminary survey and investigation work related to natural gas service lines that are customer owned and for which it does not have valid records and, further, to relocate interior natural gas meters to suitable exterior locations where such relocation can be accomplished. Duke Energy Ohio's current projected total capital and operations and maintenance expenditures under the ASRP are approximately $240 million . The filing also sought approval of a rider mechanism (Rider ASRP) to recover related expenditures. Duke Energy Ohio proposed to update Rider ASRP on an annual basis. Intervenors opposed the ASRP, primarily because they believe the program is neither required nor necessary under federal pipeline regulation. On October 26, 2016, the PUCO issued an order denying the proposed ASRP. The PUCO did, however, encourage Duke Energy Ohio to work with the PUCO Staff and intervenors. Duke Energy Ohio filed an application for rehearing of the PUCO decision. In December 2016, the PUCO granted the request for the purpose of further review. Duke Energy Ohio cannot predict the outcome of this matter. Energy Efficiency Cost Recovery On March 28, 2014, Duke Energy Ohio filed an application for recovery of program costs, lost distribution revenue and performance incentives related to its energy efficiency and peak demand reduction programs. These programs are undertaken to comply with environmental mandates set forth in Ohio law. The PUCO approved Duke Energy Ohio’s application, but found that Duke Energy Ohio was not permitted to use banked energy savings from previous years in order to calculate the amount of allowed incentive. This conclusion represented a change to the cost recovery mechanism that had been agreed upon by intervenors and approved by the PUCO in previous cases. The PUCO granted the applications for rehearing filed by Duke Energy Ohio and an intervenor. On January 6, 2016, Duke Energy Ohio and the PUCO Staff entered into a stipulation, pending the PUCO's approval, to resolve issues related to performance incentives and the PUCO Staff audit of 2013 costs, among other issues. In December 2015, based upon the stipulation, Duke Energy Ohio re-established approximately $20 million of the revenues that had been previously reversed. On October 26, 2016, the PUCO issued an order approving the stipulation without modification. Intervenors requested a rehearing of the PUCO decision. In December 2016, the PUCO granted a rehearing for the purpose of further review. Duke Energy Ohio cannot predict the outcome of this matter. 2012 Natural Gas Rate Case/Manufactured Gas Plant Cost Recovery On November 13, 2013, the PUCO issued an order approving a settlement of Duke Energy Ohio’s natural gas base rate case and authorizing the recovery of costs incurred between 2008 and 2012 for environmental investigation and remediation of two former manufactured gas plant (MGP) sites. The PUCO order also authorized Duke Energy Ohio to continue deferring MGP environmental investigation and remediation costs incurred subsequent to 2012 and to submit annual filings to adjust the MGP rider for future costs. Intervening parties appealed this decision to the Ohio Supreme Court and that appeal remains pending. Oral argument was heard on February 28, 2017. Incurred and projected investigation and remediation expenses at these MGP sites that have not been collected through the MGP rider are approximately $100 million and are recorded as Regulatory assets on Duke Energy Ohio's Condensed Consolidated Balance Sheet as of March 31, 2017 . Duke Energy Ohio cannot predict the outcome of this matter. Regional Transmission Organization Realignment Duke Energy Ohio, including Duke Energy Kentucky, transferred control of its transmission assets from Midcontinent Independent System Operator, Inc. (MISO) to PJM Interconnection, LLC (PJM), effective December 31, 2011. The PUCO approved a settlement related to Duke Energy Ohio’s recovery of certain costs of the Regional Transmission Organization (RTO) realignment via a non-bypassable rider. Duke Energy Ohio is allowed to recover all MISO Transmission Expansion Planning (MTEP) costs, including but not limited to Multi Value Project (MVP) costs, directly or indirectly charged to Ohio customers. Duke Energy Ohio also agreed to vigorously defend against any charges for MVP projects from MISO. The KPSC also approved a request to effect the RTO realignment, subject to a commitment not to seek double recovery in a future rate case of the transmission expansion fees that may be charged by MISO and PJM in the same period or overlapping periods. Duke Energy Ohio had a recorded liability for its exit obligation and share of MTEP costs, excluding MVP, of $90 million at March 31, 2017 , and December 31, 2016 , recorded within Other in Current liabilities and Other in Other Noncurrent Liabilities on the Condensed 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 March 31, 2017 , and December 31, 2016 , Duke Energy Ohio had $71 million recorded in Regulatory assets on the Condensed Consolidated Balance Sheets. MVP. MISO approved 17 MVP proposals prior to Duke Energy Ohio’s exit from MISO on December 31, 2011. Construction of these projects is expected to continue through 2020. Costs of these projects, including operating and maintenance costs, property and income taxes, depreciation and an allowed return, are allocated and billed to MISO transmission owners. On December 29, 2011, MISO filed a tariff with the FERC providing for the allocation of MVP costs to a withdrawing owner based on monthly energy usage. The FERC set for hearing (i) whether MISO’s proposed cost allocation methodology to transmission owners who withdrew from MISO prior to January 1, 2012, is consistent with the tariff at the time of their withdrawal from MISO and, (ii) if not, what the amount of and methodology for calculating any MVP cost responsibility should be. In 2012, MISO estimated Duke Energy Ohio’s MVP obligation over the period from 2012 to 2071 at $2.7 billion , on an undiscounted basis. On July 16, 2013, a FERC Administrative Law Judge (ALJ) issued an initial decision. Under this Initial Decision, Duke Energy Ohio would be liable for MVP costs. Duke Energy Ohio filed exceptions to the initial decision, requesting FERC to overturn the ALJ’s decision. On October 29, 2015, the FERC issued an order reversing the ALJ's decision. The FERC ruled the cost allocation methodology is not consistent with the MISO tariff and that Duke Energy Ohio has no liability for MVP costs after its withdrawal from MISO. On May 19, 2016, the FERC denied the request for rehearing filed by MISO and the MISO Transmission Owners. On July 15, 2016, the MISO Transmission Owners filed a petition for review with the U.S. Court of Appeals for the Sixth Circuit. Duke Energy Ohio cannot predict the outcome of this matter. Duke Energy Indiana Coal Combustion Residual Plan On March 17, 2016, Duke Energy Indiana filed with the IURC a request for approval of its first group of federally mandated Coal Combustion Residual (CCR) rule compliance projects (Phase I CCR Compliance Projects) to comply with the EPA's CCR rule. The projects in this Phase I filing are CCR compliance projects, including the conversion of Cayuga and Gibson stations to dry bottom ash handling and related water treatment. Duke Energy Indiana has requested timely recovery of approximately $380 million in retail capital costs and incremental operating and maintenance costs, including AFUDC, under a federal mandate tracker that provides for timely recovery of 80 percent of such costs and deferral with carrying costs of 20 percent of such costs for recovery in a subsequent retail base rate case. On January 24, 2017, Duke Energy Indiana and various Intervenors filed a settlement agreement with the IURC. Terms of the settlement include recovery of 60 percent of the estimated CCR compliance construction project capital costs through existing rider mechanisms and deferral of 40 percent of these costs until Duke Energy Indiana's next general retail rate case. The deferred costs will earn a return based on Duke Energy Indiana's long-term debt rate of 4.73 percent until costs are included in retail rates, at which time the deferred costs will earn a full return. Costs are to be capped at $365 million , plus actual AFUDC. Costs above the cap may be recoverable in the next rate case. Terms of the settlement agreement also require Duke Energy Indiana to perform certain reporting and groundwater monitoring. The settlement is subject to approval by the IURC. An evidentiary hearing was held on February 23, 2017, and Duke Energy Indiana filed a proposed order with the IURC on March 30, 2017. Duke Energy Indiana cannot predict the outcome of this matter. FERC Transmission Return on Equity Complaints Customer groups have filed with the FERC complaints against MISO and its transmission-owning members, including Duke Energy Indiana, alleging, among other things, that the current base rate of return on equity earned by MISO transmission owners of 12.38 percent is unjust and unreasonable. The complaints, among other things, claim that the current base rate of return on equity earned by MISO transmission owners should be reduced to 8.67 percent . On January 5, 2015, the FERC issued an order accepting the MISO transmission owners' adder of 0.50 percent to the base rate of return on equity based on participation in an RTO subject to it being applied to a return on equity that is shown to be just and reasonable in the pending return on equity complaints. On December 22, 2015, the presiding FERC ALJ in the first complaint issued an Initial Decision in which the base rate of return on equity was set at 10.32 percent . On September 28, 2016, the Initial Decision in the first complaint was affirmed by FERC, but is subject to rehearing requests. On June 30, 2016, the presiding FERC ALJ in the second complaint issued an Initial Decision setting the base rate of return on equity at 9.70 percent . The Initial Decision in the second complaint is pending FERC review. On April 14, 2017, the U.S. Court of Appeals for the District of Columbia Circuit, in Emera Maine v. FERC , reversed and remanded certain aspects of the methodology employed by FERC to establish rates of return on equity. This decision may affect the outcome of the complaints against Duke Energy Indiana. Duke Energy Indiana currently believes these matters will not have a material impact on its results of operations, cash flows and financial position. Piedmont North Carolina Integrity Management Rider Filings In October 2016, Piedmont filed a petition with the NCUC under the integrity management rider (IMR) mechanism seeking authority to collect an additional $8 million in annual revenues, effective December 2016, based on the eligible capital investments closed to integrity and safety projects over the six-month period ending September 30, 2016. In November 2016, the NCUC approved the request. On May 1, 2017, Piedmont filed a petition with the NCUC under the IMR mechanism to collect an additional $11.6 million in annual revenues, effective June 2017, based on the eligible capital investments closed to integrity and safety projects over the six-month period ending March 31, 2017. A ruling from the NCUC is pending. Tennessee IMR Filings In November 2016, Piedmont filed an annual report with the TPUC under the IMR mechanism seeking authority to collect an additional $1.7 million in annual revenues effective January 2017, based on the capital investments in integrity and safety projects over the 12-month period ending October 31, 2016. The TPUC approved the request at a hearing on April 10, 2017. OTHER REGULATORY MATTERS Atlantic Coast Pipeline On September 2, 2014, Duke Energy, Dominion Resources (Dominion), Piedmont and Southern Company Gas announced the formation of Atlantic Coast Pipeline, LLC (ACP) to build and own the proposed Atlantic Coast Pipeline (ACP pipeline), an approximately 600-mile interstate natural gas pipeline running from West Virginia to North Carolina. The ACP pipeline is designed to meet the needs identified in RFPs by Duke Energy Carolinas, Duke Energy Progress and Piedmont. The ACP pipeline development costs are estimated between $5.0 billion to $5.5 billion . Dominion will build and operate the ACP pipeline and holds a leading ownership percentage in ACP of 48 percent . Duke Energy owns a 47 percent interest through its Gas Utilities and Infrastructure segment. Southern Company Gas maintains a 5 percent interest. See Note 12 for additional information related to Duke Energy's ownership interest. Duke Energy Carolinas, Duke Energy Progress and Piedmont, among others, will be customers of the pipeline. Purchases will be made under several 20 -year supply contracts, subject to state regulatory approval. On September 18, 2015, ACP filed an application with the FERC requesting a CPCN authorizing ACP to construct the pipeline. ACP executed a construction agreement in September 2016. ACP also requested approval of an open access tariff and the precedent agreements it entered into with future pipeline customers. In December 2016, FERC issued a draft Environmental Impact Statement (EIS) indicating that the proposed pipeline would not cause significant harm to the environment or protected populations. The draft EIS comment period ended in April 2017, and ACP is working to resolve items identified through the comment process. The final EIS is expected in summer 2017. FERC approval of the application is expected within 90 days of the issuance of the final EIS. Construction is projected to begin in the second-half of 2017, with a targeted in-service date in the second half of 2019. Sabal Trail Transmission, LLC Pipeline On May 4, 2015, Duke Energy acquired a 7.5 percent ownership interest in Sabal Trail Transmission, LLC (Sabal Trail) from Spectra Energy Partners, LP, a master limited partnership, formed by Enbridge Inc. (formerly Spectra Energy Corp.). Spectra Energy Partners, LP holds a 50 percent ownership interest in Sabal Trail and NextEra Energy has a 42.5 percent ownership interest. Sabal Trail is a joint venture that is constructing a 515-mile natural gas pipeline (Sabal Trail pipeline) to transport natural gas to Florida. Total estimated project costs are approximately $3.2 billion . The Sabal Trail pipeline will traverse Alabama, Georgia and Florida. The primary customers of the Sabal Trail pipeline, Duke Energy Florida and Florida Power & Light Company (FP&L), have each contracted to buy pipeline capacity for 25 -year initial terms. On February 3, 2016, the FERC issued an order granting the request for a CPCN to construct and operate the pipeline. On September 7, 2016, FERC denied the intervenors' rehearing requests. On September 21, 2016, intervenors filed an appeal of FERC's CPCN orders to the U.S. Court of Appeals for the District of Columbia Circuit. Oral argument on the appeal was held on April 18, 2017, and a decision is expected in the summer of 2017. The Sabal Trail pipeline has received other required regulatory approvals and construction began in the summer of 2016, with an expected in-service date in mid-2017. See Note 12 for additional information related to Duke Energy's ownership interest. Constitution Pipeline Duke Energy owns a 24 percent ownership interest in Constitution Pipeline Company, LLC (Constitution). Constitution is a natural gas pipeline project slated to transport natural gas supplies from the Marcellus supply region in northern Pennsylvania to major northeastern markets. The pipeline will be constructed and operated by Williams Partners L.P., which has a 41 percent ownership share. The remaining interest is held by Cabot Oil and Gas Corporation and WGL Holdings, Inc. On April 22, 2016, the New York State Department of Environmental Conservation (NYSDEC) denied Constitution’s application for a necessary water quality certification for the New York portion of the Constitution pipeline. Constitution filed legal actions in the U.S. District Court for the Northern District of New York and in the U.S. Court of Appeals for the Second Circuit (U.S. Court of Appeals) challenging the legality and appropriateness of the NYSDEC’s decision. Both courts granted Constitution's motions to expedite the schedules for the legal actions. On November 16, 2016, oral arguments were heard in the U.S. Court of Appeals. On March 16, 2017, the U.S. District Court for the Northern District of New York dismissed without prejudice Constitution’s claim that New York State permits were preempted by the federal permitting process. The ruling on oral arguments made in the U.S. Court of Appeals regarding NYSDEC's denial of the water quality certification is currently expected in mid-2017. Constitution remains steadfastly committed to pursuing the project and intends to pursue all available options to challenge the NYSDEC's decision. In light of the denial of the certification, Constitution revised its target in-service date of the project to be as early as the second half of 2018, assuming that the challenge process is satisfactorily and promptly concluded. In July 2016, Constitution requested, and the FERC approved, an extension of the construction period and in-service deadline of the project to December 2018. Also in July, the FERC denied the New York Attorney General's (NYAG) complaint and request for a stay of the certificate order authorizing the project on the grounds that Constitution had improperly cut trees along the proposed route. The FERC found the complaint procedurally deficient and that there was no justification for a stay; it did find the filing constituted a valid request for investigation and thus referred the matter to FERC staff for further examination as may be appropriate. On November 22, 2016, the FERC denied the NYAG's request for reconsideration of this order. Since April 2016, with the actions of the NYSDEC, Constitution stopped construction and discontinued capitalization of future development costs until the project's uncertainty is resolved. As a result, Duke Energy evaluated the investment in the Constitution project for other-than-temporary impairments (OTTIs). At this time, no OTTI has been determined and therefore no impairment charge to reduce the carrying value of the investment has been recorded. However, to the extent that the legal and regulatory proceedings have unfavorable outcomes, or if Constitution concludes that the project is not viable or does not go forward as legal and regulatory actions progress, the conclusions with respect to OTTIs could change and may require that an impairment charge of up to the recorded investment in the project, net of any cash and working capital returned, be recorded. Duke Energy will continue to monitor and update the OTTI analysis as required. Different assumptions could affect the timing and amount of any charge recorded in a period. Pending the outcome of the matters described above, and when construction proceeds, Duke Energy remains committed to fund an amount in proportion to its ownership interest for the development and construction of the new pipeline. Duke Energy's total anticipated contributions are approximately $229 million . See Note 12 for additional information related to ownership interest and carrying value of the investment. Potential Coal Plant Retirements The Subsidiary Registrants periodically file Integrated Resource Plans (IRP) with their state regulatory commissions. The IRPs provide a view of forecasted energy needs over a long term (10 to 20 years) and options being considered to meet those needs. Recent IRPs filed by the Subsidiary Registrants included planning assumptions to potentially retire certain coal-fired generating facilities in North Carolina, Florida and Indiana earlier than their current estimated useful lives primarily because facilities do not have the requisite emission control equipment to meet EPA regulations recently approved or proposed. The table below contains the net carrying value of generating facilities planned for retirement or included in recent IRPs as evaluated for potential retirement. Dollar amounts in the table below are included in Net property, plant and equipme

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	COMMITMENTS AND CONTINGENCIES 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 asset retirement obligations (AROs) recorded as a result of various environmental regulations, 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 Condensed 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 Other within Other Noncurrent Liabilities on the Condensed Consolidated Balance Sheets. Three Months Ended March 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at beginning of period $ 98 $ 10 $ 18 $ 3 $ 14 $ 59 $ 10 $ 1 Provisions/adjustments 6 1 — — 1 4 (1 ) 1 Cash reductions (6 ) — (1 ) — (1 ) (4 ) — — Balance at end of period $ 98 $ 11 $ 17 $ 3 $ 14 $ 59 $ 9 $ 2 Three Months Ended March 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at beginning of period $ 94 $ 10 $ 17 $ 3 $ 14 $ 54 $ 12 $ 1 Provisions/adjustments 10 2 1 — 1 — 6 — Cash reductions (3 ) (1 ) (2 ) (1 ) (1 ) — — — Balance at end of period $ 101 $ 11 $ 16 $ 2 $ 14 $ 54 $ 18 $ 1 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 $ 71 Duke Energy Carolinas 22 Duke Energy Ohio 36 Duke Energy Indiana 7 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. Duke Energy Carolinas estimates 30,000 to 39,000 tons of ash and 24 million to 27 million gallons of basin water were released into the river. In July 2014, Duke Energy completed remediation work identified by the EPA and continues to cooperate with the EPA's civil enforcement process. Future costs related to the Dan River release, including future state or federal civil enforcement proceedings, future regulatory directives, natural resources damages, future claims or litigation and long-term environmental impact costs, cannot be reasonably estimated at this time. The North Carolina Department of Environmental Quality (NCDEQ) has historically assessed Duke Energy Carolinas and Duke Energy Progress with Notice of Violations (NOV) 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 L.V. Sutton Combined Cycle Plant (Sutton) and Dan River Steam Station. Duke Energy Carolinas and Duke Energy Progress cannot predict whether the NCDEQ will assess future penalties related to existing unresolved NOVs and if such penalties would be material. See "NCDEQ Notices of Violation" section below for additional discussion. LITIGATION Duke Energy Duke Energy no longer has exposure to litigation matters related to the International Energy Disposal Group as a result of the divestiture of the business in December 2016. See Note 2 for additional information related to the sale of International Energy. Ash Basin Shareholder Derivative Litigation Five shareholder derivative lawsuits were filed in Delaware Chancery Court relating to the release at Dan River and to the management of Duke Energy’s ash basins. On October 31, 2014, the five lawsuits were consolidated in a single proceeding titled In Re Duke Energy Corporation Coal Ash Derivative Litigation . On December 2, 2014, plaintiffs filed a Corrected Verified Consolidated Shareholder Derivative Complaint (Consolidated Complaint). The Consolidated Complaint names as defendants several current and former Duke Energy officers and directors (collectively, the Duke Energy Defendants). Duke Energy is named as a nominal defendant. The Consolidated Complaint alleges the Duke Energy Defendants breached their fiduciary duties by failing to adequately oversee Duke Energy’s ash basins and that these breaches of fiduciary duty may have contributed to the incident at Dan River and continued thereafter. The lawsuit also asserts claims against the Duke Energy Defendants for corporate waste (relating to the money Duke Energy has spent and will spend as a result of the fines, penalties and coal ash removal) and unjust enrichment (relating to the compensation and director remuneration that was received despite these alleged breaches of fiduciary duty). The lawsuit seeks both injunctive relief against Duke Energy and restitution from the Duke Energy Defendants. On April 22, 2016, plaintiffs filed an Amended Verified Consolidated Shareholder Derivative Complaint (Amended Complaint) making the same allegations as in the Consolidated Complaint. The Duke Energy Defendants filed a motion to dismiss the Amended Complaint on June 21, 2016. On December 14, 2016, the Delaware Chancery Court entered an order dismissing the Amended Complaint. Plaintiffs filed an appeal to the Delaware Supreme Court on January 9, 2017. The parties have completed briefing in the case and a date for oral argument has not been set. On October 30, 2015, shareholder Saul Bresalier filed a shareholder derivative complaint (Bresalier Complaint) in the U.S. District Court for the District of Delaware. The lawsuit alleges that several current and former Duke Energy officers and directors (Bresalier Defendants) breached their fiduciary duties in connection with coal ash environmental issues, the post-merger change in Chief Executive Officer (CEO) and oversight of political contributions. Duke Energy is named as a nominal defendant. The Bresalier Complaint contends that the appointed Demand Review Committee failed to appropriately consider the shareholder’s earlier demand for litigation and improperly decided not to pursue claims against the Bresalier Defendants. On March 30, 2017, the court granted Defendants’ Motion to Dismiss on the claims relating to coal ash environmental issues and political contributions. A notice of appeal has not been filed. As discussed below, an agreement-in-principle has been reached to settle the merger related claims in the Bresalier Complaint, and those claims were also dismissed subject to that agreement. It is not possible to predict whether Duke Energy will incur any liability or to estimate the damages, if any, it might incur in connection with these matters. Progress Energy Merger Shareholder Litigation On May 31, 2013, the Delaware Chancery Court consolidated four shareholder derivative lawsuits filed in 2012. The Court also appointed a lead plaintiff and counsel for plaintiffs and designated the case as In Re Duke Energy Corporation Derivative Litigation (Merger Chancery Litigation). The lawsuit names as defendants the Legacy Duke Energy Directors. Duke Energy is named as a nominal defendant. The case alleges claims for breach of fiduciary duties of loyalty and care in connection with the post-merger change in CEO. Two shareholder Derivative Complaints, filed in 2012 in federal district court in Delaware, were consolidated as Tansey v. Rogers, et al. The case alleges claims against the Legacy Duke Energy Directors for breach of fiduciary duty and waste of corporate assets, as well as claims under Section 14(a) and 20(a) of the Exchange Act. Duke Energy is named as a nominal defendant. On December 21, 2015, Plaintiff filed a Consolidated Amended Complaint asserting the same claims contained in the original complaints. The Legacy Duke Energy Directors have reached an agreement-in-principle to settle the Merger Chancery Litigation, conditioned on dismissal as well, of the Tansey v. Rogers, et al case and the merger related claims in the Bresalier Complaint discussed above, for a total of $27 million . The entire settlement amount is to be funded by insurance. The settlement amount, less court-approved attorney fees, will be payable to Duke Energy. Settlement documents have been submitted to the court for approval and a hearing has been set for July 13, 2017. Price Reporting Cases Duke Energy Trading and Marketing, LLC (DETM), a non-operating Duke Energy affiliate, was a defendant, along with numerous other energy companies, in four class-action lawsuits and a fifth single-plaintiff lawsuit in a consolidated federal court proceeding in Nevada. Each of these lawsuits contained similar claims that defendants allegedly manipulated natural gas markets by various means, including providing false information to natural gas trade publications and entering into unlawful arrangements and agreements in violation of the antitrust laws of the respective states. Plaintiffs sought damages in unspecified amounts. In February 2016, DETM reached agreements in principle to settle all of the pending lawsuits. Settlement of the single-plaintiff settlement was finalized and paid in March 2016. The proposed settlement of the class action lawsuits was submitted to the Court and preliminarily approved on January 26, 2017. The Court will consider final approval of the class settlement following notice to the class members. The settlement amounts are not material to Duke Energy. 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 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 North Carolina Coal Ash Management Act of 2014, as amended, (Coal Ash Act) and the EPA CCR rule at 15 coal-fired plants in North Carolina and South Carolina. 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 of their 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. On August 16, 2013, the NCDEQ filed an enforcement action against Duke Energy Carolinas and Duke Energy Progress related to their remaining 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 named in the enforcement actions. The litigation is concluded for these seven plants. Litigation continues for the remaining seven plants. In response to a motion for partial summary judgment on the groundwater claims filed by the environmental groups, on October 17, 2016, Duke Energy Carolinas and Duke Energy Progress filed a cross-motion for partial summary judgment on the groundwater claims. On February 13, 2017, the court issued an order denying both the environmental groups' motion for partial summary judgment and Duke Energy Carolinas and Duke Energy Progress' cross-motion for partial summary judgment. On March 15, 2017, Duke Energy Carolinas and Duke Energy Progress filed a Notice of Appeal to challenge the trial court’s denial of their cross-motion for partial summary judgment. The parties were unable to reach an agreement at mediation on April 18, 2017. It is not possible to predict any liability or estimate any damages Duke Energy Carolinas or Duke Energy Progress might incur in connection with these matters. Federal Citizens Suits On June 13, 2016, the Roanoke River Basin Association 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 National Pollutant Discharge Elimination System permit provisions survived the motion to dismiss, and Duke Energy Progress’ response is due on May 10, 2017. On March 16, 2017, the Roanoke River Basin Association served Duke Energy Progress with a 60-day notice of intent to bring suit pursuant to the citizen suit provision of the CWA for alleged violations of effluent standards and limitations at the Roxboro Plant. It is not possible to predict whether Duke Energy Progress will incur any liability or to estimate the damages, if any, it might incur in connection with this matter. Five previously filed cases involving the Riverbend, Cape Fear, H.F. Lee, Sutton and Buck plants were dismissed or settled in 2016. Potential 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 North Carolina Department of Health and Human Services (DHHS). The criteria, in some cases, are considerably more stringent than federal drinking water standards established to protect human health and welfare. The Coal Ash Act requires additional groundwater monitoring and assessments for each of the 14 coal-fired plants in North Carolina, including sampling of private water supply wells. The data gathered through these Comprehensive Site Assessments (CSAs) will be used by NCDEQ to determine whether the water quality of these private water supply wells has been adversely impacted by the ash basins. Duke Energy has submitted CSAs documenting the results of extensive groundwater monitoring around coal ash basins at all 14 of the plants with coal ash basins. Generally, the data gathered through the installation of new monitoring wells and soil and water samples across the state 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 leads 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 that 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. Duke Energy received a letter from Plaintiffs' counsel indicating their intent to file suit on February 2, 2017, should a settlement not be reached by that date. Plaintiff’s counsel did not file suit upon the expiration of the tolling agreement on February 2, 2017, and no suit has been filed to date. Duke Energy Carolinas and Duke Energy Progress have recognized reserves of $18 million and $4 million , respectively. It is not possible to estimate the maximum exposure of loss, if any, that may occur in connection with claims, which might be made by these residents. 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 March 31, 2017 , there were 111 asserted claims for non-malignant cases with the cumulative relief sought of up to $29 million , and 58 asserted claims for malignant cases with the cumulative relief sought of up to $16 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 $506 million at March 31, 2017 and $512 million at December 31, 2016 . These reserves are classified in Other within Other Noncurrent Liabilities and Other within Current Liabilities on the Condensed Consolidated Balance Sheets. These reserves are based upon the minimum amount of the range of loss for current and future asbestos claims through 2036, are recorded on an undiscounted basis and incorporate anticipated inflation. 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 2036 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 $814 million in excess of the self-insured retention. Receivables for insurance recoveries were $587 million at March 31, 2017 and December 31, 2016 . These amounts are classified in Other within Other Noncurrent Assets and Receivables on the Condensed 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 Florida 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 putative class of Duke Energy Florida and FP&L’s customers in Florida. The suit alleges the State of Florida’s nuclear power plant cost recovery statutes (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. Plaintiffs filed an appellate brief on March 16, 2017, and Duke Energy Florida filed responses on April 17, 2017. Duke Energy Florida cannot predict the outcome of this appeal. 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 the EPC. Duke Energy Florida recognized an exit obligation as a result of the termination of the EPC. On March 31, 2014, Westinghouse filed a lawsuit against Duke Energy Florida in U.S. District Court for the Western District of Pennsylvania. The Pennsylvania lawsuit alleged damages under the EPC 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 on the parties' respective Motions for Summary Judgment, ruling in favor of Westinghouse on a $30 million termination fee claim and dismissing Duke Energy Florida's $54 million refund claim, but stating that Duke Energy Florida could use the refund claim to offset any damages for termination costs. Westinghouse's claim for termination costs was unaffected by this ruling and continued to trial. At trial, Westinghouse reduced its claim for termination costs from $482 million to $424 million . Following a trial on the matter, the court issued its final order in December 2016 denying Westinghouse’s claim for termination costs and re-affirming its earlier ruling in favor of Westinghouse on the $30 million termination fee and Duke Energy Florida’s refund claim. Judgment was entered against Duke Energy Florida in the amount of approximately $34 million , which includes prejudgment interest. Westinghouse has appealed the trial court's order and Duke Energy Florida has cross-appealed. It is not possible to predict the ultimate outcome of the appeal of the trial court's order. Ultimate resolution of these matters could have a material effect on the results of operations, financial position or cash flows of Duke Energy Florida. However, appropriate regulatory recovery will be pursued for the retail portion of any costs incurred in connection with such resolution. On March 29, 2017, Westinghouse filed Chapter 11 bankruptcy in the Southern District of New York, which could delay the timing of the appeal. Additional impacts, if any, of this bankruptcy filing on the resolution of the pending appeal and cross-appeal are unknown at this time. MGP Cost Recovery Action On December 30, 2011, Duke Energy Florida filed a lawsuit against FirstEnergy Corp. (FirstEnergy) to recover investigation and remediation costs incurred by Duke Energy Florida in connection with the restoration of two former MGP sites in Florida. Duke Energy Florida alleged that FirstEnergy, as the successor to Associated Gas & Electric Co., owes past and future contribution and response costs of up to $43 million for the investigation and remediation of MGP sites. On December 6, 2016, the trial court entered judgment against Duke Energy Florida in the case. In January 2017, Duke Energy Florida appealed the decision to the U.S. Court of Appeals for the 6th Circuit. Duke Energy Florida cannot predict the outcome of this appeal. Duke Energy Indiana Benton County Wind Farm Dispute On December 16, 2013, Benton County Wind Farm LLC (BCWF) filed a lawsuit against Duke Energy Indiana seeking damages for past generation losses totaling approximately $16 million alleging Duke Energy Indiana violated its obligations under a 2006 PPA by refusing to offer electricity to the market at negative prices. Damage claims continue to increase during times that BCWF is not dispatched. Under 2013 revised MISO market rules, Duke Energy Indiana is required to make a price offer to MISO for the power it proposes to sell into MISO markets and MISO determines whether BCWF is dispatched. Because market prices would have been negative due to increased market participation, Duke Energy Indiana determined it would not bid at negative prices in order to balance customer needs against BCWF's need to run. BCWF contends Duke Energy Indiana must bid at the lowest negative price to ensure dispatch, while Duke Energy Indiana contends it is not obligated to bid at any particular price, that it cannot ensure dispatch with any bid and that is has reasonably balanced the parties' interests. On July 6, 2015, the U.S. District Court for the Southern District of Indiana entered judgment against BCWF on all claims. BCWF appealed the decision and on December 9, 2016, the appeals court ruled in favor of BCWF. The matter has been remanded to a lower court to determine damages. A settlement conference is scheduled on May 31, 2017. Duke Energy Indiana cannot predict the outcome of this matter. Ultimate resolution of this matter could have a material effect on the results of operations, financial position or cash flows of Duke Energy Indiana. However, appropriate regulatory recovery will be pursued for the retail portion of any costs incurred in connection with such resolution. Other Litigation and Legal Proceedings The Duke Energy Registrants are involved in other legal, tax and regulatory proceedings arising in the ordinary course of business, some of which involve significant amounts. The Duke Energy Registrants believe the final disposition of these proceedings will not have a material effect on their results of operations, cash flows or financial position. The table below presents recorded reserves based on management’s best estimate of probable loss for legal matters, excluding asbestos-related reserves and the exit obligation discussed above related to the termination of an EPC contract. Reserves are classified on the Condensed Consolidated Balance Sheets in Other within Other Noncurrent Liabilities and Accounts payable and Other within Current Liabilities. The reasonably possible range of loss in excess of recorded reserves is not material, other than as described above. (in millions) March 31, 2017 December 31, 2016 Reserves for Legal Matters Duke Energy $ 91 $ 98 Duke Energy Carolinas 23 23 Progress Energy 57 59 Duke Energy Progress 13 14 Duke Energy Florida 27 28 Duke Energy Ohio 4 4 Piedmont 2 2 OTHER COMMITMENTS AND CONTINGENCIES General As part of their normal business, the Duke Energy Registrants are party to various financial guarantees, performance guarantees and other contractual commitments to extend guarantees of credit and other assistance to various subsidiaries, investees and other third parties. These guarantees involve elements of performance and credit risk, which are not fully recognized on the Condensed Consolidated Balance Sheets and have unlimited maximum potential payments. However, the Duke Energy Registrants do not believe these guarantees will have a material effect on their results of operations, cash flows or financial position. In addition, the Duke Energy Registrants enter into various fixed-price, noncancelable commitments to purchase or sell power or natural gas, take-or-pay arrangements, transportation, or throughput agreements and other contracts that may or may not be recognized on their respective Condensed Consolidated Balance Sheets. Some of these arrangements may be recognized at fair value on their respective Condensed Consolidated Balance Sheets if such contracts meet the definition of a derivative and the normal purchase/normal sale (NPNS) exception does not apply. In most cases, the Duke Energy Registrants’ purchase obligation contracts contain provisions for price adjustments, minimum purchase levels and other financial commitments.

Debt and Credit Facilities

Debt and Credit Facilities	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Debt And Credit Facilities	DEBT AND CREDIT FACILITIES SUMMARY OF SIGNIFICANT DEBT ISSUANCES The following table summarizes significant debt issuances (in millions). Three Months Ended March 31, 2017 Duke Duke Maturity Interest Duke Energy Energy Issuance Date Date Rate Energy Florida Ohio Secured Debt February 2017 (a) June 2034 4.120 % $ 587 $ — $ — First Mortgage Bonds January 2017 (b) January 2020 1.850 % 250 250 — January 2017 (b) January 2027 3.200 % 650 650 — March 2017 (c) June 2046 3.700 % 100 — 100 Total issuances $ 1,587 $ 900 $ 100 (a) Portfolio financing of four Texas and Oklahoma wind facilities. Secured by substantially all of the assets of these wind facilities and nonrecourse to Duke Energy. Proceeds were used to reimburse Duke Energy for a portion of previously funded construction expenditures. (b) Debt issued to fund capital expenditures for ongoing construction and capital maintenance, to repay at maturity a $250 million aggregate principal amount of bonds due September 2017 and for general corporate purposes. (c) Proceeds were used to fund capital expenditures for ongoing construction, capital maintenance and for general corporate purposes. In April 2017, Duke Energy (Parent) issued $420 million of unsecured notes with a fixed interest rate of 3.364 percent and maturity date of April 2025. The net proceeds were used to refinance $400 million of unsecured debt at maturity and to repay outstanding commercial paper. CURRENT MATURITIES OF LONG-TERM DEBT The following table shows the significant components of Current Maturities of Long-Term Debt on the Condensed 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 March 31, 2017 Unsecured Debt Duke Energy (Parent) August 2017 1.625 % $ 700 Piedmont September 2017 8.510 % 35 Secured Debt Duke Energy June 2017 2.605 % 45 Duke Energy June 2017 2.455 % 34 First Mortgage Bonds Duke Energy Florida September 2017 5.800 % 250 Duke Energy Progress November 2017 1.252 % 200 Duke Energy Carolinas January 2018 5.250 % 400 Other (a) 313 Current maturities of long-term debt $ 1,977 (a) Includes capital lease obligations, amortizing debt and small bullet maturities. AVAILABLE CREDIT FACILITIES Master Credit Facility In March 2017, Duke Energy amended its Master Credit Facility to increase its capacity from $7.5 billion to $8 billion , and to extend the termination date of the facility from January 30, 2020, to March 16, 2022. The amendment also added Piedmont as a borrower within the Master Credit Facility. Piedmont's separate $850 million credit facility was terminated in connection with the amendment. With the amendment, the Duke Energy Registrants, excluding Progress Energy (Parent), have borrowing capacity under the Master Credit Facility up to a specified sublimit 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 the Master Credit Facility. March 31, 2017 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 $ 3,400 $ 1,100 $ 1,000 $ 950 $ 450 $ 600 $ 500 Reduction to backstop issuances Commercial paper (b) (3,134 ) (1,822 ) (469 ) (402 ) — (30 ) (150 ) (261 ) Outstanding letters of credit (71 ) (62 ) (4 ) (2 ) (1 ) — — (2 ) Tax-exempt bonds (81 ) — — — — — (81 ) — Coal ash set-aside (500 ) — (250 ) (250 ) — — — — Available capacity $ 4,214 $ 1,516 $ 377 $ 346 $ 949 $ 420 $ 369 $ 237 (a) Represents the sublimit of each borrower. Certain sublimits were reallocated in May 2017 to provide additional liquidity to certain borrowers in light of near-term funding needs. (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 Condensed Consolidated Balance Sheets.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	GOODWILL AND INTANGIBLE ASSETS GOODWILL Duke Energy The following table presents the goodwill by reportable operating segment on Duke Energy's Condensed Consolidated Balance Sheets at March 31, 2017 and December 31, 2016 . Electric Utilities Gas Utilities Commercial (in millions) and Infrastructure and Infrastructure Renewables Total Goodwill $ 17,379 $ 1,924 $ 122 $ 19,425 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 Condensed Consolidated Balance Sheets at March 31, 2017 and December 31, 2016 . Progress Energy Progress Energy's Goodwill is included in the Electric Utilities and Infrastructure operating segment and there are no accumulated impairment charges. Piedmont Piedmont's Goodwill is included in the Gas Utilities and Infrastructure operating segment and there are no accumulated impairment charges. Effective November 1, 2016, Piedmont's fiscal year was changed from October 31 to December 31. Effective with this change, Piedmont changed the date of their annual impairment testing of goodwill from October 31 to August 31 to align with the other Duke Energy Registrants.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS The Subsidiary Registrants engage in related party transactions in accordance with applicable state and federal commission regulations. Refer to the Condensed 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 Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively. In addition to the amounts presented above, the Subsidiary Registrants record the impact on net income of 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 to the Consolidated Financial Statements in the Annual Report on Form 10-K for the year ended December 31, 2016 for more information regarding money pool. The net impact of these transactions was not material for the three months ended March 31, 2017 and 2016 , for the Subsidiary Registrants. As discussed in Note 12 , 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 also include a subordinated note from the affiliate for a portion of the purchase price. Equity Method Investments Piedmont has related party transactions as a customer of its equity method investments in natural gas storage and transportation facilities. Below are expenses for the three months ended March 31, 2017 and 2016 , which are included in Operating Expenses – Cost of natural gas on Piedmont's Condensed Consolidated Statement of Operations and Comprehensive Income. Three Months Ended March 31, (in millions) Type of expense 2017 2016 Cardinal Transportation Costs $ 2 $ 2 Pine Needle Gas Storage Costs 2 3 Hardy Storage Gas Storage Costs 2 2 Total $ 6 $ 7 In association with these transactions, Piedmont has accounts payable to its equity method investments of $2 million at March 31, 2017 , and December 31, 2016 . These amounts are included in Accounts payable on the Condensed Consolidated Balance Sheets. 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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38

Derivatives and Hedging

Derivatives and Hedging	3 Months Ended
	Mar. 31, 2017
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 gas supply contracts to provide diversification, reliability and gas cost benefits to their 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 Condensed Consolidated Balance Sheets. Cash collateral related to derivative instruments executed under master netting arrangements is offset against the collateralized derivatives on the Condensed Consolidated Balance Sheets. The cash impacts of settled derivatives are recorded as operating activities on the Condensed 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 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 three months ended March 31, 2017 , 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 include contracts not designated as a hedge because they are accounted for under regulatory accounting and 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. As of March 31, 2016, Duke Energy entered into $1.4 billion of forward-starting interest rate swaps to manage interest rate exposure related to the Piedmont acquisition financing. The swaps did not qualify for hedge accounting and were marked-to-market, with any gains or losses included within earnings. For the three months ended March 31, 2016 , unrealized losses on the swaps of $93 million were included within Interest Expense on Duke Energy's Condensed Consolidated Statements of Operations. The swaps were unwound in August 2016 in conjunction with the acquisition financing. See Note 2 for additional information related to the Piedmont acquisition. The following table shows notional amounts of outstanding derivatives related to interest rate risk as of March 31, 2017 and December 31, 2016 . Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Cash flow hedges (a) $ 750 $ — $ — $ — $ — $ — Undesignated contracts 927 400 500 250 250 27 Total notional amount $ 1,677 $ 400 $ 500 $ 250 $ 250 $ 27 (a) Duke Energy includes amounts related to consolidated VIEs of $750 million as of March 31, 2017 and December 31, 2016 . 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 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 costs 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. March 31, 2017 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Carolinas Energy Progress Florida Indiana Piedmont Electricity (gigawatt-hours) 184 — — — — 184 — Natural gas (millions of dekatherms) 817 85 228 105 123 — 504 December 31, 2016 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Carolinas Energy Progress Florida Indiana Piedmont Electricity (gigawatt-hours) 147 — — — — 147 — Natural gas (millions of dekatherms) 890 91 269 118 151 1 529 LOCATION AND FAIR VALUE OF DERIVATIVE ASSETS AND LIABILITIES RECOGNIZED IN THE CONDENSED 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 Condensed 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 March 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 $ 58 $ 16 $ 30 $ 19 $ 11 $ — $ 9 $ 2 Noncurrent 5 1 2 1 1 1 — — Total Derivative Assets – Commodity Contracts $ 63 $ 17 $ 32 $ 20 $ 12 $ 1 $ 9 $ 2 Interest Rate Contracts Designated as Hedging Instruments Noncurrent $ 18 $ — $ — $ — $ — $ — $ — $ — Not Designated as Hedging Instruments Current 2 — 2 — 2 — — — Total Derivative Assets – Interest Rate Contracts $ 20 $ — $ 2 $ — $ 2 $ — $ — $ — Total Derivative Assets $ 83 $ 17 $ 34 $ 20 $ 14 $ 1 $ 9 $ 2 Derivative Liabilities March 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 $ 32 $ — $ 17 $ 1 $ 17 $ — $ — $ 14 Noncurrent 145 4 11 4 1 — — 131 Total Derivative Liabilities – Commodity Contracts $ 177 $ 4 $ 28 $ 5 $ 18 $ — $ — $ 145 Interest Rate Contracts Designated as Hedging Instruments Current $ 8 $ — $ — $ — $ — $ — $ — $ — Noncurrent 9 — — — — — — — Not Designated as Hedging Instruments Current 1 — — — — 1 — — Noncurrent 21 10 6 5 1 4 — — Total Derivative Liabilities – Interest Rate Contracts $ 39 $ 10 $ 6 $ 5 $ 1 $ 5 $ — $ — Total Derivative Liabilities $ 216 $ 14 $ 34 $ 10 $ 19 $ 5 $ — $ 145 Derivative Assets December 31, 2016 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 $ 108 $ 23 $ 61 $ 35 $ 26 $ 4 $ 16 $ 3 Noncurrent 32 10 21 10 11 1 — — Total Derivative Assets – Commodity Contracts $ 140 $ 33 $ 82 $ 45 $ 37 $ 5 $ 16 $ 3 Interest Rate Contracts Designated as Hedging Instruments Noncurrent $ 19 $ — $ — $ — $ — $ — $ — $ — Not Designated as Hedging Instruments Current 3 — 3 1 2 — — — Total Derivative Assets – Interest Rate Contracts $ 22 $ — $ 3 $ 1 $ 2 $ — $ — $ — Total Derivative Assets $ 162 $ 33 $ 85 $ 46 $ 39 $ 5 $ 16 $ 3 Derivative Liabilities December 31, 2016 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 $ 43 $ — $ 12 $ — $ 12 $ — $ 2 $ 35 Noncurrent 166 1 7 1 — — — 152 Total Derivative Liabilities – Commodity Contracts $ 209 $ 1 $ 19 $ 1 $ 12 $ — $ 2 $ 187 Interest Rate Contracts Designated as Hedging Instruments Current $ 8 $ — $ — $ — $ — $ — $ — $ — Noncurrent 8 — — — — — — — Not Designated as Hedging Instruments — Current 1 — — — — 1 — — Noncurrent 26 15 6 6 — 5 — — Total Derivative Liabilities – Interest Rate Contracts $ 43 $ 15 $ 6 $ 6 $ — $ 6 $ — $ — Total Derivative Liabilities $ 252 $ 16 $ 25 $ 7 $ 12 $ 6 $ 2 $ 187 OFFSETTING ASSETS AND LIABILITIES The following tables present the line items on the Condensed 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 March 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 $ 60 $ 16 $ 32 $ 19 $ 13 $ — $ 9 $ 2 Gross amounts offset (7 ) — (7 ) (1 ) (6 ) — — — Net amounts presented in Current Assets: Other $ 53 $ 16 $ 25 $ 18 $ 7 $ — $ 9 $ 2 Noncurrent Gross amounts recognized $ 23 $ 1 $ 2 $ 1 $ 1 $ 1 $ — $ — Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Assets: Other $ 21 $ — $ 1 $ — $ 1 $ 1 $ — $ — Derivative Liabilities March 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 $ 41 $ — $ 17 $ 1 $ 17 $ 1 $ — $ 14 Gross amounts offset (7 ) — (7 ) (1 ) (6 ) — — — Net amounts presented in Current Liabilities: Other $ 34 $ — $ 10 $ — $ 11 $ 1 $ — $ 14 Noncurrent Gross amounts recognized $ 175 $ 14 $ 17 $ 9 $ 2 $ 4 $ — $ 131 Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 173 $ 13 $ 16 $ 8 $ 2 $ 4 $ — $ 131 Derivative Assets December 31, 2016 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 $ 111 $ 23 $ 64 $ 36 $ 28 $ 4 $ 16 $ 3 Gross amounts offset (11 ) — (11 ) — (11 ) — — — Net amounts presented in Current Assets: Other $ 100 $ 23 $ 53 $ 36 $ 17 $ 4 $ 16 $ 3 Noncurrent Gross amounts recognized $ 51 $ 10 $ 21 $ 10 $ 11 $ 1 $ — $ — Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Assets: Other $ 49 $ 9 $ 20 $ 9 $ 11 $ 1 $ — $ — Derivative Liabilities December 31, 2016 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 $ 52 $ — $ 12 $ — $ 12 $ 1 $ 2 $ 35 Gross amounts offset (11 ) — (11 ) — (11 ) — — — Net amounts presented in Current Liabilities: Other $ 41 $ — $ 1 $ — $ 1 $ 1 $ 2 $ 35 Noncurrent Gross amounts recognized $ 200 $ 16 $ 13 $ 7 $ — $ 5 $ — $ 152 Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 198 $ 15 $ 12 $ 6 $ — $ 5 $ — $ 152 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. Amounts for Duke Energy Ohio, Duke Energy Indiana and Piedmont were not material. March 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 $ 40 $ 14 $ 25 $ 9 $ 17 Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 40 14 25 9 17 December 31, 2016 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 $ 34 $ 16 $ 18 $ 6 $ 12 Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 34 16 18 6 12 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	3 Months Ended
	Mar. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Investments In Debt And Equity Securities	INVESTMENTS IN DEBT AND EQUITY SECURITIES The Duke Energy Registrants classify their investments in debt and equity securities as either trading or available-for-sale. TRADING SECURITIES Piedmont's investments in debt and equity securities held in rabbi trusts associated with certain deferred compensation plans are classified as trading securities. The fair value of these investments was $5 million as of March 31, 2017 and December 31, 2016 . AVAILABLE-FOR-SALE SECURITIES All other investments in debt and equity securities are classified as available-for-sale. Duke Energy’s available-for-sale securities are primarily comprised of investments held in (i) the nuclear decommissioning fund (NDTF) at Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida, (ii) grantor trusts at Duke Energy Progress, Duke Energy Florida and Duke Energy Indiana related to Other Post-Retirement Benefit Obligations (OPEB) plans and (iii) Bison. Duke Energy classifies all other investments in debt and equity securities as long term, unless otherwise noted. Investment Trusts The investments within the NDTF investments and the Duke Energy Progress, Duke Energy Florida and Duke Energy Indiana grantor trusts (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 and equity securities within the Investment Trusts are considered OTTIs and are recognized immediately. Investments within the Investment Trusts generally qualify for regulatory accounting, and accordingly realized and unrealized gains and losses are deferred as a regulatory asset or liability. Other Available-for-Sale Securities Unrealized gains and losses on all other available-for-sale 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 March 31, 2017 and December 31, 2016 . DUKE ENERGY The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 114 $ — $ — $ 111 Equity securities 2,250 32 4,284 2,092 54 4,106 Corporate debt securities 10 5 576 10 8 528 Municipal bonds 3 6 336 3 10 331 U.S. government bonds 10 8 949 10 8 984 Other debt securities — 3 132 — 3 124 Total NDTF $ 2,273 $ 54 $ 6,391 $ 2,115 $ 83 $ 6,184 Other Investments Cash and cash equivalents $ — $ — $ 18 $ — $ — $ 25 Equity securities 44 — 106 38 — 104 Corporate debt securities 1 — 60 1 1 66 Municipal bonds 2 1 84 2 1 82 U.S. government bonds — — 43 — 1 51 Other debt securities — 2 42 — 2 42 Total Other Investments (b) $ 47 $ 3 $ 353 $ 41 $ 5 $ 370 Total Investments $ 2,320 $ 57 $ 6,744 $ 2,156 $ 88 $ 6,554 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets. The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 82 Due after one through five years 640 Due after five through 10 years 514 Due after 10 years 986 Total $ 2,222 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 93 $ 54 Realized losses 62 50 DUKE ENERGY CAROLINAS The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 20 $ — $ — $ 18 Equity securities 1,229 15 2,366 1,157 28 2,245 Corporate debt securities 5 4 388 5 6 354 Municipal bonds 1 1 67 1 2 67 U.S. government bonds 3 5 431 2 5 458 Other debt securities — 3 120 — 3 116 Total NDTF $ 1,238 $ 28 $ 3,392 $ 1,165 $ 44 $ 3,258 Other Investments Other debt securities $ — $ 1 $ 3 $ — $ 1 $ 3 Total Other Investments (b) $ — $ 1 $ 3 $ — $ 1 $ 3 Total Investments $ 1,238 $ 29 $ 3,395 $ 1,165 $ 45 $ 3,261 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets. The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 2 Due after one through five years 221 Due after five through 10 years 269 Due after 10 years 517 Total $ 1,009 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 66 $ 34 Realized losses 40 37 PROGRESS ENERGY The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 94 $ — $ — $ 93 Equity securities 1,021 17 1,918 935 26 1,861 Corporate debt securities 5 1 188 5 2 174 Municipal bonds 2 5 269 2 8 264 U.S. government bonds 7 3 518 8 3 526 Other debt securities — — 12 — — 8 Total NDTF $ 1,035 $ 26 $ 2,999 $ 950 $ 39 $ 2,926 Other Investments Cash and cash equivalents $ — $ — $ 12 $ — $ — $ 21 Municipal bonds 2 — 46 2 — 44 Total Other Investments (b) $ 2 $ — $ 58 $ 2 $ — $ 65 Total Investments $ 1,037 $ 26 $ 3,057 $ 952 $ 39 $ 2,991 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets. The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 72 Due after one through five years 355 Due after five through 10 years 189 Due after 10 years 417 Total $ 1,033 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 27 $ 19 Realized losses 21 13 DUKE ENERGY PROGRESS The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 43 $ — $ — $ 45 Equity securities 772 13 1,541 704 21 1,505 Corporate debt securities 4 1 131 4 1 120 Municipal bonds 2 5 268 2 8 263 U.S. government bonds 5 2 284 5 2 275 Other debt securities — — 7 — — 5 Total NDTF $ 783 $ 21 $ 2,274 $ 715 $ 32 $ 2,213 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 1 Total Other Investments (b) $ — $ — $ 1 $ — $ — $ 1 Total Investments $ 783 $ 21 $ 2,275 $ 715 $ 32 $ 2,214 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets. The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 17 Due after one through five years 215 Due after five through 10 years 142 Due after 10 years 316 Total $ 690 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 24 $ 15 Realized losses 19 11 DUKE ENERGY FLORIDA The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 51 $ — $ — $ 48 Equity securities 249 4 377 231 5 356 Corporate debt securities 1 — 57 1 1 54 Municipal bonds — — 1 — — 1 U.S. government bonds 2 1 234 3 1 251 Other debt securities — — 5 — — 3 Total NDTF (b) $ 252 $ 5 $ 725 $ 235 $ 7 $ 713 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 4 Municipal bonds 2 — 46 2 — 44 Total Other Investments (c) $ 2 $ — $ 47 $ 2 $ — $ 48 Total Investments $ 254 $ 5 $ 772 $ 237 $ 7 $ 761 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) During the three months ended March 31, 2017 , Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing commissioning activity of the Crystal River Unit 3 nuclear plant. (c) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets. The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 55 Due after one through five years 140 Due after five through 10 years 47 Due after 10 years 101 Total $ 343 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 3 $ 4 Realized losses 2 2 DUKE ENERGY INDIANA The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value Other Investments Equity securities $ 38 $ — $ 84 $ 33 $ — $ 79 Corporate debt securities — — 2 — — 2 Municipal bonds — 1 28 — 1 28 U.S. government bonds — — 1 — — 1 Total Other Investments (b) $ 38 $ 1 $ 115 $ 33 $ 1 $ 110 Total Investments $ 38 $ 1 $ 115 $ 33 $ 1 $ 110 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets. The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 2 Due after one through five years 15 Due after five through 10 years 9 Due after 10 years 5 Total $ 31 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were insignificant for the three months ended March 31, 2017 and 2016 .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2017
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: Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities that the reporting entity can access at the measurement date. An active market is one in which transactions for an asset or liability occur with sufficient frequency and volume to provide ongoing pricing information. Level 2 – A fair value measurement utilizing inputs other than quoted prices included in Level 1 that are observable, either directly or indirectly, for an asset or liability. Inputs include (i) quoted prices for similar assets or liabilities in active markets, (ii) quoted prices for identical or similar assets or liabilities in markets that are not active, (iii) and inputs other than quoted market prices that are observable for the asset or liability, such as interest rate curves and yield curves observable at commonly quoted intervals, volatilities and credit spreads. A Level 2 measurement cannot have more than an insignificant portion of its valuation based on unobservable inputs. Instruments in this category include non-exchange-traded derivatives, such as over-the-counter forwards, swaps and options; certain marketable debt securities; and financial instruments traded in less-than-active markets. Level 3 – Any fair value measurement that includes unobservable inputs for more than an insignificant portion of the valuation. These inputs may be used with internally developed methodologies that result in management’s best estimate of fair value. Level 3 measurements may include longer-term instruments that extend into periods in which observable inputs are not available. Not Categorized – Certain investments are not categorized within the Fair Value hierarchy. These investments are measured based on the fair value of the underlying investments but may not be readily redeemable at that fair value. 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 three months ended March 31, 2017 and 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 New York Stock Exchange (NYSE) and 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 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 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 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 2 related to the acquisition of Piedmont in 2016. See Note 11 in Duke Energy's Annual Report on Form 10-K for the year ended December 31, 2016 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 Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 4,284 $ 4,207 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 2,107 602 1,505 — — Other trading and available-for-sale equity securities 110 110 — — — Other trading and available-for-sale debt securities 248 61 182 5 — Derivative assets 83 2 71 10 — Total assets 6,832 4,982 1,758 15 77 Derivative liabilities (216 ) — (71 ) (145 ) — Net assets (liabilities) $ 6,616 $ 4,982 $ 1,687 $ (130 ) $ 77 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 4,106 $ 4,029 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 2,078 632 1,446 — — Other trading and available-for-sale equity securities 104 104 — — — Other trading and available-for-sale debt securities 266 75 186 5 — Derivative assets 162 5 136 21 — Total assets 6,716 4,845 1,768 26 77 Derivative liabilities (252 ) (2 ) (63 ) (187 ) — Net assets (liabilities) $ 6,464 $ 4,843 $ 1,705 $ (161 ) $ 77 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 Operating Revenues. Three Months Ended March 31, 2017 (in millions) Investments Derivatives (net) Total Balance at beginning of period $ 5 $ (166 ) $ (161 ) Purchases, sales, issuances and settlements: Settlements — (9 ) (9 ) Total amount included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities — 40 40 Balance at end of period $ 5 $ (135 ) $ (130 ) Three Months Ended March 31, 2016 (in millions) Investments Derivatives (net) Total Balance at beginning of period $ 5 $ 10 $ 15 Purchases, sales, issuances and settlements: Sales (1 ) — (1 ) Settlements — (7 ) (7 ) Total losses included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities — (1 ) (1 ) Balance at end of period $ 4 $ 2 $ 6 DUKE ENERGY CAROLINAS The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,366 $ 2,289 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 1,026 146 880 — — Other available-for-sale debt securities 3 — — 3 — Derivative assets 17 — 17 — — Total assets 3,412 2,435 897 3 77 Derivative liabilities (14 ) — (14 ) — — Net assets $ 3,398 $ 2,435 $ 883 $ 3 $ 77 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,245 $ 2,168 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 1,013 178 835 — — Other available-for-sale debt securities 3 — — 3 — Derivative assets 33 — 33 — — Total assets 3,294 2,346 868 3 77 Derivative liabilities (16 ) — (16 ) — — Net assets $ 3,278 $ 2,346 $ 852 $ 3 $ 77 There was no change to the Level 3 balance during the three months ended March 31, 2017 and March 31, 2016 . PROGRESS ENERGY The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,918 $ 1,918 $ — Nuclear decommissioning trust fund debt securities 1,081 456 625 Other available-for-sale debt securities 58 12 46 Derivative assets 34 — 34 Total assets 3,091 2,386 705 Derivative liabilities (34 ) — (34 ) Net assets $ 3,057 $ 2,386 $ 671 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,861 $ 1,861 $ — Nuclear decommissioning trust fund debt securities 1,065 454 611 Other available-for-sale debt securities 65 21 44 Derivative assets 85 — 85 Total assets 3,076 2,336 740 Derivative liabilities (25 ) — (25 ) Net assets $ 3,051 $ 2,336 $ 715 DUKE ENERGY PROGRESS The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,541 $ 1,541 $ — Nuclear decommissioning trust fund debt securities and other 733 221 512 Other available-for-sale debt securities and other 1 1 — Derivative assets 20 — 20 Total assets 2,295 1,763 532 Derivative liabilities (10 ) — (10 ) Net assets $ 2,285 $ 1,763 $ 522 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,505 $ 1,505 $ — Nuclear decommissioning trust fund debt securities and other 708 207 501 Other available-for-sale debt securities and other 1 1 — Derivative assets 46 — 46 Total assets 2,260 1,713 547 Derivative liabilities (7 ) — (7 ) Net assets $ 2,253 $ 1,713 $ 540 DUKE ENERGY FLORIDA The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 377 $ 377 $ — Nuclear decommissioning trust fund debt securities and other 348 235 113 Other available-for-sale debt securities and other 47 1 46 Derivative assets 14 — 14 Total assets 786 613 173 Derivative liabilities (19 ) — (19 ) Net assets $ 767 $ 613 $ 154 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 356 $ 356 $ — Nuclear decommissioning trust fund debt securities and other 357 247 110 Other available-for-sale debt securities and other 48 4 44 Derivative assets 39 — 39 Total assets 800 607 193 Derivative liabilities (12 ) — (12 ) Net assets $ 788 $ 607 $ 181 DUKE ENERGY OHIO The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which are disclosed in Note 9 . March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 1 $ — $ — $ 1 Derivative liabilities (5 ) — (5 ) — Net (liabilities) assets $ (4 ) $ — $ (5 ) $ 1 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 5 $ — $ — $ 5 Derivative liabilities (6 ) — (6 ) — Net (liabilities) assets $ (1 ) $ — $ (6 ) $ 5 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) Three Months Ended March 31, (in millions) 2017 2016 Balance at beginning of period $ 5 $ 3 Purchases, sales, issuances and settlements: Settlements (1 ) (2 ) Total losses included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities (3 ) (1 ) Balance at end of period $ 1 $ — DUKE ENERGY INDIANA The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other available-for-sale equity securities $ 84 $ 84 $ — $ — Other available-for-sale debt securities and other 31 — 31 — Derivative assets 9 — — 9 Net assets $ 124 $ 84 $ 31 $ 9 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other available-for-sale equity securities $ 79 $ 79 $ — $ — Other available-for-sale debt securities and other 31 — 31 — Derivative assets 16 — — 16 Total assets 126 79 31 16 Derivative liabilities (2 ) (2 ) — — Net assets $ 124 $ 77 $ 31 $ 16 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) Three Months Ended March 31, (in millions) 2017 2016 Balance at beginning of period $ 16 $ 7 Purchases, sales, issuances and settlements: Settlements (7 ) (5 ) Balance at end of period $ 9 $ 2 PIEDMONT The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. See Note 10 for additional information related to investments. March 31, 2017 (in millions) Total Fair Value Level 1 Level 3 Other trading equity securities 4 4 — Other trading debt securities 1 1 — Derivative assets 2 2 — Total assets 7 7 — Derivative liabilities (145 ) — (145 ) Net (liabilities) assets $ (138 ) $ 7 $ (145 ) December 31, 2016 (in millions) Total Fair Value Level 1 Level 3 Other trading equity securities $ 4 $ 4 $ — Other trading debt securities 1 1 — Derivative assets 3 3 — Total assets 8 8 — Derivative liabilities (187 ) — (187 ) Net (liabilities) assets $ (179 ) $ 8 $ (187 ) 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) Three Months Ended March 31, (in millions) 2017 2016 Balance at beginning of period $ (187 ) $ (149 ) Total gains and settlements 42 23 Balance at end of period $ (145 ) $ (126 ) QUANTITATIVE INFORMATION ABOUT UNOBSERVABLE INPUTS The following table includes quantitative information about the Duke Energy Registrants' derivatives classified as Level 3. March 31, 2017 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio Financial Transmission Rights (FTRs) $ 1 RTO auction pricing FTR price – per megawatt-hour (MWh) $ 0.23 - $ 2.02 Duke Energy Indiana FTRs 9 RTO auction pricing FTR price – per MWh (1.08 ) - 5.33 Piedmont Natural gas contracts (145 ) Discounted cash flow Forward natural gas curves – price per million British thermal unit (MMBtu) 2.08 - 3.57 Duke Energy Total Level 3 derivatives $ (135 ) December 31, 2016 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio FTRs $ 5 RTO auction pricing FTR price – per MWh $ 0.77 - $ 3.52 Duke Energy Indiana FTRs 16 RTO auction pricing FTR price – per MWh (0.83 ) - 9.32 Piedmont Natural gas contracts (187 ) Discounted cash flow Forward natural gas curves – price per MMBtu 2.31 - 4.18 Duke Energy Total Level 3 derivatives $ (166 ) 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. March 31, 2017 December 31, 2016 (in millions) Book Value Fair Value Book Value Fair Value Duke Energy $ 48,998 $ 50,480 $ 47,895 $ 49,161 Duke Energy Carolinas 9,491 10,405 9,603 10,494 Progress Energy 18,148 19,742 17,541 19,107 Duke Energy Progress 6,761 7,103 7,011 7,357 Duke Energy Florida 6,981 7,596 6,125 6,728 Duke Energy Ohio 1,977 2,122 1,884 2,020 Duke Energy Indiana 3,784 4,292 3,786 4,260 Piedmont 1,821 1,954 1,821 1,933 At both March 31, 2017 and December 31, 2016 , 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	3 Months Ended
	Mar. 31, 2017
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 the consolidated 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 three months ended March 31, 2017 and the year ended December 31, 2016 , or is expected to be provided in the future, that was not previously contractually required. Receivables Financing – DERF / DEPR / DEFR Duke Energy Receivables Finance Company, LLC (DERF), Duke Energy Progress Receivables, LLC (DEPR) and Duke Energy Florida Receivables, LLC (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 Condensed 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 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 Condensed 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 typically 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 consolidates CRC as it makes these decisions. Neither Duke Energy Ohio nor Duke Energy Indiana consolidate CRC. Receivables Financing – Credit Facilities The following table summarizes the amounts and expiration dates of the credit facilities described above. Duke Energy Duke Energy Duke Energy Duke Energy Carolinas Progress Florida (in millions) CRC DERF DEPR DEFR Expiration date December 2018 December 2018 February 2019 April 2019 Credit facility amount $ 325 $ 425 $ 300 $ 225 Amounts borrowed at March 31, 2017 325 425 300 225 Amounts borrowed at December 31, 2016 325 425 300 225 Nuclear Asset-Recovery Bonds – DEFPF Duke Energy Florida Project Finance, LLC (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 June 2016, DEFPF issued $ 1,294 million of 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 Note 4 . 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 Condensed Consolidated Balance Sheets. (in millions) March 31, 2017 December 31, 2016 Receivables of VIEs $ 4 $ 6 Current Assets: Regulatory assets 53 50 Current Assets: Other 14 53 Other Noncurrent Assets: Regulatory assets 1,131 1,142 Current Liabilities: Other 3 17 Current maturities of long-term debt 55 62 Long-Term Debt 1,189 1,217 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. The activities that most significantly impact the economic performance of these renewable energy facilities were decisions associated with siting, negotiating PPAs, engineering, procurement and construction and decisions associated with ongoing operations and maintenance-related activities. Duke Energy consolidates the entities as it is responsible for all of these decisions. The table below presents material balances reported on Duke Energy's Condensed Consolidated Balance Sheets related to renewables VIEs. (in millions) March 31, 2017 December 31, 2016 Current Assets: Other $ 336 $ 223 Property, plant and equipment, cost 3,671 3,419 Accumulated depreciation and amortization (448 ) (453 ) Current maturities of long-term debt 227 198 Long-Term Debt 1,645 1,097 Deferred income taxes 321 275 Other Noncurrent Liabilities: Other 251 252 NON-CONSOLIDATED VIEs The following tables summarize the impact of non-consolidated VIEs on the Condensed Consolidated Balance Sheets. March 31, 2017 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Piedmont Receivables from affiliated companies $ — $ — $ — $ — $ 53 $ 69 $ — Investments in equity method unconsolidated affiliates 673 173 92 938 — — 152 Other noncurrent assets 12 — — 12 — — — Total assets $ 685 $ 173 $ 92 $ 950 $ 53 $ 69 $ 152 Taxes accrued (a) 23 — — 23 — — (1 ) Other current liabilities — — 2 2 — — — Deferred income taxes (a) (7 ) — — (7 ) — — 4 Other noncurrent liabilities — — 13 13 — — — Total liabilities $ 16 $ — $ 15 $ 31 $ — $ — $ 3 Net assets $ 669 $ 173 $ 77 $ 919 $ 53 $ 69 $ 149 (a) Taxes accrued and Deferred income taxes are netted by jurisdiction on a consolidated basis on the Condensed Consolidated Balance Sheets. December 31, 2016 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Piedmont Receivables from affiliated companies $ — $ — $ — $ — $ 82 $ 101 $ — Investments in equity method unconsolidated affiliates 487 174 90 751 — — 139 Other noncurrent assets 12 — — 12 — — — Total assets $ 499 $ 174 $ 90 $ 763 $ 82 $ 101 $ 139 Other current liabilities — — 3 3 — — — Other noncurrent liabilities — — 13 13 — — 4 Total liabilities $ — $ — $ 16 $ 16 $ — $ — 4 Net assets $ 499 $ 174 $ 74 $ 747 $ 82 $ 101 $ 135 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, some of which are reflected in the table above as Other noncurrent liabilities. For more information on various guarantees, refer to Note 5 . 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 the ownership interest and investment balances in these joint ventures. Duke Energy Piedmont Investment Amount (in millions) Investment Amount (in millions) Ownership March 31, December 31, Ownership March 31, December 31, Entity Name Interest 2017 2016 Interest (a) 2017 2016 ACP 47 % $ 403 $ 265 7 % $ 59 $ 46 Sabal Trail 7.5 % 188 140 Constitution (b) 24 % 82 82 24 % 93 93 Total $ 673 $ 487 $ 152 $ 139 (a) On April 1, 2017, Piedmont transferred its ownership interests in ACP and Constitution to a wholly owned subsidiary of Duke Energy at Piedmont's book value. (b) Duke Energy's investment amount includes purchase accounting adjustments not recorded at the Piedmont registrant. 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. Other VIEs Duke Energy holds a 50 percent equity interest in Duke-American Transmission Company, LLC (DATC). DATC is considered a VIE due to having insufficient equity to finance their own activities without subordinated financial support. The activities that most significantly impact DATC's economic performance are decisions related to investing in existing and 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 Transmission Company, LLC, therefore Duke Energy does not consolidate DATC. Duke Energy holds a 50 percent equity interest in Pioneer Transmission, LLC (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 their activities without subordinated financial support. As a counterparty to an inter-company power agreement (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, including costs associated with its 2,256 MW of coal-fired generation capacity. Deterioration in the credit quality, or bankruptcy of one or more parties to the ICPA could increase the costs of OVEC. In addition, certain proposed environmental rulemaking could result in future increased cost allocations. 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 turn over 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 2017 2016 2017 2016 Anticipated credit loss ratio 0.5 % 0.5 % 0.3 % 0.3 % Discount rate 1.8 % 1.5 % 1.8 % 1.5 % Receivable turnover rate 13.4 % 13.3 % 10.7 % 10.6 % The following table shows the gross and net receivables sold. Duke Energy Ohio Duke Energy Indiana (in millions) March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 Receivables sold $ 238 $ 267 $ 277 $ 306 Less: Retained interests 53 82 69 101 Net receivables sold $ 185 $ 185 $ 208 $ 205 The following table shows sales and cash flows related to receivables sold. Duke Energy Ohio Duke Energy Indiana Three Months Ended Three Months Ended March 31, March 31, (in millions) 2017 2016 2017 2016 Sales Receivables sold $ 533 $ 532 $ 664 $ 635 Loss recognized on sale 2 3 3 3 Cash flows Cash proceeds from receivables sold $ 559 $ 537 $ 693 $ 643 Return received on retained interests 1 1 2 1 Cash flows from sales of receivables are reflected within Operating Activities on Duke Energy Ohio’s and Duke Energy Indiana’s Condensed 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 Condensed 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 .

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Common Stock	COMMON STOCK Basic Earnings Per Share (EPS) is computed by dividing net income attributable to Duke Energy common stockholders, 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 stock, 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 shares outstanding to the diluted weighted average number of common shares outstanding. Three Months Ended March 31, (in millions, except per share amounts) 2017 2016 Income from continuing operations attributable to Duke Energy common stockholders excluding impact of participating securities $ 715 $ 574 Weighted average shares outstanding – basic 700 689 Weighted average shares outstanding – diluted 700 689 Earnings per share from continuing operations attributable to Duke Energy common stockholders Basic $ 1.02 $ 0.83 Diluted $ 1.02 $ 0.83 Potentially dilutive items excluded from the calculation (a) 2 2 Dividends declared per common share $ 0.855 $ 0.825 (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 Forwards 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 forward sale agreements with Barclays (the Equity Forwards). 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. As of March 31, 2016, share dilution resulting from the agreements was determined under the treasury stock method. Duke Energy physically settled the Equity Forwards in full in October 2016 following the close of the Piedmont acquisition. See Note 2 for additional information related to the Piedmont acquisition.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION For employee awards, equity classified stock-based compensation cost is measured at the service inception date or the grant date, based on the estimated achievement of certain performance metrics or the fair value of the award, and is recognized as expense or capitalized as a component of property, plant and equipment over the requisite service period. 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. Three Months Ended March 31, (in millions) 2017 2016 Restricted stock unit awards $ 8 $ 7 Performance awards 7 5 Pretax stock-based compensation cost $ 15 $ 12 Tax benefit associated with stock-based compensation expense $ 5 $ 4 Stock-based compensation costs capitalized 1 1 Prior to Duke Energy acquiring Piedmont, Piedmont had an incentive compensation plan for eligible officers and other participants. Piedmont's total stock-based compensation costs were approximately $2 million for the three months ended March 31, 2016.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans	EMPLOYEE BENEFIT PLANS DEFINED BENEFIT RETIREMENT PLANS Duke Energy maintains, and the Subsidiary Registrants participate in, qualified and non-qualified, non-contributory defined benefit retirement plans. 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 did not make any contributions to its U.S. qualified defined benefit pension plans during the three months ended March 31, 2017 and 2016 . Net periodic benefit costs disclosed in the tables below represent the cost of the respective benefit plan for the periods presented. However, portions of the net periodic benefit costs disclosed in the tables below have been capitalized as a component of property, plant and equipment. Amounts presented in the tables below for the Subsidiary Registrants represent the amounts of pension and other post-retirement benefit costs allocated by Duke Energy for employees of the Subsidiary Registrants. Additionally, the Subsidiary Registrants are allocated their proportionate share of pension and post-retirement benefit costs for employees of Duke Energy’s shared services affiliate that provides support to the Subsidiary Registrants. These allocated amounts are included in the governance and shared service costs discussed in Note 8 . Duke Energy uses a December 31 measurement date for its defined benefit retirement plan assets and obligations. QUALIFIED PENSION PLANS The following tables include the components of net periodic pension costs for qualified pension plans. Three Months Ended March 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 $ 40 $ 12 $ 12 $ 6 $ 5 $ 1 $ 2 $ 3 Interest cost on projected benefit obligation 82 20 25 12 13 5 7 3 Expected return on plan assets (136 ) (35 ) (43 ) (21 ) (21 ) (7 ) (11 ) (6 ) Amortization of actuarial loss 36 8 14 6 7 1 3 3 Amortization of prior service credit (6 ) (2 ) (1 ) — — — — (1 ) Other 2 — 1 — — — — — Net periodic pension costs $ 18 $ 3 $ 8 $ 3 $ 4 $ — $ 1 $ 2 Three Months Ended March 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 36 $ 12 $ 11 $ 6 $ 5 $ 1 $ 2 $ 3 Interest cost on projected benefit obligation 83 21 26 12 14 5 7 2 Expected return on plan assets (129 ) (35 ) (42 ) (21 ) (21 ) (7 ) (10 ) (6 ) Amortization of actuarial loss 33 8 14 6 7 1 3 2 Amortization of prior service credit (4 ) (2 ) (1 ) — — — — — Other 3 1 1 — — — — — Net periodic pension costs $ 22 $ 5 $ 9 $ 3 $ 5 $ — $ 2 $ 1 NON-QUALIFIED PENSION PLANS Net periodic costs for non-qualified pension plans were not material for the three months ended March 31, 2017 and 2016 . 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. The following tables include the components of net periodic other post-retirement benefit costs. Three Months Ended March 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 $ 1 $ — $ — $ — $ — $ — $ — $ — Interest cost on accumulated post-retirement benefit obligation 9 2 4 2 2 — — — Expected return on plan assets (3 ) (2 ) — — — — — — Amortization of actuarial loss (gain) 2 (1 ) 5 3 2 — — — Amortization of prior service credit (29 ) (2 ) (21 ) (14 ) (8 ) — — — Net periodic other post-retirement benefit $ (20 ) $ (3 ) $ (12 ) $ (9 ) $ (4 ) $ — $ — $ — Three Months Ended March 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 1 $ — $ — $ — $ — $ — $ — $ — Interest cost on accumulated post-retirement benefit obligation 8 2 4 2 2 — 1 — Expected return on plan assets (3 ) (2 ) — — — — — — Amortization of actuarial loss (gain) 1 (1 ) 5 3 2 — (1 ) — Amortization of prior service credit (35 ) (3 ) (26 ) (17 ) (9 ) — — — Net periodic other post-retirement benefit $ (28 ) $ (4 ) $ (17 ) $ (12 ) $ (5 ) $ — $ — $ — DEFINED CONTRIBUTION RETIREMENT PLANS EMPLOYEE SAVINGS PLAN Duke Energy sponsors, and the Subsidiary Registrants participate in, employee savings plans that cover substantially all U.S. employees. The following table presents employer 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 Three Months Ended March 31, 2017 $ 65 $ 22 $ 18 $ 13 $ 5 $ 1 $ 3 $ 2 2016 52 18 15 11 4 1 2 2 MONEY PURCHASE PENSION PLAN Duke Energy provides, and Piedmont participates in, the Money Purchase Pension (MPP) plan, which is a defined contribution pension plan that allows employees to direct investments and assume risk of investment returns. In January 2017, a $2 million contribution was made to the MPP plan.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES EFFECTIVE TAX RATES The effective tax rates from continuing operations for each of the Duke Energy Registrants are included in the following table. Three Months Ended March 31, 2017 2016 Duke Energy 32.4 % 30.4 % Duke Energy Carolinas 35.4 % 34.1 % Progress Energy 34.1 % 36.7 % Duke Energy Progress 34.1 % 35.4 % Duke Energy Florida 36.6 % 37.9 % Duke Energy Ohio 35.4 % 26.9 % Duke Energy Indiana 39.3 % 30.2 % Piedmont 37.9 % 38.0 % The increase in the effective tax rate (ETR) for Duke Energy for the three months ended March 31, 2017 , is primarily due to lower investment tax credits due to lower solar investments in the current year, the inclusion of Piedmont's earnings at a higher ETR, and a tax charge related to the implementation of a new accounting standard related to stock compensation; partially offset by higher production tax credits related to wind projects placed in service. See Note 1 for additional information on the new accounting standard. The increase in the ETR for Duke Energy Carolinas for the three months ended March 31, 2017 , is primarily due to a favorable state resolution booked in 2016 related to prior year tax returns. The decrease in the ETR for Progress Energy for the three months ended March 31, 2017 , is primarily due to higher AFUDC equity and the amortization of excess North Carolina deferred tax. The decrease in the ETR for Duke Energy Progress for the three months ended March 31, 2017 , is primarily due to the amortization of excess North Carolina deferred tax. The decrease in the ETR for Duke Energy Florida for the three months ended March 31, 2017 , is primarily due to higher AFUDC equity. The increase in the ETR for Duke Energy Ohio for the three months ended March 31, 2017 , is primarily due to an immaterial out of period adjustment in the prior year related to deferred tax balances associated with property, plant and equipment. The increase in the ETR for Duke Energy Indiana for the three months ended March 31, 2017 , is primarily due to an immaterial out of period adjustment in the prior year related to deferred tax balances associated with property, plant and equipment. TAXES ON FOREIGN EARNINGS As of December 31, 2015, Duke Energy's intention was to indefinitely reinvest any future undistributed foreign earnings earned after December 31, 2014. 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 historical unremitted foreign earnings by approximately $95 million for the three months ended March 31, 2016 . Due to the classification of the International Disposal Group as discontinued operations, income tax amounts related to the International Disposal Group's foreign earnings are presented within Income from Discontinued Operations, net of tax on the Condensed Consolidated Statements of Operations. See Note 2 for additional information related to the sale of the International Disposal Group.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS For information on additional subsequent events related to regulatory matters, commitments and contingencies, debt and credit facilities, and variable interest entities see Notes 4, 5, 6 and 12, respectively.

Organization and Basis of Pre25

Organization and Basis of Presentation (Policy)	3 Months Ended
	Mar. 31, 2017
Policy Text Block [Line Items]
Basis of Accounting	The results of operations of the International Disposal Group have been classified as Discontinued Operations on the Condensed 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 Condensed Consolidated Financial Statements exclude amounts related to discontinued operations. BASIS OF PRESENTATION These Condensed Consolidated Financial Statements have been prepared in accordance with generally accepted accounting principles (GAAP) in the U.S. for interim financial information and with the instructions to Form 10-Q and Regulation S-X. Accordingly, these Condensed Consolidated Financial Statements do not include all information and notes required by GAAP in the U.S. for annual financial statements. Since the interim Condensed Consolidated Financial Statements and Notes do not include all information and notes required by GAAP in the U.S. for annual financial statements, the Condensed Consolidated Financial Statements and other information included in this quarterly report should be read in conjunction with the Consolidated Financial Statements and Notes in the Duke Energy Registrants’ combined Annual Report on Form 10-K for the year ended December 31, 2016 , and the Consolidated Financial Statements and Notes in the Piedmont Annual Report on Form 10-K for the year ended October 31, 2016. 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) as of December 31, 2016, for the transition period from November 1, 2016 to December 31, 2016. The information in these combined notes relates to each of the Duke Energy Registrants as noted in the Index to Combined Notes to Condensed Consolidated Financial Statements. However, none of the registrants make any representations as to information related solely to Duke Energy or the subsidiaries of Duke Energy other than itself. These Condensed Consolidated Financial Statements, in the opinion of the respective companies’ management, reflect all normal recurring adjustments necessary to fairly present the financial position and results of operations of each of the Duke Energy Registrants. Amounts reported in Duke Energy’s interim Condensed Consolidated Statements of Operations and each of the Subsidiary Registrants’ interim Condensed Consolidated Statements of Operations and Comprehensive Income are not necessarily indicative of amounts expected for the respective annual periods due to effects of seasonal temperature variations on energy consumption, regulatory rulings, timing of maintenance on electric generating units, changes in mark-to-market valuations, changing commodity prices and other factors. Piedmont's results of operations and cash flows are included in the accompanying condensed consolidated financial statements of Duke Energy for the three months ended March 31, 2017 , but not for the three months ended March 31, 2016, as Piedmont's earnings and cash flows are only included in Duke Energy's consolidated results subsequent to the acquisition date.
Consolidation	These Condensed Consolidated Financial Statements include, after eliminating intercompany transactions and balances, the accounts of the Duke Energy Registrants and subsidiaries where the respective Duke Energy Registrants have control. These Condensed Consolidated Financial Statements also reflect the Duke Energy Registrants’ proportionate share of certain jointly owned generation and transmission facilities.
Use of Estimates	In preparing financial statements that conform to GAAP, management 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.
Unbilled Revenue	UNBILLED REVENUE Revenues on sales of electricity and natural gas are recognized when service is provided or the product is delivered. Unbilled revenues are recognized by applying customer billing rates to the estimated volumes of energy and 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, meter reading schedules, and the impact of weather normalization or margin decoupling mechanisms.
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.
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, excise taxes are accounted for net.
New Accounting Standards	NEW ACCOUNTING STANDARDS The new accounting standards adopted for 2017 and 2016 had no material impact on the presentation or results of operations, cash flows or financial position of the Duke Energy Registrants. While immaterial, adoption of the following accounting standard had the most significant impact on the Duke Energy results of operations, cash flows and financial position for the three months ended March 31, 2017. Stock-Based Compensation and Income Taxes. In March 2017, Duke Energy adopted Financial Accounting Standards Board (FASB) guidance, which revised the accounting for stock-based compensation and the associated income taxes. The adopted guidance changes certain aspects of accounting for stock-based payment awards to employees including the accounting for income taxes and classification on the Condensed Consolidated Statements of Cash Flows. The primary impact to Duke Energy as a result of implementing this guidance was a cumulative-effect adjustment to retained earnings for tax benefits not previously recognized and higher income tax expense for the three months ended March 31, 2017. See the Duke Energy Condensed Consolidated Statements of Changes in Equity and Note 16 for further information. The following new Accounting Standards Updates (ASUs) have been issued, but have not yet been adopted by Duke Energy, as of March 31, 2017 . Retirement Benefits. In March 2017, the FASB issued revised accounting guidance for the presentation of net periodic costs related to benefit plans. Current GAAP permits the aggregation of all the components of net periodic costs on the income statement and does not require the disclosure of the location of net periodic costs on the Condensed Consolidated Statement of Operations. Under the amended guidance, the service cost component of net periodic costs must be included within Operating income within the same line as other compensation expenses. All other components of net periodic costs must be 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 current GAAP, which permits all components of net periodic costs to be capitalized. The guidance allows for a practical expedient that permits a company to use amounts disclosed in prior-period financial statements as the estimation basis for applying the retrospective presentation requirements. For Duke Energy, this guidance is effective for interim and annual periods beginning January 1, 2018. These amendments should be applied retrospectively for the presentation of the various components of net periodic costs and prospectively for the change in eligible costs to be capitalized. Duke Energy currently presents all of the components of net periodic costs that are not capitalized within Operation, maintenance and other on the Condensed Consolidated Statement of Operations. Under this updated guidance, Duke Energy will retrospectively move all the components of net periodic costs except for the service cost component to below Operating income. However, Duke Energy will continue to present the service cost component not capitalized within Operation, maintenance and other as this line item includes other compensation expense. Duke Energy is currently evaluating the financial statement impact, if any, of adopting this standard and whether or not the practical expedient will be utilized. Goodwill Impairment. In January 2017, the FASB issued revised guidance for subsequent measurement of goodwill. Under the guidance, a company will recognize an impairment to goodwill for the amount by which a reporting unit's carrying value exceeds the reporting unit's fair value, not to exceed the amount of goodwill allocated to that reporting unit. For Duke Energy, this guidance is effective for interim and annual periods beginning January 1, 2020. However, Duke Energy expects to early adopt this guidance on a prospective basis for the next interim or annual goodwill impairment test. Duke Energy does not expect adopting this guidance will have a material impact to its results of operations or financial position. 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 to which the entity expects to be entitled in exchange for those goods or services. The amendments in this update also require 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. Most of Duke Energy’s revenue is expected to be in scope of the new guidance. The majority of our sales, including energy provided to residential customers, are from tariff offerings that provide natural gas or electricity without a defined contractual term (‘at-will’). For such arrangements, Duke Energy expects that the revenue from contracts with customers will be equivalent to the electricity or natural gas supplied and billed in that period (including estimated billings). As such, Duke Energy does not expect that there will be a significant shift in the timing or pattern of revenue recognition for such sales. The evaluation of other revenue streams is ongoing, including long-term contracts with industrial customers and long-term purchase power agreements (PPA). Duke Energy continues to evaluate what information would be most useful for users of the financial statements, including information already provided in disclosures outside of the financial statement footnotes. These additional disclosures could include the disaggregation of revenues by geographic location, type of service, customer class or by duration of contract (‘at-will’ versus contracted revenue). Revenues from contracts with customers, revenue recognized under regulated operations accounting and revenue from lease accounting will also be disclosed. Duke Energy intends to use the modified retrospective method of adoption effective January 1, 2018. This method results in a cumulative-effect adjustment that will be recorded to retained earnings as of January 1, 2018, as if the standard had always been in effect. Disclosures for 2018 will include a comparison to what would have been reported for 2018 under the current revenue recognition rules in order to assist financial statement users in understanding how revenue recognition has changed as a result of this standard and to facilitate comparability with prior year reported results, which are not restated under the modified retrospective approach. 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, although it can be early adopted. The guidance is applied using a modified retrospective approach. Duke Energy is currently evaluating the financial statement impact of adopting this standard. Other than an expected increase in assets and liabilities, the ultimate impact of the new standard has not yet been determined. Significant system enhancements may be required to facilitate the identification, tracking and reporting of potential leases based upon requirements of the new lease standard. 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 statement of cash flows. Under the updated guidance, restricted cash and restricted cash equivalents will be included within beginning-of-period and end-of-period cash and cash equivalents on the statement of cash flows. For Duke Energy, this guidance is effective for the interim and annual periods beginning January 1, 2018, although it can be early adopted. The guidance will be applied using a retrospective transition method to each period presented. Upon adoption by Duke Energy, the revised guidance will result in a change to the amount of cash and cash equivalents and restricted cash explained when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. Prior to adoption, the Duke Energy Registrants reflect changes in restricted cash within Cash Flows from Investing Activities on the Condensed Consolidated Statement of Cash Flows. Financial Instruments Classification and Measurement. In January 2016, the FASB issued revised accounting guidance for the classification and measurement of financial instruments. Changes in the fair value of all equity securities will be required to be recorded in net income. Current GAAP allows some changes in fair value for available-for-sale equity securities to be recorded in Accumulated other comprehensive income (AOCI). Additional disclosures will be required to present separately the financial assets and financial liabilities by measurement category and form of financial asset. 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. For Duke Energy, the revised accounting guidance is effective for interim and annual periods beginning January 1, 2018, by recording a cumulative-effect adjustment to retained earnings as of January 1, 2018. This guidance is expected to have minimal impact on the Duke Energy Registrant's Condensed Consolidated Statements of Operations and Comprehensive Income as changes in the fair value of most of the Duke Energy Registrants' available-for-sale equity securities are deferred as regulatory assets or liabilities pursuant to accounting guidance for regulated operations.
Environmental Costs	Liabilities are recorded when losses become probable and are reasonably estimable. Costs are typically expensed as Operation, maintenance and other in the Condensed Consolidated Statements of Operations unless regulatory recovery of the costs is deemed probable.
Derivatives	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. 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.
Investment	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 and equity securities within the Investment Trusts are considered OTTIs and are recognized immediately. Investments within the Investment Trusts generally qualify for regulatory accounting, and accordingly realized and unrealized gains and losses are deferred as a regulatory asset or liability. Unrealized gains and losses on all other available-for-sale 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.
Earnings Per Share	Basic Earnings Per Share (EPS) is computed by dividing net income attributable to Duke Energy common stockholders, 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 stock, such as stock options and equity forward sale agreements, were exercised or settled.
Duke Energy Ohio [Member]
Policy Text Block [Line Items]
Unbilled Revenue	Additionally, Duke Energy Ohio and Duke Energy Indiana sell nearly all of their retail accounts receivable to an affiliate, Cinergy Receivables Company, LLC (CRC), on a revolving basis. These transfers of receivables are accounted for as sales and include receivables for unbilled revenues. Accordingly, the receivables sold are not reflected on the Condensed Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana.
Duke Energy Indiana [Member]
Policy Text Block [Line Items]
Unbilled Revenue	Additionally, Duke Energy Ohio and Duke Energy Indiana sell nearly all of their retail accounts receivable to an affiliate, Cinergy Receivables Company, LLC (CRC), on a revolving basis. These transfers of receivables are accounted for as sales and include receivables for unbilled revenues. Accordingly, the receivables sold are not reflected on the Condensed Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana.

Organization and Basis of Pre26

Organization and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2017
Organization And Basis Of Presentation [Line Items]
Schedule Of Unbilled Revenues With Restricted Receivables	Unbilled revenues are included within Receivables and Receivables of variable interest entities (VIEs) on the Condensed Consolidated Balance Sheets as shown in the following table. (in millions) March 31, 2017 December 31, 2016 Duke Energy $ 724 $ 831 Duke Energy Carolinas 296 313 Progress Energy 151 161 Duke Energy Progress 84 102 Duke Energy Florida 67 59 Duke Energy Ohio 2 2 Duke Energy Indiana 27 32 Piedmont 38 77
Schedule Of Net Income Amounts Attributable To Controlling Interests	The following table presents Net Income Attributable to Duke Energy Corporation for continuing operations and discontinued operations. Three Months Ended (in millions) March 31, 2016 Income from Continuing Operations $ 577 Income from Continuing Operations Attributable to Noncontrolling Interests 3 Income from Continuing Operations Attributable to Duke Energy Corporation $ 574 Income from Discontinued Operations, net of tax $ 122 Income from Discontinued Operations Attributable to Noncontrolling Interests, net of tax 2 Income from Discontinued Operations Attributable to Duke Energy Corporation, net of tax $ 120 Net Income $ 699 Net Income Attributable to Noncontrolling Interests 5 Net Income Attributable to Duke Energy Corporation $ 694
Schedule of Utility Inventory	The components of inventory are presented in the tables below. March 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 $ 2,328 $ 766 $ 1,122 $ 780 $ 341 $ 85 $ 315 $ 2 Coal 724 248 297 162 135 17 161 — Natural gas, oil and other fuel 314 37 233 111 123 16 2 27 Total inventory $ 3,366 $ 1,051 $ 1,652 $ 1,053 $ 599 $ 118 $ 478 $ 29 December 31, 2016 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 $ 2,374 $ 767 $ 1,167 $ 813 $ 354 $ 84 $ 312 $ 1 Coal 774 251 314 148 166 19 190 — Natural gas, oil and other fuel 374 37 236 115 121 34 2 65 Total inventory $ 3,522 $ 1,055 $ 1,717 $ 1,076 $ 641 $ 137 $ 504 $ 66
Schedule of Excise Taxes	Excise taxes accounted for on a gross basis as both operating revenues and property and other taxes on the Condensed Consolidated Statements of Operations were as follows. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy $ 91 $ 91 Duke Energy Carolinas 9 8 Progress Energy 46 47 Duke Energy Progress 5 5 Duke Energy Florida 41 42 Duke Energy Ohio 28 28 Duke Energy Indiana 7 8 Piedmont 1 1
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Schedule Of Unbilled Revenues With Restricted Receivables	These receivables for unbilled revenues are shown in the table below. (in millions) March 31, 2017 December 31, 2016 Duke Energy Ohio $ 69 $ 97 Duke Energy Indiana 106 123
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Schedule Of Unbilled Revenues With Restricted Receivables	These receivables for unbilled revenues are shown in the table below. (in millions) March 31, 2017 December 31, 2016 Duke Energy Ohio $ 69 $ 97 Duke Energy Indiana 106 123

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	3 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	The purchase price allocation of the Piedmont acquisition is as follows: (in millions) Current assets $ 497 Property, plant and equipment, net 4,714 Goodwill 3,353 Other long-term assets 804 Total assets 9,368 Current liabilities, including current maturities of long-term debt 576 Long-term liabilities 1,790 Long-term debt 2,002 Total liabilities 4,368 Total purchase price $ 5,000
Business Acquisition, Pro Forma Information [Table Text Block]	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. Three Months Ended (in millions) March 31, 2016 Operating Revenues $ 5,840 Net Income Attributable to Duke Energy Corporation 832
Income Statement Disclosures	The following table presents the results of the International Disposal Group, which are included in Income from Discontinued Operations, net of tax in Duke Energy's Condensed Consolidated Statements of Operations. 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. Three Months Ended (in millions) March 31, 2016 Operating Revenues $ 246 Fuel used in electric generation and purchased power 47 Cost of natural gas 11 Operation, maintenance and other 71 Depreciation and amortization 22 Property and other taxes 3 Other Income and Expenses, net 10 Interest Expense 22 Income before income taxes 80 Income tax benefit (a) (39 ) Income from discontinued operations of the International Disposal Group 119 Income from discontinued operations of other businesses 3 Income from Discontinued Operations, net of tax $ 122 (a) Includes an income tax benefit of $95 million related to historical undistributed foreign earnings. See Note 16 for additional information. Duke Energy has elected not to separately disclose discontinued operations on the Condensed Consolidated Statements of Cash Flows. The following table summarizes Duke Energy's cash flows from discontinued operations related to the International Disposal Group. Three Months Ended (in millions) March 31, 2016 Cash flows provided by (used in): Operating activities $ 85 Investing activities (9 )

Business Segments (Tables)

Business Segments (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting Information [Line Items]
Business Segment Data	Business segment information is presented in the following tables. Segment assets presented exclude intercompany assets. Three Months Ended March 31, 2017 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Consolidated Unaffiliated revenues $ 4,939 $ 648 $ 128 $ 5,715 $ 14 $ — $ 5,729 Intersegment revenues 8 22 — 30 19 (49 ) — Total revenues $ 4,947 $ 670 $ 128 $ 5,745 $ 33 $ (49 ) $ 5,729 Segment income (loss) $ 635 $ 133 $ 25 $ 793 $ (77 ) $ — $ 716 Add back noncontrolling interests 1 Net income $ 717 Segment assets $ 115,766 $ 10,866 $ 4,400 $ 131,032 $ 2,898 $ 178 $ 134,108 Three Months Ended March 31, 2016 Electric Gas Total Utilities and Utilities and Commercial Reportable (in millions) Infrastructure Infrastructure Renewables Segments Other Eliminations Consolidated Unaffiliated revenues $ 5,081 $ 169 $ 114 $ 5,364 $ 13 $ — $ 5,377 Intersegment revenues 8 1 — 9 16 (25 ) — Total revenues $ 5,089 $ 170 $ 114 $ 5,373 $ 29 $ (25 ) $ 5,377 Segment income (loss) (a) $ 664 $ 32 $ 26 $ 722 $ (148 ) $ — $ 574 Add back noncontrolling interests 3 Income from discontinued operations, net of tax 122 Net income $ 699 (a) Other includes $74 million of after-tax costs to achieve mergers, including losses on forward-starting interest rate swaps related to the Piedmont acquisition financing. See Note 9 for additional information. The following table summarizes the net loss of Other for each of these entities. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas $ (6 ) $ (17 ) Progress Energy (43 ) (49 ) Duke Energy Progress (3 ) (8 ) Duke Energy Florida (2 ) (4 ) Duke Energy Indiana (2 ) (2 ) Piedmont (4 ) 6
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Business Segment Data	Three Months Ended March 31, 2017 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Consolidated Total revenues $ 337 $ 170 $ 507 $ 11 $ — $ 518 Segment income (loss)/Net Income 24 26 50 (8 ) — 42 Segment assets 4,856 2,696 7,552 71 (14 ) 7,609 Three Months Ended March 31, 2016 Electric Gas Total Utilities and Utilities and Reportable (in millions) Infrastructure Infrastructure Segments Other Eliminations Consolidated Total revenues $ 340 $ 170 $ 510 $ 6 $ — $ 516 Segment income (loss) $ 36 $ 31 $ 67 $ (9 ) $ (1 ) $ 57 Income from discontinued operations, net of tax 2 Net income $ 59

Regulatory Matters (Tables)

Regulatory Matters (Tables)	3 Months Ended
	Mar. 31, 2017
Public Utilities, General Disclosures [Line Items]
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. Dollar amounts in the table below are included in Net property, plant and equipment on the Condensed Consolidated Balance Sheets as of March 31, 2017 , 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 $ 167 Progress Energy and Duke Energy Florida Crystal River Units 1 and 2 (b) 873 117 Duke Energy Indiana Gallagher Units 2 and 4 (c) 280 135 Total Duke Energy 1,738 $ 419 (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 Florida will likely retire these coal units by 2018 to comply with environmental regulations. (c) 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 settlement of Edwardsport IGCC matters.

Commitments and Contingencies (

Commitments and Contingencies (Table)	3 Months Ended
	Mar. 31, 2017
Valuation and Qualifying Accounts Disclosure [Line Items]
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 $ 71 Duke Energy Carolinas 22 Duke Energy Ohio 36 Duke Energy Indiana 7 Piedmont 2
Reserve for Environmental Costs [Member]
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 Other within Other Noncurrent Liabilities on the Condensed Consolidated Balance Sheets. Three Months Ended March 31, 2017 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at beginning of period $ 98 $ 10 $ 18 $ 3 $ 14 $ 59 $ 10 $ 1 Provisions/adjustments 6 1 — — 1 4 (1 ) 1 Cash reductions (6 ) — (1 ) — (1 ) (4 ) — — Balance at end of period $ 98 $ 11 $ 17 $ 3 $ 14 $ 59 $ 9 $ 2 Three Months Ended March 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Balance at beginning of period $ 94 $ 10 $ 17 $ 3 $ 14 $ 54 $ 12 $ 1 Provisions/adjustments 10 2 1 — 1 — 6 — Cash reductions (3 ) (1 ) (2 ) (1 ) (1 ) — — — Balance at end of period $ 101 $ 11 $ 16 $ 2 $ 14 $ 54 $ 18 $ 1
Legal Reserve [Member]
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 and the exit obligation discussed above related to the termination of an EPC contract. Reserves are classified on the Condensed Consolidated Balance Sheets in Other within Other Noncurrent Liabilities and Accounts payable and Other within Current Liabilities. The reasonably possible range of loss in excess of recorded reserves is not material, other than as described above. (in millions) March 31, 2017 December 31, 2016 Reserves for Legal Matters Duke Energy $ 91 $ 98 Duke Energy Carolinas 23 23 Progress Energy 57 59 Duke Energy Progress 13 14 Duke Energy Florida 27 28 Duke Energy Ohio 4 4 Piedmont 2 2

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	The following table summarizes significant debt issuances (in millions). Three Months Ended March 31, 2017 Duke Duke Maturity Interest Duke Energy Energy Issuance Date Date Rate Energy Florida Ohio Secured Debt February 2017 (a) June 2034 4.120 % $ 587 $ — $ — First Mortgage Bonds January 2017 (b) January 2020 1.850 % 250 250 — January 2017 (b) January 2027 3.200 % 650 650 — March 2017 (c) June 2046 3.700 % 100 — 100 Total issuances $ 1,587 $ 900 $ 100 (a) Portfolio financing of four Texas and Oklahoma wind facilities. Secured by substantially all of the assets of these wind facilities and nonrecourse to Duke Energy. Proceeds were used to reimburse Duke Energy for a portion of previously funded construction expenditures. (b) Debt issued to fund capital expenditures for ongoing construction and capital maintenance, to repay at maturity a $250 million aggregate principal amount of bonds due September 2017 and for general corporate purposes. (c) Proceeds were used to fund capital expenditures for ongoing construction, capital maintenance and for general corporate purposes.
Schedule Of Debt	The following table shows the significant components of Current Maturities of Long-Term Debt on the Condensed 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 March 31, 2017 Unsecured Debt Duke Energy (Parent) August 2017 1.625 % $ 700 Piedmont September 2017 8.510 % 35 Secured Debt Duke Energy June 2017 2.605 % 45 Duke Energy June 2017 2.455 % 34 First Mortgage Bonds Duke Energy Florida September 2017 5.800 % 250 Duke Energy Progress November 2017 1.252 % 200 Duke Energy Carolinas January 2018 5.250 % 400 Other (a) 313 Current maturities of long-term debt $ 1,977 (a) Includes capital lease obligations, amortizing debt and small bullet maturities.
Schedule Of Line Of Credit Facilities	The table below includes the current borrowing sublimits and available capacity under the Master Credit Facility. March 31, 2017 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 $ 3,400 $ 1,100 $ 1,000 $ 950 $ 450 $ 600 $ 500 Reduction to backstop issuances Commercial paper (b) (3,134 ) (1,822 ) (469 ) (402 ) — (30 ) (150 ) (261 ) Outstanding letters of credit (71 ) (62 ) (4 ) (2 ) (1 ) — — (2 ) Tax-exempt bonds (81 ) — — — — — (81 ) — Coal ash set-aside (500 ) — (250 ) (250 ) — — — — Available capacity $ 4,214 $ 1,516 $ 377 $ 346 $ 949 $ 420 $ 369 $ 237 (a) Represents the sublimit of each borrower. Certain sublimits were reallocated in May 2017 to provide additional liquidity to certain borrowers in light of near-term funding needs. (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 Condensed Consolidated Balance Sheets.

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill By Reportable Operating Segment	Duke Energy The following table presents the goodwill by reportable operating segment on Duke Energy's Condensed Consolidated Balance Sheets at March 31, 2017 and December 31, 2016 . Electric Utilities Gas Utilities Commercial (in millions) and Infrastructure and Infrastructure Renewables Total Goodwill $ 17,379 $ 1,924 $ 122 $ 19,425

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2017
Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively.
Intercompany Income Tax Receivable/Payable	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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38
Progress Energy [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively.
Intercompany Income Tax Receivable/Payable	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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38
Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively.
Intercompany Income Tax Receivable/Payable	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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38
Duke Energy Florida [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively.
Intercompany Income Tax Receivable/Payable	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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38
Duke Energy Ohio [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively.
Intercompany Income Tax Receivable/Payable	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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38
Duke Energy Indiana [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively.
Intercompany Income Tax Receivable/Payable	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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38
Piedmont Natural Gas [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Condensed Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Three Months Ended March 31, (in millions) 2017 2016 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 199 $ 217 Indemnification coverages (b) 6 5 JDA revenue (c) 16 9 JDA expense (c) 31 41 Intercompany natural gas purchases (d) 1 — Progress Energy Corporate governance and shared service expenses (a) $ 169 $ 174 Indemnification coverages (b) 10 9 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Progress Corporate governance and shared service expenses (a) $ 103 $ 100 Indemnification coverages (b) 4 4 JDA revenue (c) 31 41 JDA expense (c) 16 9 Intercompany natural gas purchases (d) 19 — Duke Energy Florida Corporate governance and shared service expenses (a) $ 66 $ 74 Indemnification coverages (b) 6 5 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 90 $ 85 Indemnification coverages (b) 1 1 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 90 $ 94 Indemnification coverages (b) 2 2 Piedmont Corporate governance and shared service expenses (a) $ 6 $ — Indemnification coverages (b) 1 — Intercompany natural gas sales (d) 20 — (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 recorded in Operation, maintenance and other on the Condensed 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 Condensed 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 under the JDA are recorded in Operating Revenues on the Condensed Consolidated Statements of Operations and Comprehensive Income. Expenses from the purchase of power under the JDA are recorded in Fuel used in electric generation and purchased power on the Condensed Consolidated Statements of Operations and Comprehensive Income. (d) Piedmont provides long-term natural gas delivery service to Duke Energy Carolinas and Duke Energy Progress' natural gas-fired generation facilities. Piedmont recorded the sales in Operating Revenues – Regulated natural gas, and Duke Energy Carolinas and Duke Energy Progress recorded the related purchases in Operating Expenses – Cost of natural gas on their Condensed Consolidated Statements of Operations and Comprehensive Income. The amounts are not eliminated in accordance with rate-based accounting regulations. For the three months ended March 31, 2016, which was prior to the Piedmont acquisition, Piedmont recorded $19 million and $1 million of natural gas sales with Duke Energy Progress and Duke Energy Carolinas, respectively.
Intercompany Income Tax Receivable/Payable	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 March 31, 2017 Intercompany income tax receivable $ 19 $ 139 $ 47 $ 48 $ 8 $ — $ — Intercompany income tax payable — — — — — 23 44 December 31, 2016 Intercompany income tax receivable $ 1 $ — $ — $ 37 $ — $ — $ — Intercompany income tax payable — 37 90 — 1 3 38
Equity Method Investee [Member] | Piedmont Natural Gas [Member]
Related Party Transaction [Line Items]
Schedule of Related Party Transactions, Other Revenue and Expense	Below are expenses for the three months ended March 31, 2017 and 2016 , which are included in Operating Expenses – Cost of natural gas on Piedmont's Condensed Consolidated Statement of Operations and Comprehensive Income. Three Months Ended March 31, (in millions) Type of expense 2017 2016 Cardinal Transportation Costs $ 2 $ 2 Pine Needle Gas Storage Costs 2 3 Hardy Storage Gas Storage Costs 2 2 Total $ 6 $ 7

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional Amounts of Outstanding Derivative Positions	The following table shows notional amounts of outstanding derivatives related to interest rate risk as of March 31, 2017 and December 31, 2016 . Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Cash flow hedges (a) $ 750 $ — $ — $ — $ — $ — Undesignated contracts 927 400 500 250 250 27 Total notional amount $ 1,677 $ 400 $ 500 $ 250 $ 250 $ 27 (a) Duke Energy includes amounts related to consolidated VIEs of $750 million as of March 31, 2017 and December 31, 2016 . 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. March 31, 2017 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Carolinas Energy Progress Florida Indiana Piedmont Electricity (gigawatt-hours) 184 — — — — 184 — Natural gas (millions of dekatherms) 817 85 228 105 123 — 504 December 31, 2016 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Carolinas Energy Progress Florida Indiana Piedmont Electricity (gigawatt-hours) 147 — — — — 147 — Natural gas (millions of dekatherms) 890 91 269 118 151 1 529
Location And Fair Value Of Derivatives Recognized in the Condensed 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 Condensed 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 March 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 $ 58 $ 16 $ 30 $ 19 $ 11 $ — $ 9 $ 2 Noncurrent 5 1 2 1 1 1 — — Total Derivative Assets – Commodity Contracts $ 63 $ 17 $ 32 $ 20 $ 12 $ 1 $ 9 $ 2 Interest Rate Contracts Designated as Hedging Instruments Noncurrent $ 18 $ — $ — $ — $ — $ — $ — $ — Not Designated as Hedging Instruments Current 2 — 2 — 2 — — — Total Derivative Assets – Interest Rate Contracts $ 20 $ — $ 2 $ — $ 2 $ — $ — $ — Total Derivative Assets $ 83 $ 17 $ 34 $ 20 $ 14 $ 1 $ 9 $ 2 Derivative Liabilities March 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 $ 32 $ — $ 17 $ 1 $ 17 $ — $ — $ 14 Noncurrent 145 4 11 4 1 — — 131 Total Derivative Liabilities – Commodity Contracts $ 177 $ 4 $ 28 $ 5 $ 18 $ — $ — $ 145 Interest Rate Contracts Designated as Hedging Instruments Current $ 8 $ — $ — $ — $ — $ — $ — $ — Noncurrent 9 — — — — — — — Not Designated as Hedging Instruments Current 1 — — — — 1 — — Noncurrent 21 10 6 5 1 4 — — Total Derivative Liabilities – Interest Rate Contracts $ 39 $ 10 $ 6 $ 5 $ 1 $ 5 $ — $ — Total Derivative Liabilities $ 216 $ 14 $ 34 $ 10 $ 19 $ 5 $ — $ 145 Derivative Assets December 31, 2016 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 $ 108 $ 23 $ 61 $ 35 $ 26 $ 4 $ 16 $ 3 Noncurrent 32 10 21 10 11 1 — — Total Derivative Assets – Commodity Contracts $ 140 $ 33 $ 82 $ 45 $ 37 $ 5 $ 16 $ 3 Interest Rate Contracts Designated as Hedging Instruments Noncurrent $ 19 $ — $ — $ — $ — $ — $ — $ — Not Designated as Hedging Instruments Current 3 — 3 1 2 — — — Total Derivative Assets – Interest Rate Contracts $ 22 $ — $ 3 $ 1 $ 2 $ — $ — $ — Total Derivative Assets $ 162 $ 33 $ 85 $ 46 $ 39 $ 5 $ 16 $ 3 Derivative Liabilities December 31, 2016 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 $ 43 $ — $ 12 $ — $ 12 $ — $ 2 $ 35 Noncurrent 166 1 7 1 — — — 152 Total Derivative Liabilities – Commodity Contracts $ 209 $ 1 $ 19 $ 1 $ 12 $ — $ 2 $ 187 Interest Rate Contracts Designated as Hedging Instruments Current $ 8 $ — $ — $ — $ — $ — $ — $ — Noncurrent 8 — — — — — — — Not Designated as Hedging Instruments — Current 1 — — — — 1 — — Noncurrent 26 15 6 6 — 5 — — Total Derivative Liabilities – Interest Rate Contracts $ 43 $ 15 $ 6 $ 6 $ — $ 6 $ — $ — Total Derivative Liabilities $ 252 $ 16 $ 25 $ 7 $ 12 $ 6 $ 2 $ 187
Offsetting Assets	Derivative Assets December 31, 2016 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 $ 111 $ 23 $ 64 $ 36 $ 28 $ 4 $ 16 $ 3 Gross amounts offset (11 ) — (11 ) — (11 ) — — — Net amounts presented in Current Assets: Other $ 100 $ 23 $ 53 $ 36 $ 17 $ 4 $ 16 $ 3 Noncurrent Gross amounts recognized $ 51 $ 10 $ 21 $ 10 $ 11 $ 1 $ — $ — Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Assets: Other $ 49 $ 9 $ 20 $ 9 $ 11 $ 1 $ — $ — The following tables present the line items on the Condensed 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 March 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 $ 60 $ 16 $ 32 $ 19 $ 13 $ — $ 9 $ 2 Gross amounts offset (7 ) — (7 ) (1 ) (6 ) — — — Net amounts presented in Current Assets: Other $ 53 $ 16 $ 25 $ 18 $ 7 $ — $ 9 $ 2 Noncurrent Gross amounts recognized $ 23 $ 1 $ 2 $ 1 $ 1 $ 1 $ — $ — Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Assets: Other $ 21 $ — $ 1 $ — $ 1 $ 1 $ — $ —
Offsetting Liabilities	Derivative Liabilities December 31, 2016 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 $ 52 $ — $ 12 $ — $ 12 $ 1 $ 2 $ 35 Gross amounts offset (11 ) — (11 ) — (11 ) — — — Net amounts presented in Current Liabilities: Other $ 41 $ — $ 1 $ — $ 1 $ 1 $ 2 $ 35 Noncurrent Gross amounts recognized $ 200 $ 16 $ 13 $ 7 $ — $ 5 $ — $ 152 Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 198 $ 15 $ 12 $ 6 $ — $ 5 $ — $ 152 The following tables present the line items on the Condensed 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 Liabilities March 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 $ 41 $ — $ 17 $ 1 $ 17 $ 1 $ — $ 14 Gross amounts offset (7 ) — (7 ) (1 ) (6 ) — — — Net amounts presented in Current Liabilities: Other $ 34 $ — $ 10 $ — $ 11 $ 1 $ — $ 14 Noncurrent Gross amounts recognized $ 175 $ 14 $ 17 $ 9 $ 2 $ 4 $ — $ 131 Gross amounts offset (2 ) (1 ) (1 ) (1 ) — — — — Net amounts presented in Other Noncurrent Liabilities: Other $ 173 $ 13 $ 16 $ 8 $ 2 $ 4 $ — $ 131
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. Amounts for Duke Energy Ohio, Duke Energy Indiana and Piedmont were not material. March 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 $ 40 $ 14 $ 25 $ 9 $ 17 Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 40 14 25 9 17 December 31, 2016 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 $ 34 $ 16 $ 18 $ 6 $ 12 Fair value of collateral already posted — — — — — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 34 16 18 6 12 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 Equit35

Investments in Debt and Equity Securities (Tables)	3 Months Ended
	Mar. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 114 $ — $ — $ 111 Equity securities 2,250 32 4,284 2,092 54 4,106 Corporate debt securities 10 5 576 10 8 528 Municipal bonds 3 6 336 3 10 331 U.S. government bonds 10 8 949 10 8 984 Other debt securities — 3 132 — 3 124 Total NDTF $ 2,273 $ 54 $ 6,391 $ 2,115 $ 83 $ 6,184 Other Investments Cash and cash equivalents $ — $ — $ 18 $ — $ — $ 25 Equity securities 44 — 106 38 — 104 Corporate debt securities 1 — 60 1 1 66 Municipal bonds 2 1 84 2 1 82 U.S. government bonds — — 43 — 1 51 Other debt securities — 2 42 — 2 42 Total Other Investments (b) $ 47 $ 3 $ 353 $ 41 $ 5 $ 370 Total Investments $ 2,320 $ 57 $ 6,744 $ 2,156 $ 88 $ 6,554 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets.
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 82 Due after one through five years 640 Due after five through 10 years 514 Due after 10 years 986 Total $ 2,222
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 93 $ 54 Realized losses 62 50
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 20 $ — $ — $ 18 Equity securities 1,229 15 2,366 1,157 28 2,245 Corporate debt securities 5 4 388 5 6 354 Municipal bonds 1 1 67 1 2 67 U.S. government bonds 3 5 431 2 5 458 Other debt securities — 3 120 — 3 116 Total NDTF $ 1,238 $ 28 $ 3,392 $ 1,165 $ 44 $ 3,258 Other Investments Other debt securities $ — $ 1 $ 3 $ — $ 1 $ 3 Total Other Investments (b) $ — $ 1 $ 3 $ — $ 1 $ 3 Total Investments $ 1,238 $ 29 $ 3,395 $ 1,165 $ 45 $ 3,261 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets.
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 2 Due after one through five years 221 Due after five through 10 years 269 Due after 10 years 517 Total $ 1,009
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 66 $ 34 Realized losses 40 37
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 94 $ — $ — $ 93 Equity securities 1,021 17 1,918 935 26 1,861 Corporate debt securities 5 1 188 5 2 174 Municipal bonds 2 5 269 2 8 264 U.S. government bonds 7 3 518 8 3 526 Other debt securities — — 12 — — 8 Total NDTF $ 1,035 $ 26 $ 2,999 $ 950 $ 39 $ 2,926 Other Investments Cash and cash equivalents $ — $ — $ 12 $ — $ — $ 21 Municipal bonds 2 — 46 2 — 44 Total Other Investments (b) $ 2 $ — $ 58 $ 2 $ — $ 65 Total Investments $ 1,037 $ 26 $ 3,057 $ 952 $ 39 $ 2,991 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets.
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 72 Due after one through five years 355 Due after five through 10 years 189 Due after 10 years 417 Total $ 1,033
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 27 $ 19 Realized losses 21 13
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 43 $ — $ — $ 45 Equity securities 772 13 1,541 704 21 1,505 Corporate debt securities 4 1 131 4 1 120 Municipal bonds 2 5 268 2 8 263 U.S. government bonds 5 2 284 5 2 275 Other debt securities — — 7 — — 5 Total NDTF $ 783 $ 21 $ 2,274 $ 715 $ 32 $ 2,213 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 1 Total Other Investments (b) $ — $ — $ 1 $ — $ — $ 1 Total Investments $ 783 $ 21 $ 2,275 $ 715 $ 32 $ 2,214 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets.
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 17 Due after one through five years 215 Due after five through 10 years 142 Due after 10 years 316 Total $ 690
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 24 $ 15 Realized losses 19 11
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value NDTF Cash and cash equivalents $ — $ — $ 51 $ — $ — $ 48 Equity securities 249 4 377 231 5 356 Corporate debt securities 1 — 57 1 1 54 Municipal bonds — — 1 — — 1 U.S. government bonds 2 1 234 3 1 251 Other debt securities — — 5 — — 3 Total NDTF (b) $ 252 $ 5 $ 725 $ 235 $ 7 $ 713 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ 4 Municipal bonds 2 — 46 2 — 44 Total Other Investments (c) $ 2 $ — $ 47 $ 2 $ — $ 48 Total Investments $ 254 $ 5 $ 772 $ 237 $ 7 $ 761 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) During the three months ended March 31, 2017 , Duke Energy Florida continued to receive reimbursements from the NDTF for costs related to ongoing commissioning activity of the Crystal River Unit 3 nuclear plant. (c) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets.
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 55 Due after one through five years 140 Due after five through 10 years 47 Due after 10 years 101 Total $ 343
Schedule of Realized Gain (Loss)	Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Three Months Ended March 31, (in millions) 2017 2016 Realized gains $ 3 $ 4 Realized losses 2 2
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities	The following table presents the estimated fair value of investments in available-for-sale securities. March 31, 2017 December 31, 2016 Gross Gross Gross Gross Unrealized Unrealized Estimated Unrealized Unrealized Estimated Holding Holding Fair Holding Holding Fair (in millions) Gains Losses (a) Value Gains Losses (a) Value Other Investments Equity securities $ 38 $ — $ 84 $ 33 $ — $ 79 Corporate debt securities — — 2 — — 2 Municipal bonds — 1 28 — 1 28 U.S. government bonds — — 1 — — 1 Total Other Investments (b) $ 38 $ 1 $ 115 $ 33 $ 1 $ 110 Total Investments $ 38 $ 1 $ 115 $ 33 $ 1 $ 110 (a) Substantially all amounts are considered OTTIs on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (b) These amounts are recorded in Other within Other Noncurrent Assets on the Condensed Consolidated Balance Sheets.
Investments Classified by Contractual Maturity Date	The table below summarizes the maturity date for debt securities. (in millions) March 31, 2017 Due in one year or less $ 2 Due after one through five years 15 Due after five through 10 years 9 Due after 10 years 5 Total $ 31

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2017
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 Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 4,284 $ 4,207 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 2,107 602 1,505 — — Other trading and available-for-sale equity securities 110 110 — — — Other trading and available-for-sale debt securities 248 61 182 5 — Derivative assets 83 2 71 10 — Total assets 6,832 4,982 1,758 15 77 Derivative liabilities (216 ) — (71 ) (145 ) — Net assets (liabilities) $ 6,616 $ 4,982 $ 1,687 $ (130 ) $ 77 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 4,106 $ 4,029 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 2,078 632 1,446 — — Other trading and available-for-sale equity securities 104 104 — — — Other trading and available-for-sale debt securities 266 75 186 5 — Derivative assets 162 5 136 21 — Total assets 6,716 4,845 1,768 26 77 Derivative liabilities (252 ) (2 ) (63 ) (187 ) — Net assets (liabilities) $ 6,464 $ 4,843 $ 1,705 $ (161 ) $ 77
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 Operating Revenues. Three Months Ended March 31, 2017 (in millions) Investments Derivatives (net) Total Balance at beginning of period $ 5 $ (166 ) $ (161 ) Purchases, sales, issuances and settlements: Settlements — (9 ) (9 ) Total amount included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities — 40 40 Balance at end of period $ 5 $ (135 ) $ (130 ) Three Months Ended March 31, 2016 (in millions) Investments Derivatives (net) Total Balance at beginning of period $ 5 $ 10 $ 15 Purchases, sales, issuances and settlements: Sales (1 ) — (1 ) Settlements — (7 ) (7 ) Total losses included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities — (1 ) (1 ) Balance at end of period $ 4 $ 2 $ 6
Quantitative Information Table - Level 3	The following table includes quantitative information about the Duke Energy Registrants' derivatives classified as Level 3. March 31, 2017 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio Financial Transmission Rights (FTRs) $ 1 RTO auction pricing FTR price – per megawatt-hour (MWh) $ 0.23 - $ 2.02 Duke Energy Indiana FTRs 9 RTO auction pricing FTR price – per MWh (1.08 ) - 5.33 Piedmont Natural gas contracts (145 ) Discounted cash flow Forward natural gas curves – price per million British thermal unit (MMBtu) 2.08 - 3.57 Duke Energy Total Level 3 derivatives $ (135 ) December 31, 2016 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Ohio FTRs $ 5 RTO auction pricing FTR price – per MWh $ 0.77 - $ 3.52 Duke Energy Indiana FTRs 16 RTO auction pricing FTR price – per MWh (0.83 ) - 9.32 Piedmont Natural gas contracts (187 ) Discounted cash flow Forward natural gas curves – price per MMBtu 2.31 - 4.18 Duke Energy Total Level 3 derivatives $ (166 )
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. March 31, 2017 December 31, 2016 (in millions) Book Value Fair Value Book Value Fair Value Duke Energy $ 48,998 $ 50,480 $ 47,895 $ 49,161 Duke Energy Carolinas 9,491 10,405 9,603 10,494 Progress Energy 18,148 19,742 17,541 19,107 Duke Energy Progress 6,761 7,103 7,011 7,357 Duke Energy Florida 6,981 7,596 6,125 6,728 Duke Energy Ohio 1,977 2,122 1,884 2,020 Duke Energy Indiana 3,784 4,292 3,786 4,260 Piedmont 1,821 1,954 1,821 1,933
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 Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,366 $ 2,289 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 1,026 146 880 — — Other available-for-sale debt securities 3 — — 3 — Derivative assets 17 — 17 — — Total assets 3,412 2,435 897 3 77 Derivative liabilities (14 ) — (14 ) — — Net assets $ 3,398 $ 2,435 $ 883 $ 3 $ 77 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,245 $ 2,168 $ — $ — $ 77 Nuclear decommissioning trust fund debt securities 1,013 178 835 — — Other available-for-sale debt securities 3 — — 3 — Derivative assets 33 — 33 — — Total assets 3,294 2,346 868 3 77 Derivative liabilities (16 ) — (16 ) — — Net assets $ 3,278 $ 2,346 $ 852 $ 3 $ 77
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 tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,918 $ 1,918 $ — Nuclear decommissioning trust fund debt securities 1,081 456 625 Other available-for-sale debt securities 58 12 46 Derivative assets 34 — 34 Total assets 3,091 2,386 705 Derivative liabilities (34 ) — (34 ) Net assets $ 3,057 $ 2,386 $ 671 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,861 $ 1,861 $ — Nuclear decommissioning trust fund debt securities 1,065 454 611 Other available-for-sale debt securities 65 21 44 Derivative assets 85 — 85 Total assets 3,076 2,336 740 Derivative liabilities (25 ) — (25 ) Net assets $ 3,051 $ 2,336 $ 715
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 tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,541 $ 1,541 $ — Nuclear decommissioning trust fund debt securities and other 733 221 512 Other available-for-sale debt securities and other 1 1 — Derivative assets 20 — 20 Total assets 2,295 1,763 532 Derivative liabilities (10 ) — (10 ) Net assets $ 2,285 $ 1,763 $ 522 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 1,505 $ 1,505 $ — Nuclear decommissioning trust fund debt securities and other 708 207 501 Other available-for-sale debt securities and other 1 1 — Derivative assets 46 — 46 Total assets 2,260 1,713 547 Derivative liabilities (7 ) — (7 ) Net assets $ 2,253 $ 1,713 $ 540
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 tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 377 $ 377 $ — Nuclear decommissioning trust fund debt securities and other 348 235 113 Other available-for-sale debt securities and other 47 1 46 Derivative assets 14 — 14 Total assets 786 613 173 Derivative liabilities (19 ) — (19 ) Net assets $ 767 $ 613 $ 154 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Nuclear decommissioning trust fund equity securities $ 356 $ 356 $ — Nuclear decommissioning trust fund debt securities and other 357 247 110 Other available-for-sale debt securities and other 48 4 44 Derivative assets 39 — 39 Total assets 800 607 193 Derivative liabilities (12 ) — (12 ) Net assets $ 788 $ 607 $ 181
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 tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which are disclosed in Note 9 . March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 1 $ — $ — $ 1 Derivative liabilities (5 ) — (5 ) — Net (liabilities) assets $ (4 ) $ — $ (5 ) $ 1 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 5 $ — $ — $ 5 Derivative liabilities (6 ) — (6 ) — Net (liabilities) assets $ (1 ) $ — $ (6 ) $ 5
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) Three Months Ended March 31, (in millions) 2017 2016 Balance at beginning of period $ 5 $ 3 Purchases, sales, issuances and settlements: Settlements (1 ) (2 ) Total losses included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities (3 ) (1 ) Balance at end of period $ 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 tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 9 . See Note 10 for additional information related to investments by major security type. March 31, 2017 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other available-for-sale equity securities $ 84 $ 84 $ — $ — Other available-for-sale debt securities and other 31 — 31 — Derivative assets 9 — — 9 Net assets $ 124 $ 84 $ 31 $ 9 December 31, 2016 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other available-for-sale equity securities $ 79 $ 79 $ — $ — Other available-for-sale debt securities and other 31 — 31 — Derivative assets 16 — — 16 Total assets 126 79 31 16 Derivative liabilities (2 ) (2 ) — — Net assets $ 124 $ 77 $ 31 $ 16
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) Three Months Ended March 31, (in millions) 2017 2016 Balance at beginning of period $ 16 $ 7 Purchases, sales, issuances and settlements: Settlements (7 ) (5 ) Balance at end of period $ 9 $ 2
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 tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Condensed Consolidated Balance Sheets. See Note 10 for additional information related to investments. March 31, 2017 (in millions) Total Fair Value Level 1 Level 3 Other trading equity securities 4 4 — Other trading debt securities 1 1 — Derivative assets 2 2 — Total assets 7 7 — Derivative liabilities (145 ) — (145 ) Net (liabilities) assets $ (138 ) $ 7 $ (145 ) December 31, 2016 (in millions) Total Fair Value Level 1 Level 3 Other trading equity securities $ 4 $ 4 $ — Other trading debt securities 1 1 — Derivative assets 3 3 — Total assets 8 8 — Derivative liabilities (187 ) — (187 ) Net (liabilities) assets $ (179 ) $ 8 $ (187 )
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) Three Months Ended March 31, (in millions) 2017 2016 Balance at beginning of period $ (187 ) $ (149 ) Total gains and settlements 42 23 Balance at end of period $ (145 ) $ (126 )

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	3 Months Ended
	Mar. 31, 2017
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Schedule Of Variable Interest Entities	The following table summarizes the amounts and expiration dates of the credit facilities described above. Duke Energy Duke Energy Duke Energy Duke Energy Carolinas Progress Florida (in millions) CRC DERF DEPR DEFR Expiration date December 2018 December 2018 February 2019 April 2019 Credit facility amount $ 325 $ 425 $ 300 $ 225 Amounts borrowed at March 31, 2017 325 425 300 225 Amounts borrowed at December 31, 2016 325 425 300 225
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Schedule Of Variable Interest Entities	The following tables summarize the impact of non-consolidated VIEs on the Condensed Consolidated Balance Sheets. March 31, 2017 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Piedmont Receivables from affiliated companies $ — $ — $ — $ — $ 53 $ 69 $ — Investments in equity method unconsolidated affiliates 673 173 92 938 — — 152 Other noncurrent assets 12 — — 12 — — — Total assets $ 685 $ 173 $ 92 $ 950 $ 53 $ 69 $ 152 Taxes accrued (a) 23 — — 23 — — (1 ) Other current liabilities — — 2 2 — — — Deferred income taxes (a) (7 ) — — (7 ) — — 4 Other noncurrent liabilities — — 13 13 — — — Total liabilities $ 16 $ — $ 15 $ 31 $ — $ — $ 3 Net assets $ 669 $ 173 $ 77 $ 919 $ 53 $ 69 $ 149 (a) Taxes accrued and Deferred income taxes are netted by jurisdiction on a consolidated basis on the Condensed Consolidated Balance Sheets. December 31, 2016 Duke Energy Duke Duke Pipeline Commercial Other Energy Energy (in millions) Investments Renewables VIEs Total Ohio Indiana Piedmont Receivables from affiliated companies $ — $ — $ — $ — $ 82 $ 101 $ — Investments in equity method unconsolidated affiliates 487 174 90 751 — — 139 Other noncurrent assets 12 — — 12 — — — Total assets $ 499 $ 174 $ 90 $ 763 $ 82 $ 101 $ 139 Other current liabilities — — 3 3 — — — Other noncurrent liabilities — — 13 13 — — 4 Total liabilities $ — $ — $ 16 $ 16 $ — $ — 4 Net assets $ 499 $ 174 $ 74 $ 747 $ 82 $ 101 $ 135
DEFPF [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Schedule Of Variable Interest Entities	The following table summarizes the impact of DEFPF on Duke Energy Florida's Condensed Consolidated Balance Sheets. (in millions) March 31, 2017 December 31, 2016 Receivables of VIEs $ 4 $ 6 Current Assets: Regulatory assets 53 50 Current Assets: Other 14 53 Other Noncurrent Assets: Regulatory assets 1,131 1,142 Current Liabilities: Other 3 17 Current maturities of long-term debt 55 62 Long-Term Debt 1,189 1,217
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Schedule Of Variable Interest Entities	The table below presents material balances reported on Duke Energy's Condensed Consolidated Balance Sheets related to renewables VIEs. (in millions) March 31, 2017 December 31, 2016 Current Assets: Other $ 336 $ 223 Property, plant and equipment, cost 3,671 3,419 Accumulated depreciation and amortization (448 ) (453 ) Current maturities of long-term debt 227 198 Long-Term Debt 1,645 1,097 Deferred income taxes 321 275 Other Noncurrent Liabilities: Other 251 252
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Schedule Of Variable Interest Entities	The table below presents the ownership interest and investment balances in these joint ventures. Duke Energy Piedmont Investment Amount (in millions) Investment Amount (in millions) Ownership March 31, December 31, Ownership March 31, December 31, Entity Name Interest 2017 2016 Interest (a) 2017 2016 ACP 47 % $ 403 $ 265 7 % $ 59 $ 46 Sabal Trail 7.5 % 188 140 Constitution (b) 24 % 82 82 24 % 93 93 Total $ 673 $ 487 $ 152 $ 139 (a) On April 1, 2017, Piedmont transferred its ownership interests in ACP and Constitution to a wholly owned subsidiary of Duke Energy at Piedmont's book value. (b) Duke Energy's investment amount includes purchase accounting adjustments not recorded at the Piedmont registrant.
Cinergy Receivables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [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 2017 2016 2017 2016 Anticipated credit loss ratio 0.5 % 0.5 % 0.3 % 0.3 % Discount rate 1.8 % 1.5 % 1.8 % 1.5 % Receivable turnover rate 13.4 % 13.3 % 10.7 % 10.6 % The following table shows the gross and net receivables sold. Duke Energy Ohio Duke Energy Indiana (in millions) March 31, 2017 December 31, 2016 March 31, 2017 December 31, 2016 Receivables sold $ 238 $ 267 $ 277 $ 306 Less: Retained interests 53 82 69 101 Net receivables sold $ 185 $ 185 $ 208 $ 205 The following table shows sales and cash flows related to receivables sold. Duke Energy Ohio Duke Energy Indiana Three Months Ended Three Months Ended March 31, March 31, (in millions) 2017 2016 2017 2016 Sales Receivables sold $ 533 $ 532 $ 664 $ 635 Loss recognized on sale 2 3 3 3 Cash flows Cash proceeds from receivables sold $ 559 $ 537 $ 693 $ 643 Return received on retained interests 1 1 2 1

Common Stock (Tables)

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [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 shares outstanding to the diluted weighted average number of common shares outstanding. Three Months Ended March 31, (in millions, except per share amounts) 2017 2016 Income from continuing operations attributable to Duke Energy common stockholders excluding impact of participating securities $ 715 $ 574 Weighted average shares outstanding – basic 700 689 Weighted average shares outstanding – diluted 700 689 Earnings per share from continuing operations attributable to Duke Energy common stockholders Basic $ 1.02 $ 0.83 Diluted $ 1.02 $ 0.83 Potentially dilutive items excluded from the calculation (a) 2 2 Dividends declared per common share $ 0.855 $ 0.825 (a) Performance stock awards were not included in the dilutive securities calculation because the performance measures related to the awards had not been met.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule Of Stock-Based Compensation Expense	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. Three Months Ended March 31, (in millions) 2017 2016 Restricted stock unit awards $ 8 $ 7 Performance awards 7 5 Pretax stock-based compensation cost $ 15 $ 12 Tax benefit associated with stock-based compensation expense $ 5 $ 4 Stock-based compensation costs capitalized 1 1

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan Disclosures	The following table presents employer 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 Three Months Ended March 31, 2017 $ 65 $ 22 $ 18 $ 13 $ 5 $ 1 $ 3 $ 2 2016 52 18 15 11 4 1 2 2
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	The following tables include the components of net periodic pension costs for qualified pension plans. Three Months Ended March 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 $ 40 $ 12 $ 12 $ 6 $ 5 $ 1 $ 2 $ 3 Interest cost on projected benefit obligation 82 20 25 12 13 5 7 3 Expected return on plan assets (136 ) (35 ) (43 ) (21 ) (21 ) (7 ) (11 ) (6 ) Amortization of actuarial loss 36 8 14 6 7 1 3 3 Amortization of prior service credit (6 ) (2 ) (1 ) — — — — (1 ) Other 2 — 1 — — — — — Net periodic pension costs $ 18 $ 3 $ 8 $ 3 $ 4 $ — $ 1 $ 2 Three Months Ended March 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 36 $ 12 $ 11 $ 6 $ 5 $ 1 $ 2 $ 3 Interest cost on projected benefit obligation 83 21 26 12 14 5 7 2 Expected return on plan assets (129 ) (35 ) (42 ) (21 ) (21 ) (7 ) (10 ) (6 ) Amortization of actuarial loss 33 8 14 6 7 1 3 2 Amortization of prior service credit (4 ) (2 ) (1 ) — — — — — Other 3 1 1 — — — — — Net periodic pension costs $ 22 $ 5 $ 9 $ 3 $ 5 $ — $ 2 $ 1
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	The following tables include the components of net periodic other post-retirement benefit costs. Three Months Ended March 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 $ 1 $ — $ — $ — $ — $ — $ — $ — Interest cost on accumulated post-retirement benefit obligation 9 2 4 2 2 — — — Expected return on plan assets (3 ) (2 ) — — — — — — Amortization of actuarial loss (gain) 2 (1 ) 5 3 2 — — — Amortization of prior service credit (29 ) (2 ) (21 ) (14 ) (8 ) — — — Net periodic other post-retirement benefit $ (20 ) $ (3 ) $ (12 ) $ (9 ) $ (4 ) $ — $ — $ — Three Months Ended March 31, 2016 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Piedmont Service cost $ 1 $ — $ — $ — $ — $ — $ — $ — Interest cost on accumulated post-retirement benefit obligation 8 2 4 2 2 — 1 — Expected return on plan assets (3 ) (2 ) — — — — — — Amortization of actuarial loss (gain) 1 (1 ) 5 3 2 — (1 ) — Amortization of prior service credit (35 ) (3 ) (26 ) (17 ) (9 ) — — — Net periodic other post-retirement benefit $ (28 ) $ (4 ) $ (17 ) $ (12 ) $ (5 ) $ — $ — $ —

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Summary of Effective Tax Rates	The effective tax rates from continuing operations for each of the Duke Energy Registrants are included in the following table. Three Months Ended March 31, 2017 2016 Duke Energy 32.4 % 30.4 % Duke Energy Carolinas 35.4 % 34.1 % Progress Energy 34.1 % 36.7 % Duke Energy Progress 34.1 % 35.4 % Duke Energy Florida 36.6 % 37.9 % Duke Energy Ohio 35.4 % 26.9 % Duke Energy Indiana 39.3 % 30.2 % Piedmont 37.9 % 38.0 %

Organization and Basis of Pre42

Organization and Basis of Presentation (Schedule of Unbilled Revenues with Restricted Receivables) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 724	$ 831
Duke Energy Carolinas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	296	313
Progress Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	151	161
Duke Energy Progress [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	84	102
Duke Energy Florida [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	67	59
Duke Energy Ohio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	2	2
Duke Energy Indiana [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	27	32
Piedmont Natural Gas [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	38	77
Cinergy Receivables [Member] | Duke Energy Ohio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	69	97
Cinergy Receivables [Member] | Duke Energy Indiana [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unbilled receivables	$ 106	$ 123

Organization and Basis of Pre43

Organization and Basis of Presentation (Schedule of Net Income Attributable to Noncontrolling Interest) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Schedule of Net Income Attributable to Noncontrolling Interest [Abstract]
Income From Continuing Operations	$ 717	$ 577
Income From Continuing Operations Attributable to Noncontrolling Interests	1	3
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	716	574
Income From Discontinued Operations, net of tax		122
Income From Discontinued Operations Attributable to Noncontrolling Interests, net of tax		2
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent		120
Net Income	717	699
Net Income (Loss) Attributable to Noncontrolling Interests	1	5
Net Income Attributable to Parent	$ 716	$ 694

Organization and Basis of Pre44

Organization and Basis of Presentation (Schedule of Inventory) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Public Utilities, Inventory [Line Items]
Inventory	$ 3,366	$ 3,522
Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	2,328	2,374
Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	724	774
Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	314	374
Duke Energy Carolinas [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,051	1,055
Duke Energy Carolinas [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	766	767
Duke Energy Carolinas [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	248	251
Duke Energy Carolinas [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	37	37
Progress Energy [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,652	1,717
Progress Energy [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,122	1,167
Progress Energy [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	297	314
Progress Energy [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	233	236
Duke Energy Progress [Member]
Public Utilities, Inventory [Line Items]
Inventory	1,053	1,076
Duke Energy Progress [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	780	813
Duke Energy Progress [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	162	148
Duke Energy Progress [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	111	115
Duke Energy Florida [Member]
Public Utilities, Inventory [Line Items]
Inventory	599	641
Duke Energy Florida [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	341	354
Duke Energy Florida [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	135	166
Duke Energy Florida [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	123	121
Duke Energy Ohio [Member]
Public Utilities, Inventory [Line Items]
Inventory	118	137
Duke Energy Ohio [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	85	84
Duke Energy Ohio [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	17	19
Duke Energy Ohio [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	16	34
Duke Energy Indiana [Member]
Public Utilities, Inventory [Line Items]
Inventory	478	504
Duke Energy Indiana [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	315	312
Duke Energy Indiana [Member] | Coal [Member]
Public Utilities, Inventory [Line Items]
Inventory	161	190
Duke Energy Indiana [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	2	2
Piedmont Natural Gas [Member]
Public Utilities, Inventory [Line Items]
Inventory	29	66
Piedmont Natural Gas [Member] | Materials and supplies [Member]
Public Utilities, Inventory [Line Items]
Inventory	2	1
Piedmont Natural Gas [Member] | Natural gas, oil and other fuel [Member]
Public Utilities, Inventory [Line Items]
Inventory	$ 27	$ 65

Organization and Basis of Pre45

Organization and Basis of Presentation (Schedule of Excise Taxes) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	$ 91	$ 91
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	9	8
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	46	47
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	5	5
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	41	42
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	28	28
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	7	8
Piedmont Natural Gas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	$ 1	$ 1

Acquisitions and Dispositions -

Acquisitions and Dispositions - Acquisitions (Narrative) (Details) - Piedmont Natural Gas [Member] - USD ($) $ in Millions	Oct. 03, 2016	Mar. 31, 2017	Mar. 31, 2016
Business Acquisition [Line Items]
Payments to acquire businesses	$ 5,000
Long-term debt assumed	$ 2,002
Business Combination, Integration Related Costs		$ 16	$ 101
Unrealized Losses on Forward-Starting Interest Rate Swaps			93
Business Combination, After Tax Integration Related Costs			63
Interest Expense [Member]
Business Acquisition [Line Items]
Business Combination, Integration Related Costs			$ 100

Acquisitions and Dispositions47

Acquisitions and Dispositions - Dispositions (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016USD ($)
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 Brazil Holdings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Enterprise Value	1,200
DEI Latin American [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
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	$ 78

Acquisitions and Dispositions48

Acquisitions and Dispositions (Purchase Price Allocation) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Oct. 03, 2016
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Goodwill	$ 19,425	$ 19,425
Piedmont Natural Gas [Member]
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Less Noncontrolling Interest [Abstract]
Current assets			$ 497
Property, plant and equipment, net			4,714
Goodwill			3,353
Other long-term assets			804
Total assets			9,368
Current liabilities, including current maturities of long-term debt			576
Long-term liabilities			1,790
Long-term debt			2,002
Total liabilities			4,368
Total purchase price			$ 5,000

Acquisitions and Dispositions49

Acquisitions and Dispositions (Pro Forma Information) (Details) - Piedmont Natural Gas [Member] $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Operating Revenues	$ 5,840
Net income attributable to Duke Energy Corporation	$ 832

Acquisitions and Dispositions50

Acquisitions and Dispositions (Discontinued Operations) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income From Discontinued Operations, net of tax	$ 122
International Energy [Member] | Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating Revenues	246
Fuel used in electric generation and purchased power	47
Cost of natural gas	11
Operation, maintenance and other	71
Deprecation and amortization	22
Property and other taxes	3
Other Income and Expenses, net	10
Interest Expense	22
Income before income taxes	80
Income tax benefit	(39)
Income From Discontinued Operations, net of tax	119
Other Disposal Groups [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income From Discontinued Operations, net of tax	3
Previously Remitted Earnings [Member] | International Energy [Member] | Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax benefit	$ (95)

Acquisitions and Dispositions51

Acquisitions and Dispositions (Cash Flow Statement) (Details) - International Energy [Member] $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Operating Activities	$ 85
Investing Activities	$ (9)

Business Segments (Narrative) (

Business Segments (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)segment	Mar. 31, 2016USD ($)	Dec. 31, 2016
Segment Reporting Information [Line Items]
Net Income Attributable to Parent	$ 716	$ 694
Interest Expense	$ 491	489
Duke Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 270	271
Interest Expense	$ 103	107
Progress Energy [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 199	209
Interest Expense	$ 206	160
Duke Energy Progress [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 147	137
Interest Expense	$ 82	63
Duke Energy Florida [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 90	110
Interest Expense	$ 70	41
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	2
Net Income Attributable to Parent	$ 42	59
Interest Expense	$ 22	20
Duke Energy Indiana [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 91	95
Interest Expense	$ 44	44
Piedmont Natural Gas [Member]
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	1
Net Income Attributable to Parent	$ 95	103
Interest Expense	20	17
Other [Member] | Progress Energy [Member]
Segment Reporting Information [Line Items]
Interest Expense	$ 55	56
National Methanol Company [Member] | Other [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage	25.00%
SouthStar [Member] | Piedmont Natural Gas [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Ownership Percentage			15.00%
Net Income Attributable to Parent		$ 7

Business Segments (Business Seg

Business Segments (Business Segment Data) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operating revenues	$ 5,729	$ 5,377
Segment income	716	574
Add back noncontrolling interests	1	3
Income From Discontinued Operations, net of tax		122
Net Income	717	699
Net Income Attributable to Parent	716	694
Segment assets	134,108		$ 132,761
Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,939	5,081
Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	648	169
Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Operating revenues	128	114
Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	14	13
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,715	5,364
Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,947	5,089
Segment income	635	664
Segment assets	115,766
Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	670	170
Segment income	133	32
Segment assets	10,866
Operating Segments [Member] | Commercial Renewables [Member]
Segment Reporting Information [Line Items]
Operating revenues	128	114
Segment income	25	26
Segment assets	4,400
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	5,745	5,373
Segment income	793	722
Segment assets	131,032
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues	(49)	(25)
Segment assets	178
Intersegment Eliminations [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	(8)	(8)
Intersegment Eliminations [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	(22)	(1)
Intersegment Eliminations [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	(19)	(16)
Intersegment Eliminations [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	(30)	(9)
Corporate, Non-Segment [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	33	29
Segment income	(77)	(148)
Segment assets	2,898
Costs to achieve mergers		74
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Operating revenues	518	516
Segment income	42	57
Income From Discontinued Operations, net of tax		2
Net Income Attributable to Parent	42	59
Segment assets	7,609		$ 7,528
Duke Energy Ohio [Member] | Operating Segments [Member] | Electric Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	337	340
Segment income	24	36
Segment assets	4,856
Duke Energy Ohio [Member] | Operating Segments [Member] | Gas Utilities and Infrastructure [Member]
Segment Reporting Information [Line Items]
Operating revenues	170	170
Segment income	26	31
Segment assets	2,696
Duke Energy Ohio [Member] | Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	507	510
Segment income	50	67
Segment assets	7,552
Duke Energy Ohio [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Segment income		(1)
Segment assets	(14)
Duke Energy Ohio [Member] | Corporate, Non-Segment [Member] | Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	11	6
Segment income	(8)	$ (9)
Segment assets	$ 71

Business Segments (Schedule of

Business Segments (Schedule of Segment Reporting Information, by Segment) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Segment income	$ 716	$ 574
Duke Energy Carolinas [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(6)	(17)
Progress Energy [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(43)	(49)
Duke Energy Progress [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(3)	(8)
Duke Energy Florida [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(2)	(4)
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Segment income	42	57
Duke Energy Indiana [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(2)	(2)
Piedmont Natural Gas [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	$ (4)	$ 6

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details) $ in Millions	May 01, 2017USD ($)	Dec. 31, 2015USD ($)	Mar. 31, 2017USD ($)MW	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			$ 83,516		$ 82,520
Generation Facilities To Be Retired Net			508		529
Electric Domestic Regulated Revenue			$ 4,913	$ 5,053
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW			1,738
Public Utilities, Property, Plant and Equipment, Net			$ 419
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%
Estimated Contributions			$ 229
Minimum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost			5,000
Maximum [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost			$ 5,500
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%
Spectra Energy [Member] | Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage			50.00%
NextEra [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%
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			$ 26,951		26,762
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			$ 600
Joint owner ownership percentage			13.00%
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			$ 30,792		30,181
Generation Facilities To Be Retired Net			508		529
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			18,561		18,387
Generation Facilities To Be Retired Net			$ 508		529
Duke Energy Progress [Member] | Asheville Plant [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW			376
Generation Facilities To Be Retired Net			$ 471		492
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			12,228		11,790
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			5,625		5,547
Electric Domestic Regulated Revenue			337	$ 340
Duke Energy Ohio [Member] | Regional Transmission Organization Realignment [Member]
Public Utilities, General Disclosures [Line Items]
Exit obligation			90		90
Regulatory Assets			$ 71		71
Approved MVP Proposals			17
MISO estimate of Duke Energy Ohio's MVP obligation			$ 2,700
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			9,985		9,924
Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net			4,907		$ 4,814
Storm Cost Deferrals [Member] | NCUC [Member] | Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Regulatory Costs Not yet Approved			116
Western Carolinas Modernization Plan [Member] | NCUC [Member] | Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost			893
Hines Chiller Uprate Project [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost			150
Hines Chiller Uprate Project [Member] | FPSC [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Approved Rate Increase (Decrease), Amount			19
Levy Nuclear Project [Member] | FPSC [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount			82
East Bend Coal Ash Basin Filing [Member] | KPSC [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost			93
2017 Base Rate Case [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount			$ 15
Requested Return on Equity, Percentage			10.40%
Natural Gas Pipeline Extension [Member] | PUCO [Member] | Duke Energy Ohio [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated Capital Cost Excluding AFUDC			$ 86
Natural Gas Pipeline Extension [Member] | PUCO [Member] | Duke Energy Ohio [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Estimated Capital Cost Excluding AFUDC			110
Advanced Metering Infrastructure Project [Member] | KPSC [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Regulatory Costs Not yet Approved			10
Estimated capital cost			49
Accelerated Natural Gas Service Line Replacement Rider [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Regulatory Costs Not yet Approved			240
Energy Efficiency and Peak Demand Reduction Program [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Electric Domestic Regulated Revenue		$ 20
MGP Remediation [Member] | PUCO [Member] | Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets			100
Coal Combustion Residual Plan [Member] | IURC [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount			$ 380
Federal Mandate Costs Recovered Through Tracker Mechanism			80.00%
Federally Mandated Costs Recovered In Future Rate Case			20.00%
Percentage of Costs Recovered through Existing Rider			60.00%
Percentage Recovered Through Future Rate Case			40.00%
Interest Rate on Intermediary Debt for Electric Utility Plant Construction			4.73%
Requested Rate Increase (Decrease), Amended, Amount			$ 365
FERC Transmission Rates [Member] | Federal Energy Regulatory Commission [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage			12.38%
Approved Return on Equity Percentage Adder			0.50%
FERC Complaint [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Requested Return on Equity, Percentage			8.67%
FERC Complaint 1 [Member] | Federal Energy Regulatory Commission [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage			10.32%
FERC Complaint 2 [Member] | Federal Energy Regulatory Commission [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Requested Return on Equity, Percentage			9.70%
NCUC IMR Petition Filed October 2016 [Member] | NCUC [Member] | Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Approved Rate Increase (Decrease), Amount			$ 8
NCUC IMR Petition Filed May 2017 [Member] | NCUC [Member] | Piedmont Natural Gas [Member] | Subsequent Event [Member]
Public Utilities, General Disclosures [Line Items]
Requested Rate Increase (Decrease), Amount	$ 11.6
TPUC Petition Filed IMR November 2016 [Member] | TPUC [Member] | Piedmont Natural Gas [Member]
Public Utilities, General Disclosures [Line Items]
Approved Rate Increase (Decrease), Amount			$ 1.7

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of Net Carrying Value Of Facilities and Megawatt Capacity) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)MW	Dec. 31, 2016USD ($)
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net	$ 83,516	$ 82,520
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net	26,951	26,762
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net	30,792	30,181
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net	12,228	11,790
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Property, Plant and Equipment, Net	$ 9,985	$ 9,924
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	1,738
Public Utilities, Property, Plant and Equipment, Net	$ 419
Allen Steam Station Units 1-3 [Member] | Generation Facilities To Be Retired [Member] | Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	585
Public Utilities, Property, Plant and Equipment, Net	$ 167
Crystal River Units 1 and 2 [Member] | Generation Facilities To Be Retired [Member] | Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	873
Public Utilities, Property, Plant and Equipment, Net	$ 117
Crystal River Units 1 and 2 [Member] | Generation Facilities To Be Retired [Member] | Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	873
Public Utilities, Property, Plant and Equipment, Net	$ 117
Gallagher Units 2 and 4 [Member] | Generation Facilities To Be Retired [Member] | Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	280
Public Utilities, Property, Plant and Equipment, Net	$ 135

Commitments and Contingencies57

Commitments and Contingencies (Narrative) (Details) gal in Millions	1 Months Ended	3 Months Ended
	Feb. 28, 2014Tgal	Mar. 31, 2017USD ($)plantClaims	Dec. 31, 2016USD ($)	Mar. 31, 2014USD ($)
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		$ 91,000,000	$ 98,000,000
Progress Energy Merger Shareholder Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount		$ 27,000,000
Coal Ash Insurance Coverage Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Number of NC and SC Plants with Ash Basins | plant		15
NCDEQ State Enforcement Actions [Member]
Valuation and Qualifying Accounts [Abstract]
Number of Plants with No Disputed Facts | plant		7
Number of NC Plants with Ash Basins | plant		14
Number of Plants with Disputed Facts | plant		7
Potential Groundwater Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Number of NC Plants with Ash Basins | plant		14
Goodwill Payment		$ 5,000
Water Bill Stipend Period		25 years
Duke Energy Carolinas [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		$ 23,000,000	23,000,000
Duke Energy Carolinas [Member] | Potential Groundwater Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		18,000,000
Duke Energy Carolinas [Member] | Asbestos-related Injuries and Damages Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Asbestos-related injuries and damages reserves		506,000,000	512,000,000
Reinsurance retention policy, excess retention, amount reinsured		814,000,000
Probable insurance recoveries		$ 587,000,000	587,000,000
Duke Energy Carolinas [Member] | Asbestos-related Injuries and Damages Claims [Member] | Non-Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims		111
Asbestos-related injuries and damages reserves		$ 29,000,000
Duke Energy Carolinas [Member] | Asbestos-related Injuries and Damages Claims [Member] | Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims		58
Asbestos-related injuries and damages reserves		$ 16,000,000
Duke Energy Carolinas [Member] | Minimum [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Coal ash released, in tons | T	30,000
Basin water released, in gallons | gal	24
Duke Energy Carolinas [Member] | Maximum [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Coal ash released, in tons | T	39,000
Basin water released, in gallons | gal	27
Progress Energy [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		57,000,000	59,000,000
Duke Energy Progress [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		13,000,000	14,000,000
Duke Energy Progress [Member] | Potential Groundwater Claims [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		4,000,000
Duke Energy Florida [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		27,000,000	28,000,000
Duke Energy Florida [Member] | Westinghouse Electric Company Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount		54,000,000
Loss Contingency, Damages Sought, Original Amount		482,000,000		$ 510,000,000
Loss Contingency, Damages Awarded, Value		30,000,000
Gain Contingency, Dismissed Amount		54,000,000
Loss contingency, damages sought, value		424,000,000
Loss Contingency Damages Awarded and Interest, Value		34,000,000
Duke Energy Florida [Member] | MGP Cost Recovery Action [Member]
Valuation and Qualifying Accounts [Abstract]
Gain contingency, unrecorded amount		43,000,000
Duke Energy Ohio [Member]
Valuation and Qualifying Accounts [Abstract]
Loss Contingency Accrual		4,000,000	$ 4,000,000
Duke Energy Indiana [Member] | Benton County Wind Farm Dispute [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, damages sought, value		$ 16,000,000

Commitments and Contingencies58

Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	$ 71
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	98	$ 94
Provisions/adjustments	6	10
Cash reductions	(6)	(3)
Ending balance	98	101
Duke Energy Carolinas [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	22
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	10	10
Provisions/adjustments	1	2
Cash reductions	0	(1)
Ending balance	11	11
Progress Energy [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	18	17
Provisions/adjustments		1
Cash reductions	(1)	(2)
Ending balance	17	16
Duke Energy Progress [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	3	3
Cash reductions	0	(1)
Ending balance	3	2
Duke Energy Florida [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	14	14
Provisions/adjustments	1	1
Cash reductions	(1)	(1)
Ending balance	14	14
Duke Energy Ohio [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	36
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	59	54
Provisions/adjustments	4
Cash reductions	(4)
Ending balance	59	54
Duke Energy Indiana [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	7
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	10	12
Provisions/adjustments	(1)	6
Cash reductions	0
Ending balance	9	18
Piedmont Natural Gas [Member]
Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	2
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	1	1
Provisions/adjustments	1
Cash reductions	0
Ending balance	$ 2	$ 1

Commitments and Contingencies59

Commitments and Contingencies (Schedule of Legal Reserves) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Reserves for legal matters	$ 91	$ 98
Duke Energy Carolinas [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	23	23
Progress Energy [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	57	59
Duke Energy Progress [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	13	14
Duke Energy Florida [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	27	28
Duke Energy Ohio [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	4	4
Piedmont Natural Gas [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	$ 2	$ 2

Debt and Credit Facilities (Nar

Debt and Credit Facilities (Narrative) (Details) - USD ($)	3 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt issuances		$ 1,587,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size		8,000,000,000	$ 7,500,000,000
Parent Company [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size		3,400,000,000
Piedmont Natural Gas [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size		500,000,000	$ 850,000,000
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size		1,100,000,000
Duke Energy Carolinas [Member] | USDOJ [Member] | North Carolina Ash Basins [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Minimum Master Credit Facility Balance Required		250,000,000
Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility size		1,000,000,000
Duke Energy Progress [Member] | USDOJ [Member] | North Carolina Ash Basins [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Minimum Master Credit Facility Balance Required		$ 250,000,000
April 2017 Debt Issuance, 3.364% Coupon [Member] | Subsequent Event [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	$ 420,000,000
Interest rate	3.364%
April 2017 Debt Issuance, 3.364% Coupon [Member] | Parent Company [Member] | Subsequent Event [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	$ 420,000,000
Interest rate	3.364%
April 2017 Maturity [Member] | Subsequent Event [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Repayments of Debt	$ 400,000,000
April 2017 Maturity [Member] | Parent Company [Member] | Subsequent Event [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Repayments of Debt	$ 400,000,000

Debt and Credit Facilities (Sum

Debt and Credit Facilities (Summary of Debt Issuances) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt issuances	$ 1,587
Current maturities of long-term debt	1,977	$ 2,319
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	404	116
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	202	452
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Debt issuances	900
Current maturities of long-term debt	319	326
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Debt issuances	100
Current maturities of long-term debt	1	1
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	3	$ 3
Secured Debt [Member] | February 2017 Debt Issuance, 4.120% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 587
Interest rate	4.12%
First Mortgage [Member] | January 2017 Debt Issuance, 1.850% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 250
Interest rate	1.85%
First Mortgage [Member] | January 2017 Debt Issuance, 3.200% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 650
Interest rate	3.20%
First Mortgage [Member] | March 2017 Debt Issuance, 3.700% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 100
Interest rate	3.70%
First Mortgage [Member] | Duke Energy Florida [Member] | January 2017 Debt Issuance, 1.850% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 250
Interest rate	1.85%
First Mortgage [Member] | Duke Energy Florida [Member] | January 2017 Debt Issuance, 3.200% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 650
Interest rate	3.20%
First Mortgage [Member] | Duke Energy Florida [Member] | First Mortgage Bonds Maturing September 2017, 5.800% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.80%
Current maturities of long-term debt	$ 250
First Mortgage [Member] | Duke Energy Ohio [Member] | March 2017 Debt Issuance, 3.700% Coupon [Member]
Debt Instrument [Line Items]
Debt issuances	$ 100
Interest rate	3.70%

Debt and Credit Facilities (S62

Debt and Credit Facilities (Summary of Current Maturities of Long-term Debt)(Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 1,977	$ 2,319
Secured Debt [Member] | Secured Debt Maturing June 2017, 2.605% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	2.605%
Current maturities of long-term debt	$ 45
Secured Debt [Member] | Secured Debt Maturing June 2017, 2.455% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	2.455%
Current maturities of long-term debt	$ 34
Other Debt Obligations [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 313
Parent Company [Member] | Unsecured Debt [Member] | Unsecured Debt Maturing August 2017, 1.625% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	1.625%
Current maturities of long-term debt	$ 700
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 404	116
Duke Energy Carolinas [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing January 2018, 5.250% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.25%
Current maturities of long-term debt	$ 400
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 202	452
Duke Energy Progress [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing November 2017, 1.252% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	1.252%
Current maturities of long-term debt	$ 200
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 319	326
Duke Energy Florida [Member] | First Mortgage Bonds [Member] | First Mortgage Bonds Maturing September 2017, 5.800% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	5.80%
Current maturities of long-term debt	$ 250
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	1	1
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	3	3
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 35	$ 35
Piedmont Natural Gas [Member] | Unsecured Debt [Member] | Unsecured Debt Maturing September 2017, 8.510% Coupon [Member]
Debt Instrument [Line Items]
Interest rate	8.51%
Current maturities of long-term debt	$ 35

Debt and Credit Facilities (Sch

Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - Revolving Credit Facility [Member] - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Line of Credit Facility [Line Items]
Facility size	$ 8,000,000,000	$ 7,500,000,000
Commercial paper	(3,134,000,000)
Outstanding letters of credit	(71,000,000)
Tax exempt bonds	(81,000,000)
Coal ash set-aside	(500,000,000)
Available capacity	4,214,000,000
Parent Company [Member]
Line of Credit Facility [Line Items]
Facility size	3,400,000,000
Commercial paper	(1,822,000,000)
Outstanding letters of credit	(62,000,000)
Available capacity	1,516,000,000
Duke Energy Carolinas [Member]
Line of Credit Facility [Line Items]
Facility size	1,100,000,000
Commercial paper	(469,000,000)
Outstanding letters of credit	(4,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	377,000,000
Duke Energy Progress [Member]
Line of Credit Facility [Line Items]
Facility size	1,000,000,000
Commercial paper	(402,000,000)
Outstanding letters of credit	(2,000,000)
Coal ash set-aside	(250,000,000)
Available capacity	346,000,000
Duke Energy Florida [Member]
Line of Credit Facility [Line Items]
Facility size	950,000,000
Outstanding letters of credit	(1,000,000)
Available capacity	949,000,000
Duke Energy Ohio [Member]
Line of Credit Facility [Line Items]
Facility size	450,000,000
Commercial paper	(30,000,000)
Available capacity	420,000,000
Duke Energy Indiana [Member]
Line of Credit Facility [Line Items]
Facility size	600,000,000
Commercial paper	(150,000,000)
Tax exempt bonds	(81,000,000)
Available capacity	369,000,000
Piedmont Natural Gas [Member]
Line of Credit Facility [Line Items]
Facility size	500,000,000	$ 850,000,000
Commercial paper	(261,000,000)
Outstanding letters of credit	(2,000,000)
Available capacity	237,000,000
Proceeds Loaned To Subsidiary Registrants [Member] | Parent Company [Member]
Line of Credit Facility [Line Items]
Commercial paper	$ (625,000,000)

Goodwill and Intangible Asset64

Goodwill and Intangible Assets (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill	$ 19,425,000,000	$ 19,425,000,000
Electric Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill	17,379,000,000	17,379,000,000
Gas Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill	1,924,000,000	1,924,000,000
Commercial Renewables [Member]
Goodwill [Roll Forward]
Goodwill	122,000,000	122,000,000
Duke Energy Ohio [Member]
Goodwill [Roll Forward]
Goodwill	920,000,000	920,000,000
Accumulated impairment charges	216,000,000	216,000,000
Duke Energy Ohio [Member] | Electric Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill	596,000,000	596,000,000
Duke Energy Ohio [Member] | Gas Utilities and Infrastructure [Member]
Goodwill [Roll Forward]
Goodwill	324,000,000	324,000,000
Progress Energy [Member]
Goodwill [Roll Forward]
Goodwill	3,655,000,000	3,655,000,000
Accumulated impairment charges	0	0
Piedmont Natural Gas [Member]
Goodwill [Roll Forward]
Goodwill	49,000,000	49,000,000
Accumulated impairment charges	$ 0	$ 0

Related Party Transactions (Oth

Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 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	$ 199	$ 217
Duke Energy Carolinas [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6	5
Duke Energy Carolinas [Member] | Joint Dispatch Agreement [Member] | Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	16	9
Related party transaction, expenses from transactions with related party	31	41
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	1
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	169	174
Progress Energy [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	10	9
Progress Energy [Member] | Joint Dispatch Agreement [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	31	41
Related party transaction, expenses from transactions with related party	16	9
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	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	103	100
Duke Energy Progress [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	4	4
Duke Energy Progress [Member] | Joint Dispatch Agreement [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	31	41
Related party transaction, expenses from transactions with related party	16	9
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	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	66	74
Duke Energy Florida [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6	5
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	90	85
Duke Energy Ohio [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1	1
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	90	94
Duke Energy Indiana [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] | Corporate Governance And Shared Service Expenses [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6
Piedmont Natural Gas [Member] | Indemnification Coverages [Member] | Affiliated Entity [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	1
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	$ 20
Piedmont Natural Gas [Member] | Intercompany Natural Gas Transactions [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party		1
Piedmont Natural Gas [Member] | Intercompany Natural Gas Transactions [Member] | Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party		$ 19

Related Party Transactions (Equ

Related Party Transactions (Equity Method Investments) (Details) - Piedmont Natural Gas [Member] - Equity Method Investee [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Accounts Payable, Related Parties, Current	$ 2		$ 2
Related party transaction, expenses from transactions with related party	6	$ 7
Cardinal Pipeline Company, LLC [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	2	2
Pine Needle LNG Company, LLC [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	2	3
Hardy Storage Company, LLC [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 2	$ 2

Related Party Transactions (Int

Related Party Transactions (Intercompany Income Taxes) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	$ 109	$ 163
Intercompany income tax payable	250	247
Progress Energy [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	2	106
Intercompany income tax payable	316	348
Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	6	5
Intercompany income tax payable	244	227
Duke Energy Florida [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	2	5
Intercompany income tax payable	77	125
Duke Energy Ohio [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	88	129
Intercompany income tax payable	64	63
Duke Energy Indiana [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	88	114
Intercompany income tax payable	75	74
Piedmont Natural Gas [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	7	7
Intercompany income tax payable	3	8
Income Taxes [Member] | Affiliated Entity [Member] | Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	19	1
Income Taxes [Member] | Affiliated Entity [Member] | Progress Energy [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	139
Intercompany income tax payable		37
Income Taxes [Member] | Affiliated Entity [Member] | Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	47
Intercompany income tax payable		90
Income Taxes [Member] | Affiliated Entity [Member] | Duke Energy Florida [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	48	37
Income Taxes [Member] | Affiliated Entity [Member] | Duke Energy Ohio [Member]
Related Party Transaction [Line Items]
Intercompany income tax receivable	8
Intercompany income tax payable		1
Income Taxes [Member] | Affiliated Entity [Member] | Duke Energy Indiana [Member]
Related Party Transaction [Line Items]
Intercompany income tax payable	23	3
Income Taxes [Member] | Affiliated Entity [Member] | Piedmont Natural Gas [Member]
Related Party Transaction [Line Items]
Intercompany income tax payable	$ 44	$ 38

Derivatives and Hedging (Notion

Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Mcf in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017USD ($)GWhMcf	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)GWhMcf
Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	184		147
Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Mcf	817		890
Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 1,677
Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	750
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	927
Variable Interest Entity, Primary Beneficiary [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 750		$ 750
Piedmont Natural Gas [Member]
Derivative [Line Items]
Notional amount		$ 1,400
Gain (Loss) on Interest Rate Derivative Instruments Not Designated as Hedging Instruments		$ 93
Duke Energy Carolinas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Mcf	85		91
Duke Energy Carolinas [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 400
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 400
Progress Energy [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Mcf	228		269
Progress Energy [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 500
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 500
Duke Energy Progress [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Mcf	105		118
Duke Energy Progress [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250
Duke Energy Florida [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Mcf	123		151
Duke Energy Florida [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 250
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	250
Duke Energy Ohio [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	27
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Notional amount	$ 27
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	184		147
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Mcf			1
Piedmont Natural Gas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of decatherms | Mcf	504		529

Derivatives and Hedging (Locati

Derivatives and Hedging (Location and Fair Value Amounts of Derivatives Reflected in the Condensed Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	$ 83	$ 162
Location and fair value amounts of derivatives (Liability)	216	252
Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	60	111
Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	23	51
Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	41	52
Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	175	200
Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	63	140
Location and fair value amounts of derivatives (Liability)	177	209
Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	20	22
Location and fair value amounts of derivatives (Liability)	39	43
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	18	19
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	8	8
Designated As Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	9	8
Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	58	108
Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	5	32
Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	32	43
Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	145	166
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	1
Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	21	26
Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	17	33
Location and fair value amounts of derivatives (Liability)	14	16
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	16	23
Duke Energy Carolinas [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	10
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	14	16
Duke Energy Carolinas [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	17	33
Location and fair value amounts of derivatives (Liability)	4	1
Duke Energy Carolinas [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	10	15
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	16	23
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	10
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	1
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	10	15
Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	34	85
Location and fair value amounts of derivatives (Liability)	34	25
Progress Energy [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	32	64
Progress Energy [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	21
Progress Energy [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	17	12
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	17	13
Progress Energy [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	32	82
Location and fair value amounts of derivatives (Liability)	28	19
Progress Energy [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Location and fair value amounts of derivatives (Liability)	6	6
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	30	61
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	21
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	17	12
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	11	7
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	6
Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	20	46
Location and fair value amounts of derivatives (Liability)	10	7
Duke Energy Progress [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	19	36
Duke Energy Progress [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	10
Duke Energy Progress [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	9	7
Duke Energy Progress [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	20	45
Location and fair value amounts of derivatives (Liability)	5	1
Duke Energy Progress [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Location and fair value amounts of derivatives (Liability)	5	6
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	19	35
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	10
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	1
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [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)	14	39
Location and fair value amounts of derivatives (Liability)	19	12
Duke Energy Florida [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	13	28
Duke Energy Florida [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	11
Duke Energy Florida [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	17	12
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	2
Duke Energy Florida [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12	37
Location and fair value amounts of derivatives (Liability)	18	12
Duke Energy Florida [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	2
Location and fair value amounts of derivatives (Liability)	1
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	11	26
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	11
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	17	12
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	2
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1
Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	5
Location and fair value amounts of derivatives (Liability)	5	6
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		4
Duke Energy Ohio [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	1
Duke Energy Ohio [Member] | Current Liabilities, Other [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	5
Duke Energy Ohio [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	5
Duke Energy Ohio [Member] | Interest Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5	6
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		4
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Noncurrent Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1	1
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contracts [Member] | Current Liabilities, Other [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 Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	4	5
Duke Energy Indiana [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	9	16
Location and fair value amounts of derivatives (Liability)		2
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	9	16
Duke Energy Indiana [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		2
Duke Energy Indiana [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	9	16
Location and fair value amounts of derivatives (Liability)		2
Duke Energy Indiana [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	9	16
Duke Energy Indiana [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		2
Piedmont Natural Gas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Location and fair value amounts of derivatives (Liability)	145	187
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Piedmont Natural Gas [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	14	35
Piedmont Natural Gas [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	131	152
Piedmont Natural Gas [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Location and fair value amounts of derivatives (Liability)	145	187
Piedmont Natural Gas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	3
Piedmont Natural Gas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	14	35
Piedmont Natural Gas [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contracts [Member] | Other Noncurrent Liabilities [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	$ 131	$ 152

Derivatives and Hedging (Schedu

Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 83	$ 162
Net amounts recognized on the Condensed Consolidated Balance Sheet	83	162
Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	60	111
Gross amounts offset	(7)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	53	100
Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	23	51
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	21	49
Duke Energy Carolinas [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	17	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	17	33
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	16	23
Net amounts recognized on the Condensed Consolidated Balance Sheet	16	23
Duke Energy Carolinas [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	10
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet		9
Progress Energy [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	34	85
Net amounts recognized on the Condensed Consolidated Balance Sheet	34	85
Progress Energy [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	32	64
Gross amounts offset	(7)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	25	53
Progress Energy [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	21
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	20
Duke Energy Progress [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	20	46
Net amounts recognized on the Condensed Consolidated Balance Sheet	20	46
Duke Energy Progress [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	19	36
Gross amounts offset	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	18	36
Duke Energy Progress [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	10
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet		9
Duke Energy Florida [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	14	39
Net amounts recognized on the Condensed Consolidated Balance Sheet	14	39
Duke Energy Florida [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	13	28
Gross amounts offset	(6)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	7	17
Duke Energy Florida [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	11
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	11
Duke Energy Ohio [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	5
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	5
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		4
Net amounts recognized on the Condensed Consolidated Balance Sheet		4
Duke Energy Ohio [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	1
Duke Energy Indiana [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	9	16
Net amounts recognized on the Condensed Consolidated Balance Sheet	9	16
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	9	16
Net amounts recognized on the Condensed Consolidated Balance Sheet	9	16
Piedmont Natural Gas [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	3
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 2	$ 3

Derivatives and Hedging (Sche71

Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 216	$ 252
Net amounts recognized on the Condensed Consolidated Balance Sheet	216	252
Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	41	52
Gross amounts offset	(7)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	34	41
Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	175	200
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	173	198
Duke Energy Carolinas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	14	16
Net amounts recognized on the Condensed Consolidated Balance Sheet	14	16
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	14	16
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	13	15
Progress Energy [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	34	25
Net amounts recognized on the Condensed Consolidated Balance Sheet	34	25
Progress Energy [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	17	12
Gross amounts offset	(7)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	10	1
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	17	13
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	16	12
Duke Energy Progress [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	10	7
Net amounts recognized on the Condensed Consolidated Balance Sheet	10	7
Duke Energy Progress [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1
Gross amounts offset	(1)
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	9	7
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	6
Duke Energy Florida [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	19	12
Net amounts recognized on the Condensed Consolidated Balance Sheet	19	12
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	17	12
Gross amounts offset	(6)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	11	1
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	2
Net amounts recognized on the Condensed Consolidated Balance Sheet	2
Duke Energy Ohio [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	5	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	6
Duke Energy Ohio [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	1
Duke Energy Ohio [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	4	5
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	5
Duke Energy Indiana [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		2
Net amounts recognized on the Condensed Consolidated Balance Sheet		2
Duke Energy Indiana [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		2
Net amounts recognized on the Condensed Consolidated Balance Sheet		2
Piedmont Natural Gas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	145	187
Net amounts recognized on the Condensed Consolidated Balance Sheet	145	187
Piedmont Natural Gas [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	14	35
Net amounts recognized on the Condensed Consolidated Balance Sheet	14	35
Piedmont Natural Gas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	131	152
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 131	$ 152

Derivatives and Hedging (Deriva

Derivatives and Hedging (Derivative Instruments with Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	$ 40	$ 34
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	40	34
Duke Energy Carolinas [Member]
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	14	16
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	14	16
Progress Energy [Member]
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	25	18
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	25	18
Duke Energy Progress [Member]
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	9	6
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	9	6
Duke Energy Florida [Member]
Schedule of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value amounts of derivative instruments in a net liability position	17	12
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	$ 17	$ 12

Investments in Debt and Equit73

Investments in Debt and Equity Securities (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 5	$ 5
Piedmont Natural Gas [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities	$ 5	$ 5

Investments in Debt and Equit74

Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 2,320	$ 2,156
Gross Unrealized Holding Losses	57	88
Estimated Fair Value	6,744	6,554
Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2,273	2,115
Gross Unrealized Holding Losses	54	83
Estimated Fair Value	6,391	6,184
Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	114	111
Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2,250	2,092
Gross Unrealized Holding Losses	32	54
Estimated Fair Value	4,284	4,106
Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10	10
Gross Unrealized Holding Losses	5	8
Estimated Fair Value	576	528
Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	3
Gross Unrealized Holding Losses	6	10
Estimated Fair Value	336	331
Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	10	10
Gross Unrealized Holding Losses	8	8
Estimated Fair Value	949	984
Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	3	3
Estimated Fair Value	132	124
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	47	41
Gross Unrealized Holding Losses	3	5
Estimated Fair Value	353	370
Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	18	25
Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	44	38
Estimated Fair Value	106	104
Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1	1
Gross Unrealized Holding Losses		1
Estimated Fair Value	60	66
Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	2
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	84	82
Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses		1
Estimated Fair Value	43	51
Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	2	2
Estimated Fair Value	42	42
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,238	1,165
Gross Unrealized Holding Losses	29	45
Estimated Fair Value	3,395	3,261
Duke Energy Carolinas [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,238	1,165
Gross Unrealized Holding Losses	28	44
Estimated Fair Value	3,392	3,258
Duke Energy Carolinas [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	20	18
Duke Energy Carolinas [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,229	1,157
Gross Unrealized Holding Losses	15	28
Estimated Fair Value	2,366	2,245
Duke Energy Carolinas [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	5
Gross Unrealized Holding Losses	4	6
Estimated Fair Value	388	354
Duke Energy Carolinas [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1	1
Gross Unrealized Holding Losses	1	2
Estimated Fair Value	67	67
Duke Energy Carolinas [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	2
Gross Unrealized Holding Losses	5	5
Estimated Fair Value	431	458
Duke Energy Carolinas [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	3	3
Estimated Fair Value	120	116
Duke Energy Carolinas [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	3	3
Duke Energy Carolinas [Member] | Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	3	3
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,037	952
Gross Unrealized Holding Losses	26	39
Estimated Fair Value	3,057	2,991
Progress Energy [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,035	950
Gross Unrealized Holding Losses	26	39
Estimated Fair Value	2,999	2,926
Progress Energy [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	94	93
Progress Energy [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,021	935
Gross Unrealized Holding Losses	17	26
Estimated Fair Value	1,918	1,861
Progress Energy [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	5
Gross Unrealized Holding Losses	1	2
Estimated Fair Value	188	174
Progress Energy [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	2
Gross Unrealized Holding Losses	5	8
Estimated Fair Value	269	264
Progress Energy [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	7	8
Gross Unrealized Holding Losses	3	3
Estimated Fair Value	518	526
Progress Energy [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	12	8
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	2
Estimated Fair Value	58	65
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	12	21
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	2
Estimated Fair Value	46	44
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	783	715
Gross Unrealized Holding Losses	21	32
Estimated Fair Value	2,275	2,214
Duke Energy Progress [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	783	715
Gross Unrealized Holding Losses	21	32
Estimated Fair Value	2,274	2,213
Duke Energy Progress [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	43	45
Duke Energy Progress [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	772	704
Gross Unrealized Holding Losses	13	21
Estimated Fair Value	1,541	1,505
Duke Energy Progress [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	4
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	131	120
Duke Energy Progress [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	2
Gross Unrealized Holding Losses	5	8
Estimated Fair Value	268	263
Duke Energy Progress [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	5
Gross Unrealized Holding Losses	2	2
Estimated Fair Value	284	275
Duke Energy Progress [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	7	5
Duke Energy Progress [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	1
Duke Energy Progress [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	1
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	254	237
Gross Unrealized Holding Losses	5	7
Estimated Fair Value	772	761
Duke Energy Florida [Member] | Ndtf [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	252	235
Gross Unrealized Holding Losses	5	7
Estimated Fair Value	725	713
Duke Energy Florida [Member] | Ndtf [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	51	48
Duke Energy Florida [Member] | Ndtf [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	249	231
Gross Unrealized Holding Losses	4	5
Estimated Fair Value	377	356
Duke Energy Florida [Member] | Ndtf [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1	1
Gross Unrealized Holding Losses		1
Estimated Fair Value	57	54
Duke Energy Florida [Member] | Ndtf [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	1
Duke Energy Florida [Member] | Ndtf [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	3
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	234	251
Duke Energy Florida [Member] | Ndtf [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	5	3
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	2
Estimated Fair Value	47	48
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	1	4
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	2	2
Estimated Fair Value	46	44
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	38	33
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	115	110
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	38	33
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	115	110
Duke Energy Indiana [Member] | Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	38	33
Estimated Fair Value	84	79
Duke Energy Indiana [Member] | Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	2	2
Duke Energy Indiana [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	28	28
Duke Energy Indiana [Member] | Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	$ 1	$ 1

Investments in Debt and Equit75

Investments in Debt and Equity Securities (Maturities) (Details) $ in Millions	Mar. 31, 2017USD ($)
Debt Instrument [Line Items]
Due in one year or less	$ 82
Due after one through five years	640
Due after five through 10 years	514
Due after 10 years	986
Total	2,222
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Due in one year or less	2
Due after one through five years	221
Due after five through 10 years	269
Due after 10 years	517
Total	1,009
Progress Energy [Member]
Debt Instrument [Line Items]
Due in one year or less	72
Due after one through five years	355
Due after five through 10 years	189
Due after 10 years	417
Total	1,033
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Due in one year or less	17
Due after one through five years	215
Due after five through 10 years	142
Due after 10 years	316
Total	690
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Due in one year or less	55
Due after one through five years	140
Due after five through 10 years	47
Due after 10 years	101
Total	343
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Due in one year or less	2
Due after one through five years	15
Due after five through 10 years	9
Due after 10 years	5
Total	$ 31

Investments in Debt and Equit76

Investments in Debt and Equity Securities (Realized Gains and Losses)(Details) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	$ 93	$ 54
Realized losses	62	50
Duke Energy Carolinas [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	66	34
Realized losses	40	37
Progress Energy [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	27	19
Realized losses	21	13
Duke Energy Progress [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	24	15
Realized losses	19	11
Duke Energy Florida [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	3	4
Realized losses	$ 2	$ 2

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Measurement Amounts for Assets and Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	$ 83	$ 162
Total assets	6,832	6,716
Derivative liabilities	(216)	(252)
Net assets (liabilities)	6,616	6,464
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2	5
Total assets	4,982	4,845
Derivative liabilities	0	(2)
Net assets (liabilities)	4,982	4,843
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	71	136
Total assets	1,758	1,768
Derivative liabilities	(71)	(63)
Net assets (liabilities)	1,687	1,705
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	10	21
Total assets	15	26
Derivative liabilities	(145)	(187)
Net assets (liabilities)	(130)	(161)
Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative Investments, Fair Value Disclosure	77	77
Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative Investments, Fair Value Disclosure	77	77
Investments	4,284	4,106
Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	4,207	4,029
Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	110	104
Equity Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	110	104
Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,107	2,078
Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	602	632
Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,505	1,446
Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	248	266
Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	61	75
Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	182	186
Debt Securities [Member] | Other Classification [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	5	5
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	17	33
Total assets	3,412	3,294
Derivative liabilities	(14)	(16)
Net assets (liabilities)	3,398	3,278
Duke Energy Carolinas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0
Total assets	2,435	2,346
Net assets (liabilities)	2,435	2,346
Duke Energy Carolinas [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	17	33
Total assets	897	868
Derivative liabilities	(14)	(16)
Net assets (liabilities)	883	852
Duke Energy Carolinas [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	3	3
Net assets (liabilities)	3	3
Duke Energy Carolinas [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative Investments, Fair Value Disclosure	77	77
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Alternative Investments, Fair Value Disclosure	77	77
Investments	2,366	2,245
Duke Energy Carolinas [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,289	2,168
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,026	1,013
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	146	178
Duke Energy Carolinas [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	880	835
Duke Energy Carolinas [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Duke Energy Carolinas [Member] | Debt Securities [Member] | Other Classification [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	34	85
Total assets	3,091	3,076
Derivative liabilities	(34)	(25)
Net assets (liabilities)	3,057	3,051
Progress Energy [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0
Total assets	2,386	2,336
Net assets (liabilities)	2,386	2,336
Progress Energy [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	34	85
Total assets	705	740
Derivative liabilities	(34)	(25)
Net assets (liabilities)	671	715
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,918	1,861
Progress Energy [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,918	1,861
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,081	1,065
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	456	454
Progress Energy [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	625	611
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	58	65
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	12	21
Progress Energy [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	46	44
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	20	46
Total assets	2,295	2,260
Derivative liabilities	(10)	(7)
Net assets (liabilities)	2,285	2,253
Duke Energy Progress [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0
Total assets	1,763	1,713
Net assets (liabilities)	1,763	1,713
Duke Energy Progress [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	20	46
Total assets	532	547
Derivative liabilities	(10)	(7)
Net assets (liabilities)	522	540
Duke Energy Progress [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,541	1,505
Duke Energy Progress [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,541	1,505
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	733	708
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	221	207
Duke Energy Progress [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	512	501
Duke Energy Progress [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1	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	1
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	14	39
Total assets	786	800
Derivative liabilities	(19)	(12)
Net assets (liabilities)	767	788
Duke Energy Florida [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	613	607
Net assets (liabilities)	613	607
Duke Energy Florida [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	14	39
Total assets	173	193
Derivative liabilities	(19)	(12)
Net assets (liabilities)	154	181
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	377	356
Duke Energy Florida [Member] | Equity Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	377	356
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	348	357
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	235	247
Duke Energy Florida [Member] | Debt Securities [Member] | Ndtf [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	113	110
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	47	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	4
Duke Energy Florida [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	46	44
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	1	5
Derivative liabilities	(5)	(6)
Net assets (liabilities)	(4)	(1)
Duke Energy Ohio [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(5)	(6)
Net assets (liabilities)	(5)	(6)
Duke Energy Ohio [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	1	5
Net assets (liabilities)	1	5
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	9	16
Total assets		126
Derivative liabilities		(2)
Net assets (liabilities)	124	124
Duke Energy Indiana [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0
Total assets		79
Derivative liabilities		(2)
Net assets (liabilities)	84	77
Duke Energy Indiana [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets		31
Net assets (liabilities)	31	31
Duke Energy Indiana [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	9	16
Total assets		16
Net assets (liabilities)	9	16
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	84	79
Duke Energy Indiana [Member] | Equity Securities [Member] | Other Classification [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	84	79
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	31	31
Duke Energy Indiana [Member] | Debt Securities [Member] | Other Classification [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	31	31
Piedmont Natural Gas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2	3
Total assets	7	8
Derivative liabilities	(145)	(187)
Net assets (liabilities)	(138)	(179)
Piedmont Natural Gas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2	3
Total assets	7	8
Net assets (liabilities)	7	8
Piedmont Natural Gas [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative liabilities	(145)	(187)
Net assets (liabilities)	(145)	(187)
Piedmont Natural Gas [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	4	4
Piedmont Natural Gas [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	4	4
Piedmont Natural Gas [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1	1
Piedmont Natural Gas [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 1	$ 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 ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivatives (net)
Beginning balance	$ (166)	$ 10
Settlements	(9)	(7)
Total amount included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities	40	(1)
Ending balance	(135)	2
Investments and Derivatives, Net
Beginning balance	(161)	15
Sales		(1)
Settlements	(9)	(7)
Total amount included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities	40	(1)
Ending balance	(130)	6
Investments [Member]
Investments
Beginning balance	5	5
Sales		(1)
Ending balance	5	4
Duke Energy Ohio [Member]
Derivatives (net)
Beginning balance	5	3
Settlements	(1)	(2)
Total amount included on the Condensed Consolidated Balance Sheet as regulatory assets or liabilities	(3)	(1)
Ending balance	1
Duke Energy Indiana [Member]
Derivatives (net)
Beginning balance	16	7
Settlements	(7)	(5)
Ending balance	9	2
Piedmont Natural Gas [Member]
Derivatives (net)
Beginning balance	(187)	(149)
Total gains and settlements	42	23
Ending balance	$ (145)	$ (126)

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Level 3 Fair Value Disclosure - Assets) (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017USD ($)$ / MWh	Dec. 31, 2016USD ($)$ / MWh	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net derivative asset (liability)	$ (135)	$ (166)	$ 2	$ 10
Duke Energy Ohio [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net derivative asset (liability)	1	5		3
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net derivative asset (liability)	$ 1	$ 5
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input Price Per Unit | $ / MWh	0.23	0.77
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input Price Per Unit | $ / MWh	2.02	3.52
Duke Energy Indiana [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net derivative asset (liability)	$ 9	$ 16	$ 2	$ 7
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Net derivative asset (liability)	$ 9	$ 16
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input Price Per Unit | $ / MWh	(1.08)	(0.83)
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Input Price Per Unit | $ / MWh	5.33	9.32

Fair Value Measurements (Quan80

Fair Value Measurements (Quantitative Level 3 Fair Value Disclosure - Liabilities) (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017USD ($)$ / MMBTU	Dec. 31, 2016USD ($)$ / MMBTU	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Net derivative asset (liability)	$ (135)	$ (166)	$ 2	$ 10
Piedmont Natural Gas [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Net derivative asset (liability)	(145)	(187)	$ (126)	$ (149)
Derivative Financial Instruments, Liabilities [Member] | Discounted Cash Flow [Member] | Piedmont Natural Gas [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Net derivative asset (liability)	$ (145)	$ (187)
Derivative Financial Instruments, Liabilities [Member] | Minimum [Member] | Discounted Cash Flow [Member] | Piedmont Natural Gas [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair Value Input Price Per Unit | $ / MMBTU	2.08	2.31
Derivative Financial Instruments, Liabilities [Member] | Maximum [Member] | Discounted Cash Flow [Member] | Piedmont Natural Gas [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair Value Input Price Per Unit | $ / MMBTU	3.57	4.18

Fair Value Measurements (Additi

Fair Value Measurements (Additional Fair Value Disclosure) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	$ 48,998	$ 47,895
Long-term debt, fair value	50,480	49,161
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	9,491	9,603
Long-term debt, fair value	10,405	10,494
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	18,148	17,541
Long-term debt, fair value	19,742	19,107
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	6,761	7,011
Long-term debt, fair value	7,103	7,357
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	6,981	6,125
Long-term debt, fair value	7,596	6,728
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,977	1,884
Long-term debt, fair value	2,122	2,020
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	3,784	3,786
Long-term debt, fair value	4,292	4,260
Piedmont Natural Gas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term Debt	1,821	1,821
Long-term debt, fair value	$ 1,954	$ 1,933

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 1,587
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [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
Duke American Transmission Company [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	50.00%
Pioneer Transmission [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	50.00%
OVEC [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	9.00%
Duke Energy Florida [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 900
Duke Energy Florida [Member] | DEFPF [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	1,294
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Debt Instrument, Face Amount	$ 100
Duke Energy Ohio [Member] | Cinergy Receivables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%
Duke Energy Indiana [Member] | Cinergy Receivables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%

Variable Interest Entities (Sch

Variable Interest Entities (Schedule of Accounts Receivable Securitizations) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entities [Line Items]
Long-Term Debt	$ 47,021	$ 45,576
Duke Energy Carolinas [Member]
Variable Interest Entities [Line Items]
Long-Term Debt	8,787	9,187
Duke Energy Progress [Member]
Variable Interest Entities [Line Items]
Long-Term Debt	6,409	6,409
Duke Energy Florida [Member]
Variable Interest Entities [Line Items]
Long-Term Debt	$ 6,662	5,799
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Dec. 1, 2018
Facility size	$ 325
Long-Term Debt	$ 325	325
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Dec. 1, 2018
Facility size	$ 425
Long-Term Debt	$ 425	425
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Feb. 1, 2019
Facility size	$ 300
Long-Term Debt	$ 300	300
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Line of Credit Facility, Expiration Date	Apr. 1, 2019
Facility size	$ 225
Long-Term Debt	$ 225	$ 225

Variable Interest Entities (S84

Variable Interest Entities (Schedule of Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	$ 1,031	$ 1,023
Current Assets: Other	425	458
Other Noncurrent Assets: Regulatory assets	12,838	12,878
Property, plant and equipment, cost	123,301	121,397
Accumulated depreciation and amortization	(40,293)	(39,406)
Current Liabilities: Other	1,570	2,044
Current maturities of long-term debt	1,977	2,319
Long-Term Debt	47,021	45,576
Deferred income taxes	14,443	14,155
Noncurrent Liabilities: Other	1,707	1,753
Duke Energy Carolinas [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	233	238
Current Assets: Other	65	37
Other Noncurrent Assets: Regulatory assets	3,098	3,159
Property, plant and equipment, cost	41,600	41,127
Accumulated depreciation and amortization	(14,649)	(14,365)
Current Liabilities: Other	345	468
Current maturities of long-term debt	404	116
Long-Term Debt	8,787	9,187
Deferred income taxes	6,668	6,544
Noncurrent Liabilities: Other	595	607
Duke Energy Progress [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	187	188
Current Assets: Other	102	57
Other Noncurrent Assets: Regulatory assets	3,338	3,243
Property, plant and equipment, cost	28,769	28,419
Accumulated depreciation and amortization	(10,716)	(10,561)
Current Liabilities: Other	294	365
Current maturities of long-term debt	202	452
Long-Term Debt	6,409	6,409
Deferred income taxes	3,453	3,323
Noncurrent Liabilities: Other	49	51
Duke Energy Florida [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Regulatory assets	260	213
Current Assets: Other	104	125
Other Noncurrent Assets: Regulatory assets	2,476	2,480
Property, plant and equipment, cost	17,122	16,434
Accumulated depreciation and amortization	(4,894)	(4,644)
Current Liabilities: Other	309	352
Current maturities of long-term debt	319	326
Long-Term Debt	6,662	5,799
Deferred income taxes	2,800	2,694
Noncurrent Liabilities: Other	104	105
DEFPF [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Receivables of VIEs	4	6
Current Assets: Regulatory assets	53	50
Current Assets: Other	14	53
Other Noncurrent Assets: Regulatory assets	1,131	1,142
Current Liabilities: Other	3	17
Current maturities of long-term debt	55	62
Long-Term Debt	1,189	1,217
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Long-Term Debt	425	425
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
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]
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]
Long-Term Debt	325	325
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Current Assets: Other	336	223
Property, plant and equipment, cost	3,671	3,419
Accumulated depreciation and amortization	(448)	(453)
Current maturities of long-term debt	227	198
Long-Term Debt	1,645	1,097
Deferred income taxes	321	275
Noncurrent Liabilities: Other	$ 251	$ 252

Variable Interest Entities (S85

Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entities [Line Items]
Other noncurrent assets	$ 2,754	$ 2,769
Taxes accrued	363	384
Current Liabilities: Other	1,570	2,044
Deferred income taxes	14,443	14,155
Noncurrent Liabilities: Other	1,707	1,753
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	938	751
Other noncurrent assets	12	12
Total assets	950	763
Taxes accrued	23
Current Liabilities: Other	2	3
Deferred income taxes	(7)
Noncurrent Liabilities: Other	13	13
Total liabilities	31	16
Net assets	919	747
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	673	487
Other noncurrent assets	12	12
Total assets	685	499
Taxes accrued	23
Deferred income taxes	(7)
Total liabilities	16
Net assets	669	499
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	173	174
Total assets	173	174
Net assets	173	174
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	92	90
Total assets	92	90
Current Liabilities: Other	2	3
Noncurrent Liabilities: Other	13	13
Total liabilities	15	16
Net assets	77	74
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	88	129
Other noncurrent assets	23	23
Taxes accrued	127	178
Current Liabilities: Other	83	91
Deferred income taxes	1,472	1,443
Noncurrent Liabilities: Other	166	166
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	53	82
Total assets	53	82
Net assets	53	82
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	88	114
Other noncurrent assets	156	147
Taxes accrued	72	31
Current Liabilities: Other	75	93
Deferred income taxes	1,921	1,900
Noncurrent Liabilities: Other	24	27
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	69	101
Total assets	69	101
Net assets	69	101
Piedmont Natural Gas [Member]
Variable Interest Entities [Line Items]
Receivables from affiliated companies	7	7
Other noncurrent assets	19	21
Taxes accrued	69	67
Current Liabilities: Other	70	102
Deferred income taxes	981	931
Noncurrent Liabilities: Other	169	189
Piedmont Natural Gas [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	152	139
Total assets	152	139
Taxes accrued	(1)
Deferred income taxes	4
Noncurrent Liabilities: Other		4
Total liabilities	3	4
Net assets	149	135
Piedmont Natural Gas [Member] | Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Investments in equity method unconsolidated affiliates	$ 152	$ 139

Variable Interest Entities (Pip

Variable Interest Entities (Pipeline Investments) (Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Variable Interest Entities [Line Items]
Investments in Joint Ventures	$ 938	$ 751
Atlantic Coast Pipeline [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	47.00%
Investments in Joint Ventures	$ 403	265
Sabal Trail Transmission Pipeline [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	7.50%
Investments in Joint Ventures	$ 188	140
Constitution Pipeline [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	24.00%
Investments in Joint Ventures	$ 82	82
Pipeline Investments [Member]
Variable Interest Entities [Line Items]
Investments in Joint Ventures	673	487
Piedmont Natural Gas [Member]
Variable Interest Entities [Line Items]
Investments in Joint Ventures	$ 152	139
Piedmont Natural Gas [Member] | Atlantic Coast Pipeline [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	7.00%
Investments in Joint Ventures	$ 59	46
Piedmont Natural Gas [Member] | Constitution Pipeline [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity Ownership Interest	24.00%
Investments in Joint Ventures	$ 93	93
Piedmont Natural Gas [Member] | Pipeline Investments [Member]
Variable Interest Entities [Line Items]
Investments in Joint Ventures	$ 152	$ 139

Variable Interest Entities (Fai

Variable Interest Entities (Fair Value Assumptions)(Details) - Cinergy Receivables [Member]	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Anticipated credit loss ratio	0.50%	0.50%
Discount rate	1.80%	1.50%
Receivable turnover rate	13.40%	13.30%
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Anticipated credit loss ratio	0.30%	0.30%
Discount rate	1.80%	1.50%
Receivable turnover rate	10.70%	10.60%

Variable Interest Entities (Rec

Variable Interest Entities (Receivables Sold)(Details) - Cinergy Receivables [Member] - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables sold	$ 238	$ 267
Less: Retained interests	53	82
Net receivables sold	185	185
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables sold	277	306
Less: Retained interests	69	101
Net receivables sold	$ 208	$ 205

Variable Interest Entities (Sal

Variable Interest Entities (Sales and Cash Flows)(Details) - Cinergy Receivables [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Duke Energy Ohio [Member]
Variable Interest Entities [Line Items]
Receivables sold	$ 533	$ 532
Loss recognized on sale	2	3
Cash proceeds from receivables sold	559	537
Return received on retained interests	1	1
Duke Energy Indiana [Member]
Variable Interest Entities [Line Items]
Receivables sold	664	635
Loss recognized on sale	3	3
Cash proceeds from receivables sold	693	643
Return received on retained interests	$ 2	$ 1

Common Stock (Earnings Per Shar

Common Stock (Earnings Per Share Data)(Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Common Stock [Line Items]
Income from continuing operations attributable to Duke Energy common stockholders excluding impact of participating securities	$ 715	$ 574
Average shares, basic	700	689
Average shares, diluted	700	689
EPS, basic (usd per share)	$ 1.02	$ 0.83
EPS, diluted (usd per share)	$ 1.02	$ 0.83
Number of stock options and performance and unvested stock awards excluded from the dilutive securities calculation	2	2
Dividends declared per share (usd per share)	$ 0.855	$ 0.825

Common Stock (Equity Securities

Common Stock (Equity Securities Offering) (Details) shares in Millions	Mar. 31, 2016shares
Piedmont Natural Gas [Member]
Forward Contract Indexed to Issuer's Equity [Line Items]
Shares offered	10.6

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule of Stock-Based Compensation Expense) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation cost	$ 15	$ 12
Tax benefit associated with stock-based compensation expense	5	4
Stock-based compensation costs capitalized	1	1
Restricted Stock Units Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation cost	8	7
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation cost	$ 7	5
Piedmont Natural Gas [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation cost		$ 2

Employee Benefit Plans (Plan Co

Employee Benefit Plans (Plan Contributions) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Qualified Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	$ 0	$ 0

Employee Benefit Plans (Compone

Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Qualified Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 40	$ 36
Interest cost on projected benefit obligation	82	83
Expected return on plan assets	(136)	(129)
Amortization of actuarial loss (gain)	36	33
Amortization of prior service credit	(6)	(4)
Other	2	3
Net periodic costs	18	22
Qualified Pension Plan [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	12	12
Interest cost on projected benefit obligation	20	21
Expected return on plan assets	(35)	(35)
Amortization of actuarial loss (gain)	8	8
Amortization of prior service credit	(2)	(2)
Other		1
Net periodic costs	3	5
Qualified Pension Plan [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	12	11
Interest cost on projected benefit obligation	25	26
Expected return on plan assets	(43)	(42)
Amortization of actuarial loss (gain)	14	14
Amortization of prior service credit	(1)	(1)
Other	1	1
Net periodic costs	8	9
Qualified Pension Plan [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	6
Interest cost on projected benefit obligation	12	12
Expected return on plan assets	(21)	(21)
Amortization of actuarial loss (gain)	6	6
Net periodic costs	3	3
Qualified Pension Plan [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	5	5
Interest cost on projected benefit obligation	13	14
Expected return on plan assets	(21)	(21)
Amortization of actuarial loss (gain)	7	7
Net periodic costs	4	5
Qualified Pension Plan [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1
Interest cost on projected benefit obligation	5	5
Expected return on plan assets	(7)	(7)
Amortization of actuarial loss (gain)	1	1
Qualified Pension Plan [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2	2
Interest cost on projected benefit obligation	7	7
Expected return on plan assets	(11)	(10)
Amortization of actuarial loss (gain)	3	3
Net periodic costs	1	2
Qualified Pension Plan [Member] | Piedmont Natural Gas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	3
Interest cost on projected benefit obligation	3	2
Expected return on plan assets	(6)	(6)
Amortization of actuarial loss (gain)	3	2
Amortization of prior service credit	(1)
Net periodic costs	2	1
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1
Interest cost on projected benefit obligation	9	8
Expected return on plan assets	(3)	(3)
Amortization of actuarial loss (gain)	2	1
Amortization of prior service credit	(29)	(35)
Net periodic costs	(20)	(28)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	2
Expected return on plan assets	(2)	(2)
Amortization of actuarial loss (gain)	(1)	(1)
Amortization of prior service credit	(2)	(3)
Net periodic costs	(3)	(4)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	4	4
Amortization of actuarial loss (gain)	5	5
Amortization of prior service credit	(21)	(26)
Net periodic costs	(12)	(17)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	2
Amortization of actuarial loss (gain)	3	3
Amortization of prior service credit	(14)	(17)
Net periodic costs	(9)	(12)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	2
Amortization of actuarial loss (gain)	2	2
Amortization of prior service credit	(8)	(9)
Net periodic costs	$ (4)	(5)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation		1
Amortization of actuarial loss (gain)		$ (1)

Employee Benefit Plans (Employe

Employee Benefit Plans (Employee Savings Plans) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Employee Savings Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	$ 65	$ 52
Employee Savings Plan [Member] | Duke Energy Carolinas [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	22	18
Employee Savings Plan [Member] | Progress Energy [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	18	15
Employee Savings Plan [Member] | Duke Energy Progress [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	13	11
Employee Savings Plan [Member] | Duke Energy Florida [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	5	4
Employee Savings Plan [Member] | Duke Energy Ohio [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	1	1
Employee Savings Plan [Member] | Duke Energy Indiana [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	3	2
Employee Savings Plan [Member] | Piedmont Natural Gas [Member]
Defined Contribution Plan Disclosure [Line Items]
Employer contributions	2	$ 2
Pension Plan [Member] | Piedmont Natural Gas [Member]
Defined Contribution Plan Disclosure [Line Items]
Pension Contributions	$ 2

Income Taxes (Effective Tax Rat

Income Taxes (Effective Tax Rates) (Details)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Effective tax rate	32.40%	30.40%
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]
Effective tax rate	35.40%	34.10%
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]
Effective tax rate	34.10%	36.70%
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]
Effective tax rate	34.10%	35.40%
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]
Effective tax rate	36.60%	37.90%
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]
Effective tax rate	35.40%	26.90%
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]
Effective tax rate	39.30%	30.20%
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]
Effective tax rate	37.90%	38.00%

Income Taxes Income Taxes (Taxe

Income Taxes Income Taxes (Taxes on Foreign Earnings) (Details) - Discontinued Operations, Disposed of by Sale [Member] - International Energy [Member] $ in Millions	3 Months Ended
	Mar. 31, 2016USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax benefit	$ (39)
Previously Remitted Earnings [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax benefit	$ (95)