Progress Energy (PREX) 10-K 25 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Jan. 31, 2016	Jun. 30, 2015
Document Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Entity Registrant Name	Duke Energy Corporation
Entity Central Index Key	1,326,160
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock, Shares Outstanding		688,377,923
Entity Public Float			$ 48,570,203,631
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Duke Energy Carolinas [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Carolinas, LLC
Entity Central Index Key	30,371
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Progress Energy [Member]
Document Information [Line Items]
Entity Registrant Name	Progress Energy, Inc.
Entity Central Index Key	1,094,093
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Duke Energy Progress [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Progress, Inc.
Entity Central Index Key	17,797
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Duke Energy Florida [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Florida, Inc.
Entity Central Index Key	37,637
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Duke Energy Ohio [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Ohio, Inc.
Entity Central Index Key	20,290
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Duke Energy Indiana [Member]
Document Information [Line Items]
Entity Registrant Name	Duke Energy Indiana, Inc.
Entity Central Index Key	81,020
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Revenues [Abstract]
Regulated electric		$ 21,379	$ 21,550	$ 20,329
Nonregulated electric, natural gas, and other		1,544	1,802	1,916
Regulated natural gas		536	573	511
Total operating revenues		23,459	23,925	22,756
Operating Expenses [Abstract]
Fuel used in electric generation and purchased power - regulated		7,308	7,686	7,108
Fuel used in electric generation and purchased power - nonregulated		354	533	540
Cost of natural gas		195	248	224
Operation, maintenance and other		5,871	5,856	5,673
Depreciation and amortization		3,144	3,066	2,668
Property and other taxes		1,135	1,213	1,274
Impairment charges		120	81	399
Total operating expenses		18,127	18,683	17,886
Gains (Losses) on Sales of Other Assets and Other, net		35	16	(16)
Operating Income (Loss)		5,367	5,258	4,854
Other Income and Expenses [Abstract]
Equity in earnings of unconsolidated affiliates		69	130	122
Gains on sales of unconsolidated affiliates		7	17	100
Other income and expenses, net		307	351	262
Total other income and expenses		383	498	484
Interest Expense		1,613	1,622	1,543
Income (Loss) From Continuing Operations Before Income Taxes		4,137	4,134	3,795
Income Tax Expense (Benefit) from Continuing Operations		1,326	1,669	1,205
Income (Loss) from Continuing Operations		2,811	2,465	2,590
(Loss) Income From Discontinued Operations, net of tax		20	(576)	86
Less: Net Income (Loss) Attributable to Noncontrolling Interests		15	6	11
Net Income (Loss) Attributable to Parent		2,816	1,883	2,665
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Pension and OPEB adjustments	[1]	(13)	4	38
Net unrealized gain (loss) on cash flow hedges	[2]		(26)	59
Reclassification into earnings from cash flow hedges		9	7	1
Unrealized gain (loss) on investments in available for sale securities		(6)	3	(4)
Other comprehensive income (loss), net of tax		(274)	(136)	(99)
Comprehensive Income (Loss)		2,557	1,753	2,577
Less: Comprehensive Income Attributable to Noncontrolling Interests		4	14	5
Comprehensive income (loss)		$ 2,553	$ 1,739	$ 2,572
Income From Continuing Operations Attributable To Parent Common Shareholders [Abstract]
Basic		$ 4.02	$ 3.46	$ 3.64
Diluted		4.02	3.46	3.63
Income (loss) from discontinued operations attributable To Duke Energy Corporation common shareholders [Abstract]
Basic		0.03	(0.80)	0.13
Diluted		0.03	(0.80)	0.13
Net income attributable to Duke Energy Corporation common shareholders [Abstract]
Basic		4.05	2.66	3.77
Diluted		$ 4.05	$ 2.66	$ 3.76
Weighted-average shares outstanding [Abstract]
Basic		694	707	706
Diluted		694	707	706
Duke Energy Carolinas [Member]
Operating Revenues [Abstract]
Total operating revenues		$ 7,229	$ 7,351	$ 6,954
Operating Expenses [Abstract]
Fuel used in electric generation and purchased power - regulated		1,881	2,133	1,982
Operation, maintenance and other		2,066	1,995	1,868
Depreciation and amortization		1,051	1,009	921
Property and other taxes		269	316	374
Impairment charges		1	3
Total operating expenses		5,268	5,456	5,145
Gains (Losses) on Sales of Other Assets and Other, net		(1)
Operating Income (Loss)		1,960	1,895	1,809
Other Income and Expenses [Abstract]
Other income and expenses, net		160	172	120
Interest Expense		412	407	359
Income (Loss) From Continuing Operations Before Income Taxes		1,708	1,660	1,570
Income Tax Expense (Benefit) from Continuing Operations		627	588	594
Net Income (Loss) Attributable to Parent		1,081	1,072	976
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassification into earnings from cash flow hedges		1	2	1
Unrealized gain (loss) on investments in available for sale securities		1
Other comprehensive income (loss), net of tax		2	2	1
Comprehensive income (loss)		1,083	1,074	977
Progress Energy [Member]
Operating Revenues [Abstract]
Total operating revenues		10,277	10,166	9,533
Operating Expenses [Abstract]
Fuel used in electric generation and purchased power - regulated		4,224	4,195	3,851
Operation, maintenance and other		2,298	2,335	2,247
Depreciation and amortization		1,116	1,128	883
Property and other taxes		492	517	557
Impairment charges		12	(16)	380
Total operating expenses		8,142	8,159	7,918
Gains (Losses) on Sales of Other Assets and Other, net		25	11	3
Operating Income (Loss)		2,160	2,018	1,618
Other Income and Expenses [Abstract]
Other income and expenses, net		97	77	94
Interest Expense		670	675	680
Income (Loss) From Continuing Operations Before Income Taxes		1,587	1,420	1,032
Income Tax Expense (Benefit) from Continuing Operations		522	540	373
Income (Loss) from Continuing Operations		1,065	880	659
(Loss) Income From Discontinued Operations, net of tax		(3)	(6)	16
Less: Net Income (Loss) Attributable to Noncontrolling Interests		11	5	3
Net Income (Loss) Attributable to Parent		1,051	869	672
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Pension and OPEB adjustments		(10)	9	9
Reclassification into earnings from cash flow hedges		4	8	(1)
Unrealized gain (loss) on investments in available for sale securities		(1)	1
Other comprehensive income (loss), net of tax		(7)	18	8
Comprehensive Income (Loss)		1,055	892	683
Less: Comprehensive Income Attributable to Noncontrolling Interests		11	5	3
Comprehensive income (loss)		1,044	887	680
Duke Energy Progress [Member]
Operating Revenues [Abstract]
Total operating revenues		5,290	5,176	4,992
Operating Expenses [Abstract]
Fuel used in electric generation and purchased power - regulated		2,029	2,036	1,925
Operation, maintenance and other		1,452	1,470	1,357
Depreciation and amortization		643	582	534
Property and other taxes		140	174	223
Impairment charges		5	(18)	22
Total operating expenses		4,269	4,244	4,061
Gains (Losses) on Sales of Other Assets and Other, net		3	3	1
Operating Income (Loss)		1,024	935	932
Other Income and Expenses [Abstract]
Other income and expenses, net		71	51	57
Interest Expense		235	234	201
Income (Loss) From Continuing Operations Before Income Taxes		860	752	788
Income Tax Expense (Benefit) from Continuing Operations		294	285	288
Net Income (Loss) Attributable to Parent		566	467	500
Duke Energy Florida [Member]
Operating Revenues [Abstract]
Total operating revenues		4,977	4,975	4,527
Operating Expenses [Abstract]
Fuel used in electric generation and purchased power - regulated		2,195	2,158	1,927
Operation, maintenance and other		835	850	898
Depreciation and amortization		473	545	330
Property and other taxes		352	343	327
Impairment charges		7	2	358
Total operating expenses		3,862	3,898	3,840
Gains (Losses) on Sales of Other Assets and Other, net			1	1
Operating Income (Loss)		1,115	1,078	688
Other Income and Expenses [Abstract]
Other income and expenses, net		24	20	30
Interest Expense		198	201	180
Income (Loss) From Continuing Operations Before Income Taxes		941	897	538
Income Tax Expense (Benefit) from Continuing Operations		342	349	213
Net Income (Loss) Attributable to Parent		599	548	325
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net unrealized gain (loss) on cash flow hedges				(1)
Reclassification into earnings from cash flow hedges			1
Other comprehensive income (loss), net of tax			1	(1)
Comprehensive income (loss)		599	549	324
Duke Energy Ohio [Member]
Operating Revenues [Abstract]
Regulated electric		1,331	1,316	1,258
Nonregulated electric, natural gas, and other		33	19	34
Regulated natural gas		541	578	513
Total operating revenues		1,905	1,913	1,805
Operating Expenses [Abstract]
Fuel used in electric generation and purchased power - regulated		446	459	428
Fuel used in electric generation and purchased power - nonregulated		47	25	41
Cost of natural gas		141	185	152
Operation, maintenance and other		495	516	546
Depreciation and amortization		227	214	213
Property and other taxes		254	234	242
Impairment charges			94	5
Total operating expenses		1,610	1,727	1,627
Gains (Losses) on Sales of Other Assets and Other, net		8	1	4
Operating Income (Loss)		303	187	182
Other Income and Expenses [Abstract]
Other income and expenses, net		6	10	2
Interest Expense		79	86	74
Income (Loss) From Continuing Operations Before Income Taxes		230	111	110
Income Tax Expense (Benefit) from Continuing Operations		81	43	43
Income (Loss) from Continuing Operations		149	68	67
(Loss) Income From Discontinued Operations, net of tax		23	(563)	35
Net Income (Loss) Attributable to Parent		172	(495)	102
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Pension and OPEB adjustments				1
Other comprehensive income (loss), net of tax				1
Comprehensive income (loss)		172	(495)	103
Duke Energy Indiana [Member]
Operating Revenues [Abstract]
Total operating revenues		2,890	3,175	2,926
Operating Expenses [Abstract]
Fuel used in electric generation and purchased power - regulated		982	1,259	1,131
Operation, maintenance and other		682	670	649
Depreciation and amortization		434	413	342
Property and other taxes		61	128	71
Impairment charges		88
Total operating expenses		2,247	2,470	2,193
Gains (Losses) on Sales of Other Assets and Other, net		1
Operating Income (Loss)		644	705	733
Other Income and Expenses [Abstract]
Other income and expenses, net		11	22	18
Interest Expense		176	171	170
Income (Loss) From Continuing Operations Before Income Taxes		479	556	581
Income Tax Expense (Benefit) from Continuing Operations		163	197	223
Net Income (Loss) Attributable to Parent		316	359	358
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Reclassification into earnings from cash flow hedges		(2)		(2)
Other comprehensive income (loss), net of tax		(2)		(2)
Comprehensive income (loss)		$ 314	$ 359	$ 356
[1]	Net of insignificant tax expense in 2015, 2014 and $17 million tax expense in 2013. See Note 21 for additional information.
[2]	Net of insignificant tax expense in 2015, $13 million tax benefit in 2014 and $20 million tax expense in 2013.

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax			$ 13	$ 20
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 2,831	1,889	2,676
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments		(264)	(124)	(197)
Pension and OPEB adjustments	[1]	(13)	4	38
Net unrealized gain (loss) on cash flow hedges	[2]		(26)	59
Reclassification into earnings from cash flow hedges		9	7	1
Unrealized gain (loss) on investments in available for sale securities		(6)	3	(4)
Reclassification into earnings from available for sale securities				4
Other comprehensive income (loss), net of tax		(274)	(136)	(99)
Comprehensive Income		2,557	1,753	2,577
Less: Comprehensive Income Attributable to Noncontrolling Interests		4	14	5
Comprehensive income (loss)		$ 2,553	$ 1,739	$ 2,572
[1]	Net of insignificant tax expense in 2015, 2014 and $17 million tax expense in 2013. See Note 21 for additional information.
[2]	Net of insignificant tax expense in 2015, $13 million tax benefit in 2014 and $20 million tax expense in 2013.

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income (Parenthetical) (Parentheticals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax		$ (17)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax	$ 13	$ 20

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets [Abstract]
Cash and cash equivalents	$ 857	$ 2,036
Receivables (net of allowance for doubtful accounts)	703	791
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	1,748	1,973
Inventory	3,810	3,459
Assets held for sale		364
Regulatory assets	877	1,115
Other	327	1,837
Total current assets	8,322	11,575
Investments and Other Assets [Abstract]
Investments in equity method unconsolidated affiliates	499	358
Nuclear decommissioning trust funds	5,825	5,546
Goodwill	16,343	16,321
Assets held for sale		2,642
Other	3,042	3,008
Total investments and other assets	25,709	27,875
Property, Plant and Equipment [Abstract]
Cost	112,826	104,861
Accumulated depreciation and amortization	(37,665)	(34,824)
Generation facilities to be retired, net	548	9
Net property, plant and equipment	75,709	70,046
Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	11,373	11,042
Other	43	19
Total regulatory assets and deferred debits	11,416	11,061
Total Assets	121,156	120,557
Current Liabilities [Abstract]
Accounts payable	2,400	2,271
Notes payable and commercial paper	3,633	2,514
Taxes accrued	348	569
Interest accrued	430	418
Current maturities of long-term debt	2,074	2,807
Liabilities associated with assets held for sale		262
Regulatory liabilities	400	204
Other	2,115	2,188
Total current liabilities	11,400	11,233
Long-Term debt	37,495	37,061
Deferred Credits and Other Liabilities [Abstract]
Deferred income taxes	12,705	13,423
Investment tax credits	472	427
Accrued pension and other post-retirement benefit costs	1,088	1,145
Liabilities associated with assets held for sale		35
Asset retirement obligations	10,264	8,466
Regulatory liabilities	6,255	6,193
Other	1,706	1,675
Total deferred credits and other liabilities	$ 32,490	$ 31,364
Commitments and Contingencies
Equity [Abstract]
Common stock	$ 1	$ 1
Additional paid-in capital	37,968	39,405
Retained earnings	2,564	2,012
Accumulated other comprehensive (loss) income	(806)	(543)
Total Common Shareholders' Equity	39,727	40,875
Noncontrolling interests	44	24
Total equity	39,771	40,899
Total Liabilities and Equity	121,156	120,557
Duke Energy Carolinas [Member]
Current Assets [Abstract]
Cash and cash equivalents	13	13
Receivables (net of allowance for doubtful accounts)	142	129
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	596	647
Receivables from affiliated companies	107	75
Notes receivable from affiliated companies	163	150
Inventory	1,276	1,124
Regulatory assets	305	399
Other	128	77
Total current assets	2,730	2,614
Investments and Other Assets [Abstract]
Nuclear decommissioning trust funds	3,050	3,042
Other	999	959
Total investments and other assets	4,049	4,001
Property, Plant and Equipment [Abstract]
Cost	39,398	37,372
Accumulated depreciation and amortization	(13,521)	(12,700)
Net property, plant and equipment	25,877	24,672
Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	2,766	2,465
Other	4	4
Total regulatory assets and deferred debits	2,770	2,469
Total Assets	35,426	33,756
Current Liabilities [Abstract]
Accounts payable	753	709
Accounts payable to affiliated companies	229	154
Taxes accrued	25	146
Interest accrued	95	95
Current maturities of long-term debt	356	507
Regulatory liabilities	39	34
Other	519	434
Total current liabilities	2,016	2,079
Long-Term debt	7,711	7,546
Long-term debt payable to affiliated companies	300	300
Deferred Credits and Other Liabilities [Abstract]
Deferred income taxes	6,146	5,812
Investment tax credits	199	204
Accrued pension and other post-retirement benefit costs	107	111
Asset retirement obligations	3,918	3,428
Regulatory liabilities	2,802	2,710
Other	621	642
Total deferred credits and other liabilities	$ 13,793	$ 12,907
Commitments and Contingencies
Equity [Abstract]
Member's equity	$ 11,617	$ 10,937
Accumulated other comprehensive (loss) income	(11)	(13)
Total Member's Equity	11,606	10,924
Total Liabilities and Equity	35,426	33,756
Progress Energy [Member]
Current Assets [Abstract]
Cash and cash equivalents	44	42
Receivables (net of allowance for doubtful accounts)	151	129
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	658	741
Receivables from affiliated companies	375	59
Notes receivable from affiliated companies		220
Inventory	1,751	1,590
Regulatory assets	362	491
Other	156	1,285
Total current assets	3,497	4,557
Investments and Other Assets [Abstract]
Nuclear decommissioning trust funds	2,775	2,503
Goodwill	3,655	3,655
Other	834	670
Total investments and other assets	7,264	6,828
Property, Plant and Equipment [Abstract]
Cost	42,666	38,650
Accumulated depreciation and amortization	(14,867)	(13,506)
Generation facilities to be retired, net	548
Net property, plant and equipment	28,347	25,144
Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	5,435	5,408
Other	5	5
Total regulatory assets and deferred debits	5,440	5,413
Total Assets	44,548	41,942
Current Liabilities [Abstract]
Accounts payable	722	847
Accounts payable to affiliated companies	311	203
Notes payable to affiliated companies	1,308	835
Taxes accrued	53	114
Interest accrued	195	184
Current maturities of long-term debt	315	1,507
Regulatory liabilities	286	106
Other	891	1,021
Total current liabilities	4,081	4,817
Long-Term debt	13,999	13,161
Long-term debt payable to affiliated companies	150
Deferred Credits and Other Liabilities [Abstract]
Deferred income taxes	4,790	4,759
Accrued pension and other post-retirement benefit costs	536	533
Asset retirement obligations	5,369	4,711
Regulatory liabilities	2,387	2,379
Other	383	406
Total deferred credits and other liabilities	$ 13,465	$ 12,788
Commitments and Contingencies
Equity [Abstract]
Additional paid-in capital	$ 8,092	$ 7,467
Retained earnings	4,831	3,782
Accumulated other comprehensive (loss) income	(48)	(41)
Total Common Shareholders' Equity	12,875	11,208
Noncontrolling interests	(22)	(32)
Total equity	12,853	11,176
Total Liabilities and Equity	44,548	41,942
Duke Energy Progress [Member]
Current Assets [Abstract]
Cash and cash equivalents	15	9
Receivables (net of allowance for doubtful accounts)	87	43
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	349	436
Receivables from affiliated companies	16	10
Notes receivable from affiliated companies		237
Inventory	1,088	966
Regulatory assets	264	287
Other	121	384
Total current assets	1,940	2,372
Investments and Other Assets [Abstract]
Nuclear decommissioning trust funds	2,035	1,701
Other	486	412
Total investments and other assets	2,521	2,113
Property, Plant and Equipment [Abstract]
Cost	27,313	24,207
Accumulated depreciation and amortization	(10,141)	(9,021)
Generation facilities to be retired, net	548
Net property, plant and equipment	17,720	15,186
Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	2,710	2,675
Other	3	3
Total regulatory assets and deferred debits	2,713	2,678
Total Assets	24,894	22,349
Current Liabilities [Abstract]
Accounts payable	399	481
Accounts payable to affiliated companies	190	120
Notes payable to affiliated companies	209
Taxes accrued	15	47
Interest accrued	96	81
Current maturities of long-term debt	2	945
Regulatory liabilities	85	71
Other	412	409
Total current liabilities	1,408	2,154
Long-Term debt	6,366	5,225
Long-term debt payable to affiliated companies	150
Deferred Credits and Other Liabilities [Abstract]
Deferred income taxes	3,027	2,908
Investment tax credits	132	79
Accrued pension and other post-retirement benefit costs	262	290
Asset retirement obligations	4,567	3,905
Regulatory liabilities	1,878	1,832
Other	45	89
Total deferred credits and other liabilities	9,911	9,103
Equity [Abstract]
Common stock		2,159
Member's equity	7,059
Retained earnings		3,708
Total equity	7,059	5,867
Total Member's Equity	7,059
Total Liabilities and Equity	24,894	22,349
Duke Energy Florida [Member]
Current Assets [Abstract]
Cash and cash equivalents	8	8
Receivables (net of allowance for doubtful accounts)	60	84
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	308	305
Receivables from affiliated companies	84	40
Notes receivable from affiliated companies	0	0
Inventory	663	623
Regulatory assets	98	203
Other	21	521
Total current assets	1,242	1,784
Investments and Other Assets [Abstract]
Nuclear decommissioning trust funds	740	803
Other	292	204
Total investments and other assets	1,032	1,007
Property, Plant and Equipment [Abstract]
Cost	15,343	14,433
Accumulated depreciation and amortization	(4,720)	(4,478)
Net property, plant and equipment	10,623	9,955
Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	2,725	2,733
Other	2	2
Total regulatory assets and deferred debits	2,727	2,735
Total Assets	15,624	15,481
Current Liabilities [Abstract]
Accounts payable	322	365
Accounts payable to affiliated companies	116	70
Notes payable to affiliated companies	813	84
Taxes accrued	132	65
Interest accrued	43	47
Current maturities of long-term debt	13	562
Regulatory liabilities	200	35
Other	452	586
Total current liabilities	2,091	1,814
Long-Term debt	4,253	4,261
Deferred Credits and Other Liabilities [Abstract]
Deferred income taxes	2,460	2,452
Accrued pension and other post-retirement benefit costs	242	221
Asset retirement obligations	802	806
Regulatory liabilities	509	547
Other	146	158
Total deferred credits and other liabilities	$ 4,159	$ 4,184
Commitments and Contingencies
Equity [Abstract]
Common stock		$ 1,762
Member's equity	$ 5,121
Retained earnings		3,460
Total equity	5,121	5,222
Total Member's Equity	5,121
Total Liabilities and Equity	15,624	15,481
Duke Energy Ohio [Member]
Current Assets [Abstract]
Cash and cash equivalents	14	20
Receivables (net of allowance for doubtful accounts)	66	93
Receivables from affiliated companies	84	107
Notes receivable from affiliated companies		145
Inventory	105	97
Assets held for sale		316
Regulatory assets	36	49
Other	110	167
Total current assets	415	994
Investments and Other Assets [Abstract]
Goodwill	920	920
Assets held for sale		2,605
Other	20	23
Total investments and other assets	940	3,548
Property, Plant and Equipment [Abstract]
Cost	7,750	7,141
Accumulated depreciation and amortization	(2,507)	(2,213)
Generation facilities to be retired, net		9
Net property, plant and equipment	5,243	4,937
Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	497	512
Other	2	2
Total regulatory assets and deferred debits	499	514
Total Assets	7,097	9,993
Current Liabilities [Abstract]
Accounts payable	207	209
Accounts payable to affiliated companies	53	74
Notes payable to affiliated companies	103	491
Taxes accrued	171	163
Interest accrued	18	19
Current maturities of long-term debt	106	157
Liabilities associated with assets held for sale		246
Regulatory liabilities	12	10
Other	153	66
Total current liabilities	823	1,435
Long-Term debt	1,467	1,578
Long-term debt payable to affiliated companies	25	25
Deferred Credits and Other Liabilities [Abstract]
Deferred income taxes	1,407	1,765
Accrued pension and other post-retirement benefit costs	56	48
Liabilities associated with assets held for sale		34
Asset retirement obligations	125	27
Regulatory liabilities	245	241
Other	165	166
Total deferred credits and other liabilities	1,998	2,281
Equity [Abstract]
Common stock	762	762
Additional paid-in capital	2,720	4,782
Retained earnings	(698)	(870)
Total equity	2,784	4,674
Total Liabilities and Equity	7,097	9,993
Duke Energy Indiana [Member]
Current Assets [Abstract]
Cash and cash equivalents	9	6
Receivables (net of allowance for doubtful accounts)	96	87
Receivables from affiliated companies	71	115
Notes receivable from affiliated companies	83
Inventory	570	537
Regulatory assets	102	93
Other	15	326
Total current assets	946	1,164
Investments and Other Assets [Abstract]
Total investments and other assets	212	251
Property, Plant and Equipment [Abstract]
Cost	14,007	13,034
Accumulated depreciation and amortization	(4,484)	(4,219)
Net property, plant and equipment	9,523	8,815
Regulatory Assets and Deferred Debits [Abstract]
Regulatory assets	716	685
Other	2	2
Total regulatory assets and deferred debits	718	687
Total Assets	11,399	10,917
Current Liabilities [Abstract]
Accounts payable	189	179
Accounts payable to affiliated companies	83	58
Notes payable to affiliated companies		71
Taxes accrued	89	54
Interest accrued	56	56
Current maturities of long-term debt	547	5
Regulatory liabilities	62	54
Other	97	98
Total current liabilities	1,123	575
Long-Term debt	3,071	3,614
Long-term debt payable to affiliated companies	150	150
Deferred Credits and Other Liabilities [Abstract]
Deferred income taxes	1,657	1,591
Investment tax credits	138	139
Accrued pension and other post-retirement benefit costs	80	82
Asset retirement obligations	525	32
Regulatory liabilities	754	796
Other	65	90
Total deferred credits and other liabilities	$ 3,219	$ 2,730
Commitments and Contingencies
Equity [Abstract]
Common stock	$ 1	$ 1
Additional paid-in capital	1,384	1,384
Retained earnings	2,450	2,460
Accumulated other comprehensive (loss) income	1	3
Total equity	3,836	3,848
Total Liabilities and Equity	$ 11,399	$ 10,917

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Receivables, allowance for doubtful accounts	$ 18	$ 17
Restricted receivables, allowance for doubtful accounts	$ 53	$ 51
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	688,000,000	707,000,000
Duke Energy Carolinas [Member]
Receivables, allowance for doubtful accounts	$ 3	$ 3
Restricted receivables, allowance for doubtful accounts	7	6
Progress Energy [Member]
Receivables, allowance for doubtful accounts	6	8
Restricted receivables, allowance for doubtful accounts	$ 8	$ 8
Common stock, par or stated value	$ 0.01	$ 0.01
Common stock, shares authorized	100	100
Common stock, shares outstanding	100	100
Duke Energy Progress [Member]
Receivables, allowance for doubtful accounts	$ 4	$ 7
Restricted receivables, allowance for doubtful accounts	$ 5	$ 5
Common stock, par or stated value		$ 0
Common stock, shares authorized		200,000,000
Common stock, shares outstanding		160,000,000
Duke Energy Florida [Member]
Receivables, allowance for doubtful accounts	$ 2	$ 2
Restricted receivables, allowance for doubtful accounts	3	$ 3
Common stock, par or stated value		$ 0
Common stock, shares authorized		60,000,000
Common stock, shares outstanding		100
Duke Energy Ohio [Member]
Receivables, allowance for doubtful accounts	$ 2	$ 2
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]
Receivables, allowance for doubtful accounts	$ 1	$ 1
Common stock, par or stated value	$ 0.01	$ 0.01
Common stock, shares authorized	60,000,000	60,000,000
Common stock, shares outstanding	53,913,701	53,913,701

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income	$ 2,831	$ 1,889	$ 2,676
Net Income (Loss) Attributable to Parent	2,816	1,883	2,665
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Depreciation, amortization and accretion (including amortization of nuclear fuel)	3,613	3,507	3,229
Equity component of AFUDC	(164)	(135)	(157)
FERC mitigation costs		(15)
Community support and charitable contributions expense			34
(Gains) losses on sales of other assets	(48)	(33)	(79)
Impairment charges	153	915	400
Deferred income taxes	1,244	1,149	1,264
Equity in earnings of unconsolidated affiliates	(69)	(130)	(122)
Accrued pension and other post-retirement benefit costs	71	108	307
Contributions to qualified pension plans	(302)		(250)
Payments for asset retirement obligations	(346)	(68)	(12)
(Increase) decrease in [Abstract]
Net realized and unrealized mark-to-market and hedging transactions	(29)	44	1
Receivables	359	58	(281)
Inventory	(237)	(269)	(31)
Other current assets	(65)	(414)	(35)
Increase (decrease) in [Abstract]
Accounts payable	(6)	(30)	73
Taxes accrued	(38)	(14)	77
Other current liabilities	168	(201)	24
Other assets	(216)	16	(384)
Other liabilities	(243)	209	(352)
Net cash provided by operating activities	6,676	6,586	6,382
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Capital expenditures	(6,766)	(5,384)	(5,526)
Investment expenditures	(263)	(90)	(81)
Acquisitions, net of cash acquired	(1,334)	(54)
Purchases of available-for-sale securities	(4,037)	(4,110)	(6,142)
Proceeds from sales and maturities of available-for-sale securities	4,040	4,133	6,315
Net proceeds from the sale of Midwest generation business and sales of equity investments and other assets	2,968	179	277
Change in Restricted Cash	191	9	167
Other	(76)	(56)	12
Net cash used in investing activities	(5,277)	(5,373)	(4,978)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt	2,955	2,914	3,601
Proceeds from the issuance of common stock related to employee benefit plans	17	25	9
Payments for the redemption of long-term debt	(3,029)	(3,037)	(2,761)
Payments for the redemption of preferred stock			(96)
Proceeds from issuance of short-term debt with original maturities greater than 90 days	379	1,066
Payments for the redemption of short-term debt with original maturities greater than 90 days	(931)	(564)
Notes payable and commercial paper	1,797	1,186	93
Distributions to noncontrolling interests	(9)	(65)	(15)
Contributions from noncontrolling Interests			9
Dividends paid	(2,254)	(2,234)	(2,188)
Repurchase of common shares	(1,500)
Other	(3)	31	21
Net cash provided by (used in) financing activities	(2,578)	(678)	(1,327)
Net increase (decrease) in cash and cash equivalents	(1,179)	535	77
Cash and cash equivalents at beginning of period	2,036	1,501	1,424
Cash and cash equivalents at end of period	857	2,036	1,501
Supplemental Disclosures [Abstract]
Cash paid for interest, net of amount capitalized	1,607	1,659	1,665
Cash paid for (received from) income taxes	170	158	(202)
Significant Non-cash Transactions [Abstract]
Accrued capital expenditures	771	664	594
Duke Energy Carolinas [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income	1,081	1,072
Net Income (Loss) Attributable to Parent	1,081	1,072	976
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Depreciation, amortization and accretion (including amortization of nuclear fuel)	1,361	1,273	1,167
Equity component of AFUDC	(96)	(91)	(91)
FERC mitigation costs		3	14
(Gains) losses on sales of other assets	1
Impairment charges	1
Deferred income taxes	397	376	534
Accrued pension and other post-retirement benefit costs	15	22	38
Contributions to qualified pension plans	(91)
Payments for asset retirement obligations	(167)
(Increase) decrease in [Abstract]
Net realized and unrealized mark-to-market and hedging transactions			(9)
Receivables	42	48	(12)
Receivables from affiliated companies	(32)		(72)
Inventory	(157)	(60)	(9)
Other current assets	(51)	(236)	(1)
Increase (decrease) in [Abstract]
Accounts payable	(4)	10	58
Accounts payable to affiliated companies	75	(7)	33
Taxes accrued	(128)	(15)	4
Other current liabilities	127	(10)	(40)
Other assets	76	17	(102)
Other liabilities	(77)	(22)	(77)
Net cash provided by operating activities	2,373	2,380	2,411
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Capital expenditures	(1,933)	(1,879)	(1,695)
Purchases of available-for-sale securities	(2,555)	(2,064)	(2,405)
Proceeds from sales and maturities of available-for-sale securities	2,555	2,044	2,363
Notes receivable from affiliated companies		72	160
Notes receivable from affiliated companies payments	(13)
Other	(35)	(18)	(24)
Net cash used in investing activities	(1,981)	(1,845)	(1,601)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt	516		100
Payments for the redemption of long-term debt	(506)	(45)	(405)
Distribution to parent	(401)	(500)	(499)
Other	(1)		(2)
Net cash provided by (used in) financing activities	(392)	(545)	(806)
Net increase (decrease) in cash and cash equivalents		(10)	4
Cash and cash equivalents at beginning of period	13	23	19
Cash and cash equivalents at end of period	13	13	23
Supplemental Disclosures [Abstract]
Cash paid for interest, net of amount capitalized	389	388	336
Cash paid for (received from) income taxes	342	305	(7)
Significant Non-cash Transactions [Abstract]
Accrued capital expenditures	239	194	199
Progress Energy [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income	1,062	874	675
Net Income (Loss) Attributable to Parent	1,051	869	672
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Depreciation, amortization and accretion (including amortization of nuclear fuel)	1,312	1,313	1,041
Equity component of AFUDC	(54)	(26)	(50)
FERC mitigation costs		(18)
Community support and charitable contributions expense			20
(Gains) losses on sales of other assets	(31)	(6)	2
Impairment charges	12	2	380
Deferred income taxes	714	1,014	616
Accrued pension and other post-retirement benefit costs	(5)	27	172
Contributions to qualified pension plans	(83)		(250)
Payments for asset retirement obligations	(156)	(68)	(12)
(Increase) decrease in [Abstract]
Net realized and unrealized mark-to-market and hedging transactions	(6)	12	55
Receivables	105	(31)	(148)
Receivables from affiliated companies	(316)	(56)	11
Inventory	(67)	(101)	17
Other current assets	553	(934)	(156)
Increase (decrease) in [Abstract]
Accounts payable	(193)	6	(81)
Accounts payable to affiliated companies	108	80	93
Taxes accrued	(63)	(20)	22
Other current liabilities	136	(144)	61
Other assets	(167)	(14)	(243)
Other liabilities	(112)	56	(103)
Net cash provided by operating activities	2,749	1,966	2,122
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Capital expenditures	(2,698)	(1,940)	(2,490)
Asset Acquisition	(1,249)
Purchases of available-for-sale securities	(1,174)	(1,689)	(2,558)
Proceeds from sales and maturities of available-for-sale securities	1,211	1,652	2,513
Proceeds from the sale of nuclear fuel	102
Notes receivable from affiliated companies	220
Notes receivable from affiliated companies payments		(145)	(75)
Other	(34)	(44)	13
Net cash used in investing activities	(3,622)	(2,166)	(2,597)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt	1,186	1,572	845
Payments for the redemption of long-term debt	(1,553)	(931)	(1,196)
Payments for the redemption of preferred stock			(96)
Notes payable to affiliated companies	623	(378)	758
Distributions to noncontrolling interests	(4)	(37)	(3)
Capital contribution from parent	625
Other	(2)	(42)	(6)
Net cash provided by (used in) financing activities	875	184	302
Net increase (decrease) in cash and cash equivalents	2	(16)	(173)
Cash and cash equivalents at beginning of period	42	58	231
Cash and cash equivalents at end of period	44	42	58
Supplemental Disclosures [Abstract]
Cash paid for interest, net of amount capitalized	649	664	678
Cash paid for (received from) income taxes	(426)	141	(167)
Significant Non-cash Transactions [Abstract]
Accrued capital expenditures	329	294	255
Duke Energy Progress [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income	566	467	500
Net Income (Loss) Attributable to Parent	566	467	500
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Depreciation, amortization and accretion (including amortization of nuclear fuel)	821	761	685
Equity component of AFUDC	(47)	(25)	(42)
FERC mitigation costs		(18)
Community support and charitable contributions expense			20
(Gains) losses on sales of other assets	(7)	(3)	(1)
Impairment charges	5		22
Deferred income taxes	354	455	368
Accrued pension and other post-retirement benefit costs	(14)	(7)	72
Contributions to qualified pension plans	(42)		(63)
Payments for asset retirement obligations	(109)
(Increase) decrease in [Abstract]
Net realized and unrealized mark-to-market and hedging transactions	(3)	13	(9)
Receivables	43	78	(88)
Receivables from affiliated companies	(6)	(8)	3
Inventory	(50)	(65)	(26)
Other current assets	185	(416)	(39)
Increase (decrease) in [Abstract]
Accounts payable	(65)	27	(18)
Accounts payable to affiliated companies	70	17	27
Taxes accrued	(34)	10	15
Other current liabilities	76	(68)	(86)
Other assets	(83)	48	(74)
Other liabilities	(66)	(21)	(78)
Net cash provided by operating activities	1,594	1,245	1,188
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Capital expenditures	(1,669)	(1,241)	(1,567)
Asset Acquisition	(1,249)
Purchases of available-for-sale securities	(727)	(499)	(901)
Proceeds from sales and maturities of available-for-sale securities	672	458	856
Notes receivable from affiliated companies	237
Notes receivable from affiliated companies payments		(237)
Other	(30)	(12)	4
Net cash used in investing activities	(2,766)	(1,531)	(1,608)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt	1,186	1,347	845
Payments for the redemption of long-term debt	(991)	(379)	(451)
Payments for the redemption of preferred stock			(62)
Notes payable to affiliated companies	359	(462)	98
Dividends to parent		(225)
Capital contribution from parent	626
Other	(2)	(7)	(7)
Net cash provided by (used in) financing activities	1,178	274	423
Net increase (decrease) in cash and cash equivalents	6	(12)	3
Cash and cash equivalents at beginning of period	9	21	18
Cash and cash equivalents at end of period	15	9	21
Supplemental Disclosures [Abstract]
Cash paid for interest, net of amount capitalized	218	220	217
Cash paid for (received from) income taxes	(197)	81	(94)
Significant Non-cash Transactions [Abstract]
Accrued capital expenditures	143	194	166
Duke Energy Florida [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income	599	548	325
Net Income (Loss) Attributable to Parent	599	548	325
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Depreciation, amortization and accretion (including amortization of nuclear fuel)	480	550	335
Equity component of AFUDC	(7)		(8)
(Gains) losses on sales of other assets		(1)	(1)
Impairment charges	7	2	358
Deferred income taxes	348	400	368
Accrued pension and other post-retirement benefit costs	5	29	79
Contributions to qualified pension plans	(40)		(133)
Payments for asset retirement obligations	(47)	(68)	(12)
(Increase) decrease in [Abstract]
Net realized and unrealized mark-to-market and hedging transactions	(3)	(9)	55
Receivables	61	(33)	(44)
Receivables from affiliated companies	(44)	(37)	17
Inventory	(17)	(36)	42
Other current assets	116	(269)	(109)
Increase (decrease) in [Abstract]
Accounts payable	(127)	18	(22)
Accounts payable to affiliated companies	46	32	(6)
Taxes accrued	67	(31)	18
Other current liabilities	57	(80)	159
Other assets	(84)	(59)	(154)
Other liabilities	(44)	10	(62)
Net cash provided by operating activities	1,373	966	1,205
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Capital expenditures	(1,029)	(699)	(915)
Asset Acquisition	(166)
Purchases of available-for-sale securities	(447)	(1,189)	(1,656)
Proceeds from sales and maturities of available-for-sale securities	538	1,195	1,658
Proceeds from the sale of nuclear fuel	102
Notes receivable from affiliated companies			207
Other	(3)	(31)
Net cash used in investing activities	(839)	(724)	(706)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt		225
Payments for the redemption of long-term debt	(562)	(252)	(435)
Payments for the redemption of preferred stock			(34)
Notes payable to affiliated companies	729	(97)	181
Dividends to parent	(350)	(124)	(325)
Distribution to parent	(350)
Other	(1)	(2)	(1)
Net cash provided by (used in) financing activities	(534)	(250)	(614)
Net increase (decrease) in cash and cash equivalents		(8)	(115)
Cash and cash equivalents at beginning of period	8	16	131
Cash and cash equivalents at end of period	8	8	16
Supplemental Disclosures [Abstract]
Cash paid for interest, net of amount capitalized	205	203	201
Cash paid for (received from) income taxes	(229)	59	(84)
Significant Non-cash Transactions [Abstract]
Accrued capital expenditures	186	100	88
Duke Energy Ohio [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income	172	(495)	102
Net Income (Loss) Attributable to Parent	172	(495)	102
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Depreciation, amortization and accretion (including amortization of nuclear fuel)	230	258	357
Equity component of AFUDC	(3)	(4)	(1)
(Gains) losses on sales of other assets	(8)	(1)	(5)
Impairment charges	40	941	5
Deferred income taxes	206	(219)	98
Accrued pension and other post-retirement benefit costs	9	8	17
Contributions to qualified pension plans	(8)
Payments for asset retirement obligations	(4)
(Increase) decrease in [Abstract]
Net realized and unrealized mark-to-market and hedging transactions	(10)	27	17
Receivables	23	(56)	(15)
Receivables from affiliated companies	23	14	(39)
Inventory		8	(3)
Other current assets		(5)	(1)
Increase (decrease) in [Abstract]
Accounts payable	(1)	27	13
Accounts payable to affiliated companies	(21)	(3)	15
Taxes accrued	(21)	(9)	1
Other current liabilities	88	27	14
Other assets	25	(4)	(6)
Other liabilities	(73)	(33)	(73)
Net cash provided by operating activities	667	481	496
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Capital expenditures	(399)	(322)	(434)
Net proceeds from the sale of Midwest generation business and sales of equity investments and other assets			11
Notes receivable from affiliated companies	145
Notes receivable from affiliated companies payments		(88)	(56)
Other	(15)	(12)	1
Net cash used in investing activities	(269)	(422)	(478)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt			450
Payments for the redemption of long-term debt	(157)	(449)	(258)
Notes payable to affiliated companies	(95)	473	(202)
Dividends to parent	(150)	(100)
Other	(2)	1	(3)
Net cash provided by (used in) financing activities	(404)	(75)	(13)
Net increase (decrease) in cash and cash equivalents	(6)	(16)	5
Cash and cash equivalents at beginning of period	20	36	31
Cash and cash equivalents at end of period	14	20	36
Supplemental Disclosures [Abstract]
Cash paid for interest, net of amount capitalized	76	76	71
Cash paid for (received from) income taxes	410	(5)	9
Significant Non-cash Transactions [Abstract]
Accrued capital expenditures	20	24	27
Distribution of membership interest of Duke Energy SAM, LLC to parent	1,912
Duke Energy Indiana [Member]
CASH FLOWS FROM OPERATING ACTIVITIES [Abstract]
Net income	316	359
Net Income (Loss) Attributable to Parent	316	359	358
Adjustments to reconcile net income to net cash provided by operating activities: [Abstract]
Depreciation, amortization and accretion (including amortization of nuclear fuel)	439	416	346
Equity component of AFUDC	(11)	(14)	(15)
(Gains) losses on sales of other assets	(1)
Impairment charges	88
Deferred income taxes	262	308	304
Accrued pension and other post-retirement benefit costs	13	16	25
Contributions to qualified pension plans	(19)
Payments for asset retirement obligations	(19)
(Increase) decrease in [Abstract]
Net realized and unrealized mark-to-market and hedging transactions			(30)
Receivables	(7)	(35)	3
Receivables from affiliated companies	44	36	(47)
Inventory	(21)	(103)	(53)
Other current assets	90	(8)	(40)
Increase (decrease) in [Abstract]
Accounts payable	33	(41)	32
Accounts payable to affiliated companies	25	2	(4)
Taxes accrued	35	(32)	(30)
Other current liabilities	26	5	(5)
Other assets	(82)	(21)	(16)
Other liabilities	(35)	17	(84)
Net cash provided by operating activities	1,176	905	744
CASH FLOWS FROM INVESTING ACTIVITIES [Abstract]
Capital expenditures	(690)	(625)	(545)
Purchases of available-for-sale securities	(9)	(20)	(11)
Proceeds from sales and maturities of available-for-sale securities	11	16	7
Net proceeds from the sale of Midwest generation business and sales of equity investments and other assets	17
Notes receivable from affiliated companies		96
Notes receivable from affiliated companies payments	(83)		(96)
Other	(17)	4	(3)
Net cash used in investing activities	(771)	(529)	(648)
CASH FLOWS FROM FINANCING ACTIVITIES [Abstract]
Proceeds from the issuance of long-term debt			498
Payments for the redemption of long-term debt	(5)	(5)	(405)
Notes payable to affiliated companies	(71)	71	(81)
Dividends to parent	(326)	(450)	(125)
Other		(1)	(4)
Net cash provided by (used in) financing activities	(402)	(385)	(117)
Net increase (decrease) in cash and cash equivalents	3	(9)	(21)
Cash and cash equivalents at beginning of period	6	15	36
Cash and cash equivalents at end of period	9	6	15
Supplemental Disclosures [Abstract]
Cash paid for interest, net of amount capitalized	175	169	194
Cash paid for (received from) income taxes	(253)	(61)	46
Significant Non-cash Transactions [Abstract]
Accrued capital expenditures	$ 64	$ 87	$ 73

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Foreign Currency Adjustments [Member]	Net Gains (Losses) on Cash Flow Hedges [Member]	Net Gains (Losses) on Available for Sale Securities [Member]	Pension And OPEB Related Adjustments To AOCI [Member]	Common Stockholders' Equity [Member]	Noncontrolling Interest [Member]		Duke Energy Carolinas [Member]	Duke Energy Carolinas [Member]Members Equity [Member]	Duke Energy Carolinas [Member]Net Gains (Losses) on Cash Flow Hedges [Member]	Duke Energy Carolinas [Member]Net Gains (Losses) on Available for Sale Securities [Member]	Progress Energy [Member]	Progress Energy [Member]Additional Paid In Capital [Member]	Progress Energy [Member]Retained Earnings [Member]	Progress Energy [Member]Net Gains (Losses) on Cash Flow Hedges [Member]	Progress Energy [Member]Net Gains (Losses) on Available for Sale Securities [Member]	Progress Energy [Member]Pension And OPEB Related Adjustments To AOCI [Member]	Progress Energy [Member]Common Stockholders' Equity [Member]	Progress Energy [Member]Noncontrolling Interest [Member]	Duke Energy Progress [Member]	Duke Energy Progress [Member]Common Stock [Member]	Duke Energy Progress [Member]Members Equity [Member]	Duke Energy Progress [Member]Retained Earnings [Member]	Duke Energy Florida [Member]	Duke Energy Florida [Member]Common Stock [Member]	Duke Energy Florida [Member]Members Equity [Member]	Duke Energy Florida [Member]Retained Earnings [Member]	Duke Energy Florida [Member]Net Gains (Losses) on Cash Flow Hedges [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 Ohio [Member]Pension And OPEB Related Adjustments To AOCI [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]Net Gains (Losses) on Cash Flow Hedges [Member]
Balance at Dec. 31, 2012	$ 40,941	$ 1	$ 39,279	$ 1,889	$ (116)	$ (100)		$ (90)	$ 40,863	$ 78						$ 10,185	$ 7,465	$ 2,783	$ (42)		$ (25)	$ 10,181	$ 4	$ 5,127	$ 2,159		$ 2,968	$ 4,799	$ 1,762		$ 3,037		$ 5,166	$ 762	$ 4,882	$ (477)	$ (1)	$ 3,708	$ 1	$ 1,384	$ 2,318	$ 5
Balance (in shares) at Dec. 31, 2012		704,000,000
Beginning member's equity at Dec. 31, 2012												$ 9,872	$ 9,888	$ (15)	$ (1)
Net income	2,676			2,665					2,665	11						675		672				672	3	500				325					102
Net Income (Loss) Attributable to Parent	2,665											976	976			672								500			500	325			325		102			102		358			358
Other comprehensive income (loss), net of tax	(99)				(191)	60		38	(93)	(6)		1		1		8			(1)		9	8						(1)				$ (1)	1				$ 1	(2)				(2)
Common stock issuances, including dividend reinvestment and employee benefits (in shares)		2,000,000
Common stock issuances, including dividend reinvestment and employee benefits	86		86						86
Common stock dividends	(2,188)			(2,188)					(2,188)																			(325)			(325)							(125)			(125)
Premium on the redemption of preferred stock of subsidiaries	(3)			(3)					(3)							(3)		(3)				(3)		(2)			(2)	(1)			(1)
Contributions from noncontrolling Interests	9									9
Distributions to noncontrolling interest in subsidiaries	(14)									(14)						(3)							(3)
Distribution to parent												(499)	(499)
Other																2	2					2
Balance at Dec. 31, 2013	41,408	$ 1	39,365	2,363	(307)	(40)		(52)	41,330	78						10,864	7,467	3,452	(43)		(16)	10,860	4	5,625	2,159		3,466	4,797	1,762		3,036	(1)	5,269	762	4,882	(375)		3,939	1	1,384	2,551	3
Balance (in shares) at Dec. 31, 2013		706,000,000
Ending member's equity at Dec. 31, 2013												10,350	10,365	(14)	(1)
Net income	1,889			1,883					1,883	6		1,072				874		869				869	5	467				548					(495)					359
Net Income (Loss) Attributable to Parent	1,883											1,072	1,072			869								467			467	548			548		(495)			(495)		359			359
Other comprehensive income (loss), net of tax	(136)				(132)	(19)	$ 3	4	(144)	8		2		2		18			8	$ 1	9	18						1				$ 1
Common stock issuances, including dividend reinvestment and employee benefits (in shares)		1,000,000
Common stock issuances, including dividend reinvestment and employee benefits	40		40						40
Common stock dividends	(2,234)			(2,234)					(2,234)															(225)			(225)	(124)			(124)		(100)		(100)			(450)			(450)
Distributions to noncontrolling interest in subsidiaries	(65)									(65)	[1]					(37)							(37)
Transfer of service company net assets to Duke Energy																(539)		(539)				(539)
Distribution to parent												(500)	(500)
Other	(3)									(3)						(4)							(4)
Balance at Dec. 31, 2014	$ 40,899	$ 1	39,405	2,012	(439)	(59)	3	(48)	40,875	24						$ 11,176	7,467	3,782	(35)	1	(7)	11,208	(32)	$ 5,867	2,159		3,708	$ 5,222	1,762		3,460		$ 4,674	762	4,782	(870)		$ 3,848	1	1,384	2,460	3
Balance (in shares) at Dec. 31, 2014	707,000,000	707,000,000														100								160,000,000				100					89,663,086					53,913,701
Ending member's equity at Dec. 31, 2014												10,924	10,937	(12)	(1)
Net income	$ 2,831			2,816					2,816	15		1,081				$ 1,062		1,051				1,051	11	$ 566				$ 599					$ 172					$ 316
Net Income (Loss) Attributable to Parent	2,816											1,081	1,081			1,051								566		$ 211	355	599		$ 248	351		172			172		316			316
Other comprehensive income (loss), net of tax	(274)				(253)	9	(6)	(13)	(263)	(11)		2		1	$ 1	(7)			4	$ (1)	(10)	(7)																(2)				(2)
Common stock issuances, including dividend reinvestment and employee benefits (in shares)		1,000,000
Common stock issuances, including dividend reinvestment and employee benefits	$ 63		63						63
Stock repurchase, shares	(19,800,000)	(20,000,000)
Stock repurchase	$ (1,500)		(1,500)						(1,500)
Common stock dividends	(2,254)			(2,254)					(2,254)																			(350)			(350)		(150)		(150)			(326)			(326)
Distributions to noncontrolling interest in subsidiaries	(9)									(9)						(4)							(4)
Capital contribution from parent																625	625					625		626		626
Distribution to parent												(401)	(401)															(350)		(350)
Distribution of membership interest of Duke Energy SAM, LLC to parent																																	(1,912)		(1,912)
Other	15			(10)					(10)	25	[2]					1		(2)				(2)	3		$ (2,159)	6,222	$ (4,063)		$ (1,762)	5,223	$ (3,461)
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)	$ 7,059				5,121					$ 2,784	$ 762	$ 2,720	$ (698)		$ 3,836	$ 1	$ 1,384	$ 2,450	$ 1
Balance (in shares) at Dec. 31, 2015	688,000,000	688,000,000														100																	89,663,086					53,913,701
Ending member's equity at Dec. 31, 2015												$ 11,606	$ 11,617	$ (11)										$ 7,059		$ 7,059		$ 5,121		$ 5,121
[1]	This decrease primarily relates to cash distributions to noncontrolling interests.
[2]	The $25 million change in Noncontrolling Interests is primarily related to the acquisitions of a majority interest in a provider of energy management systems and services for commercial customers and a solar company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Index to Combined Notes To Consolidated Financial Statements The notes to the consolidated financial statements are a combined presentation. The following list indicates the registrants to which the notes apply. Tables within the notes may not sum across due to Progress Energy's consolidation of Duke Energy Progress, Duke Energy Florida and other subsidiaries that are not registrants as the Duke Energy amounts include balances from subsidiaries that are not registrants. Applicable Notes Registrant 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 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, Inc. • • • • • • • • • • • • • • • • • • • • • SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES 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.) and Latin America primarily through its direct and indirect subsidiaries. Duke Energy’s subsidiaries include its subsidiary registrants, Duke Energy Carolinas, LLC (Duke Energy Carolinas); Progress Energy, Inc. (Progress Energy); Duke Energy Progress, LLC (formerly Duke Energy Progress, Inc.) (Duke Energy Progress); Duke Energy Florida, LLC (formerly Duke Energy Florida, Inc.) (Duke Energy Florida); Duke Energy Ohio, Inc. (Duke Energy Ohio) and Duke Energy Indiana, Inc. (subsequently Duke Energy Indiana, LLC) (Duke Energy Indiana). When discussing Duke Energy’s consolidated financial information, it necessarily includes the results of its six separate subsidiary registrants (collectively referred to as the Subsidiary Registrants), which, along with Duke Energy, are collectively referred to as the Duke Energy Registrants (Duke Energy Registrants). The information in these combined notes relate to each of the Duke Energy Registrants as noted in the Index to the Combined Notes to Consolidated Financial Statements. However, none of the registrants makes any representations as to information related solely to Duke Energy or the subsidiaries of Duke Energy other than itself. These Consolidated Financial Statements include, after eliminating intercompany transactions and balances, the accounts of the Duke Energy Registrants and subsidiaries where the respective Duke Energy Registrants have control. These Consolidated Financial Statements also reflect the Duke Energy Registrants’ proportionate share of certain jointly owned generation and transmission facilities. 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. Substantially all of Duke Energy Carolinas’ operations qualify for regulatory accounting. Progress Energy is a public utility holding company headquartered in Raleigh, North Carolina, subject to regulation by the FERC. Progress Energy conducts operations through its wholly owned subsidiaries, Duke Energy Progress and Duke Energy Florida. Substantially all of Progress Energy’s operations qualify for regulatory accounting. 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. Substantially all of Duke Energy Progress’ operations qualify for regulatory accounting. On August 1, 2015, Duke Energy Progress, a North Carolina corporation, converted into a North Carolina limited liability company. 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. Substantially all of Duke Energy Florida’s operations qualify for regulatory accounting. On August 1, 2015, Duke Energy Florida, a Florida corporation, converted into a Florida limited liability company. 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 also conducts competitive auctions for retail electricity supply in Ohio whereby recovery of the energy price is from retail customers and recorded in Operating Revenues on the Consolidated Statements of Operations and Comprehensive Income. Operations in Kentucky are conducted through its wholly owned subsidiary, Duke Energy Kentucky, Inc. (Duke Energy Kentucky). References herein to Duke Energy Ohio 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. On April 2, 2015, Duke Energy completed the sale of its nonregulated Midwest generation business, which sold power into wholesale energy markets, to a subsidiary of Dynegy Inc. (Dynegy). For further information about the sale of the Midwest Generation business, refer to Note 2 "Acquisitions and Dispositions." Substantially all of Duke Energy Ohio's operations that remain after the sale qualify for regulatory accounting. 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. Substantially all of Duke Energy Indiana’s operations qualify for regulatory accounting. On January 1, 2016, Duke Energy Indiana, an Indiana corporation, converted into an Indiana limited liability company. Certain prior year amounts have been reclassified to conform to the current year presentation. Other Current Assets and Liabilities The following table provides detail of amounts included in Other within Current Assets or Current Liabilities on the Consolidated Balance Sheets. December 31, (in millions) Location 2015 2014 Duke Energy Accrued compensation Current Liabilities $ 621 $ 638 Duke Energy Carolinas Accrued compensation Current Liabilities $ 213 $ 216 Collateral liabilities Current Liabilities 141 128 Progress Energy Income taxes receivable Current Assets $ 129 $ 718 Customer deposits Current Liabilities 373 360 Derivative liabilities Current Liabilities 201 271 Duke Energy Progress Income taxes receivable Current Assets $ 111 $ 272 Customer deposits Current Liabilities 141 135 Accrued compensation Current Liabilities 108 116 Derivative liabilities Current Liabilities 76 108 Duke Energy Florida Income taxes receivable Current Assets $ — $ 177 Customer deposits Current Liabilities 232 225 Derivative liabilities Current Liabilities 125 163 Duke Energy Ohio Income taxes receivable Current Assets $ 59 $ 40 Other receivable Current Assets 33 39 Accrued litigation reserve Current Liabilities 80 — Collateral Liabilities Current Liabilities 48 $ 42 Duke Energy Indiana Income taxes receivable Current Assets $ — $ 98 Collateral liabilities Current Liabilities 44 43 The current portion of deferred tax assets is included within Other in Current Assets at December 31, 2014. Due to the adoption of new accounting guidance issued by the Financial Accounting Standards Board (FASB) related to the balance sheet classification of deferred taxes, all deferred tax assets and liabilities are classified as noncurrent at December 31, 2015. See Note 22 for information related to the presentation of deferred tax assets and liabilities on the Consolidated Balance Sheets. Discontinued Operations The results of operations of the nonregulated Midwest generation business have been classified as Discontinued Operations on the Consolidated Statements of Operations. Duke Energy has elected to present cash flows of discontinued operations combined with cash flows of continuing operations. Unless otherwise noted, the notes to these consolidated financial statements exclude amounts related to discontinued operations for all periods presented, assets held for sale and liabilities associated with assets held for sale as of December 31, 2014. See Note 2 for additional information. For the year ended December 31, 2015, Duke Energy's Income from Discontinued Operations, net of tax was primarily related to results of operations of the nonregulated Midwest generation business and Duke Energy Retail Sales, LLC (collectively, the Disposal Group) prior to its sale on April 2, 2015, partially offset by a charge for a litigation reserve related to the Disposal Group. For the year ended December 31, 2014, Duke Energy’s Loss from Discontinued Operations, net of tax was primarily related to a write-down of the carrying amount of the assets to the estimated fair value of the Disposal Group, based on the transaction price included in the purchase sale agreement, and the operations of the Disposal Group. For the years ended December 31, 2013, Duke Energy’s Income From Discontinued Operations, net of tax was primarily related to the operations of the Disposal Group. See Note 2 for additional information. For the years ended December 31, 2015 , 2014 and 2013, Progress Energy’s (Loss) Income From Discontinued Operations, net of tax was primarily due to tax impacts related to prior sales of diversified businesses. Amounts Attributable to Controlling Interests For the year ended December 31, 2015, the amount of Income from Discontinued Operations, net of tax presented on the Consolidated Statements of Operations is fully attributable to controlling interests. During 2014, Duke Energy and Progress Energy's amount of Income (Loss) from Discontinued Operations, net of tax presented on the Consolidated Statements of Operations includes amounts attributable to noncontrolling interest. The following table presents Net Income Attributable to Duke Energy Corporation for continuing operations and discontinued operations for the years ended December 31, 2014 and 2013. Years ended December 31, 2014 2013 Duke Progress Duke Progress (in millions) Energy Energy Energy Energy Income from Continuing Operations $ 2,465 $ 880 2,590 659 Income from Continuing Operations Attributable to Noncontrolling Interests 14 5 16 3 Income from Continuing Operations Attributable to Duke Energy Corporation $ 2,451 $ 875 $ 2,574 $ 656 (Loss) Income From Discontinued Operations, net of tax $ (576 ) $ (6 ) 86 16 Loss from Discontinued Operations Attributable to Noncontrolling Interests, net of tax (8 ) — (5 ) — (Loss) Income From Discontinued Operations Attributable to Duke Energy Corporation, net of tax $ (568 ) $ (6 ) $ 91 $ 16 Net Income $ 1,889 $ 874 $ 2,676 $ 675 Net Income Attributable to Noncontrolling Interests 6 5 11 3 Net Income Attributable to Duke Energy Corporation $ 1,883 $ 869 $ 2,665 $ 672 Significant Accounting Policies Use of Estimates In preparing financial statements that conform to generally accepted accounting principles (GAAP) in the U.S., the Duke Energy Registrants must make estimates and assumptions that affect the reported amounts of assets and liabilities, the reported amounts of revenues and expenses and the disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. Regulatory Accounting The majority of the Duke Energy Registrants’ operations are subject to price regulation for the sale of electricity and gas by state utility commissions or FERC. When prices are set on the basis of specific costs of the regulated operations and an effective franchise is in place such that sufficient gas or electric services can be sold to recover those costs, the Duke Energy Registrants apply regulatory accounting. Regulatory accounting changes the timing of the recognition of costs or revenues relative to a company that does not apply regulatory accounting. As a result, Regulatory assets and Regulatory liabilities are recognized on the Consolidated Balance Sheets. Regulatory assets and liabilities are amortized consistent with the treatment of the related cost in the ratemaking process. See Note 4 for further information. Regulatory accounting rules also require recognition of a disallowance (also called "impairment") loss if it becomes probable that part of the cost of a plant under construction (or a recently completed plant or an abandoned plant) will be disallowed for ratemaking purposes and a reasonable estimate of the amount of the disallowance can be made. Other disallowances can require judgments on allowed future rate recovery. When it becomes probable that regulated generation, transmission or distribution assets will be abandoned, the cost of the asset is removed from plant in service. The value that may be retained as a regulatory asset on the balance sheet for the abandoned property is dependent upon amounts that may be recovered through regulated rates, including any return. As such, an impairment charge could be offset by the establishment of a regulatory asset if rate recovery is probable. The impairment for a disallowance of costs for regulated plants under construction, recently completed or abandoned is based on discounted cash flows. Regulated Fuel Costs and Purchased Power The Duke Energy Registrants utilize cost-tracking mechanisms, commonly referred to as fuel adjustment clauses. These clauses allow for the recovery of fuel and fuel-related costs and portions of purchased power costs through surcharges on customer rates. The difference between the costs incurred and the surcharge revenues is recorded either as an adjustment to Operating Revenues – Regulated electric or Operating Expenses – Fuel used in electric generation on the Consolidated Statements of Operations with an off-setting impact on regulatory assets or liabilities. Cash and Cash Equivalents All highly liquid investments with maturities of three months or less at the date of acquisition are considered cash equivalents. At December 31, 2015 , $534 million of Duke Energy’s total cash and cash equivalents is held by entities domiciled in foreign jurisdictions. During the fourth quarter of 2014, Duke Energy declared a taxable dividend of historical foreign earnings in the form of notes payable that will result in the repatriation of approximately $2.7 billion in cash held and expected to be generated by International Energy over a period of up to eight years . Approximately $1.5 billion was remitted in 2015. See Note 22 to the Consolidated Financial Statements, “Income Taxes,” for additional information. Restricted Cash The Duke Energy Registrants have restricted cash related primarily to collateral assets, escrow deposits and variable interest entities (VIEs). Restricted cash balances are reflected in Other within Current Assets and in Other within Investments and Other Assets on the Consolidated Balance Sheets. At December 31, 2015 and 2014 , Duke Energy had restricted cash totaling $108 million and $298 million , respectively. 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. Reserves are established for excess and obsolete inventory. Inventory reserves were not material at December 31, 2015 and 2014. The components of inventory are presented in the tables below. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Materials and supplies $ 2,389 $ 785 $ 1,133 $ 776 $ 357 $ 81 $ 301 Coal held for electric generation 1,114 451 370 192 178 16 267 Oil, gas and other fuel held for electric generation 307 40 248 120 128 8 2 Total inventory $ 3,810 $ 1,276 $ 1,751 $ 1,088 $ 663 $ 105 $ 570 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Materials and supplies $ 2,102 $ 719 $ 981 $ 676 $ 305 $ 67 $ 258 Coal held for electric generation 997 362 329 150 178 21 275 Oil, gas and other fuel held for electric generation 360 43 280 140 140 9 4 Total inventory $ 3,459 $ 1,124 $ 1,590 $ 966 $ 623 $ 97 $ 537 Investments in Debt and Equity Securities The Duke Energy Registrants classify investments into two categories – trading and available-for-sale. Both categories are recorded at fair value on the Consolidated Balance Sheets. Realized and unrealized gains and losses on trading securities are included in earnings. For certain investments of regulated operations such as the Nuclear Decommissioning Trust Fund (NDTF), realized and unrealized gains and losses (including any other-than-temporary impairments) on available-for-sale securities are recorded as a regulatory asset or liability. Otherwise, unrealized gains and losses are included in Accumulated Other Comprehensive Income (AOCI), unless other-than-temporarily impaired. Other-than-temporary impairments for equity securities and the credit loss portion of debt securities of nonregulated operations are included in earnings. Investments in debt and equity securities are classified as either current or noncurrent based on management’s intent and ability to sell these securities, taking into consideration current market liquidity. See Note 15 for further information. Goodwill and Intangible Assets Goodwill Duke Energy, Progress Energy and Duke Energy Ohio perform annual goodwill impairment tests as of August 31 each year at the reporting unit level, which is determined to be an operating segment or one level below. Duke Energy, Progress Energy and Duke Energy Ohio update these tests between annual tests if events or circumstances occur that would more likely than not reduce the fair value of a reporting unit below its carrying value. Intangible Assets Intangible assets are included in Other in Investments and Other Assets on the Consolidated Balance Sheets. Generally, intangible assets are amortized using an amortization method that reflects the pattern in which the economic benefits of the intangible asset are consumed, or on a straight-line basis if that pattern is not readily determinable. Amortization of intangibles is reflected in Depreciation and amortization on the Consolidated Statements of Operations. Intangible assets are subject to impairment testing and if impaired, the carrying value is accordingly reduced. Emission allowances permit the holder of the allowance to emit certain gaseous byproducts of fossil fuel combustion, including sulfur dioxide (SO 2 ) and nitrogen oxide (NO X ). Allowances are issued by the U.S. Environmental Protection Agency (EPA) at zero cost and may also be bought and sold via third-party transactions. Allowances allocated to or acquired by the Duke Energy Registrants are held primarily for consumption. Carrying amounts for emission allowances are based on the cost to acquire the allowances or, in the case of a business combination, on the fair value assigned in the allocation of the purchase price of the acquired business. Emission allowances are expensed to Fuel used in electric generation and purchased power – regulated on the Consolidated Statements of Operations. Renewable energy certificates are used to measure compliance with renewable energy standards and are held primarily for consumption. See Note 11 for further information. Long-Lived Asset Impairments The Duke Energy Registrants evaluate long-lived assets, excluding goodwill, for impairment when circumstances indicate the carrying value of those assets may not be recoverable. An impairment exists when a long-lived asset’s carrying value exceeds the estimated undiscounted cash flows expected to result from the use and eventual disposition of the asset. The estimated cash flows may be based on alternative expected outcomes that are probability weighted. If the carrying value of the long-lived asset is not recoverable based on these estimated future undiscounted cash flows, the carrying value of the asset is written-down to its then-current estimated fair value and an impairment charge is recognized. The Duke Energy Registrants assess fair value of long-lived assets using various methods, including recent comparable third-party sales, internally developed discounted cash flow analysis and analysis from outside advisers. Significant changes in commodity prices, the condition of an asset or management’s interest in selling the asset are generally viewed as triggering events to reassess cash flows. Property, Plant and Equipment Property, plant and equipment are stated at the lower of depreciated historical cost net of any disallowances or fair value, if impaired. The Duke Energy Registrants capitalize all construction-related direct labor and material costs, as well as indirect construction costs such as general engineering, taxes and financing costs. See “Allowance for Funds Used During Construction (AFUDC) and Interest Capitalized” for information on capitalized financing costs. Costs of renewals and betterments that extend the useful life of property, plant and equipment are also capitalized. The cost of repairs, replacements and major maintenance projects, which do not extend the useful life or increase the expected output of the asset, are expensed as incurred. Depreciation is generally computed over the estimated useful life of the asset using the composite straight-line method. Depreciation studies are conducted periodically to update composite rates and are approved by state utility commissions and/or the FERC when required. The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows. Years Ended December 31, 2015 2014 2013 Duke Energy 2.9 % 2.8 % 2.8 % Duke Energy Carolinas 2.8 % 2.7 % 2.8 % Progress Energy 2.6 % 2.5 % 2.5 % Duke Energy Progress 2.6 % 2.5 % 2.5 % Duke Energy Florida 2.7 % 2.7 % 2.4 % Duke Energy Ohio 2.7 % 2.3 % 3.3 % Duke Energy Indiana 3.0 % 3.0 % 2.8 % In general, when the Duke Energy Registrants retire regulated property, plant and equipment, original cost plus the cost of retirement, less salvage value, is charged to accumulated depreciation. However, when it becomes probable a regulated asset will be retired substantially in advance of its original expected useful life or is abandoned, the cost of the asset and the corresponding accumulated depreciation is recognized as a separate asset. If the asset is still in operation, the net amount is classified as Generation facilities to be retired, net on the Consolidated Balance Sheets. If the asset is no longer operating, the net amount is classified in Regulatory Assets on the Consolidated Balance Sheets. The carrying value of the asset is based on historical cost if the Duke Energy Registrants are allowed to recover the remaining net book value and a return equal to at least the incremental borrowing rate. If not, an impairment is recognized to the extent the net book value of the asset exceeds the present value of future revenues discounted at the incremental borrowing rate. When the Duke Energy Registrants sell entire regulated operating units, or retire or sell nonregulated properties, the original cost and accumulated depreciation and amortization balances are removed from Property, Plant and Equipment on the Consolidated Balance Sheets. Any gain or loss is recorded in earnings, unless otherwise required by the applicable regulatory body. See Note 10 for further information. Nuclear Fuel Nuclear fuel is classified as Property, Plant and Equipment on the Consolidated Balance Sheets, except for Duke Energy Florida. Refer to Note 4, “Regulatory Matters,” for additional information on Crystal River Unit 3 investments, including nuclear fuel. Nuclear fuel in the front-end fuel processing phase is considered work in progress and not amortized until placed in service. Amortization of nuclear fuel is included within Fuel used in electric generation and purchased power – regulated in the Consolidated Statements of Operations. Amortization is recorded using the units-of-production method. Allowance for Funds Used During Construction and Interest Capitalized For regulated operations, the debt and equity costs of financing the construction of property, plant and equipment are reflected as AFUDC and capitalized as a component of the cost of property, plant and equipment. AFUDC equity is reported on the Consolidated Statements of Operations as non-cash income in Other income and expenses, net. AFUDC debt is reported as a non-cash offset to Interest Expense. After construction is completed, the Duke Energy Registrants are permitted to recover these costs through their inclusion in rate base and the corresponding subsequent depreciation or amortization of those regulated assets. AFUDC equity, a permanent difference for income taxes, reduces the effective tax rate when capitalized and increases the effective tax rate when depreciated or amortized. See Note 22 for additional information. For nonregulated operations, interest is capitalized during the construction phase with an offsetting non-cash credit to Interest Expense on the Consolidated Statements of Operations. Asset Retirement Obligations Asset retirement obligations are recognized for legal obligations associated with the retirement of property, plant and equipment. Substantially all asset retirement obligations are related to regulated operations. When recording an asset retirement obligation, the present value of the projected liability is recognized in the period in which it is incurred, if a reasonable estimate of fair value can be made. The liability is accreted over time. For operating plants, the present value of the liability is added to the cost of the associated asset and depreciated over the remaining life of the asset. For retired plants, the present value of the liability is recorded as a regulatory asset. The present value of the initial obligation and subsequent updates are based on discounted cash flows, which include estimates regarding timing of future cash flows, selection of discount rates and cost escalation rates, among other factors. These estimates are subject to change. Depreciation expense is adjusted prospectively for any changes to the carrying amount of the associated asset. The Duke Energy Registrants receive amounts to fund the cost of the asset retirement obligation for regulated operations through a combination of regulated revenues and earnings on the NDTF. As a result, amounts recovered in regulated revenues, earnings on the NDTF, accretion expense and depreciation of the associated asset are all deferred as a regulatory asset or liability. Obligations for nuclear decommissioning are based on-site-specific cost studies. Duke Energy Carolinas and Duke Energy Progress assume prompt dismantlement of the nuclear facilities after operations are ceased. Duke Energy Florida assumes Crystal River Unit 3 will be placed into a safe storage configuration until eventual dismantlement is completed by 2074. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida also assume that spent fuel will be stored on-site until such time that it can be transferred to a U.S. Department of Energy (DOE) facility. Obligations for closure of ash basins are based upon discounted cash flows of estimated costs for site specific plans, if known, or probability weightings of the potential closure methods if the closure plans are under development and multiple closure options are being considered and evaluated on a site-by-site basis. See Note 9 for additional information. Revenue Recognition and Unbilled Revenue Revenues on sales of electricity and 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 delivered but not yet billed. Unbilled revenues can vary significantly from period to period as a result of seasonality, weather, customer usage patterns, customer mix, average price in effect for customer classes, timing of rendering customer bills and meter reading schedules. Unbilled revenues are included within Receivables and Restricted receivables of variable interest entities on the Consolidated Balance Sheets as shown in the following table. This table excludes amounts included in assets held for sale (AHFS) at December 31, 2014. December 31, (in millions) 2015 2014 Duke Energy $ 748 $ 827 Duke Energy Carolinas 283 295 Progress Energy 172 217 Duke Energy Progress 102 135 Duke Energy Florida 70 82 Duke Energy Ohio 3 — Duke Energy Indiana 31 27 Additionally, Duke Energy Ohio and Duke Energy Indiana sell, on a revolving basis, nearly all of their retail accounts receivable, including receivables for unbilled revenues, to an affiliate, Cinergy Receivables Company, LLC (CRC) and account for the transfers of receivables as sales. Accordingly, the receivables sold are not reflected on the Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana. See Note 17 for further information. These receivables for unbilled revenues are shown in the table below. December 31, (in millions) 2015 2014 Duke Energy Ohio $ 71 $ 79 Duke Energy Indiana 97 112 Allowance for Doubtful Accounts Allowances for doubtful accounts are presented in the following table. December 31, (in millions) 2015 2014 2013 Allowance for Doubtful Accounts Duke Energy $ 18 17 30 Duke Energy Carolinas 3 3 3 Progress Energy 6 8 14 Duke Energy Progress 4 7 10 Duke Energy Florida 2 2 4 Duke Energy Ohio 2 2 2 Duke Energy Indiana 1 1 1 Allowance for Doubtful Accounts – VIEs Duke Energy $ 53 51 43 Duke Energy Carolinas 7 6 6 Progress Energy 8 8 — Duke Energy Progress 5 5 — Duke Energy Florida 3 3 — Derivatives and Hedging Derivative and non-derivative instruments may be used in connection with commodity price, interest rate and foreign currency risk management activities, including swaps, futures, forwards and options. All derivative instruments, except those that qualify for the normal purchase/normal sale (NPNS) exception, are recorded on the Consolidated Balance Sheets at fair value. Qualifying derivative instruments may be designated as either cash flow hedges or fair value hedges. Other derivative instruments (undesignated contracts) either have not been designated or do not qualify as hedges. The effective portion of the change in the fair value of cash flow hedges is recorded in AOCI. The effective portion of the change in the fair value of a fair value hedge is offset in net income by changes in the hedged item. For activity subject to regulatory accounting, gains and losses on derivative contracts are reflected as regulatory assets or liabilities and not as other comprehensive income or current period income. As a result, changes in fair value of these derivatives have no immediate earnings impact. Formal documentation, including transaction type and risk management strategy, is maintained for all contracts accounted for as a hedge. At inception and at least every three months thereafter, the hedge contract is assessed to see if it is highly effective in offsetting changes in cash flows or fair values of hedged items. See Note 14 for further information. Captive Insurance Reserves Duke Energy has captive insurance subsidiaries that provide coverage, on an indemnity basis, to the Subsidiary Registrants as well as certain third parties, on a limited basis, for various business risks and losses, such as property, workers

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 31, 2015
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 24, 2015, Duke Energy entered into an Agreement and Plan of Merger (Merger Agreement) with Piedmont Natural Gas Company, Inc. (Piedmont), a North Carolina corporation. Under the terms of the Merger Agreement, Duke Energy will acquire Piedmont for $4.9 billion in cash. Upon closing, Piedmont will become a wholly owned subsidiary of Duke Energy. Pursuant to the Merger Agreement, upon the closing of the merger, each share of Piedmont common stock issued and outstanding immediately prior to the closing will be converted automatically into the right to receive $60 in cash per share. In addition, Duke Energy will assume Piedmont's existing debt, which was approximately $1.9 billion at October 31, 2015, the end of Piedmont's most recent fiscal year. Duke Energy expects to finance the transaction with a combination of debt, equity issuances and other cash sources. As of December 31, 2015, Duke Energy entered into $900 million of forward starting interest rate swaps to lock in components of interest rates for the expected financing. The change in the fair value of the swaps from inception to December 31, 2015, was not material. For additional information on the forward-starting swaps, see Note 14. In connection with the Merger Agreement with Piedmont, Duke Energy entered into a $4.9 billion senior unsecured bridge financing facility (Bridge Facility) with Barclays Capital, Inc. (Barclays). The Bridge Facility, if drawn upon, may be used to (i) fund the cash consideration for the transaction and (ii) pay certain fees and expenses in connection with the transaction. In November 2015, Barclays syndicated its commitment under the Bridge Facility to a broader group of lenders. Duke Energy does not expect to draw upon the Bridge Facility. The Federal Trade Commission (FTC) has granted early termination of the 30-day waiting period under the federal Hart-Scott-Rodino Antitrust Improvements Act of 1976. On January 22, 2016, shareholders of Piedmont Natural Gas approved the company's acquisition by Duke Energy. On January 15, 2016, Duke Energy filed for approval of the transaction and associated financing requests with the NCUC. On January 29, 2016, the NCUC approved the financing requests. On January 15, 2016, Duke Energy and Piedmont filed a joint request with the Tennessee Regulatory Authority for approval of a change in control of Piedmont that will result from Duke Energy's acquisition of Piedmont. In that request, Duke Energy and Piedmont requested that the Authority approve the change in control on or before April 30, 2016. Subject to receipt of required regulatory approvals and meeting closing conditions, Duke Energy and Piedmont target a closing by the end of 2016. On December 11, 2015, Duke Energy Kentucky filed a declaratory request with the KPSC seeking a finding that the transaction does not constitute a change in control of Duke Energy Kentucky requiring KPSC approval. Duke Energy also presented the transaction for information before the PSCSC on January 13, 2016. The Merger Agreement contains certain termination rights for both Duke Energy and Piedmont, and provides that, upon termination of the Merger Agreement under specified circumstances, Duke Energy would be required to pay a termination fee of $250 million to Piedmont and Piedmont would be required to pay Duke Energy a termination fee of $125 million . See Note 4 for additional information regarding Duke Energy and Piedmont's joint investment in Atlantic Coast Pipeline, LLC (ACP). Purchase of NCEMPA's Generation On July 31, 2015, Duke Energy Progress completed the purchase of North Carolina Eastern Municipal Power Agency’s (NCEMPA) ownership interests in certain generating assets, fuel and spare parts inventory jointly owned with and operated by Duke Energy Progress for approximately $1.25 billion . This purchase was accounted for as an asset acquisition. The purchase resulted in the acquisition of a total of approximately 700 megawatts (MW) of generating capacity at Brunswick Nuclear Plant, Shearon Harris Nuclear Plant, Mayo Steam Plant and Roxboro Steam Plant. In connection with this transaction, Duke Energy Progress and NCEMPA entered into a 30-year wholesale power agreement, whereby Duke Energy Progress will sell power to NCEMPA to continue to meet the needs of NCEMPA customers. The purchase price exceeds the historical carrying value of the acquired assets by $350 million , which was recognized as an acquisition adjustment, recorded in property, plant and equipment. Duke Energy Progress received FERC approval for inclusion of the acquisition adjustment in wholesale power formula rates on December 9, 2014. On July 8, 2015, the NCUC adopted a new rule that enables a rider mechanism for recovery of the costs to acquire, operate and maintain interests in the assets purchased as allocated to Duke Energy Progress' North Carolina retail operations, including the acquisition adjustment. Pursuant to the NCUC's approval, Duke Energy Progress implemented a rider to recover costs associated with the NCEMPA asset acquisition effective December 1, 2015. Duke Energy Progress also received an order from the PSCSC to defer the recovery of the South Carolina retail allocated costs of the asset purchased until the Company's next general rate case. Assets Acquired The ownership interests in generating assets acquired are subject to rate-setting authority of the FERC, NCUC and PSCSC and accordingly, the assets are recorded at historical cost. The assets acquired are presented in the following table. (in millions) Inventory $ 56 Net property, plant and equipment 845 Total assets 901 Acquisition adjustment, recorded within property, plant and equipment 350 Total purchase price $ 1,251 In connection with the acquisition, Duke Energy Progress acquired NCEMPA's nuclear decommissioning trust fund assets of $287 million and assumed asset retirement obligations of $204 million associated with NCEMPA's interest in the generation assets. The nuclear decommissioning trust fund and the asset retirement obligation are subject to regulatory accounting treatment. DISPOSITIONS Potential Sale of International Energy On February 18, 2016, Duke Energy announced it had initiated a process to divest the International Energy business segment, excluding the equity method investment in National Methanol Company (NMC). Duke Energy is in the preliminary stage and there have been no binding or non-binding offers requested or submitted. Duke Energy can provide no assurance that this process will result in a transaction and there is no specific timeline for execution of a potential transaction. Proceeds from a successful exit would be used by Duke Energy to fund the operations and growth of domestic businesses. If the potential of a sale were to progress, it could result in classification of International Energy as assets held for sale and as a discontinued operation. As of December 31, 2015, the International Energy segment had a carrying value of approximately $2.7 billion , adjusted to include the cumulative foreign currency translation losses currently classified as accumulated other comprehensive income. Midwest Generation Exit Duke Energy, through indirect subsidiaries, completed the sale of the nonregulated Midwest generation business and Duke Energy Retail Sales (collectively, the Disposal Group) to a subsidiary of Dynegy on April 2, 2015, for approximately $2.8 billion in cash. On April 1, 2015, prior to the sale, Duke Energy Ohio distributed its indirect ownership interest in the nonregulated Midwest generation business to a subsidiary of Duke Energy Corporation. The assets and liabilities of the Disposal Group prior to the sale were included in the Commercial Portfolio (formerly Commercial Power) segment and classified as held for sale in Duke Energy's and Duke Energy Ohio's Consolidated Balance Sheet at December 31, 2014. The following table presents information at the time of the sale related to the Duke Energy Ohio generation plants included in the Disposal Group. Total MW Owned MW Ownership Facility Plant Type Primary Fuel Location Capacity (d) Capacity (d) Interest Stuart (a)(c) Fossil Steam Coal OH 2,308 900 39 % Zimmer (a) Fossil Steam Coal OH 1,300 605 46.5 % Hanging Rock Combined Cycle Gas OH 1,226 1,226 100 % Miami Fort (Units 7 and 8) (b) Fossil Steam Coal OH 1,020 652 64 % Conesville (a)(c) Fossil Steam Coal OH 780 312 40 % Washington Combined Cycle Gas OH 617 617 100 % Fayette Combined Cycle Gas PA 614 614 100 % Killen (b)(c) Fossil Steam Coal OH 600 198 33 % Lee Combustion Turbine Gas IL 568 568 100 % Dick's Creek Combustion Turbine Gas OH 136 136 100 % Miami Fort Combustion Turbine Oil OH 56 56 100 % Total Midwest Generation 9,225 5,884 (a) Jointly owned with American Electric Power Generation Resources and The Dayton Power and Light Company. (b) Jointly owned with The Dayton Power and Light Company. (c) Not operated by Duke Energy Ohio. (d) Total MW capacity is based on summer capacity. The Disposal Group also included a retail sales business owned by Duke Energy. In the second quarter of 2014, Duke Energy Ohio removed Ohio Valley Electric Corporation's (OVEC) purchase power agreement from the Disposal Group as it no longer intended to sell it with the Disposal Group. The results of operations of the Disposal Group prior to the date of sale are classified as discontinued operations in the accompanying Consolidated Statements of Operations and Comprehensive Income. Certain immaterial costs that were eliminated as a result of the sale remained in continuing operations. The following table presents the results of discontinued operations. Duke Energy Years Ended December 31, (in millions) 2015 2014 2013 Operating Revenues $ 543 $ 1,748 $ 1,885 Loss on disposition (a) (45 ) (929 ) — Income (loss) before income taxes (b) $ 59 $ (818 ) $ 141 Income tax expense (benefit) 26 (294 ) 56 Income (loss) from discontinued operations of the Disposal Group 33 (524 ) 85 Other, net of tax (c) (13 ) (52 ) 1 Income (Loss) From Discontinued Operations, net of tax $ 20 $ (576 ) $ 86 (a) The Loss on disposition includes impairments recorded to adjust the carrying amount of the assets to the estimated fair value of the business, based on the selling price to Dynegy less cost to sell. (b) The Income (loss) before income taxes includes the pretax impact of an $81 million charge for the settlement agreement reached in a lawsuit related to the Disposal Group for the year ended December 31, 2015. Refer to Note 5 for further information related to the lawsuit. (c) Relates to discontinued operations of businesses not related to the Disposal Group. Amounts include indemnifications provided for certain legal, tax and environmental matters, and foreign currency translation adjustments. Duke Energy Ohio Years Ended December 31, (in millions) 2015 2014 2013 Operating Revenues $ 412 $ 1,299 $ 1,503 Loss on disposition (a) (52 ) (959 ) — Income (loss) before income taxes (b) $ 44 $ (863 ) $ 67 Income tax expense (benefit) 21 (300 ) 32 Income (Loss) From Discontinued Operations, net of tax $ 23 $ (563 ) $ 35 (a) The Loss on disposition includes impairments recorded to adjust the carrying amount of the assets to the estimated fair value of the business, based on the selling price to Dynegy less cost to sell. (b) The Income (loss) before income taxes includes the pretax impact of an $81 million charge for the settlement agreement reached in a lawsuit related to the Disposal Group for the year ended December 31, 2015, respectively. Refer to Note 5 for further information related to the lawsuit. Commercial Portfolio has a revolving credit agreement (RCA) which was used to support the operations of the nonregulated Midwest generation business. Interest expense associated with the RCA was allocated to discontinued operations. No other interest expense related to corporate level debt was allocated to discontinued operations. Duke Energy Ohio had a power purchase agreement with the Disposal Group for a portion of its standard service offer (SSO) supply requirement. The agreement and the SSO expired in May 2015. Duke Energy received reimbursement for transition services provided to Dynegy through December 2015. The continuing cash flows were not considered direct cash flows or material. Duke Energy or Duke Energy Ohio did not significantly influence the operations of the Disposal Group during the transition service period. See Notes 4 and 5 for a discussion of contingencies related to the Disposal Group that are retained by Duke Energy Ohio subsequent to the sale.

Business Segments

Business Segments	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Business Segments	BUSINESS SEGMENTS Duke Energy evaluates segment performance based on segment income. Segment income is defined as income from continuing operations net of income attributable to noncontrolling interests. Segment income, as discussed below, includes intercompany revenues and expenses that are eliminated in the Consolidated Financial Statements. Certain governance costs are allocated to each segment. In addition, direct interest expense and income taxes are included in segment income. Operating segments are determined based on information used by the chief operating decision maker in deciding how to allocate resources and evaluate the performance. Products and services are sold between affiliate companies and reportable segments of Duke Energy at cost. Segment assets as presented in the tables that follow exclude all intercompany assets. Duke Energy Duke Energy has the following reportable operating segments: Regulated Utilities, International Energy and Commercial Portfolio. Regulated Utilities conducts electric and natural gas operations that are substantially all regulated and, accordingly, qualify for regulatory accounting treatment. These operations are primarily conducted through the Subsidiary Registrants and are subject to the rules and regulations of the FERC, NRC, NCUC, PSCSC, FPSC, PUCO, IURC and KPSC. International Energy principally operates and manages power generation facilities and engages in sales and marketing of electric power, natural gas and natural gas liquids outside the U.S. Its activities principally target power generation in Latin America. Additionally, International Energy owns a 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. On February 4, 2016, Duke Energy announced it had initiated a process to divest its International Energy business segment, excluding the investment in NMC. See Note 2 for further information. Commercial Portfolio builds, develops and operates wind and solar renewable generation and energy transmission projects throughout the U.S. The segment was renamed as a result of the sale of the Disposal Group, as discussed in Note 2. For periods subsequent to the sale, beginning in the second quarter of 2015, certain immaterial results of operations and related assets previously presented in the Commercial Portfolio segment are presented in Regulated Utilities and Other. 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).On December 31, 2013, Duke Energy sold its interest in DukeNet Communications Holdings, LLC (DukeNet) to Time Warner Cable, Inc. Year Ended December 31, 2015 Total Regulated International Commercial Reportable (in millions) Utilities Energy Portfolio Segments Other Eliminations Total Unaffiliated Revenues $ 22,024 $ 1,088 $ 301 $ 23,413 $ 46 $ — $ 23,459 Intersegment Revenues 38 — — 38 77 (115 ) — Total Revenues $ 22,062 $ 1,088 $ 301 $ 23,451 $ 123 $ (115 ) $ 23,459 Interest Expense $ 1,097 $ 85 $ 44 $ 1,226 $ 393 $ (6 ) $ 1,613 Depreciation and amortization 2,814 92 104 3,010 134 — 3,144 Equity in earnings of unconsolidated affiliates (4 ) 74 (3 ) 67 2 — 69 Income tax expense (benefit) 1,647 74 (92 ) 1,629 (303 ) — 1,326 Segment income (loss) (a)(b)(c)(d) 2,893 225 4 3,122 (322 ) (4 ) 2,796 Add back noncontrolling interest component 15 Income from discontinued operations, net of tax (e) 20 Net income $ 2,831 Capital investments expenditures and acquisitions $ 6,974 $ 45 $ 1,131 $ 8,150 $ 213 $ — $ 8,363 Segment Assets 111,562 3,271 4,010 118,843 2,125 188 121,156 (a) Regulated Utilities includes an after-tax charge of $58 million related to the Edwardsport settlement. Refer to Note 4 for further information. (b) Commercial Portfolio includes state tax expense of $41 million , resulting from changes to state apportionment factors due to the sale of the Disposal Group, that does not qualify for discontinued operations. Refer to Note 2 for further information related to the sale. (c) Other includes $60 million of after-tax costs to achieve mergers. (d) Other includes an after-tax charge of $77 million related to cost savings initiatives. Refer to Note 19 for further information related to the cost savings initiatives. (e) Includes after-tax impact of $53 million for the settlement agreement reached in a lawsuit related to the Disposal Group. Refer to Note 5 for further information related to the lawsuit. Year Ended December 31, 2014 Total Regulated International Commercial Reportable (in millions) Utilities Energy Portfolio Segments Other Eliminations Total Unaffiliated Revenues $ 22,228 $ 1,417 $ 255 $ 23,900 $ 25 $ — $ 23,925 Intersegment Revenues 43 — — 43 80 (123 ) — Total Revenues $ 22,271 $ 1,417 $ 255 $ 23,943 $ 105 $ (123 ) $ 23,925 Interest Expense $ 1,093 $ 93 $ 58 $ 1,244 $ 400 $ (22 ) $ 1,622 Depreciation and amortization 2,759 97 92 2,948 118 — 3,066 Equity in earnings of unconsolidated affiliates (3 ) 120 10 127 3 — 130 Income tax expense (benefit) (a) 1,628 449 (171 ) 1,906 (237 ) — 1,669 Segment income (loss) (b)(c)(d) 2,795 55 (55 ) 2,795 (334 ) (10 ) 2,451 Add back noncontrolling interest component 14 Loss from discontinued operations, net of tax (576 ) Net income $ 1,889 Capital investments expenditures and acquisitions $ 4,744 $ 67 $ 555 $ 5,366 $ 162 $ — $ 5,528 Segment Assets 106,574 5,093 6,278 117,945 2,423 189 120,557 (a) International Energy includes a tax adjustment of $373 million related to deferred tax impact resulting from the decision to repatriate all cumulative historical undistributed foreign earnings. See Note 22 for additional information. (b) Commercial Portfolio recorded a $94 million pretax impairment charge related to OVEC. (c) Other includes costs to achieve mergers. (d) Regulated Utilities includes an increase in the litigation reserve related to the criminal investigation of the Dan River coal ash spill. See Note 5 for additional information. Year Ended December 31, 2013 Total Regulated International Commercial Reportable (in millions) Utilities Energy Portfolio Segments Other Eliminations Total Unaffiliated Revenues (a)(b)(c) $ 20,871 $ 1,546 $ 254 $ 22,671 $ 85 $ — $ 22,756 Intersegment Revenues 39 — 6 45 90 (135 ) — Total Revenues $ 20,910 $ 1,546 $ 260 $ 22,716 $ 175 $ (135 ) $ 22,756 Interest Expense $ 986 $ 86 $ 61 $ 1,133 $ 416 $ (6 ) $ 1,543 Depreciation and amortization 2,323 100 110 2,533 135 — 2,668 Equity in earnings of unconsolidated affiliates (1 ) 110 7 116 6 — 122 Income tax expense (benefit) 1,522 166 (148 ) 1,540 (335 ) — 1,205 Segment income (loss) (a)(b)(c)(d)(e)(f)(g) 2,504 408 (88 ) 2,824 (238 ) (12 ) 2,574 Add back noncontrolling interest component 16 Income from discontinued operations, net of tax 86 Net income $ 2,676 Capital investments expenditures and acquisitions $ 5,049 $ 67 $ 268 $ 5,384 $ 223 $ — $ 5,607 Segment Assets 99,884 4,998 6,955 111,837 2,754 188 114,779 (a) In May 2013, the PUCO approved a Duke Energy Ohio settlement agreement that provides for a net annual increase in electric distribution revenues beginning in May 2013. This rate increase impacts Regulated Utilities. (b) In June 2013, NCUC approved a Duke Energy Progress settlement agreement that included an increase in rates in the first year beginning in June 2013. This rate increase impacts Regulated Utilities. (c) In September 2013, Duke Energy Carolinas implemented revised customer rates approved by the NCUC and the PSCSC. These rate increases impact Regulated Utilities. (d) Regulated Utilities recorded an impairment charge related to Duke Energy Florida's Crystal River Unit 3. See Note 4 for additional information. (e) Regulated Utilities recorded an impairment charge related to the letter Duke Energy Progress filed with the NRC requesting the NRC to suspend its review activities associated with the combined construction and operating license (COL) at the Harris site. Regulated Utilities also recorded an impairment charge related to the write-off of the wholesale portion of the Levy investments at Duke Energy Florida in accordance with the 2013 Settlement. See Note 4 for additional information. (f) Other includes costs to achieve mergers. (g) Other includes gain from the sale of Duke Energy's ownership interest in DukeNet. See Note 12 for additional information on the sale of DukeNet. Geographical Information (in millions) U.S. Latin America (a) Consolidated 2015 Consolidated revenues $ 22,371 $ 1,088 $ 23,459 Consolidated long-lived assets 87,552 2,012 89,564 2014 Consolidated revenues $ 22,508 $ 1,417 $ 23,925 Consolidated long-lived assets 80,709 2,458 83,167 2013 Consolidated revenues $ 21,211 $ 1,545 $ 22,756 Consolidated long-lived assets 78,581 2,781 81,362 (a) Change in amounts of long-lived assets in Latin America includes foreign currency translation adjustments on property, plant and equipment and other long-lived asset balances. Products and Services The following table summarizes revenues of the reportable segments by type. Retail Wholesale Retail Wholesale Total (in millions) Electric Electric Natural Gas Natural Gas Other Revenues 2015 Regulated Utilities $ 18,695 $ 2,014 $ 546 $ — $ 807 $ 22,062 International Energy — 1,025 — 63 — 1,088 Commercial Portfolio — 260 — — 41 301 Total Reportable Segments $ 18,695 $ 3,299 $ 546 $ 63 $ 848 $ 23,451 2014 Regulated Utilities $ 19,007 $ 1,879 $ 571 $ — $ 814 $ 22,271 International Energy — 1,326 — 91 — 1,417 Commercial Portfolio — 255 — — — 255 Total Reportable Segments $ 19,007 $ 3,460 $ 571 $ 91 $ 814 $ 23,943 2013 Regulated Utilities $ 17,837 $ 1,720 $ 506 $ — $ 847 $ 20,910 International Energy — 1,447 — 99 — 1,546 Commercial Portfolio — 260 — — — 260 Total Reportable Segments $ 17,837 $ 3,427 $ 506 $ 99 $ 847 $ 22,716 Duke Energy Ohio Duke Energy Ohio had two reportable operating segments, Regulated Utilities and Commercial Portfolio, prior to the sale of the nonregulated Midwest generation business. As a result of the sale discussed in Note 2, Commercial Portfolio no longer qualifies as a Duke Energy Ohio reportable operating segment. Therefore, for periods subsequent to the sale, beginning in the second quarter of 2015, all of the remaining assets and related results of operations previously presented in Commercial Portfolio are presented in Regulated Utilities and Other. Regulated Utilities transmits and distributes electricity in portions of Ohio and generates, distributes and sells electricity in portions of Kentucky. Regulated Utilities also 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 OVEC's power plants. For additional information on related party transactions refer to Note 9. See Note 13 for additional information. All of Duke Energy Ohio’s revenues are generated domestically and its long-lived assets are all in the U.S. Year Ended December 31, 2015 Total Regulated Commercial Reportable (in millions) Utilities Portfolio Segments Other Eliminations Total Unaffiliated revenues $ 1,872 $ 14 $ 1,886 $ 19 $ — $ 1,905 Intersegment revenues 1 — 1 — (1 ) — Total revenues $ 1,873 $ 14 $ 1,887 $ 19 $ (1 ) $ 1,905 Interest expense $ 78 $ — $ 78 $ 1 $ — $ 79 Depreciation and amortization 226 — 226 1 — 227 Income tax expense (benefit) 105 (5 ) 100 (19 ) — 81 Segment income (loss) 191 (8 ) 183 (33 ) (1 ) 149 Income from discontinued operations, net of tax 23 Net income $ 172 Capital expenditures $ 399 $ — $ 399 $ — $ — $ 399 Segment assets 7,050 — 7,050 55 (8 ) 7,097 Year Ended December 31, 2014 Total Regulated Commercial Reportable (in millions) Utilities Portfolio Segments Other Eliminations Total Unaffiliated revenues $ 1,894 $ 19 $ 1,913 $ — $ — $ 1,913 Intersegment revenues 1 — 1 — (1 ) — Total revenues $ 1,895 $ 19 $ 1,914 $ — $ (1 ) $ 1,913 Interest expense $ 81 $ 5 $ 86 $ — $ — $ 86 Depreciation and amortization 211 2 213 1 — 214 Income tax expense (benefit) 117 (67 ) 50 (7 ) — 43 Segment income (loss) (a) 202 (121 ) 81 (13 ) — 68 Income from discontinued operations, net of tax (563 ) Net loss $ (495 ) Capital expenditures $ 300 $ 22 $ 322 $ — $ — $ 322 Segment assets 6,902 3,187 10,089 134 (230 ) 9,993 (a) Commercial Portfolio recorded a $94 million pretax impairment charge related to OVEC. Year Ended December 31, 2013 Total Regulated Commercial Reportable (in millions) Utilities Portfolio Segments Other Eliminations Total Total revenues $ 1,765 $ 40 $ 1,805 $ — $ — $ 1,805 Interest expense $ 74 $ — $ 74 $ — $ — $ 74 Depreciation and amortization 200 13 213 — — 213 Income tax expense (benefit) 91 (36 ) 55 (12 ) — 43 Segment income (loss) 151 (65 ) 86 (19 ) — 67 Income from discontinued operations, net of tax 35 Net income $ 102 Capital expenditures $ 375 $ 58 $ 433 $ — $ — $ 433 Segment assets 6,649 4,170 10,819 99 (155 ) 10,763 DUKE ENERGY CAROLINAS, PROGRESS ENERGY, DUKE ENERGY PROGRESS, DUKE ENERGY FLORIDA AND DUKE ENERGY INDIANA The remaining Subsidiary Registrants each have one reportable operating segment, Regulated Utilities, 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 $240 million , $241 million and $300 million for the years ended December 31, 2015 , 2014 and 2013 . The following table summarizes the net loss for Other for each of these entities. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas $ (95 ) $ (79 ) $ (97 ) Progress Energy (159 ) (190 ) (241 ) Duke Energy Progress (32 ) (31 ) (46 ) Duke Energy Florida (16 ) (19 ) (24 ) Duke Energy Indiana (10 ) (11 ) (16 ) Duke Energy Progress earned approximately 10 percent of its consolidated operating revenues from North Carolina Electric Membership Corporation (NCEMC) in 2015. These revenues relate to wholesale contracts and transmission revenues. The assets Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida and Duke Energy Indiana are substantially all included within the Regulated Utilities segment at December 31, 2015 , 2014 and 2013 .3

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2015
Regulated Operations [Abstract]
Regulatory Matters	REGULATORY MATTERS Regulatory Assets and Liabilities The Duke Energy Registrants record regulatory assets and liabilities that result from the ratemaking process. See Note 1 for further information. The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Assets Asset retirement obligations – coal ash $ 2,555 $ 1,120 $ 1,394 $ 1,386 $ 8 $ 4 $ 37 Asset retirement obligations – nuclear and other 838 104 487 195 292 — — Accrued pension and OPEB 2,151 479 807 366 441 139 220 Retired generation facilities 509 49 409 179 230 — 51 Debt fair value adjustment 1,191 — — — — — — Net regulatory asset related to income taxes 1,075 564 318 106 212 55 120 Nuclear asset securitizable balance, net 1,237 — 1,237 — 1,237 — — Hedge costs and other deferrals 571 127 410 171 239 7 27 Demand side management (DSM)/Energy efficiency (EE) 340 80 250 237 13 10 — Grid Modernization 68 — — — — 68 — Vacation accrual 192 79 38 38 — 5 10 Deferred fuel and purchased power 151 21 129 93 36 1 — Nuclear deferral 245 107 138 62 76 — — Post-in-service carrying costs and deferred operating expenses 383 97 38 38 — 21 227 Gasification services agreement buyout 32 — — — — — 32 Transmission expansion obligation 72 — — — — 72 — Manufactured gas plant (MGP) 104 — — — — 104 — NCEMPA deferrals 21 — 21 21 — — — East Bend deferrals 16 — — — — 16 — Other 499 244 121 82 39 31 94 Total regulatory assets 12,250 3,071 5,797 2,974 2,823 533 818 Less: current portion 877 305 362 264 98 36 102 Total noncurrent regulatory assets $ 11,373 $ 2,766 $ 5,435 $ 2,710 $ 2,725 $ 497 $ 716 December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Liabilities Costs of removal $ 5,329 $ 2,413 $ 2,078 $ 1,725 $ 353 $ 222 $ 616 Amounts to be refunded to customers 71 — — — — — 71 Storm reserve 150 24 125 — 125 1 — Accrued pension and OPEB 288 68 51 25 26 21 83 Deferred fuel and purchased power 311 55 255 58 197 1 — Other 506 281 164 155 8 12 46 Total regulatory liabilities 6,655 2,841 2,673 1,963 709 257 816 Less: current portion 400 39 286 85 200 12 62 Total noncurrent regulatory liabilities $ 6,255 $ 2,802 $ 2,387 $ 1,878 $ 509 $ 245 $ 754 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Assets Asset retirement obligations – coal ash $ 1,992 $ 840 $ 1,152 $ 1,152 $ — $ — $ — Asset retirement obligations – nuclear and other 1,025 67 730 432 298 — — Accrued pension and OPEB 2,015 412 812 354 458 132 217 Retired generation facilities 1,659 58 1,545 152 1,393 — 56 Debt fair value adjustment 1,305 — — — — — — Net regulatory asset related to income taxes 1,144 614 354 141 213 64 111 Hedge costs and other deferrals 628 103 490 217 273 7 28 DSM/EE 330 106 203 193 10 21 — Grid Modernization 76 — — — — 76 — Vacation accrual 213 86 46 46 — 6 12 Deferred fuel and purchased power 246 50 182 138 44 9 5 Nuclear deferral 296 141 155 43 112 — — Post-in-service carrying costs and deferred operating expenses 494 124 121 28 93 21 228 Gasification services agreement buyout 55 — — — — — 55 Transmission expansion obligation 70 — — — — 74 — MGP 115 — — — — 115 — Other 494 263 109 66 42 36 66 Total regulatory assets 12,157 2,864 5,899 2,962 2,936 561 778 Less: current portion 1,115 399 491 287 203 49 93 Total noncurrent regulatory assets $ 11,042 $ 2,465 $ 5,408 $ 2,675 $ 2,733 $ 512 $ 685 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Liabilities Costs of removal $ 5,221 $ 2,420 $ 1,975 $ 1,692 $ 283 $ 222 $ 613 Amounts to be refunded to customers 166 — 70 — 70 — 96 Storm reserve 150 25 125 — 125 — — Accrued pension and OPEB 379 76 121 61 60 19 91 Deferred fuel and purchased power 37 6 23 23 — — 8 Other 444 217 171 127 44 10 42 Total regulatory liabilities 6,397 2,744 2,485 1,903 582 251 850 Less: current portion 204 34 106 71 35 10 54 Total noncurrent regulatory liabilities $ 6,193 $ 2,710 $ 2,379 $ 1,832 $ 547 $ 241 $ 796 Descriptions of regulatory assets and liabilities, summarized in the tables above, as well as their recovery and amortization periods follow. Items are excluded from rate base unless otherwise noted. Asset retirement obligations – coal ash. Represents regulatory assets including deferred depreciation and accretion related to the legal obligation to close ash basins. The costs are deferred until recovery treatment has been determined. The recovery period for these costs has yet to be established. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Ohio earn a debt return on their expenditures. See Notes 1 and 9 for additional information. Asset retirement obligations – nuclear and other. Represents regulatory assets, including deferred depreciation and accretion, related to legal obligations associated with the future retirement of property, plant and equipment, excluding amounts related to coal ash. The Asset retirement obligations relate primarily to decommissioning nuclear power facilities. The amounts also include certain deferred gains on NDTF investments. The recovery period for costs related to nuclear facilities runs through the decommissioning period of each nuclear unit, the latest of which is currently estimated to be 2086. See Notes 1 and 9 for additional information. Accrued pension and OPEB. Accrued pension and OPEB represent regulatory assets and liabilities related to each of the Duke Energy Registrants’ respective shares of unrecognized actuarial gains and losses and unrecognized prior service cost and credit attributable to Duke Energy’s pension plans and OPEB plans. The regulatory asset or liability is amortized with the recognition of actuarial gains and losses and prior service cost and credit to net periodic benefit costs for pension and OPEB plans. See Note 21 for additional detail. Retired generation facilities. Duke Energy Florida earns a full return on a portion of the regulatory asset related to the retired nuclear plant currently recovered in the nuclear cost recovery clause (NCRC), with the remaining portion earning a reduced return. Duke Energy Carolinas earns a return on the outstanding retail balance with recovery periods ranging from five to 10 years . Duke Energy Progress earns a return on the outstanding balance with recovery over a period of 10 years for retail purposes and over the longer of 10 years or the previously estimated planned retirement date for wholesale purposes. Duke Energy Indiana earns a return on the outstanding balances and the costs are included in rate base. Debt fair value adjustment. Purchase accounting adjustment recorded to state the carrying value of Progress Energy at fair value in connection with the 2012 merger. Amount is amortized over the life of the related debt. Net regulatory asset related to income taxes. Regulatory assets principally associated with the depreciation and recovery of AFUDC equity. Amounts have no impact on rate base as regulatory assets are offset by deferred tax liabilities. The recovery period is over the life of the associated assets. Amounts for Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress include regulatory liabilities related to the change in the North Carolina corporate tax rate discussed in Note 22. Nuclear asset securitizable balance, net. Represents the balance associated with Crystal River Unit 3 retirement approved for recovery by the FPSC on September 15, 2015, and the deferred operating expenses expected to be securitized in 2016 upon issuance of the associated bonds. The regulatory asset balance is net of the AFUDC equity portion of the $1.283 billion amount approved by the FPSC. The regulatory asset balance approved for recovery by the FPSC will earn a reduced return until the expected bond issuance, after which it will earn a return in rates to recover the interest costs of the associated debt. Once bonds are issued, the balance will be recovered over approximately 20 years . This regulatory asset is not included in rate base. Hedge costs and other deferrals. Amounts relate to unrealized gains and losses on derivatives recorded as a regulatory asset or liability, respectively, until the contracts are settled. The recovery period varies for these costs and currently extends to 2048. DSM/EE. The recovery period varies for these costs, with some currently unknown. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida are required to pay interest on the outstanding liability balance. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida collect a return on DSM/EE investments. Grid Modernization. Represents deferred depreciation and operating expenses as well as carrying costs on the portion of capital expenditures placed in service but not yet reflected in retail rates as plant in service. Recovery period is generally one year for depreciation and operating expenses. Recovery for post-in-service carrying costs is over the life of the assets. Duke Energy Ohio is earning a return on these costs. Vacation accrual. Generally recovered within one year. Deferred fuel and purchased power. Represents certain energy related costs that are recoverable or refundable as approved by the applicable regulatory body. Duke Energy Florida amount includes capacity costs. Duke Energy Florida earns a return on the retail portion of under-recovered costs. Duke Energy Ohio earns a return on under-recovered costs. Duke Energy Florida and Duke Energy Ohio pay interest on over-recovered costs. Duke Energy Carolinas and Duke Energy Progress amounts include certain purchased power costs in both North Carolina and South Carolina and costs of distributed energy resource programs in South Carolina. Duke Energy Carolinas and Duke Energy Progress pay interest on over-recovered costs in North Carolina. Recovery period is generally over one year. Duke Energy Indiana recovery period is quarterly. Nuclear deferral. Includes (i) amounts related to levelizing nuclear plant outage costs at Duke Energy Carolinas in North Carolina and South Carolina, and Duke Energy Progress in North Carolina, which allows for the recognition of nuclear outage expenses over the refueling cycle rather than when the outage occurs, resulting in the deferral of operations and maintenance costs associated with refueling and (ii) certain deferred preconstruction and carrying costs at Duke Energy Florida as approved by the FPSC primarily associated with Levy, with a final true-up to be filed by May 2017. Post-in-service carrying costs and deferred operating expenses. Represents deferred depreciation and operating expenses as well as carrying costs on the portion of capital expenditures placed in service but not yet reflected in retail rates as plant in service. Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio and Duke Energy Indiana earn a return on the outstanding balance. Duke Energy Florida earns a return at a reduced rate. For Duke Energy Ohio and Duke Energy Indiana, some amounts are included in rate base. Recovery is over various lives, and the latest recovery period is 2082. Gasification services agreement buyout. The IURC authorized Duke Energy Indiana to recover costs incurred to buyout a gasification services agreement, including carrying costs through 2018. Transmission expansion obligation. Represents transmission expansion obligations related to Duke Energy Ohio’s withdrawal from Midcontinent Independent System Operator, Inc. (MISO). MGP. Represents remediation costs for former MGP sites. In November 2013, the PUCO approved recovery of costs incurred through 2019. Duke Energy Ohio does not earn a return on these costs. NCEMPA deferrals. Represents retail allocated cost deferrals and returns associated with the additional ownership interest in assets acquired from NCEMPA discussed in Note 2. The North Carolina retail allocated costs are generally being recovered, over a period of time between three years and the remaining life of the assets purchased, through a rider that became effective on December 1, 2015. The South Carolina retail allocated costs are being deferred until Duke Energy Progress' next general rate case, earning a return pursuant to an order received from the PSCSC. East Bend deferrals. Represents both deferred operating expenses and deferred depreciation as well as carrying costs on the portion of East Bend that was acquired from Dayton Power and Light and that had been previously operated as a jointly owned facility. Recovery will not commence until the settlement of the next rate case in Kentucky. Duke Energy Ohio is earning a return on these deferred costs. Costs of removal. Represents funds received from customers to cover the future removal of property, plant and equipment from retired or abandoned sites as property is retired. Also includes certain deferred gains on NDTF investments. Amounts to be refunded to customers. Represents required rate reductions to retail customers by the applicable regulatory body. The period of refund for Duke Energy Indiana is through 2017. Storm reserve. Duke Energy Carolinas and Duke Energy Florida are allowed to petition the PSCSC and FPSC, respectively, to seek recovery of named storms. Funds are used to offset future incurred costs. Restrictions on the Ability of Certain Subsidiaries to Make Dividends, Advances and Loans to Duke Energy As a condition to the approval of merger transactions, the NCUC, PSCSC, PUCO, KPSC and IURC imposed conditions on the ability of Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio, Duke Energy Kentucky and Duke Energy Indiana to transfer funds to Duke Energy through loans or advances, as well as restricted amounts available to pay dividends to Duke Energy. Certain subsidiaries may transfer funds to Duke Energy Corporation Holding Company (the parent) by obtaining approval of the respective state regulatory commissions. These conditions imposed restrictions on the ability of the public utility subsidiaries to pay cash dividends as discussed below. Duke Energy Progress and Duke Energy Florida also have restrictions imposed by their first mortgage bond indentures and Articles of Incorporation which, in certain circumstances, limit their ability to make cash dividends or distributions on common stock. Amounts restricted as a result of these provisions were not material at December 31, 2015 . Additionally, certain other subsidiaries of Duke Energy have restrictions on their ability to dividend, loan or advance funds to Duke Energy due to specific legal or regulatory restrictions, including, but not limited to, minimum working capital and tangible net worth requirements. Duke Energy Carolinas Duke Energy Carolinas must limit cumulative distributions subsequent to mergers to (i) the amount of retained earnings on the day prior to the closing of the mergers, plus (ii) any future earnings recorded. Duke Energy Progress Duke Energy Progress must limit cumulative distributions subsequent to the merger between Duke Energy and Progress Energy to (i) the amount of retained earnings on the day prior to the closing of the merger, plus (ii) any future earnings recorded. Duke Energy Ohio Duke Energy Ohio will not declare and pay dividends out of capital or unearned surplus without the prior authorization of the PUCO. Duke Energy Ohio received FERC and PUCO approval to pay dividends from its equity accounts that are reflective of the amount that it would have in its retained earnings account had push-down accounting for the Cinergy Corp. (Cinergy) merger not been applied to Duke Energy Ohio’s balance sheet. The conditions include a commitment from Duke Energy Ohio that equity, adjusted to remove the impacts of push-down accounting, will not fall below 30 percent of total capital. Duke Energy Kentucky is required to pay dividends solely out of retained earnings and to maintain a minimum of 35 percent equity in its capital structure. Duke Energy Indiana Duke Energy Indiana must limit cumulative distributions subsequent to the merger between Duke Energy and Cinergy to (i) the amount of retained earnings on the day prior to the closing of the merger, plus (ii) any future earnings recorded. In addition, Duke Energy Indiana will not declare and pay dividends out of capital or unearned surplus without prior authorization of the IURC. The restrictions discussed above were less than 25 percent of Duke Energy's net assets at December 31, 2015 . Rate Related Information The NCUC, PSCSC, FPSC, IURC, PUCO 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. Duke Energy Carolinas FERC Transmission Return on Equity Complaint On January 7, 2016, a customer group filed a complaint with the FERC that the rate of return on equity of 10.2 percent in Duke Energy Carolinas' transmission formula rates is excessive and should be reduced to no higher than 8.49 percent , effective upon the complaint date. The customer group requests consolidation with a similar complaint filed against Duke Energy Progress on the same day. Duke Energy Carolinas cannot predict the outcome of this matter. William States Lee Combined Cycle Facility On April 9, 2014, the PSCSC granted Duke Energy Carolinas and 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 and Southern Alliance for Clean Energy jointly filed a Notice of Appeal with the Court of Appeals of South Carolina 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 Court of Appeals affirmed the PSCSC's decision on February 10, 2016. On February 23, 2016, the South Carolina Coastal Conservation League and Southern Alliance for Clean Energy filed a petition for rehearing with the Court of Appeals. William States Lee III Nuclear Station In December 2007, Duke Energy Carolinas applied to the NRC for a COL for two Westinghouse AP1000 (advanced passive) reactors for the proposed William States Lee III Nuclear Station (Lee Nuclear Station) at a site in Cherokee County, South Carolina. Submitting the COL application did not commit Duke Energy Carolinas to build nuclear units. Through several separate orders, the NCUC and PSCSC concurred with the prudency of Duke Energy Carolinas incurring certain project development and pre-construction costs, although recovery of costs is not guaranteed. Duke Energy Carolinas has incurred approximately $471 million , including AFUDC through December 31, 2015 . This amount is included in Net property, plant and equipment on Duke Energy Carolinas’ Consolidated Balance Sheets. Design changes have been identified in the Westinghouse AP1000 certified design that must be addressed before NRC can complete its review of the Lee Nuclear Station COL application. These design changes set the schedule for completion of the NRC COL application review and issuance of the Lee COL. Receipt of the Lee Nuclear Station COL is currently expected by late 2016. Duke Energy Progress FERC Transmission Return on Equity Complaint On January 7, 2016, a customer group filed a complaint with the FERC that the rate of return on equity of 10.8 percent in Duke Energy Progress' transmission formula rates is excessive and should be reduced to no higher than 8.49 percent , effective upon the complaint date. The customer group requests consolidation with a similar complaint filed against Duke Energy Carolinas on the same day. Duke Energy Progress cannot predict the outcome of this matter. Sutton Black Start Combustion Turbine CPCN On April 15, 2015, Duke Energy Progress filed a Certificate of Public Convenience and Necessity (CPCN) application with the NCUC for approval to construct an 84 MW black start combustion turbine (CT) project at the existing Sutton Plant (Sutton Black Start CT Project). The Sutton Black Start CT Project would replace three existing CTs with total capacity of 61 MW with two new 42 MW CT units with black start and fast start capability. In addition to peaking system capacity, the Sutton Black Start CT Project will provide regional black start capability and tertiary backup power services for the Brunswick Nuclear Plant. In June 2015, the Public Staff of the NCUC recommended the NCUC approve Duke Energy Progress' application. On August 3, 2015, the NCUC issued an order granting the application and requiring annual construction and cost progress reports. The new units are expected to be commercially available in the summer of 2017. Western Carolinas Modernization Plan In May 2015, Duke Energy Progress announced a $1.1 billion plan to modernize the Western Carolinas energy system. The plan included retirement of the Asheville coal-fired plant, building a 650 MW combined-cycle natural gas power plant, installing solar generation at the site, building new transmission lines, a new substation and upgrades to area substations. On June 24, 2015, the North Carolina governor signed into law the North Carolina Mountain Energy Act of 2015 (Mountain Energy Act) which provides for an expedited CPCN process for the proposed Asheville combined-cycle project and extends certain North Carolina Coal Ash Management Act of 2014 (Coal Ash Act) deadlines for the coal ash basin at the Asheville Plant site. On November 4, 2015, in response to community feedback, Duke Energy Progress announced a revised plan. The revised plan replaces the planned 650 MW plant with 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 revised plan includes upgrades to existing transmission lines and substations, but eliminates the need for a new transmission line and a new substation associated with the project in South Carolina. The revised plan has the same overall project cost as the original plan, and the plans to install solar generation remain unchanged. Duke Energy Progress has also proposed to add 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. The plan requires various approvals including regulatory approvals in North Carolina. Duke Energy Progress filed for a CPCN with the NCUC for the new gas units on January 15, 2016. At the NCUC's staff conference on February 22, 2016, the Public Staff recommended approval of the CPCN for the two combined cycle natural gas plants and recommended that the NCUC not issue a CPCN for the simple cycle unit at this time. The NCUC also heard arguments from intervenors and Duke Energy Progress. Pursuant to the Mountain Energy Act, the NCUC's deadline to issue a decision on the CPCN is February 29, 2016. The carrying value of the 376 MW Asheville coal-fired plant, including associated ash basin closure costs, of $548 million is included in Generation facilities to be retired, net on Duke Energy Progress' Consolidated Balance Sheet as of December 31, 2015 . Shearon Harris Nuclear Plant Expansion In 2006, Duke Energy Progress selected a site at Harris to evaluate for possible future nuclear expansion. On February 19, 2008, Duke Energy Progress filed its COL application with the NRC for two Westinghouse AP1000 reactors at Harris, which the NRC docketed for review. On May 2, 2013, Duke Energy Progress filed a letter with the NRC requesting the NRC to suspend its review activities associated with the COL at the Harris site. As a result of the decision to suspend the COL applications, during the second quarter of 2013, Duke Energy Progress recorded a pretax impairment charge of $22 million which represented costs associated with the COL, which were not probable of recovery. The NCUC and PSCSC have approved deferral for $48 million of retail costs recorded in Regulatory assets on Duke Energy Progress’ Consolidated Balance Sheets. Duke Energy Florida FERC Transmission Return on Equity Complaint Seminole Electric Cooperative, Inc. and Florida Municipal Power Agency filed multiple complaints with the FERC alleging Duke Energy Florida's current rate of return on equity in transmission formula rates of 10.8 percent is unjust and unreasonable. The latest complaint, filed on August 12, 2014, claims the rate of return on equity should be reduced to 8.69 percent . The FERC consolidated all complaints for the purposes of settlement, hearing and decision. On July 21, 2015, the parties filed with the FERC for approval of a settlement agreement under which (i) Duke Energy Florida will pay a total of $14.1 million as refunds for all periods through December 31, 2014, (ii) the rate of return on equity will be 10 percent effective January 1, 2015, and (iii) none of the parties will seek a change in the rate of return on equity prior to January 1, 2018. On November 19, 2015, the FERC approved the settlement agreement resolving all complaints. Duke Energy Florida paid $14.1 million in refunds during December 2015. Citrus County Combined Cycle Facility On October 2, 2014, the FPSC granted Duke Energy Florida a Determination of Need for the construction of a 1,640 MW combined-cycle natural gas plant in Citrus County, Florida. On May 5, 2015, the Florida Department of Environmental Protection approved Duke Energy Florida's Site Certification Application. The facility is expected to be commercially available in 2018 at an estimated cost of $1.5 billion , including AFUDC. The project has received all required permits and approvals and construction began in October 2015. Purchase of Osprey Energy Center In December 2014, Duke Energy Florida and Osprey Energy Center, LLC, a wholly owned subsidiary of Calpine Corporation (Calpine), entered into an Asset Purchase and Sale Agreement for the purchase of a 599 MW combined-cycle natural gas plant in Auburndale, Florida (Osprey Plant acquisition) for approximately $166 million . On January 30, 2015, Duke Energy Florida petitioned the FPSC requesting a determination that the Osprey Plant acquisition or, alternatively, the construction of a 320 MW combustion turbine at its existing Suwannee generating facility (Suwannee project) with an estimated cost of $197 million , is the most cost-effective generation alternative to meet Duke Energy Florida's remaining generation need prior to 2018. On July 21, 2015, the FPSC approved the Osprey Plant acquisition as the most cost-effective alternative and issued an order of approval on July 31, 2015. On July 24, 2015, the FERC issued an order approving the Osprey Plant acquisition. Closing of the acquisition is contingent upon the expiration of the Hart-Scott-Rodino waiting period and is expected to occur by the first quarter of 2017, upon the expiration of an existing Power Purchase Agreement between Calpine and Duke Energy Florida. FPSC Settlement Agreements On February 22, 2012, the FPSC approved a settlement agreement (the 2012 Settlement) among Duke Energy Florida, the Florida Office of Public Counsel (OPC) and other customer advocates. The 2012 Settlement was to continue through the last billing cycle of December 2016. On October 17, 2013, the FPSC approved a settlement agreement (the 2013 Settlement) between Duke Energy Florida, OPC, and other customer advocates. The 2013 Settlement replaces and supplants the 2012 Settlement and substantially resolves issues related to (i) Crystal River Unit 3, (ii) Levy, (iii) Crystal River 1 and 2 coal units, and (iv) future generation needs in Florida. Refer to the remaining sections below for further discussion of these settlement agreements. Crystal River Unit 3 On February 5, 2013, Duke Energy Florida announced the retirement of Crystal River Unit 3. On February 20, 2013, Duke Energy Florida filed with the NRC a certification of permanent cessation of power operations and permanent removal of fuel from the reactor vessel. In December 2013, and March 2014, Duke Energy Florida filed an updated site-specific decommissioning plan with the NRC and FPSC, respectively. The plan, which was approved by the FPSC in November 2014, included a decommissioning cost estimate of $1,180 million , including amounts applicable to joint owners at that time, under the SAFSTOR option. Duke Energy Florida’s decommissioning study assumes Crystal River Unit 3 will be in SAFSTOR configuration, requiring limited staffing to monitor plant conditions, until the eventual dismantling and decontamination activities to be completed by 2074. This decommissioning approach is currently utilized at a number of retired domestic nuclear power plants and is one of three accepted approaches to decommissioning approved by the NRC. Pursuant to the 2013 Settlement, Duke Energy Florida reclassified all Crystal River Unit 3 investments, including property, plant and equipment, nuclear fuel, inventory, and other assets, to regulatory assets. Portions of the nuclear fuel balances that are under contract for sale were subsequently moved to Other within Current Assets and Other within Investments and Other Assets on the Consolidated Balance Sheets. Duke Energy Florida agreed to forgo recovery of $295 million of regulatory assets and an impairment charge was recorded in the second quarter of 2013 for this matter. Duke Energy Florida also accelerated cash recovery of approximately $47 million , net of tax, of the Crystal River Unit 3 regulatory asset from retail customers during 2014 and 2015, through its fuel clause. On May 22, 2015, Duke Energy Florida petitioned the FPSC for approval to include in base rates the revenue requirement for the projected $1.298 billion Crystal River Unit 3 regulatory asset as authorized by the 2013 Revised and Restated Stipulation and Settlement Agreement (2013 Agreement). On September 15, 2015, the FPSC approved Duke Energy Florida's motion for approval of a settlement agreement with intervenors to reduce the value of the projected Crystal River Unit 3 regulatory asset to be recovered to $1.283 billion as of December 31, 2015. An impairment charge of $15 million was recognized in the third quarter of 2015 to adjust the regulatory asset balance. In June 2015, the governor of Florida signed legislation to allow utilities to securitize certain retired nuclear generation assets, with approval of the FPSC. On November 19, 2015, the FPSC issued a financing order approving Duke Energy Florida’s request to securitize its unrecovered regulatory asset related to Crystal River Unit 3 through a debt issuance at a wholly owned special purpose entity. Securitization would replace the base rate recovery methodology authorized by the 2013 Agreement and result in a lower rate impact to customers with an approximately 20 year recovery period. On February 9, 2016, Duke Energy Florida filed a registration statement for the proposed initial public offering of the bonds. Use of the registration statement for purposes of the offering is subject to review and declaration of its effectiveness by the SEC. Duke Energy Florida expects to issue securitization bonds in the first half of 2016. In December 2014, the FPSC approved Duke Energy Florida's decision to construct an independent spent fuel storage installation (ISFSI) and approved Duke Energy Florida's request to defer amortization of the ISFSI pending resolution of its litigation against the federal government as a result of the Department of Energy's breach of its obligation to accept spent nuclear fuel. The return rate will b

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES General Insurance The Duke Energy Registrants have insurance and reinsurance coverage either directly or through indemnification from Duke Energy’s captive insurance company, Bison, and its affiliates, consistent with companies engaged in similar commercial operations with similar type properties. The Duke Energy Registrants’ coverage includes (i) commercial general liability coverage for liabilities arising to third parties for bodily injury and property damage; (ii) workers’ compensation; (iii) automobile liability coverage; and (iv) property coverage for all real and personal property damage. Real and personal property damage coverage excludes electric transmission and distribution lines, but includes damages arising from boiler and machinery breakdowns, earthquakes, flood damage and extra expense, but not outage or replacement power coverage. All coverage is subject to certain deductibles or retentions, sublimits, exclusions, terms and conditions common for companies with similar types of operations. The Duke Energy Registrants self-insure their electric transmission and distribution lines against loss due to storm damage and other natural disasters. As discussed further in Note 4 , Duke Energy Florida maintains a storm damage reserve and has a regulatory mechanism to recover the cost of named storms on an expedited basis. The cost of the Duke Energy Registrants’ coverage can fluctuate year to year reflecting claims history and conditions of the insurance and reinsurance markets. In the event of a loss, terms and amounts of insurance and reinsurance available might not be adequate to cover claims and other expenses incurred. Uninsured losses and other expenses, to the extent not recovered by other sources, could have a material effect on the Duke Energy Registrants’ results of operations, cash flows or financial position. Each company is responsible to the extent losses may be excluded or exceed limits of the coverage available. Nuclear Insurance Duke Energy Carolinas owns and operates the McGuire Nuclear Station (McGuire) and the Oconee Nuclear Station (Oconee) and operates and has a partial ownership interest in the Catawba Nuclear Station (Catawba). McGuire and Catawba each have two reactors. Oconee has three reactors. The other joint owners of Catawba reimburse Duke Energy Carolinas for certain expenses associated with nuclear insurance per the Catawba joint owner agreements. Duke Energy Progress owns and operates the Robinson Nuclear Plant (Robinson), Brunswick and Harris. Robinson and Harris each have one reactor. Brunswick has two reactors. Duke Energy Florida manages and has a partial ownership interest in Crystal River Unit 3, which has been retired. The other joint owner of Crystal River Unit 3 reimburses Duke Energy Florida for certain expenses associated with nuclear insurance per the Crystal River Unit 3 joint owner agreement. In the event of a loss, terms and amounts of insurance available might not be adequate to cover property damage and other expenses incurred. Uninsured losses and other expenses, to the extent not recovered by other sources, could have a material effect on Duke Energy Carolinas’, Duke Energy Progress’ and Duke Energy Florida’s results of operations, cash flows or financial position. Each company is responsible to the extent losses may be excluded or exceed limits of the coverage available. Nuclear Liability Coverage The Price-Anderson Act requires owners of nuclear reactors to provide for public nuclear liability protection per nuclear incident up to a maximum total financial protection liability. The maximum total financial protection liability, which is currently $13.5 billion , is subject to change every five years for inflation and for the number of licensed reactors. Total nuclear liability coverage consists of a combination of private primary nuclear liability insurance coverage and a mandatory industry risk-sharing program to provide for excess nuclear liability coverage above the maximum reasonably available private primary coverage. The United States Congress could impose revenue-raising measures on the nuclear industry to pay claims. Primary Liability Insurance Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida have purchased the maximum reasonably available private primary nuclear liability insurance as required by law, which currently is $375 million per station. Excess Liability Program This program provides $13.1 billion of coverage per incident through the Price-Anderson Act’s mandatory industrywide excess secondary financial protection program of risk pooling. This amount is the product of potential cumulative retrospective premium assessments of $127 million times the current 103 licensed commercial nuclear reactors in the U.S. Under this program, licensees could be assessed retrospective premiums to compensate for public nuclear liability damages in the event of a nuclear incident at any licensed facility in the U.S. Retrospective premiums may be assessed at a rate not to exceed $19 million per year per licensed reactor for each incident. The assessment may be subject to state premium taxes. Nuclear Property and Accidental Outage Coverage Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida are members of Nuclear Electric Insurance Limited (NEIL), an industry mutual insurance company, which provides "all risk" property damage, decontamination, and premature decommissioning insurance for each station for losses resulting from damage to its nuclear plants, either due to accidents or acts of terrorism. Additionally, NEIL provides some replacement power cost insurance for each station for losses in the event of a major accidental outage at an insured nuclear station. NEIL requires its members to maintain an investment grade credit rating or to ensure collectability of their annual retrospective premium obligation by providing a financial guarantee, letter of credit, deposit premium or other means of assurance. The companies are required each year to report to the NRC the current levels and sources of insurance that demonstrate it possesses sufficient financial resources to stabilize and decontaminate its reactors and reactor station sites in the event of an accident. Pursuant to regulations of the NRC, each company’s property damage insurance policies provide that all proceeds from such insurance be applied, first, to place the plant in a safe and stable condition after a qualifying accident, and second, to decontaminate the plant before any proceeds can be used for decommissioning, plant repair or restoration. Losses resulting from acts of terrorism are covered as common occurrences, such that if terrorist acts occur against one or more commercial nuclear power plants insured by NEIL within a 12-month period, they would be treated as one event and the owners of the plants where the act occurred would share one full limit of liability. The full limit of liability is currently $3.2 billion . NEIL sublimits the total aggregate for all of their policies for non-nuclear terrorist events to approximately $1.83 billion . Each nuclear facility has accident property damage, decontamination and premature decommissioning liability insurance from NEIL with limits of $1.5 billion , except for Crystal River Unit 3. Crystal River Unit 3’s limit is $1 billion and is on an actual cash value basis. NEIL coverage for Crystal River Unit 3 does not include property damage to or resulting from the containment structure although the coverage does apply to decontamination and debris removal, if required following an accident, to ensure public health and safety or if property damage results from a terrorism event. All nuclear facilities except for Catawba and Crystal River Unit 3 also share an additional $1.25 billion nuclear accident insurance limit above their dedicated underlying limit. This shared additional excess limit is not subject to reinstatement in the event of a loss. Catawba has a dedicated $1.25 billion of additional nuclear accident insurance limit above its dedicated underlying limit. Catawba and Oconee also have an additional $750 million of non-nuclear accident property damage limit. All coverages are subject to sublimits and significant deductibles. NEIL’s Accidental Outage policy provides some replacement power cost insurance for losses in the event of a major accident property damage outage of a nuclear unit. Coverage is provided on a weekly limit basis after a significant waiting period deductible and at 100 percent of the available weekly limits for 52 weeks and 80 percent of the available weekly limits for the next 110 weeks. Coverage is provided until these available weekly periods are met where the accidental outage policy limit will not exceed $490 million for McGuire, Catawba, Oconee, Brunswick, and Harris and $457 million for Robinson. NEIL sublimits the accidental outage recovery to the first 104 weeks of coverage not to exceed $328 million from non-nuclear accidental property damage. Coverage amounts decrease in the event more than one unit at a station is out of service due to a common accident. All coverages are subject to sublimits and significant deductibles. Potential Retroactive Premium Assessments In the event of NEIL losses, NEIL’s board of directors may assess member companies retroactive premiums of amounts up to 10 times their annual premiums for up to six years after a loss. NEIL has never exercised this assessment. The maximum aggregate annual retrospective premium obligations for Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida are $159 million , $108 million and $7 million , respectively. The maximum assessment amounts include 100 percent of Duke Energy Carolinas’ and Duke Energy Florida’s potential obligations to NEIL for their share of jointly owned reactors. ENVIRONMENTAL Duke Energy is subject to international, federal, state and local regulations regarding air and water quality, hazardous and solid waste disposal and other environmental matters. The Subsidiary Registrants are subject to federal, state and local regulations regarding air and water quality, hazardous and solid waste disposal and other environmental matters. These regulations can be changed from time to time, imposing new obligations on the Duke Energy Registrants. The following environmental matters impact all of the Duke Energy Registrants. Remediation Activities In addition to the Asset Retirement Obligations discussed in Note 9, the Duke Energy Registrants are responsible for environmental remediation at various sites. These include certain properties that are part of ongoing operations and sites formerly owned or used by Duke Energy entities. These sites are in various stages of investigation, remediation and monitoring. Managed in conjunction with relevant federal, state and local agencies, remediation activities vary based upon site conditions and location, remediation requirements, complexity and sharing of responsibility. If remediation activities involve joint and several liability provisions, strict liability, or cost recovery or contribution actions, the Duke Energy Registrants could potentially be held responsible for environmental impacts caused by other potentially responsible parties, and may also benefit from insurance policies or contractual indemnities that cover some or all cleanup costs. Liabilities are recorded when losses become probable and are reasonably estimable. The total costs that may be incurred cannot be estimated because the extent of environmental impact, allocation among potentially responsible parties, remediation alternatives and/or regulatory decisions have not yet been determined. Additional costs associated with remediation activities are likely to be incurred in the future and could be significant. Costs are typically expensed as Operation, maintenance and other in the Consolidated Statements of Operations unless regulatory recovery of the costs is deemed probable. The following tables contain information regarding reserves for probable and estimable costs related to the various environmental sites. These reserves are recorded in Other within Deferred Credits and Other Liabilities on the Consolidated Balance Sheets. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Balance at December 31, 2012 $ 75 $ 12 $ 33 $ 14 $ 19 $ 15 $ 8 Provisions/adjustments 26 — 4 (1 ) 5 20 1 Cash reductions (22 ) (1 ) (10 ) (5 ) (5 ) (8 ) (2 ) Balance at December 31, 2013 79 11 27 8 19 27 7 Provisions/adjustments 32 (1 ) 1 4 (3 ) 28 4 Cash reductions (14 ) — (11 ) (7 ) (4 ) (1 ) (1 ) Balance at December 31, 2014 97 10 17 5 12 54 10 Provisions/adjustments 9 1 4 — 4 1 5 Cash reductions (9 ) (1 ) (4 ) (2 ) (2 ) (1 ) (3 ) Balance at December 31, 2015 $ 97 $ 10 $ 17 $ 3 $ 14 $ 54 $ 12 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 $ 74 Duke Energy Carolinas 22 Duke Energy Ohio 42 Duke Energy Indiana 7 North Carolina and South Carolina Ash Basins On February 2, 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. On February 8, 2014, a permanent plug was installed in the stormwater pipe, stopping the release of materials into the 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. During 2014, Duke Energy Carolinas incurred repairs and remediation expenses related to the release of approximately $24 million . No additional expenses were recorded in 2015. Duke Energy Carolinas will not seek recovery of these costs from customers. Other costs related to the Dan River release, including pending or future state or federal civil enforcement proceedings, future regulatory directives, natural resources damages, additional pending litigation, future claims or litigation and long-term environmental impact costs, cannot be reasonably estimated at this time. North Carolina Department of Environmental Quality (NCDEQ), formerly the North Carolina Department of Environment and Natural Resources, 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 matter discussed above, Duke Energy Carolina and Duke Energy Progress have been served with a higher level of NOVs, including for violations at L.V. Sutton Plant and Dan River Steam Station. In August 2014, NCDEQ issued an NOV for alleged groundwater violations at Duke Energy Progress' L.V. Sutton Plant. On March 10, 2015, NCDEQ issued a civil penalty of approximately $25 million to Duke Energy Progress for environmental damages related to groundwater contamination at the L.V. Sutton Plant. See "Litigation" section below for information related to the resolution of this civil penalty. On February 8, 2016, NCDEQ assessed a penalty of approximately $6.8 million , including enforcement costs, against Duke Energy Carolinas related to storm-water pipes and associated discharges at the Dan River Steam Station. Duke Energy Carolinas recorded a charge to Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income in December 2015. Duke Energy Carolinas is reviewing the NCDEQ action to determine next steps and cannot predict the outcome of this matter. These fines and penalties are unprecedented and were not consistent with historic enforcement practices of NCDEQ. Based on historic practices the expected liability of any existing notice of violations would not be material. Duke Energy Carolinas and Duke Energy Progress cannot predict whether the NCDEQ will assess future penalties related to existing NOVs and if such penalties would be material. See the "Litigation" section below for additional information on litigation, investigations and enforcement actions related to ash basins, including the Memorandum of Plea Agreement (Plea Agreements) in connection to the North Carolina Ash Basin Grand Jury Investigation and NCDEQ matters. Litigation Duke 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 January 21, 2015, the Duke Energy Defendants filed a Motion to Stay and an alternative Motion to Dismiss. On August 31, 2015, the court issued an order staying the case through November 15, 2015. A ruling on defendants' motion to further extend the stay remains pending. On March 5, 2015, shareholder Judy Mesirov filed a shareholder derivative complaint (Mesirov Complaint) in North Carolina state court. The lawsuit, styled Mesirov v. Good , is similar to the consolidated derivative action pending in Delaware Chancery Court and was filed against the same current directors and former directors and officers as the Delaware litigation. Duke Energy Corporation, Duke Energy Progress and Duke Energy Carolinas are named as nominal defendants. The Mesirov Complaint alleges that the Duke Energy Board of Directors was aware of Clean Water Act (CWA) compliance issues and failures to maintain structures in ash basins, but that the Board of Directors did not require Duke Energy Carolinas and Duke Energy Progress to take action to remedy deficiencies. The Mesirov Complaint further alleges that the Board of Directors sanctioned activities to avoid compliance with the law by allowing improper influence of NCDEQ to minimize regulation and by opposing previously anticipated citizen suit litigation. The Mesirov Complaint seeks corporate governance reforms and damages relating to costs associated with the Dan River release, remediation of ash basins that are out of compliance with the CWA and defending and payment of fines, penalties and settlements relating to criminal and civil investigations and lawsuits. On December 7, 2015, the Duke Energy Defendants filed a Motion to Stay the proceedings. A hearing was held on February 17, 2016, and a ruling on this motion is pending. In addition to the above derivative complaints, in 2014, Duke Energy also received two shareholder litigation demand letters. The letters allege that the members of the Board of Directors and certain officers breached their fiduciary duties by allowing the company to illegally dispose of and store coal ash pollutants. One of the letters also alleges a breach of fiduciary duty in the decision-making relating to the leadership changes following the close of the Progress Energy merger in July 2012. By letter dated September 4, 2015, attorneys for the shareholders were informed that, on the recommendation of the Demand Review Committee formed to consider such matters, the Board of Directors concluded not to pursue potential claims against individuals. One of the shareholders, Mitchell Pinsly, sent a formal demand for records and Duke Energy is responding to this request. On October 30, 2015, shareholder Saul Bresalier filed a shareholder derivative 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 and oversight of political contributions. Duke Energy is named as a nominal defendant. The Bresalier Complaint contends that the 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. The Bresalier Defendants filed a Motion to Dismiss the Bresalier litigation on January 15, 2016. 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 Duke Energy, the 11 members of the Board of Directors who were also members of the pre-merger Board of Directors (Legacy Duke Energy Directors) and certain Duke Energy officers are defendants in a purported securities class action lawsuit (Nieman v. Duke Energy Corporation, et al) . This lawsuit consolidates three lawsuits originally filed in July 2012 and is pending in the United States District Court for the Western District of North Carolina. The plaintiffs allege federal Securities Act of 1933 and Securities Exchange Act of 1934 (Exchange Act) claims based on allegations of materially false and misleading representations and omissions in the Registration Statement filed on July 7, 2011, and purportedly incorporated into other documents, all in connection with the post-merger change in Chief Executive Officer (CEO). On August 15, 2014, the parties reached an agreement in principle to settle the litigation. On March 10, 2015, the parties filed a Stipulation of Settlement and a Motion for Preliminary Approval of the Settlement. The court issued an order for preliminary approval of the settlement on March 25, 2015. Under the terms of the agreement, Duke Energy agreed to pay $146 million to settle the claim. On April 22, 2015, Duke Energy made a payment of $25 million into the settlement escrow account. The remainder of $121 million was paid by insurers into the settlement escrow account. Notice has been sent to members of the class and a final approval hearing was held on August 12, 2015. The final order approving the settlement was issued on November 2, 2015, thus closing the matter. 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 . 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. On December 10, 2015, the Duke Energy defendants filed a Motion to Dismiss the litigation. 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 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. Duke Energy filed a Motion to Dismiss on February 19, 2016. 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 the remaining litigation. Price Reporting Cases Duke Energy Trading and Marketing, LLC (DETM), a non-operating Duke Energy affiliate, is a defendant, along with numerous other energy companies, in four class-action lawsuits and a fifth single-plaintiff lawsuit pending in a consolidated federal court proceeding in Nevada. Each of these lawsuits contains 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 seek damages in unspecified amounts. On July 18, 2011, the judge granted a defendant’s motion for summary judgment in two of five cases. The U.S. Court of Appeals for the Ninth Circuit subsequently reversed the lower court’s decision. On April 21, 2015, the Supreme Court affirmed the U.S. Court of Appeals decision. The case has been reassigned to the same consolidated federal court proceeding in Nevada for further proceedings. In February 2016, DETM reached agreements in principle to settle all of the pending lawsuits. The class-action settlements will be subject to court approval, which is pending. The settlement amount is not material to Duke Energy. Brazil Expansion Lawsuit On August 9, 2011, the State of São Paulo sued Duke Energy International Geracao Paranapenema S.A. (DEIGP) in Brazilian state court. The lawsuit claims DEIGP is under a continuing obligation to expand installed generation capacity in the State of São Paulo by 15 percent pursuant to a stock purchase agreement under which DEIGP purchased generation assets from the state. On August 10, 2011, a judge granted an ex parte injunction ordering DEIGP to present a detailed expansion plan in satisfaction of the 15 percent obligation. DEIGP has previously taken a position that the expansion obligation is no longer viable given changes that have occurred in the electric energy sector since privatization. DEIGP submitted its proposed expansion plan on November 11, 2011, but reserved objections regarding enforceability. In January 2013, DEIGP filed appeals in the federal courts, which are still pending, regarding various procedural issues. A decision on the merits in the first instance court is also pending. 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 this matter. Brazil Generation Record drought conditions in Brazil continue to impact Duke Energy International, Geracao Paranapanema S.A. (DEIGP). A number of electric generators have filed lawsuits seeking relief in the Brazilian courts to mitigate hydrological exposure and diminishing dispatch levels. Some courts have granted injunction orders to limit the financial exposure of certain generators. The implication of these orders is that other electricity market participants not covered by the injunctions may be required to compensate for the financial impact of the liability limitations. The Independent Power Producer Association (APINE) filed one such lawsuit on behalf of DEIGP and other hydroelectric generators against the Brazilian electric regulatory agency. On July 2, 2015, an injunction was granted in favor of APINE limiting the financial exposure of DEIGP and the other plaintiff generators, until the merits of the lawsuit are determined. The APINE decision is subject to appeal and the outcome of these lawsuits is uncertain. It is not possible to predict the impact to Duke Energy from the outcome of these matters. Duke Energy Carolinas and Duke Energy Progress NCDEQ Notice of Violation (NOV) In August 2014, NCDEQ issued an NOV for alleged groundwater violations at Duke Energy Progress' L.V. Sutton Plant. On March 10, 2015, NCDEQ issued a civil penalty of approximately $25 million to Duke Energy Progress for environmental damages related to the groundwater contamination at the L.V. Sutton Plant. On April 9, 2015, Duke Energy Progress filed a Petition for Contested Case hearing in the Office of Administrative Hearings. In February 2015, NCDEQ issued an NOV for alleged groundwater violations at Duke Energy Progress' Asheville Plant. Duke Energy Progress responded to NCDEQ regarding this NOV. On September 29, 2015, Duke Energy Progress and Duke Energy Carolinas entered into a settlement agreement with NCDEQ resolving all former, current and future groundwater penalties at all Duke Energy Carolinas and Duke Energy Progress coal facilities in North Carolina. Under the agreement, Duke Energy Progress paid approximately $6 million and Duke Energy Carolinas paid approximately $1 million . In addition to these payments, Duke Energy Progress and Duke Energy Carolinas will accelerate remediation actions at the Sutton, Asheville, Belews Creek and H.F. Lee plants. The court entered a consent order resolving the contested case relating to the Sutton Plant and NCDEQ rescinded the NOVs relating to alleged groundwater violations at both the Sutton and Asheville plants. On October 13, 2015, the Southern Environmental Law Center (SELC), representing multiple conservation groups, filed a lawsuit in North Carolina Superior Court seeking judicial review of the order approving the settlement agreement with NCDEQ. The conservation groups contend that the Administrative Law Judge exceeded his statutory authority in approving a settlement that provided for past, present, and future resolution of groundwater issues at facilities which were not at issue in the penalty appeal. On December 18, 2015, Duke Energy Carolinas and Duke Energy Progress filed a Motion to Dismiss the complaint. At a hearing held on February 12, 2016, Duke Energy Carolinas and Duke Energy Progress stated that a proposed revised order would be submitted to the Administrative Law Judge to address the court's and SELC's concerns. It is not possible to 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 groundwater violations and CWA violations from coal ash basins at two of their coal-fired power plants in North Carolina. 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, 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, on behalf of several environmental groups, has been permitted to intervene in these cases. On July 10, 2015, Duke Energy Carolinas and Duke Energy Progress filed Motions for Partial Summary Judgment in the case on the basis that there is no longer either a genuine controversy or disputed material facts about the relief for seven of the 14 North Carolina plants with coal ash basins. On September 14, 2015, the court granted the Motions for Partial Summary Judgment pending court approval of the terms through an order. In November 2015, NCDEQ submitted a proposed order. On November 23, 2015, Duke Energy Carolinas, Duke Energy Progress and SELC filed separate objections to portions of the NCDEQ filing. The parties are drafting a consolidated order to comply with the ruling made by the judge at a hearing held on February 12, 2016. 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. North Carolina Declaratory Judgment Action On October 10, 2012, the SELC, on behalf of the same environmental groups that are involved in the state enforcement actions discuss

Debt and Credit Facilities

Debt and Credit Facilities	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt and Credit Facilities	DEBT AND CREDIT FACILITIES Summary of Debt and Related Terms The following tables summarize outstanding debt. December 31, 2015 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Unsecured debt, maturing 2016 - 2073 4.99 % $ 13,392 $ 1,152 $ 3,850 $ — $ 150 $ 765 $ 740 Secured debt, maturing 2016 - 2037 2.57 % 2,635 425 479 254 225 — — First mortgage bonds, maturing 2016 - 2045 (a) 4.74 % 18,980 6,161 9,750 5,975 3,775 750 2,319 Capital leases, maturing 2016 - 2051 (b) 5.38 % 1,336 24 300 144 156 13 14 Tax-exempt bonds, maturing 2017 - 2041 (c) 2.59 % 1,053 355 48 48 — 77 572 Notes payable and commercial paper (d) 0.88 % 4,258 — — — — — — Money pool/intercompany borrowings — 300 1,458 359 813 128 150 Fair value hedge carrying value adjustment 6 6 — — — — — Unamortized debt discount and premium, net (e) 1,712 (17 ) (28 ) (16 ) (8 ) (28 ) (8 ) Unamortized debt issuance costs (f) (170 ) (39 ) (85 ) (37 ) (32 ) (4 ) (19 ) Total debt 4.25 % $ 43,202 $ 8,367 $ 15,772 $ 6,727 $ 5,079 $ 1,701 $ 3,768 Short-term notes payable and commercial paper (3,633 ) — — — — — — Short-term money pool/intercompany borrowings — — (1,308 ) (209 ) (813 ) (103 ) — Current maturities of long-term debt (g) (2,074 ) (356 ) (315 ) (2 ) (13 ) (106 ) (547 ) Total long-term debt (g) $ 37,495 $ 8,011 $ 14,149 $ 6,516 $ 4,253 $ 1,492 $ 3,221 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $114 million and $731 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds or letters of credit. (d) Includes $625 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that back-stop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for commercial paper was 15 days. (e) Duke Energy includes $1,798 million in purchase accounting adjustments related to the merger with Progress Energy. (f) Duke Energy includes $59 million in purchase accounting adjustments primarily related to the merger with Progress Energy. (g) Refer to Note 17 for additional information on amounts from consolidated VIEs. December 31, 2014 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Unsecured debt, maturing 2015 - 2073 4.92 % $ 12,937 $ 1,155 $ 3,850 $ — $ 150 $ 773 $ 742 Secured debt, maturing 2016 - 2037 2.50 % 2,806 400 525 300 225 — — First mortgage bonds, maturing 2015 - 2044 (a) 4.76 % 19,180 6,161 9,800 5,475 4,325 900 2,319 Capital leases, maturing 2015 - 2051 (b) 5.30 % 1,428 27 314 146 168 20 16 Tax-exempt bonds, maturing 2015 - 2041 (c) 2.13 % 1,296 355 291 291 — 77 573 Notes payable and commercial paper (d) 0.70 % 2,989 — — — — — — Money pool/intercompany borrowings — 300 835 — 84 516 221 Fair value hedge carrying value adjustment 8 8 — — — — — Unamortized debt discount and premium, net (e) 1,890 (15 ) (26 ) (11 ) (8 ) (29 ) (9 ) Unamortized debt issuance costs (152 ) (38 ) (86 ) (31 ) (37 ) (6 ) (22 ) Total debt 4.29 % $ 42,382 $ 8,353 $ 15,503 $ 6,170 $ 4,907 $ 2,251 $ 3,840 Short-term notes payable and commercial paper (2,514 ) — — — — — — Short-term money pool/intercompany borrowings — — (835 ) — (84 ) (491 ) (71 ) Current maturities of long-term debt (f) (2,807 ) (507 ) (1,507 ) (945 ) (562 ) (157 ) (5 ) Total long-term debt (f) $ 37,061 $ 7,846 $ 13,161 $ 5,225 $ 4,261 $ 1,603 $ 3,764 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $129 million and $787 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds or letters of credit. (d) Includes $475 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that back-stop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for commercial paper was 27 days. (e) Duke Energy includes $1,975 million in purchase accounting adjustments related to the merger with Progress Energy. (f) Refer to Note 17 for additional information on amounts from consolidated VIEs. Current Maturities of Long-Term Debt The following table shows the significant components of Current maturities of long-term debt on the Consolidated Balance Sheets. The Duke Energy Registrants currently anticipate satisfying these obligations with cash on hand and proceeds from additional borrowings. (in millions) Maturity Date Interest Rate December 31, 2015 Unsecured Debt Progress Energy (Parent) January 2016 5.625 % $ 300 Duke Energy Indiana June 2016 6.05 % 325 Duke Energy (Parent) November 2016 2.150 % 500 First Mortgage Bonds Duke Energy Indiana July 2016 0.670 % 150 Duke Energy Carolinas December 2016 1.750 % 350 Other 449 Current maturities of long-term debt $ 2,074 Maturities and Call Options The following table shows the annual maturities of long-term debt for the next five years and thereafter. Amounts presented exclude short-term notes payable and commercial paper and money pool borrowings for the Subsidiary Registrants. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy (a) Carolinas Energy Progress Florida Ohio Indiana 2016 $ 2,074 $ 356 $ 315 $ 2 $ 13 $ 106 $ 547 2017 2,468 115 923 446 482 1 2 2018 3,441 1,629 510 — 512 5 3 2019 3,022 5 1,667 855 14 552 63 2020 2,091 755 415 152 265 25 653 Thereafter 24,616 5,507 10,634 5,063 2,980 909 2,500 Total long-term debt, including current maturities $ 37,712 $ 8,367 $ 14,464 $ 6,518 $ 4,266 $ 1,598 $ 3,768 (a) Excludes $1,857 million in purchase accounting adjustments related to the merger with Progress Energy. The Duke Energy Registrants have the ability under certain debt facilities to call and repay the obligation prior to its scheduled maturity. Therefore, the actual timing of future cash repayments could be materially different than as presented above. Short-Term Obligations Classified as Long-Term Debt Tax-exempt bonds that may be put to the Duke Energy Registrants at the option of the holder and certain commercial paper issuances and money pool borrowings are classified as Long-Term Debt on the Consolidated Balance Sheets. These tax-exempt bonds, commercial paper issuances and money pool borrowings, which are short-term obligations by nature, are classified as long term due to Duke Energy’s intent and ability to utilize such borrowings as long-term financing. As Duke Energy’s Master Credit Facility and other bilateral letter of credit agreements have non-cancelable terms in excess of one year as of the balance sheet date, Duke Energy has the ability to refinance these short-term obligations on a long-term basis. The following tables show short-term obligations classified as long-term debt. December 31, 2015 Duke Duke Duke Duke Duke Energy Energy Energy Energy (in millions) Energy Carolinas Progress Ohio Indiana Tax-exempt bonds $ 347 $ 35 $ — $ 27 $ 285 Commercial paper (a) 625 300 150 25 150 Total $ 972 $ 335 $ 150 $ 52 $ 435 December 31, 2014 Duke Duke Duke Duke Energy Energy Energy (in millions) Energy Carolinas Ohio Indiana Tax-exempt bonds $ 347 $ 35 $ 27 $ 285 Commercial paper 475 300 25 150 Secured debt (b) 200 — — — Total $ 1,022 $ 335 $ 52 $ 435 (a) Progress Energy amounts are equal to Duke Energy Progress amounts. (b) In December 2015, Duke Energy used cash held by the lender to repay debt. Instrument had a term of less than one year with the right to extend the maturity date for additional one-year periods with a final maturity date no later than December 2026. Summary of Significant Debt Issuances In January 2016, Duke Energy Kentucky issued $95 million of unsecured debentures, of which $45 million carry a fixed interest rate of 3.42 percent and mature January 15, 2026 and $50 million carry a fixed interest rate of 4.45 percent and mature January 15, 2046. Proceeds will primarily be used to refinance existing debt, including money pool borrowings, capital expenditures and for general corporate purposes. The following tables summarize significant debt issuances (in millions). Year Ended December 31, 2015 Duke Duke Duke Maturity Interest Duke Energy Energy Energy Issuance Date Date Rate Energy (Parent) Carolinas Progress Unsecured Debt November 2015 (a)(b) April 2024 3.750 % $ 400 $ 400 $ — $ — November 2015 (a)(b) December 2045 4.800 % 600 600 — — First Mortgage Bonds March 2015 (c) June 2045 3.750 % 500 — 500 — August 2015 (a)(d) August 2025 3.250 % 500 — — 500 August 2015 (a)(d) August 2045 4.200 % 700 — — 700 Total issuances $ 2,700 $ 1,000 $ 500 $ 1,200 (a) Proceeds were used to repay short-term money pool and commercial paper borrowing issued to fund a portion of the NCEMPA acquisition, see Note 2 for further information. (b) Proceeds were used to refinance at maturity $300 million of unsecured notes at Progress Energy due January 2016. (c) Proceeds were used to redeem at maturity $500 million of first mortgage bonds due October 2015. (d) Proceeds were used to refinance at maturity $400 million of first mortgage bonds due December 2015. Year Ended December 31, 2014 Duke Duke Duke Maturity Interest Duke Energy Energy Energy Issuance Date Date Rate Energy (Parent) Progress Florida Unsecured Debt April 2014 (a) April 2024 3.750 % $ 600 $ 600 $ — $ — April 2014 (a)(b) April 2017 0.613 % 400 400 — — June 2014 (c) May 2019 11.970 % 108 — — — June 2014 (c) May 2021 13.680 % 110 — — — Secured Debt March 2014 (d) March 2017 0.863 % 225 — — 225 July 2014 (e) July 2036 5.340 % 129 — — — First Mortgage Bonds March 2014 (f) March 2044 4.375 % 400 — 400 — March 2014 (f)(g) March 2017 0.435 % 250 — 250 — November 2014 (h) December 2044 4.150 % 500 — 500 — November 2014 (g)(h) November 2017 0.432 % 200 — 200 — Total issuances $ 2,922 $ 1,000 $ 1,350 $ 225 (a) Proceeds were used to redeem $402 million of tax-exempt bonds at Duke Energy Ohio, the repayment of outstanding commercial paper and for general corporate purposes. See Note 13 for additional information related to the redemption of Duke Energy Ohio's tax-exempt bonds. (b) The debt is floating rate based on three-month London Interbank Offered Rate (LIBOR) plus a fixed credit spread of 38 basis points. (c) Proceeds were used to repay $196 million of debt for International Energy and for general corporate purposes. The interest rates include country specific risk premiums. (d) Relates to the securitization of accounts receivable at a subsidiary of Duke Energy Florida. Proceeds were used to repay short-term borrowings under the intercompany money pool borrowing arrangement and for general corporate purposes. See Note 17 for further details. (e) Proceeds were used to fund a portion of Duke Energy's prior investment in the existing Wind Star renewables portfolio. (f) Proceeds were used to repay short-term borrowings under the intercompany money pool borrowing arrangement and for general corporate purposes. (g) The debt is floating rate based on three-month LIBOR plus a fixed credit spread of 20 basis points. (h) Proceeds were used to redeem $450 million of tax-exempt bonds, repay short-term borrowings under the intercompany money pool borrowing arrangement and for general corporate purposes. Available Credit Facilities Duke Energy has a Master Credit Facility with a capacity of $7.5 billion through January 2020. The Duke Energy Registrants, excluding Progress Energy (Parent), have borrowing capacity under the Master Credit Facility up to specified sublimits for each borrower. Duke Energy has the unilateral ability at any time to increase or decrease the borrowing sublimits of each borrower, subject to a maximum sublimit for each borrower. The amount available under the Master Credit Facility has been reduced to backstop the 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 and as security to meet obligations under the Plea Agreements. The table below includes the current borrowing sublimits and available capacity under the Master Credit Facility. December 31, 2015 Duke Duke Duke Duke Duke Duke Duke Energy Energy Energy Energy Energy Energy (in millions) Energy (Parent) Carolinas Progress Florida Ohio Indiana Facility size (a) $ 7,500 $ 3,475 $ 800 $ 1,000 $ 1,200 $ 425 $ 600 Reduction to backstop issuances Commercial paper (b) (3,138 ) (1,531 ) (300 ) (333 ) (709 ) (115 ) (150 ) Outstanding letters of credit (72 ) (65 ) (4 ) (2 ) (1 ) — — Tax-exempt bonds (116 ) — (35 ) — — — (81 ) Coal ash set-aside (c) (500 ) — (250 ) (250 ) — — — Available capacity $ 3,674 $ 1,879 $ 211 $ 415 $ 490 $ 310 $ 369 (a) Represents the sublimit of each borrower. (b) Duke Energy issued $625 million of commercial paper and loaned the proceeds through the money pool to Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio and Duke Energy Indiana. The balances are classified as Long-Term Debt Payable to Affiliated Companies in the Consolidated Balance Sheets. (c) On May 14, 2015, the United States District Court for the Eastern District of North Carolina approved the separate Plea Agreements entered into by Duke Energy Carolinas, Duke Energy Progress and DEBS, a wholly owned subsidiary of Duke Energy, in connection with the investigation initiated by the USDOJ. Duke Energy Carolinas and Duke Energy Progress are required to each maintain $250 million of available capacity under the Master Credit Facility as security to meet their obligations under the Plea Agreements, in addition to certain other conditions. See Note 5 for further details. In connection with the Merger Agreement with Piedmont, Duke Energy entered into a $4.9 billion senior unsecured bridge financing facility (Bridge Facility) with Barclays Capital, Inc. (Barclays). The Bridge Facility, if drawn upon, may be used (i) to fund the cash consideration for the transaction and (ii) to pay certain fees and expenses in connection with the transaction. In November 2015, Barclays syndicated its commitment under the Bridge Facility to a broader group of lenders. Duke Energy intends to finance the transaction with proceeds raised through the issuance of debt, equity, and other sources and, therefore, does not expect to draw upon the Bridge Facility. See Note 2 for further details. On February 22, 2016, Duke Energy entered into a six months term loan facility (Term Loan) with commitments totaling $1 billion to provide additional flexibility in managing short-term liquidity. The Term Loan can be drawn upon in a single borrowing of up to $1 billion , which must occur no later than 45 calendar days following February 22, 2016. As of February 24, 2016, no amounts have been drawn under the Term Loan. Amounts drawn under this facility, if any, will be due on August 19, 2016. The terms and conditions of this Term Loan are generally consistent with those governing the Master Credit Facility discussed above. Other Debt Matters Duke Energy Florida expects to issue $1.3 billion of securitization bonds related to Crystal River Unit 3 in the first half of 2016. See Note 4 for additional details. In September 2013, Duke Energy filed a registration statement (Form S-3) with the Securities and Exchange Commission (SEC). Under this Form S-3, which is uncapped, the Duke Energy Registrants, excluding Progress Energy, may issue debt and other securities in the future at amounts, prices and with terms to be determined at the time of future offerings. The registration statement also allows for the issuance of common stock by Duke Energy. Duke Energy has an effective Form S-3 with the SEC to sell up to $3 billion of variable denomination floating-rate demand notes, called PremierNotes. The Form S-3 states that no more than $1.5 billion of the notes will be outstanding at any particular time. The notes are offered on a continuous basis and bear interest at a floating rate per annum determined by the Duke Energy PremierNotes Committee, or its designee, on a weekly basis. The interest rate payable on notes held by an investor may vary based on the principal amount of the investment. The notes have no stated maturity date, are non-transferable and may be redeemed in whole or in part by Duke Energy or at the investor’s option at any time. The balance as of December 31, 2015 and 2014 was $1,121 million and $968 million , respectively. The notes are short-term debt obligations of Duke Energy and are reflected as Notes payable and commercial paper on Duke Energy’s Consolidated Balance Sheets. At December 31, 2015 and 2014 , $767 million of debt issued by Duke Energy Carolinas was guaranteed by Duke Energy. Money Pool The Subsidiary Registrants, excluding Progress Energy, receive support for their short-term borrowing needs through participation with Duke Energy and certain of its subsidiaries in a money pool arrangement. Under this arrangement, those companies with short-term funds may provide short-term loans to affiliates participating in this arrangement. The money pool is structured such that the Subsidiary Registrants, excluding Progress Energy, separately manage their cash needs and working capital requirements. Accordingly, there is no net settlement of receivables and payables between money pool participants. Duke Energy (Parent), may loan funds to its participating subsidiaries, but may not borrow funds through the money pool. Accordingly, as the money pool activity is between Duke Energy and its wholly owned subsidiaries, all money pool balances are eliminated within Duke Energy’s Consolidated Balance Sheets. Money pool receivable balances are reflected within Notes receivable from affiliated companies on the Subsidiary Registrants’ Consolidated Balance Sheets. Money pool payable balances are reflected within either Notes payable to affiliated companies or Long-Term Debt Payable to Affiliated Companies on the Subsidiary Registrants’ Consolidated Balance Sheets. Restrictive Debt Covenants The Duke Energy Registrants’ debt and credit agreements contain various financial and other covenants. The Master Credit Facility contains a covenant requiring the debt-to-total capitalization ratio not exceed 65 percent for each borrower. Failure to meet those covenants beyond applicable grace periods could result in accelerated due dates and/or termination of the agreements. As of December 31, 2015 , each of the Duke Energy Registrants were in compliance with all covenants related to their debt agreements. In addition, some credit agreements may allow for acceleration of payments or termination of the agreements due to nonpayment, or acceleration of other significant indebtedness of the borrower or some of its subsidiaries. None of the debt or credit agreements contain material adverse change clauses. Other Loans As of December 31, 2015 and 2014, Duke Energy had loans outstanding of $629 million , including $41 million at Duke Energy Progress and $603 million , including $44 million at Duke Energy Progress, respectively, against the cash surrender value of life insurance policies it owns on the lives of its executives. The amounts outstanding were carried as a reduction of the related cash surrender value that is included in Other within Investments and Other Assets on the Consolidated Balance Sheets.

Guarantees and Indemnifications

Guarantees and Indemnifications	12 Months Ended
	Dec. 31, 2015
Guarantees [Abstract]
Guarantees and Indemnifications	GUARANTEES AND INDEMNIFICATIONS Duke Energy and Progress Energy have various financial and performance guarantees and indemnifications, which are issued in the normal course of business. As discussed below, these contracts include performance guarantees, stand-by letters of credit, debt guarantees, surety bonds and indemnifications. Duke Energy and Progress Energy enter into these arrangements to facilitate commercial transactions with third parties by enhancing the value of the transaction to the third party. At December 31, 2015 , Duke Energy and Progress Energy do not believe conditions are likely for significant performance under these guarantees. To the extent liabilities are incurred as a result of the activities covered by the guarantees, such liabilities are included on the accompanying Consolidated Balance Sheets. On January 2, 2007, Duke Energy completed the spin-off of its natural gas businesses to shareholders. Guarantees issued by Duke Energy or its affiliates, or assigned to Duke Energy prior to the spin-off, remained with Duke Energy subsequent to the spin-off. Guarantees issued by Spectra Energy Capital, LLC, formerly known as Duke Capital LLC, (Spectra Capital) or its affiliates prior to the spin-off remained with Spectra Capital subsequent to the spin-off, except for guarantees that were later assigned to Duke Energy. Duke Energy has indemnified Spectra Capital against any losses incurred under certain of the guarantee obligations that remain with Spectra Capital. At December 31, 2015 , the maximum potential amount of future payments associated with these guarantees was $205 million , the majority of which expires by 2028. Duke Energy has issued performance guarantees to customers and other third parties that guarantee the payment and performance of other parties, including certain non-wholly owned entities, as well as guarantees of debt of certain non-consolidated entities and less than wholly owned consolidated entities. If such entities were to default on payments or performance, Duke Energy would be required under the guarantees to make payments on the obligations of the less than wholly owned entity. The maximum potential amount of future payments required under these guarantees as of December 31, 2015 , was $253 million . Of this amount, $15 million relates to guarantees issued on behalf of less than wholly owned consolidated entities, with the remainder related to guarantees issued on behalf of third parties and unconsolidated affiliates of Duke Energy. Of the guarantees noted above, $112 million of the guarantees expire between 2016 and 2033, with the remaining performance guarantees having no contractual expiration. Duke Energy has guaranteed certain issuers of surety bonds, obligating itself to make payment upon the failure of a wholly owned and former non-wholly owned entity to honor its obligations to a third party. Under these arrangements, Duke Energy has payment obligations that are triggered by a draw by the third party or customer due to the failure of the wholly owned or former non-wholly owned entity to perform according to the terms of its underlying contract. At December 31, 2015 , Duke Energy had guaranteed $47 million of outstanding surety bonds, most of which have no set expiration. Duke Energy uses bank-issued stand-by letters of credit to secure the performance of wholly owned and non-wholly owned entities to a third party or customer. Under these arrangements, Duke Energy has payment obligations to the issuing bank which are triggered by a draw by the third party or customer due to the failure of the wholly owned or non-wholly owned entity to perform according to the terms of its underlying contract. At December 31, 2015 , Duke Energy had issued a total of $427 million in letters of credit, which expire between 2016 and 2020. The unused amount under these letters of credit was $58 million . Duke Energy and Progress Energy have issued indemnifications for certain asset performance, legal, tax and environmental matters to third parties, including indemnifications made in connection with sales of businesses. At December 31, 2015 , the estimated maximum exposure for these indemnifications was $97 million , the majority of which expires in 2017. Of this amount, $7 million has no contractual expiration. For certain matters for which Progress Energy receives timely notice, indemnity obligations may extend beyond the notice period. Certain indemnifications related to discontinued operations have no limitations as to time or maximum potential future payments. The following table includes the liabilities recognized for the guarantees discussed above. These amounts are primarily recorded in Other within Deferred Credits and other Liabilities on the Consolidated Balance Sheets. As current estimates change, additional losses related to guarantees and indemnifications to third parties, which could be material, may be recorded by the Duke Energy Registrants in the future. December 31, 2015 2014 Duke Energy $ 21 $ 28 Progress Energy 7 13 Duke Energy Florida 7 7

Joint Ownership of Generating a

Joint Ownership of Generating and Transmission Facilities	12 Months Ended
	Dec. 31, 2015
Joint Ownership Of Generating And Transmission Facilities [Abstract]
Joint Ownership of Generating and Transmission Facilities	JOINT OWNERSHIP OF GENERATING AND TRANSMISSION FACILITIES The Duke Energy Registrants maintain ownership interests in certain jointly owned generating and transmission facilities. The Duke Energy Registrants are entitled to a share of the generating capacity and output of each unit equal to their respective ownership interests, except as otherwise noted below. The Duke Energy Registrants pay their ownership share of additional construction costs, fuel inventory purchases and operating expenses, except in certain instances where agreements have been executed to limit certain joint owners’ maximum exposure to the additional costs. The Duke Energy Registrants share of revenues and operating costs of the jointly owned facilities is included within the corresponding line in the Consolidated Statements of Operations. Each participant in the jointly owned facilities must provide its own financing, except in certain instances where agreements have been executed to limit certain joint owners’ maximum exposure to the additional costs. The following table presents the Duke Energy Registrants' interest of jointly owned plant or facilities and amounts included on the Consolidated Balance Sheets. All facilities are operated by the Duke Energy Registrants and are included in the Regulated Utilities segment unless otherwise noted. December 31, 2015 Construction Ownership Property, Plant Accumulated Work in Interest and Equipment Depreciation Progress Duke Energy Carolinas Catawba Nuclear Station (units 1 and 2) (a) 19.25 % $ 926 $ 567 $ 9 Duke Energy Florida Intercession City Plant (unit 11) (b) 24 15 — Duke Energy Ohio Transmission facilities (c) Various 85 50 1 Duke Energy Indiana Gibson Station (unit 5) (d) 50.05 % 329 151 5 Vermillion (e) 62.5 % 153 108 — Transmission and local facilities (d) Various 4,094 1,688 — International Energy Brazil – Canoas I and II (f) 47.2 % 160 57 — (a) Jointly owned with North Carolina Municipal Power Agency Number One, NCEMC and Piedmont Municipal Power Agency. (b) Jointly owned with Georgia Power Company (GPC). GPC has exclusive rights to the output of the unit during the months of June through September and pays all fuel and water costs during this period. Duke Energy Florida pays all fuel and water costs during the remaining months. Other costs are allocated 66.67 percent to Duke Energy Florida and the remainder to GPC. (c) Jointly owned with America Electric Power Generation Resources and The Dayton Power and Light Company. (d) Jointly owned with Wabash Valley Power Association, Inc. (WVPA) and Indiana Municipal Power Agency. (e) Jointly owned with WVPA. (f) Jointly owned with Companhia Brasileira de Aluminio and included in the International segment. On July 31, 2015, Duke Energy Progress completed the purchase of NCEMPA's ownership interests in jointly owned facilities. See Note 2 for additional information. Duke Energy Florida owns 98.3 percent interest in the retired Crystal River Unit 3 nuclear plant and is in the process of obtaining the remaining 1.7 percent interest from Seminole Electric Cooperative. On October 30, 2015, Duke Energy Florida completed the purchase of 6.52 percent ownership interest in Crystal River Unit 3 from the Florida Municipal Joint Owners (FMJO) and settled other disputes for $55 million . All costs associated with Crystal River Unit 3 are included within Regulatory assets on the Consolidated Balance Sheets of Duke Energy, Progress Energy and Duke Energy Florida. See Note 4 for additional information.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation [Abstract]
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS Duke Energy records an asset retirement obligation (ARO) when it has a legal obligation to incur retirement costs associated with the retirement of a long-lived asset and the obligation can be reasonably estimated. Certain assets of the Duke Energy Registrants’ have an indeterminate life, such as transmission and distribution facilities, and thus the fair value of the retirement obligation is not reasonably estimable. A liability for these asset retirement obligations will be recorded when a fair value is determinable. The Duke Energy Registrants’ regulated operations accrue costs of removal for property that does not have an associated legal retirement obligation based on regulatory orders from state commissions. These costs of removal are recorded as a regulatory liability in accordance with regulatory accounting treatment. The Duke Energy Registrants do not accrue the estimated cost of removal for any nonregulated assets. See Note 4 for the estimated cost of removal for assets without an associated legal retirement obligation, which are included in Regulatory liabilities on the Consolidated Balance Sheets. The following table presents the AROs recorded on the Consolidated Balance Sheets. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Decommissioning of Nuclear Power Facilities $ 5,072 $ 1,730 $ 3,093 $ 2,349 $ 744 $ — $ — Closure of Ash Impoundments 4,958 2,161 2,196 2,188 7 94 507 Other (a) 234 27 80 30 51 31 18 Total Asset retirement obligation $ 10,264 $ 3,918 $ 5,369 $ 4,567 $ 802 $ 125 $ 525 (a) Includes obligations related to asbestos removal and the closure of certain landfills at fossil generation facilities. Duke Energy Ohio also includes AROs related to the retirement of natural gas mains. Duke Energy also includes AROs related to the removal of renewable energy generation assets. North Carolina and South Carolina Ash Impoundments On September 20, 2014, the Coal Ash Act became law and was amended on June 24, 2015, by the Mountain Energy Act. The Coal Ash Act, as amended, (i) establishes a Coal Ash Management Commission (Coal Ash Commission) to oversee handling of coal ash within the state; (ii) prohibits construction of new and expansion of existing ash impoundments and use of existing impoundments at retired facilities; (iii) requires closure of ash impoundments at Duke Energy Progress' Asheville and Sutton plants and Duke Energy Carolinas' Riverbend and Dan River stations no later than August 1, 2019 (the Mountain Energy Act provides for the potential extension of closure of the Asheville impoundment until 2022); (iv) requires dry disposal of fly ash at active plants, excluding the Asheville Plant, not retired by December 31, 2018; (v) requires dry disposal of bottom ash at active plants, excluding the Asheville Plant, by December 31, 2019, or retirement of active plants; (vi) requires all remaining ash impoundments in North Carolina to be categorized as high-risk, intermediate-risk or low-risk no later than December 31, 2015, by the NCDEQ with the method of closure and timing to be based upon the assigned risk, with closure no later than December 31, 2029; (vii) establishes requirements to deal with groundwater and surface water impacts from impoundments; and (viii) increases the level of regulation for structural fills utilizing coal ash. In January 2016, NCDEQ published its draft risk classifications. These risk rankings were generally determined based on three primary criteria: structural integrity of the impoundments and impact to both surface and groundwaters. NCDEQ categorized 12 basins at four sites as intermediate risk and four basins at three plants as low risk. NCDEQ also categorized nine basins at six plants as “low-to-intermediate” risk, thereby not assigning a proposed risk ranking at this time. The risk rankings of these sites will be based upon receipt of additional data primarily related to groundwater quality and the completion of specific modifications and repairs to the impoundments. NCDEQ is expected to finalize its risk classifications as part of a public comment process. Duke Energy cannot predict the final classification. The Coal Ash Act includes a variance procedure for compliance deadlines and modification of requirements regarding structural fills and compliance boundaries. Provisions of the Coal Ash Act prohibit cost recovery in customer rates for unlawful discharge of ash impoundment waters occurring after January 1, 2014. The Coal Ash Act leaves the decision on cost recovery determinations related to closure of ash impoundments to the normal ratemaking processes before utility regulatory commissions. Duke Energy has and will periodically submit to NCDEQ site-specific coal ash impoundment closure plans or excavation plans in advance of closure. These plans and all associated permits must be approved by NCDEQ before any excavation or closure work can begin. In September 2014, Duke Energy Carolinas executed a consent agreement with the South Carolina Department of Health and Environmental Control (SCDHEC) requiring the excavation of an inactive ash basin and ash fill area at the W.S. Lee Steam Station. As part of this agreement, in December 2014, Duke Energy Carolinas filed an ash removal plan and schedule with SCDHEC. In April 2015, the federal Coal Combustion Residuals (CCR) rules were published and Duke Energy Carolinas subsequently executed an agreement with the conservation groups Upstate Forever and Save Our Saluda that requires Duke Energy Carolinas to remediate all active and inactive ash storage areas at the W.S. Lee Steam Station. Coal-fired generation at W.S. Lee ceased in 2014 and unit 3 was converted to natural gas in March 2015. In July 2015, Duke Energy Progress executed a consent agreement with the SCDHEC requiring the excavation of an inactive ash fill area at the Robinson Plant within eight years. Coal ash impoundments at the Robinson Plant and W.S. Lee Station sites are required to be closed pursuant to the recently issued CCR rule and the provisions of these consent agreements are consistent with the federal CCR closure requirements. Coal Combustion Residuals On April 17, 2015, the EPA published in the Federal Register a rule to regulate the disposal of CCR from electric utilities as solid waste. The federal regulation, which became effective in October 2015, classifies CCR as nonhazardous waste under Subtitle D of the Resource Conservation and Recovery Act and allows for beneficial use of CCR with some restrictions. The regulation applies to all new and existing landfills, new and existing surface impoundments receiving CCR and existing surface impoundments that are no longer receiving CCR but contain liquid located at stations currently generating electricity (regardless of fuel source). The rule establishes requirements regarding landfill design, structural integrity design and assessment criteria for surface impoundments, groundwater monitoring and protection procedures and other operational and reporting procedures to ensure the safe disposal and management of CCR. In addition to the requirements of the federal CCR regulation, CCR landfills and surface impoundments will continue to be independently regulated by most states. As a result of the EPA rule, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Ohio and Duke Energy Indiana recorded additional asset retirement obligation amounts during 2015. Coal Ash Liability The ARO amount recorded on the Consolidated Balance Sheets is based upon estimated closure costs for impacted ash impoundments. The amount recorded represents the discounted cash flows for estimated closure costs based upon either specific closure plans or the probability weightings of the potential closure methods as evaluated on a site-by-site basis. Actual costs to be incurred will be dependent upon factors that vary from site to site. The most significant factors are the method and time frame of closure at the individual sites. Closure methods considered include removing the water from the basins, consolidating material as necessary, and capping the ash with a synthetic barrier, excavating and relocating the ash to a lined structural fill or lined landfill, or recycling the ash for concrete or some other beneficial use. The ultimate method and timetable for closure will be in compliance with standards set by federal and state regulations. The ARO amount will be adjusted as additional information is gained through the closure process, including acceptance and approval of compliance approaches which may change management assumptions, and may result in a material change to the balance. Asset retirement costs associated with the asset retirement obligations for operating plants and retired plants are included in Net property, plant and equipment, and Regulatory assets, respectively, on the Consolidated Balance Sheets. See Note 4 for additional information on Regulatory assets related to AROs. Cost recovery for future expenditures will be pursued through the normal ratemaking process with federal and state utility commissions, which permit recovery of necessary and prudently incurred costs associated with Duke Energy’s regulated operations. Nuclear Decommissioning Liability Asset retirement obligations related to nuclear decommissioning are based on site-specific cost studies. The NCUC, PSCSC, and FPSC require updated cost estimates for decommissioning nuclear plants every five years. The following table summarizes information about the most recent site-specific nuclear decommissioning cost studies. Decommissioning costs in the table below are presented in dollars of the year of the cost study and include costs to decommission plant components not subject to radioactive contamination. Annual Funding Decommissioning (in millions) Requirement (a) Costs (a)(b) Year of Cost Study Duke Energy $ 14 $ 8,130 2013 and 2014 Duke Energy Carolinas — 3,420 2013 Duke Energy Progress 14 3,550 2014 Duke Energy Florida — 1,160 2013 (a) Amounts for Progress Energy equal the sum of Duke Energy Progress and Duke Energy Florida. (b) Amounts include the Subsidiary Registrant's ownership interest in jointly owned reactors. Other joint owners are responsible for decommissioning costs related to their interest in the reactors. Duke Energy Progress’ site-specific nuclear decommissioning cost studies were filed with the NCUC and PSCSC in 2015. New funding studies were completed and filed with the NCUC and PSCSC in 2015 as well. Accordingly, in January 2016 Duke Energy Progress received approval from the PSCSC to reduce the annual funding requirement. The NCUC will decide on the appropriate funding level in 2016. Duke Energy Progress will complete and file new funding studies with the FERC in 2016. Nuclear Decommissioning Trust Funds (NDTF) Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida each maintain Nuclear Decommissioning Trust Funds (NDTF) that are intended to pay for the decommissioning costs of the respective nuclear power plants. The NDTF investments are managed and invested in accordance with applicable requirements of various regulatory bodies including the NRC, FERC, NCUC, PSCSC, FPSC and the Internal Revenue Service. Use of the NTDF investments is restricted to nuclear decommissioning activities including license termination, spent fuel and site restoration. The license termination and spent fuel obligations relate to contaminated decommissioning and are recorded as ARO’s. The site restoration obligation relates to non-contaminated decommissioning and is recorded to cost of removal within Regulatory liabilities on the Consolidated Balance Sheets. The following table presents the fair value of NDTF assets legally restricted for purposes of settling asset retirement obligations associated with nuclear decommissioning. December 31, (in millions) 2015 2014 Duke Energy $ 4,670 $ 5,182 Duke Energy Carolinas 2,686 2,678 Duke Energy Progress (a) 1,984 1,701 Duke Energy Florida (a)(b) — 803 (a) Amounts for Progress Energy equal the sum of Duke Energy Progress and Duke Energy Florida. (b) Duke Energy Florida is actively decommissioning Crystal River Unit 3 and was granted an exemption from the NRC which allows for unrestricted use of the NDTF. Therefore, the entire balance of Duke Energy Florida’s NDTF may be applied towards license termination, spent fuel and site restoration costs incurred to decommission Crystal River Unit 3. Nuclear Operating Licenses Operating licenses for nuclear units are potentially subject to extension. The following table includes the current expiration of nuclear operating licenses. Duke Energy Florida has requested the NRC terminate the operating license for Crystal River Unit 3 as it permanently ceased operation in February 2013. Refer to Note 4 for further information on decommissioning activity and transition to SAFSTOR. Unit Year of Expiration Duke Energy Carolinas Catawba Units 1 and 2 2043 McGuire Unit 1 2041 McGuire Unit 2 2043 Oconee Units 1 and 2 2033 Oconee Unit 3 2034 Duke Energy Progress Brunswick Unit 1 2036 Brunswick Unit 2 2034 Harris 2046 Robinson 2030 ARO Liability Rollforward The following table presents changes in the liability associated with AROs. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Balance at December 31, 2013 4,958 1,594 2,570 1,737 833 28 30 Acquisitions 4 — — — — — — Accretion expense (a) 246 113 135 97 38 2 2 Liabilities settled (b) (68 ) — (68 ) — (68 ) — — Liabilities incurred in the current year (c) 3,500 1,717 1,783 1,783 — — — Revisions in estimates of cash flows (d) (174 ) 4 291 288 3 (3 ) — Balance at December 31, 2014 8,466 3,428 4,711 3,905 806 27 32 Acquisitions (e) 226 — 226 204 23 — — Accretion expense (a) 384 165 203 169 34 4 15 Liabilities settled (b) (422 ) (200 ) (195 ) (125 ) (70 ) (4 ) (23 ) Liabilities incurred in the current year (c) 1,016 178 282 282 — 116 418 Revisions in estimates of cash flows (f) 594 347 142 132 9 (18 ) 83 Balance at December 31, 2015 $ 10,264 $ 3,918 $ 5,369 $ 4,567 $ 802 $ 125 $ 525 (a) Substantially all accretion expense for the years ended December 31, 2015 and 2014 relates to Duke Energy’s regulated electric operations and has been deferred in accordance with regulatory accounting treatment. (b) For 2014, amounts relate to nuclear decommissioning of Crystal River Unit 3. For 2015, amounts primarily relate to ash impoundment closures and nuclear decommissioning of Crystal River Unit 3. (c) For 2014, amounts primarily relate to AROs recorded as a result of the Coal Ash Act and an agreement with the SCDHEC related to the W.S. Lee Steam Station. For 2015, amounts primarily relate to AROs recorded as a result of the EPA's rule for disposal of CCR. (d) Amounts for Progress Energy and Duke Energy Progress primarily relate to Duke Energy Progress' site-specific nuclear decommissioning cost studies. The Duke Energy amount also includes the impact of Duke Energy Progress' site-specific nuclear decommissioning cost studies on purchase accounting amounts. (e) Duke Energy Progress amount relates to the NCEMPA acquisition. See footnote 2 for additional information. (f) Primarily relates to the closure of ash impoundments.

Property, Plant and Equipment

Property, Plant and Equipment	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT The following tables summarize the property, plant and equipment for Duke Energy and its subsidiary registrants. December 31, 2015 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Land $ 1,466 $ 407 $ 719 $ 392 $ 327 $ 118 $ 108 Plant – Regulated Electric generation, distribution and transmission 8 - 100 87,593 33,623 36,422 22,888 13,534 4,429 13,118 Natural gas transmission and distribution 12 - 67 2,322 — — — — 2,322 — Other buildings and improvements 15 - 100 1,480 477 621 294 322 204 179 Plant – Nonregulated Electric generation, distribution and transmission 1 - 30 3,348 — — — — — — Other buildings and improvements 5 - 50 2,363 — — — — — — Nuclear fuel 3,194 1,827 1,367 1,367 — — — Equipment 3 - 38 1,791 368 530 398 132 344 173 Construction in process 4,525 1,860 1,827 1,118 709 180 214 Other 2 - 60 4,744 836 1,180 856 319 153 215 Total property, plant and equipment (a)(d) 112,826 39,398 42,666 27,313 15,343 7,750 14,007 Total accumulated depreciation – regulated (b)(c)(d) (35,367 ) (13,521 ) (14,867 ) (10,141 ) (4,720 ) (2,507 ) (4,484 ) Total accumulated depreciation – nonregulated (c)(d) (2,298 ) — — — — — — Generation facilities to be retired, net 548 — 548 548 — — — Total net property, plant and equipment $ 75,709 $ 25,877 $ 28,347 $ 17,720 $ 10,623 $ 5,243 $ 9,523 (a) Includes capitalized leases of $1,470 million , $40 million , $302 million , $144 million , $158 million , $96 million , and $39 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, and Duke Energy Indiana, respectively, primarily within Plant - Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $85 million , $7 million and $78 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,621 million , $976 million , $645 million and $645 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $58 million , $11 million , $27 million and $7 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $2,033 million and accumulated depreciation of consolidated VIEs of $327 million at Duke Energy. December 31, 2014 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Land $ 1,459 $ 403 $ 704 $ 380 $ 324 $ 114 $ 108 Plant – Regulated Electric generation, distribution and transmission 2 - 138 82,206 31,751 33,672 20,616 13,056 3,956 11,911 Natural gas transmission and distribution 12 - 67 2,230 — — — — 2,230 — Other buildings and improvements 9 - 100 1,445 465 607 286 318 200 173 Plant – Nonregulated Electric generation, distribution and transmission 1- 30 2,380 — — — — — — Other buildings and improvements 5 - 50 2,498 — — — — — — Nuclear fuel 2,865 1,676 1,190 1,190 — — — Equipment 3 - 34 1,762 341 506 388 118 330 166 Construction in process 4,519 2,081 1,215 908 307 97 481 Other 5 - 80 3,497 655 756 439 310 214 195 Total property, plant and equipment (a)(d) 104,861 37,372 38,650 24,207 14,433 7,141 13,034 Total accumulated depreciation – regulated (b)(c)(d) (32,628 ) (12,700 ) (13,506 ) (9,021 ) (4,478 ) (2,213 ) (4,219 ) Total accumulated depreciation – nonregulated (c)(d) (2,196 ) — — — — — — Generation facilities to be retired, net 9 — — — — 9 — Total net property, plant and equipment $ 70,046 $ 24,672 $ 25,144 $ 15,186 $ 9,955 $ 4,937 $ 8,815 (a) Includes capitalized leases of $1,548 million , $40 million , $315 million , $146 million , $169 million , $98 million , and $30 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, and Duke Energy Indiana, respectively, primarily in regulated plant. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $72 million , $5 million and $67 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,408 million , $847 million , $561 million and $561 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $52 million , $8 million , $25 million and $6 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $1,873 million and accumulated depreciation of consolidated VIEs of $257 million at Duke Energy. The following table presents capitalized interest, which includes the debt component of AFUDC. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy $ 98 $ 75 $ 89 Duke Energy Carolinas 38 38 41 Progress Energy 24 11 19 Duke Energy Progress 20 10 16 Duke Energy Florida 4 1 3 Duke Energy Ohio 10 10 11 Duke Energy Indiana 6 6 9 Operating Leases Duke Energy's Commercial Portfolio segment operates various renewable energy projects and sells the generated output to utilities, electric cooperatives, municipalities, and commercial and industrial customers through long-term contracts. In certain situations, these long-term contracts and the associated renewable energy projects qualify as operating leases. Rental income from these leases is accounted for as Operating Revenues in the Consolidated Statements of Operations. There are no minimum lease payments as all payments are contingent based on actual electricity generated by the renewable energy projects. Contingent lease payments were $172 million , $164 million and $154 million for the years ended December 31, 2015, 2014 and 2013. As of December 31, 2015, renewable energy projects owned by Duke Energy and accounted for as operating leases had a cost basis of $2,455 million and accumulated depreciation of $258 million . These assets are principally classified as nonregulated electric generation and transmission assets.

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	GOODWILL AND INTANGIBLE ASSETS Goodwill The following table presents goodwill by reportable operating segment for Duke Energy. Duke Energy Regulated International Commercial (in millions) Utilities Energy Portfolio Total Goodwill at December 31, 2014 (a) $ 15,950 $ 307 $ 64 $ 16,321 Foreign exchange and other changes — (36 ) — (36 ) Acquisitions — — 58 58 Goodwill at December 31, 2015 $ 15,950 $ 271 $ 122 $ 16,343 (a) Excludes fully impaired Goodwill related to the nonregulated Midwest Generation business which was sold in the second quarter of 2015. See Note 2 for further information related to the sale. Duke Energy Ohio Duke Energy Ohio's Goodwill balance of $920 million is included in the Regulated Utilities operating segment and presented net of accumulated impairment charges of $216 million on the Consolidated Balance Sheets at December 31, 2015 and 2014. Progress Energy Progress Energy's Goodwill is included in the Regulated Utilities operating segment and there are no accumulated impairment charges. Impairment Testing Duke Energy, Duke Energy Ohio and Progress Energy perform annual goodwill impairment tests each year as of August 31. Duke Energy, Duke Energy Ohio and Progress Energy update their test between annual tests if events or circumstances occur that would more likely than not reduce the fair value of a reporting unit below its carrying value. As the fair value of Duke Energy, Duke Energy Ohio and Progress Energy’s reporting units exceeded their respective carrying values at the date of the annual impairment analysis, no impairment charges were recorded in 2015 . Intangible Assets The following tables show the carrying amount and accumulated amortization of intangible assets within Other on the Consolidated Balance Sheets of the Duke Energy Registrants at December 31, 2015 and 2014 . December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Emission allowances $ 20 $ 1 $ 6 $ 2 $ 4 $ — $ 14 Renewable energy certificates 116 30 80 80 — 5 — Gas, coal and power contracts 24 — — — — — 24 Wind development rights 115 — — — — — — Other 68 — — — — — — Total gross carrying amounts 343 31 86 82 4 5 38 Accumulated amortization – gas, coal and power contracts (16 ) — — — — — (16 ) Accumulated amortization – wind development rights (18 ) — — — — — — Accumulated amortization – other (24 ) — — — — — — Total accumulated amortization (58 ) — — — — — (16 ) Total intangible assets, net $ 285 $ 31 $ 86 $ 82 $ 4 $ 5 $ 22 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Emission allowances $ 23 $ 1 $ 7 $ 3 $ 4 $ — $ 16 Renewable energy certificates 97 25 69 69 — 3 — Gas, coal and power contracts 24 — — — — — 24 Wind development rights 97 — — — — — — Other 76 — — — — — — Total gross carrying amounts 317 26 76 72 4 3 40 Accumulated amortization – gas, coal and power contracts (15 ) — — — — — (15 ) Accumulated amortization – wind development rights (14 ) — — — — — — Accumulated amortization – other (25 ) — — — — — — Total accumulated amortization (54 ) — — — — — (15 ) Total intangible assets, net $ 263 $ 26 $ 76 $ 72 $ 4 $ 3 $ 25 Amortization Expense The following table presents amortization expense for gas, coal and power contracts, wind development rights and other intangible assets. December 31, (in millions) 2015 2014 2013 Duke Energy $ 4 $ 6 $ 13 Duke Energy Ohio — 2 8 Duke Energy Indiana 1 1 1 The table below shows the expected amortization expense for the next five years for intangible assets as of December 31, 2015 . The expected amortization expense includes estimates of emission allowances consumption and estimates of consumption of commodities such as gas and coal under existing contracts, as well as estimated amortization related to the wind development projects. The amortization amounts discussed below are estimates and actual amounts may differ from these estimates due to such factors as changes in consumption patterns, sales or impairments of emission allowances or other intangible assets, delays in the in-service dates of wind assets, additional intangible acquisitions and other events. (in millions) 2016 2017 2018 2019 2020 Duke Energy $ 8 $ 8 $ 8 $ 7 $ 7 Duke Energy Indiana 2 2 2 2 2

Investments in Unconsolidated A

Investments in Unconsolidated Affiliates	12 Months Ended
	Dec. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investment in Unconsolidated Affiliates	INVESTMENTS IN UNCONSOLIDATED AFFILIATES EQUITY METHOD INVESTMENTS Investments in domestic and international affiliates that are not controlled by Duke Energy, but over which it has significant influence, are accounted for using the equity method. As of December 31, 2015 , the carrying amount of investments in affiliates with carrying amounts greater than zero exceeded the underlying investment by $60 million . These differences are attributable to intangibles associated with underlying contracts which are reflected in the investments balance and the equity in earnings reported in the table below. The following table presents Duke Energy’s investments in unconsolidated affiliates accounted for under the equity method, as well as the respective equity in earnings, by segment. Years Ended December 31, 2015 2014 2013 Equity in Equity in Equity in (in millions) Investments earnings Investments earnings earnings Regulated Utilities $ 2 $ (4 ) $ 3 $ (3 ) $ (1 ) International Energy 39 74 69 120 110 Commercial Portfolio 433 (3 ) 258 10 7 Other 25 2 28 3 6 Total $ 499 $ 69 $ 358 $ 130 $ 122 During the years ended December 31, 2015 , 2014 and 2013 , Duke Energy received distributions from equity investments of $104 million , $154 million and $144 million , respectively, which are included in Other assets within Cash Flows from Operating Activities on the Consolidated Statements of Cash Flows. Significant investments in affiliates accounted for under the equity method are discussed below. International Energy Duke Energy owns a 25 percent indirect interest in NMC, which owns and operates a methanol and MTBE business in Jubail, Saudi Arabia. International Energy’s economic ownership interest will decrease to 17.5 percent upon successful startup of NMC's polyacetal production facility, which is expected to occur in January 2017. Commercial Portfolio Investments accounted for under the equity method primarily consist of Duke Energy’s approximate 50 percent ownership interest in the five Catamount Sweetwater, LLC wind farm projects (Phase I-V), and DS Cornerstone, LLC. All of these entities own wind power projects in the United States. Duke Energy also owns a 50 percent interest in Duke American Transmission Co., LLC, which builds, owns and operates electric transmission facilities in North America. Duke Energy also owns a 40 percent and 7.5 percent interest in Atlantic Coast Pipeline, LLC and Sabal Trail Transmission, LLC, respectively, which will build and own natural gas pipelines. Other On December 31, 2013, Duke Energy completed the sale of its 50 percent ownership interest in DukeNet, which owned and operated telecommunications businesses, to Time Warner Cable, Inc. After retiring existing DukeNet debt and payment of transaction expenses, Duke Energy received $215 million in cash proceeds and recorded a $105 million pretax gain in the fourth quarter of 2013.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS The Subsidiary Registrants engage in related party transactions in accordance with the applicable state and federal commission regulations. Refer to the Consolidated Balance Sheets of the Subsidiary Registrants for balances due to or due from related parties. Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 914 $ 851 $ 927 Indemnification coverages (b) 24 21 22 JDA revenue (c) 51 133 121 JDA expense (c) 183 198 116 Progress Energy Corporate governance and shared services provided by Duke Energy (a) $ 712 $ 732 $ 290 Corporate governance and shared services provided to Duke Energy (d) — — 96 Indemnification coverages (b) 38 33 34 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Progress Corporate governance and shared service expenses (a) $ 403 $ 386 $ 266 Indemnification coverages (b) 16 17 20 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Florida Corporate governance and shared service expenses (a) $ 309 $ 346 $ 182 Indemnification coverages (b) 22 16 14 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 342 $ 316 $ 347 Indemnification coverages (b) 6 13 15 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 349 $ 384 $ 422 Indemnification coverages (b) 9 11 14 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These amounts are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power under the JDA are recorded in Operating Revenues on the 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 Consolidated Statements of Operations and Comprehensive Income. (d) In 2013, Progress Energy Service Company (PESC), a consolidated subsidiary of Progress Energy, charged a proportionate share of corporate governance and other costs to consolidated affiliates of Duke Energy. Corporate governance and other shared costs were primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These charges were recorded as an offset to Operation, maintenance and other in the Consolidated Statements of Operations and Comprehensive Income. Effective January 1, 2014, PESC was contributed to Duke Energy Corporate Services (DECS), a consolidated subsidiary of Duke Energy, and these costs were no longer charged out of Progress Energy. Progress Energy recorded a non-cash after-tax equity transfer related to the contribution of PESC to DECS in its Consolidated Statements of Changes in Common Stockholder's Equity. 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 for more information regarding money pool. The net impact of these transactions was not material for the years ended December 31, 2015 , 2014 and 2013 for the Subsidiary Registrants. As discussed in Note 17 , certain trade receivables have been sold by Duke Energy Ohio and Duke Energy Indiana to CRC, an affiliate formed by a subsidiary of Duke Energy. The proceeds obtained from the sales of receivables are largely cash but do include a subordinated note from CRC for a portion of the purchase price. Duke Energy Ohio's nonregulated indirect subsidiary, Duke Energy Commercial Asset Management (DECAM), owned generating plants included in the Disposal Group sold to Dynegy on April 2, 2015. On April 1, 2015, Duke Energy Ohio distributed its indirect ownership interest in DECAM to a Duke Energy subsidiary and non-cash settled DECAM's intercompany loan payable of $294 million . The intercompany loan payable recorded in Notes payable to affiliated companies on Duke Energy Ohio’s Consolidated Balance Sheets was $459 million as of December 31, 2014. Refer to Note 2 for further information on the sale of the Disposal Group. Intercompany Income Taxes Duke Energy and its subsidiaries 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 for the subsidiary registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana December 31, 2015 Intercompany income tax receivable $ 122 $ 120 $ 104 $ — $ 54 $ — Intercompany income tax payable — — — 96 — 47 December 31, 2014 Intercompany income tax receivable $ 43 $ 713 $ 267 $ 174 $ 39 $ 95

Derivatives and Hedging

Derivatives and Hedging	12 Months Ended
	Dec. 31, 2015
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. Interest rate swaps are used to manage interest rate risk associated with borrowings. All derivative instruments not identified as normal purchase/normal sale (NPNS) are recorded at fair value as assets or liabilities on the Consolidated Balance Sheets. Cash collateral related to derivative instruments executed under master netting arrangements is offset against the collateralized derivatives on the Consolidated Balance Sheets. The cash impacts of settled derivatives are recorded as operating activities on the Consolidated Statements of Cash Flows. INTEREST RATE RISK The Duke Energy Registrants are exposed to changes in interest rates as a result of their issuance or anticipated issuance of variable-rate and fixed-rate debt and commercial paper. Interest rate risk is managed by limiting variable-rate exposures to a percentage of total debt and by monitoring changes in interest rates. To manage risk associated with changes in interest rates, the Duke Energy Registrants may enter into interest rate swaps, U.S. Treasury lock agreements and other financial contracts. In anticipation of certain fixed-rate debt issuances, a series of forward-starting interest rate swaps 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 effects earnings. Amounts for interest rate contracts are reclassified to earnings as interest expense over the term of the related debt. Gains and losses reclassified out of AOCI for the years ended December 31, 2015 and 2014 were not material. Duke Energy's interest rate derivatives designated as hedges include interest rate swaps used to hedge existing debt within the International Energy and Renewables' businesses. 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 Utilities 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. Interest rate contracts issued in 2015 that use regulatory accounting include $400 million notional amount of forward-starting interest rate swaps issued in October 2015 at Duke Energy Carolinas to hedge debt anticipated to be issued in 2018. In January 2015, Duke Energy Progress executed fixed-to-floating rate swaps that also use regulatory accounting. The swaps were issued to economically convert $250 million of fixed-rate first mortgage bonds due September 15, 2021, to floating-rate with an initial rate of approximately 1.75 percent . As of December 31, 2015, Duke Energy entered into $900 million of forward-starting interest rate swaps to lock in components of interest rates for the expected financing of the Piedmont acquisition. In January 2016, Duke Energy entered into an additional $500 million notional amount. The swaps do not qualify for hedge accounting and are marked-to-market, with any gains or losses included in earnings. The impact on net income was not material in 2015. The swaps will be terminated in conjunction with the acquisition financing. See note 2 for additional information related to the Piedmont acquisition. The following table shows notional amounts for derivatives related to interest rate risk. December 31, 2015 December 31, 2014 Duke Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Duke Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Energy Energy Florida Ohio Cash flow hedges (a) $ 700 $ — $ — $ — $ — $ — $ 750 $ — $ — $ — Undesignated contracts 1,827 400 500 250 250 27 277 250 250 27 Total notional amount $ 2,527 $ 400 $ 500 $ 250 $ 250 $ 27 $ 1,027 $ 250 $ 250 $ 27 (a) Duke Energy includes amounts related to consolidated Variable Interest Entities (VIEs) of $497 million and $541 million at December 31, 2015 and 2014 , respectively. COMMODITY PRICE RISK The Duke Energy Registrants are exposed to the impact of changes in the prices of electricity, coal and natural gas. Exposure to commodity price risk is influenced by a number of factors including the term of contracts, the liquidity of markets and delivery locations. Regulated public utilities may have cost-based rate regulations and various other cost recovery mechanisms that result in a limited exposure to market volatility of commodity fuel prices. Financial derivative contracts, where approved by the respective state regulatory commissions, can be used to manage the risk of price volatility. At December 31, 2015 all of Duke Energy's open commodity derivative instruments were undesignated because they are accounted for under regulatory accounting. Mark-to-market gains or losses on contracts that use regulatory accounting are deferred as regulatory liabilities or regulatory assets, respectively. Undesignated contracts expire as late as 2048 . The Subsidiary Registrants utilize cost-tracking mechanisms, commonly referred to as fuel adjustment clauses. These clauses allow for the recovery of fuel and fuel-related costs, including settlements of undesignated derivatives for fuel commodities, and portions of purchased power costs through surcharges on customer rates. The difference between the costs incurred and the surcharge revenues is recorded as an adjustment to Fuel used in electric generation and purchased power – regulated or as Operating Revenues: Regulated electric on the Consolidated Statements of Operations with an offsetting impact on regulatory assets or liabilities. Therefore, due to the regulatory accounting followed by the Subsidiary Registrants for undesignated derivatives, realized and unrealized gains and losses on undesignated commodity derivatives do not have an immediate impact on reported net income. Mark-to-market gains and losses related to the nonregulated Midwest generation business were recorded in discontinued operations and open positions at April 2, 2014, were included in the sale of the Disposal Group. Refer to Note 2 for further information on the sale of the Disposal Group. Gains and losses on undesignated derivative contracts for nonregulated continuing operations are not material. Volumes The tables below show information relating to volumes of outstanding commodity derivatives. Amounts disclosed represent the absolute value of notional volumes of commodity contracts excluding NPNS. The Duke Energy Registrants have netted contractual amounts where offsetting purchase and sale contracts exist with identical delivery locations and times of delivery. Where all commodity positions are perfectly offset, no quantities are shown. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Energy Carolinas Energy Progress Florida Ohio Indiana Electricity (gigawatt-hours) 70 — — — — 34 36 Natural gas (millions of decatherms) 398 66 332 117 215 — — December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Energy Carolinas Energy Progress Florida Ohio Indiana Electricity (gigawatt-hours) (a)(b) 25,370 — — — — 19,141 — Natural gas (millions of decatherms) (a) 676 35 328 116 212 313 — (a) Duke Energy Ohio includes amounts related to the Disposal Group. Refer to Note 2 for further information on the sale. (b) Amounts at Duke Energy Ohio include intercompany positions that eliminate at Duke Energy. LOCATION AND FAIR VALUE OF DERIVATIVE ASSETS AND LIABILITIES RECOGNIZED IN THE CONSOLIDATED BALANCE SHEETS The following tables show the fair value and balance sheet location of derivative instruments. Although derivatives subject to master netting arrangements are netted on the Consolidated Balance Sheets, the fair values presented below are shown gross and cash collateral on the derivatives has not been netted against the fair values shown. Derivative Assets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Not Designated as Hedging Instruments Current 12 — 1 — 1 3 7 Noncurrent 4 — 4 — 4 — — Total Derivative Assets – Commodity Contracts $ 16 $ — $ 5 $ — $ 5 $ 3 $ 7 Interest Rate Contracts Designated as Hedging Instruments Noncurrent $ 4 $ — $ — $ — $ — $ — $ — Not Designated as Hedging Instruments Current 6 — 6 2 2 — — Total Derivative Assets – Interest Rate Contracts $ 10 $ — $ 6 $ 2 $ 2 $ — $ — Total Derivative Assets $ 26 $ — $ 11 $ 2 $ 7 $ 3 $ 7 Derivative Liabilities December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Not Designated as Hedging Instruments Current $ 256 $ 32 $ 222 $ 77 $ 145 $ — $ — Noncurrent 100 8 92 16 71 — — Total Derivative Liabilities – Commodity Contracts $ 356 $ 40 $ 314 $ 93 $ 216 $ — $ — Interest Rate Contracts Designated as Hedging Instruments Current $ 11 $ — $ — $ — $ — $ — $ — Noncurrent 33 — — — — — — Not Designated as Hedging Instruments Current 4 — 3 — — 1 — Noncurrent 15 5 5 5 — 6 — Total Derivative Liabilities – Interest Rate Contracts $ 63 $ 5 $ 8 $ 5 $ — $ 7 $ — Total Derivative Liabilities $ 419 $ 45 $ 322 $ 98 $ 216 $ 7 $ — Derivative Assets December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Not Designated as Hedging Instruments Current Assets: Other $ 18 $ — $ — $ — $ — $ 1 $ 14 Current Assets: Assets held for sale 15 — — — — 28 — Investments and Other Assets: Other 3 — — — — — — Investments and Other Assets: Assets held for sale 15 — — — — 26 — Current Liabilities: Other 1 — — — — — — Current Liabilities: Assets held for sale 174 — — — — 175 — Deferred Credits and Other Liabilities: Other 2 — — — — — — Deferred Credits and Other Liabilities: Assets held for sale 111 — — — — 111 — Total Derivative Assets – Commodity Contracts $ 339 $ — $ — $ — $ — $ 341 $ 14 Interest Rate Contracts Designated as Hedging Instruments Investments and Other Assets: Other 10 — — — — — — Not Designated as Hedging Instruments Current Assets: Other 2 — 2 — 2 — — Total Derivative Assets – Interest Rate Contracts $ 12 $ — $ 2 $ — $ 2 $ — $ — Total Derivative Assets $ 351 $ — $ 2 $ — $ 2 $ 341 $ 14 Derivative Liabilities December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Designated as Hedging Instruments Current Liabilities: Other $ — $ — $ 1 $ 1 $ — $ — $ — Not Designated as Hedging Instruments Current Assets: Assets held for sale — — — — — 4 — Investments and Other Assets: Assets held for sale — — — — — 4 — Current Liabilities: Other 307 14 288 108 180 — — Current Liabilities: Assets held for sale 253 — — — — 252 — Deferred Credits and Other Liabilities: Other 91 5 80 23 57 — — Deferred Credits and Other Liabilities: Assets held for sale 208 — — — — 207 — Total Derivative Liabilities – Commodity Contracts $ 859 $ 19 $ 369 $ 132 $ 237 $ 467 $ — Interest Rate Contracts Designated as Hedging Instruments Current Liabilities: Other $ 13 $ — $ — $ — $ — $ — $ — Deferred Credits and Other Liabilities: Other 29 — — — — — — Not Designated as Hedging Instruments Current Liabilities: Other 1 — — — — 1 — Deferred Credits and Other Liabilities: Other 7 — 2 — 2 5 — Total Derivative Liabilities – Interest Rate Contracts $ 50 $ — $ 2 $ — $ 2 $ 6 $ — Total Derivative Liabilities $ 909 $ 19 $ 371 $ 132 $ 239 $ 473 $ — OFFSETTING ASSETS AND LIABILITIES The following tables present the line items on the Consolidated Balance Sheets where derivatives are reported. Substantially all of Duke Energy's outstanding derivative contracts are subject to enforceable master netting arrangements. The Gross amounts offset in the tables below show the effect of these netting arrangements on financial position, and include collateral posted to offset the net position. The amounts shown are calculated by counterparty. Accounts receivable or accounts payable may also be available to offset exposures in the event of bankruptcy. These amounts are not included in the tables below. Derivative Assets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current Gross amounts recognized $ 18 $ — $ 7 $ 2 $ 3 $ 3 $ 7 Gross amounts offset (3 ) — (2 ) — (2 ) — — Net amounts presented in Current Assets: Other $ 15 $ — $ 5 $ 2 $ 1 $ 3 $ 7 Noncurrent Gross amounts recognized $ 8 $ — $ 4 $ — $ 4 $ — $ — Gross amounts offset (4 ) — (4 ) — (4 ) — — Net amounts presented in Investments and Other Assets: Other $ 4 $ — $ — $ — $ — $ — $ — Derivative Liabilities December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current Gross amounts recognized $ 271 $ 32 $ 225 $ 77 $ 145 $ 1 $ — Gross amounts offset (22 ) — (21 ) (1 ) (20 ) — — Net amounts presented in Current Liabilities: Other $ 249 $ 32 $ 204 $ 76 $ 125 $ 1 $ — Noncurrent Gross amounts recognized $ 148 $ 13 $ 97 $ 21 $ 71 $ 6 $ — Gross amounts offset (16 ) — (15 ) — (15 ) — — Net amounts presented in Deferred Credits and Other Liabilities: Other $ 132 $ 13 $ 82 $ 21 $ 56 $ 6 $ — Derivative Assets December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current (a) Gross amounts recognized $ 210 $ — $ 2 $ — $ 2 $ 204 $ 14 Gross amounts offset (153 ) — (2 ) — (2 ) (179 ) — Net amounts subject to master netting 57 — — — — 25 14 Amounts not subject to master netting — — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 57 $ — $ — $ — $ — $ 25 $ 14 Noncurrent (b) Gross amounts recognized $ 136 $ — $ — $ — $ — $ 137 $ — Gross amounts offset (88 ) — — — — (114 ) — Net amounts subject to master netting 48 — — — — 23 — Amounts not subject to master netting 5 — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 53 $ — $ — $ — $ — $ 23 $ — (a) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Current Assets on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Assets held for sale within Current Assets on the Condensed Consolidated Balance Sheets. (b) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Assets held for sale within Investments and Other Assets on the Condensed Consolidated Balance Sheets. Derivative Liabilities December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current (c) Gross amounts recognized $ 573 $ 14 $ 289 $ 109 $ 180 $ 257 $ — Gross amounts offset (213 ) — (17 ) — (17 ) (222 ) — Net amounts subject to master netting 360 14 272 109 163 35 — Amounts not subject to master netting 1 — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 361 $ 14 $ 272 $ 109 $ 163 $ 35 $ — Noncurrent (d) Gross amounts recognized $ 319 $ 5 $ 82 $ 23 $ 59 $ 216 $ — Gross amounts offset (173 ) — (8 ) — (8 ) (193 ) — Net amounts subject to master netting 146 5 74 23 51 23 — Amounts not subject to master netting 16 — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 162 $ 5 $ 74 $ 23 $ 51 $ 23 $ — (c) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Current Liabilities on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Liabilities associated with assets held for sale within Current Liabilities on the Condensed Consolidated Balance Sheets. (d) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Liabilities associated with assets held for sale within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets. 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 Indiana were not material. December 31, 2015 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Aggregate fair value of derivatives in a net liability position $ 334 $ 45 $ 290 $ 93 $ 194 $ — Fair value of collateral already posted 30 — 30 — 30 — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 304 45 260 93 164 — December 31, 2014 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio (a) Aggregate fair value of derivatives in a net liability position $ 845 $ 19 $ 370 $ 131 $ 239 $ 456 Fair value of collateral already posted 209 — 23 — 23 186 Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 407 19 347 131 216 41 (a) Duke Energy Ohio includes amounts related to the Disposal Group for the year ended December 31, 2014. The Duke Energy Registrants have elected to offset cash collateral and fair values of derivatives. For amounts to be netted, the derivative must be executed with the same counterparty under the same master netting arrangement. Amounts disclosed below represent the receivables related to the right to reclaim cash collateral under master netting arrangements. December 31, 2015 December 31, 2014 (in millions) Receivables Receivables Duke Energy Amounts offset against net derivative positions $ 30 $ 145 Amounts not offset against net derivative positions — 64 Progress Energy Amounts offset against net derivative positions 30 23 Duke Energy Florida Amounts offset against net derivative positions 30 23 Duke Energy Ohio Amounts offset against net derivative positions — 122 Amounts not offset against net derivative positions — 64

Investments in Debt and Equity

Investments in Debt and Equity Securities	12 Months Ended
	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investments in Debt and Equity Securities	INVESTMENTS IN DEBT AND EQUITY SECURITIES AVAILABLE-FOR-SALE SECURITIES The Duke Energy Registrants classify their investments in debt and equity securities as available-for-sale. Duke Energy’s available-for-sale securities are primarily comprised of investments held in (i) the 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 OPEB plans, (iii) Duke Energy’s captive insurance investment portfolio, and (iv) Duke Energy’s foreign operations investment portfolio. 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 other-than-temporary impairments 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. Certain investments held in Duke Energy Florida's NDTF were acquired in a settlement with FMJO and do not qualify for regulatory accounting. Unrealized gains and losses on these assets are included in other comprehensive income until realized, unless it is determined the carrying value of an investment is other-than-temporarily impaired, and realized gains and losses are included within Other income and expense, net on the Consolidated Statements of Operations. The value of these assets have not materially changed since the assets were acquired from FMJO. As a result, there is no material impact on earnings of the Duke Energy Registrants. 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. If an other-than-temporary impairment exists, the unrealized loss is included in earnings based on the criteria discussed below. 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. Criteria used to evaluate whether an impairment associated with equity securities is other-than-temporary includes, but is not limited to, (i) the length of time over which the market value has been lower than the cost basis of the investment, (ii) the percentage decline compared to the cost of the investment, and (iii) management’s intent and ability to retain its investment for a period of time sufficient to allow for any anticipated recovery in market value. If a decline in fair value is determined to be other-than-temporary, the investment is written down to its fair value through a charge to earnings. If the entity does not have an intent to sell a debt security and it is not more likely than not management will be required to sell the debt security before the recovery of its cost basis, the impairment write-down to fair value would be recorded as a component of other comprehensive income, except for when it is determined a credit loss exists. In determining whether a credit loss exists, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than the amortized cost basis, (ii) changes in the financial condition of the issuer of the security, or in the case of an asset backed security, the financial condition of the underlying loan obligors, (iii) consideration of underlying collateral and guarantees of amounts by government entities, (iv) ability of the issuer of the security to make scheduled interest or principal payments, and (v) any changes to the rating of the security by rating agencies. If a credit loss exists, the amount of impairment write-down to fair value is split between credit loss and other factors. The amount related to credit loss is recognized in earnings. The amount related to other factors is recognized in other comprehensive income. There were no credit losses as of December 31, 2015 and 2014 . DUKE ENERGY The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 179 $ — $ — $ 136 Equity securities 1,823 58 3,590 1,926 29 3,650 Corporate debt securities 7 8 432 14 2 454 Municipal bonds 5 1 185 5 — 184 U.S. government bonds 11 5 1,254 19 2 978 Other debt securities — 4 177 1 2 147 Total NDTF (c) $ 1,846 $ 76 $ 5,817 $ 1,965 $ 35 $ 5,549 Other Investments Cash and cash equivalents $ — $ — $ 29 $ — $ — $ 15 Equity securities 32 1 95 34 — 96 Corporate debt securities 1 3 92 1 1 58 Municipal bonds 3 1 74 3 1 76 U.S. government bonds — — 45 — — 27 Other debt securities — 2 62 1 1 80 Total Other Investments (a) $ 36 $ 7 $ 397 $ 39 $ 3 $ 352 Total Investments $ 1,882 $ 83 $ 6,214 $ 2,004 $ 38 $ 5,901 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts are considered other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) The increase in estimated fair value of the NDTF as of December 31, 2015 , is primarily due to NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets and the NDTF assets acquired in a settlement with FMJO. This is partially offset due to reimbursements from the NDTF for Duke Energy Florida's costs related to ongoing decommissioning activity of the Crystal River Unit 3 Nuclear Plant. Refer to Note 2 for further information. The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less 120 Due after one through five years 775 Due after five through 10 years 598 Due after 10 years 828 Total 2,321 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 193 $ 271 $ 209 Realized losses 98 105 65 DUKE ENERGY CAROLINAS The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 34 $ — $ — $ 51 Equity securities 1,021 27 2,094 1,102 17 2,162 Corporate debt securities 3 5 292 8 2 316 Municipal bonds 1 — 33 1 — 62 U.S. government bonds 3 3 438 7 1 308 Other debt securities — 4 147 1 2 133 Total NDTF $ 1,028 $ 39 $ 3,038 $ 1,119 $ 22 $ 3,032 Other Investments Other debt securities $ — $ 1 $ 3 $ — $ 1 $ 3 Total Other Investments (a) $ — $ 1 $ 3 $ — $ 1 $ 3 Total Investments $ 1,028 $ 40 $ 3,041 $ 1,119 $ 23 $ 3,035 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 13 Due after one through five years 187 Due after five through 10 years 275 Due after 10 years 438 Total $ 913 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 158 $ 109 $ 115 Realized losses 83 93 12 PROGRESS ENERGY The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 145 $ — $ — $ 85 Equity securities 802 31 1,496 824 12 1,488 Corporate debt securities 4 3 140 6 — 138 Municipal bonds 4 1 152 4 — 122 U.S. government bonds 8 2 816 12 1 670 Other debt securities — — 30 — — 14 Total NDTF (c) $ 818 $ 37 $ 2,779 $ 846 $ 13 $ 2,517 Other Investments Cash and cash equivalents $ — $ — $ 18 $ — $ — $ 15 Municipal bonds 3 — 45 3 — 43 Total Other Investments (a) $ 3 $ — $ 63 $ 3 $ — $ 58 Total Investments $ 821 $ 37 $ 2,842 $ 849 $ 13 $ 2,575 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts are considered other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) The increase in estimated fair value of the NDTF as of December 31, 2015 , is primarily due to NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets and the NDTF assets acquired in a settlement with FMJO. This is partially offset due to reimbursements from the NDTF for Duke Energy Florida's costs related to ongoing decommissioning activity of the Crystal River Unit 3 Nuclear Plant. Refer to Note 2 for further information. The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 94 Due after one through five years 496 Due after five through 10 years 254 Due after 10 years 339 Total $ 1,183 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 33 $ 157 $ 90 Realized losses 13 11 46 DUKE ENERGY PROGRESS The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 110 $ — $ — $ 50 Equity securities 596 25 1,178 612 10 1,171 Corporate debt securities 3 2 96 5 — 97 Municipal bonds 4 1 150 4 — 120 U.S. government bonds 6 2 486 9 1 265 Other debt securities — — 18 — — 8 Total NDTF (c) $ 609 $ 30 $ 2,038 $ 630 $ 11 $ 1,711 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ — Total Other Investments (a) $ — $ — $ 1 $ — $ — $ — Total Investments $ 609 $ 30 $ 2,039 $ 630 $ 11 $ 1,711 (a) These amounts are recorded in Other with Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) As of December 31, 2015 , the estimated fair value of the NDTF includes NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets. Refer to Note 2 for further information. The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 15 Due after one through five years 285 Due after five through 10 years 206 Due after 10 years 244 Total $ 750 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 26 $ 19 $ 58 Realized losses 11 5 26 DUKE ENERGY FLORIDA The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 35 $ — $ — $ 35 Equity securities 206 6 318 212 2 317 Corporate debt securities 1 1 44 1 — 41 Municipal bonds — — 2 — — 2 U.S. government bonds 2 — 330 3 — 405 Other debt securities — — 12 — — 6 Total NDTF (c) $ 209 $ 7 $ 741 $ 216 $ 2 $ 806 Other Investments Cash and cash equivalents $ — $ — $ 6 $ — $ — $ 1 Municipal bonds 3 — 45 3 — 43 Total Other Investments (a) $ 3 $ — $ 51 $ 3 $ — $ 44 Total Investments $ 212 $ 7 $ 792 $ 219 $ 2 $ 850 (a) These amounts are recorded in Other with Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) The decrease in estimated fair value of the NDTF as of December 31, 2015 , is primarily due to reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 Nuclear Plant, partially offset by the NDTF asset acquired in a settlement with FMJO. Refer to Note 2 for further information. The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 79 Due after one through five years 211 Due after five through 10 years 48 Due after 10 years 95 Total $ 433 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were as follows. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 7 $ 138 $ 32 Realized losses 2 5 20 DUKE ENERGY INDIANA The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value Other Investments Cash and cash equivalents $ — $ — $ 2 $ — $ — $ — Equity securities 27 — 71 28 — 71 Corporate debt securities — — 2 — — — Municipal bonds — 1 26 — 1 30 Total Other Investments (a) $ 27 $ 1 $ 101 $ 28 $ 1 $ 101 Total Investments $ 27 $ 1 $ 101 $ 28 $ 1 $ 101 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 2 Due after one through five years 14 Due after five through 10 years 9 Due after 10 years 3 Total $ 28 Realized gains and losses, which were determined on a specific identification basis, from sales of available-for-sale securities were insignificant for the years ended December 31, 2015 , 2014 and 2013 .

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
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 which 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 – As discussed in Note 1, 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 1 and 2 during the years ended December 31, 2015 , 2014 and 2013 . Transfers out of Level 3 during the year ended December 31, 2014, were the result of forward commodity prices becoming observable due to the passage of time. 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 NASDAQ and New York Stock Exchange (NYSE). 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 are primarily valued using internally developed discounted cash flow models which 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 which 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. Goodwill and Long-Lived Assets and Assets Held for Sale See Note 11 for a discussion of the valuation of goodwill and long-lived assets. See Note 2 related to the assets and related liabilities of the Disposal Group classified as held for sale, and the purchase of NCEMPA's ownership interests in certain generating assets. DUKE ENERGY The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 3,590 $ 3,418 $ — $ — $ 172 Nuclear decommissioning trust fund debt securities 2,227 672 1,555 — Other available-for-sale equity securities 95 95 — — — Other available-for-sale debt securities 302 75 222 5 Derivative assets 26 — 16 10 Total assets 6,240 4,260 1,793 15 172 Derivative liabilities (419 ) — (419 ) — Net assets $ 5,821 $ 4,260 $ 1,374 $ 15 $ 172 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 3,650 $ 3,493 $ 6 $ — $ 151 Nuclear decommissioning trust fund debt securities 1,899 648 1,251 — Other trading and available-for-sale equity securities 96 96 — — — Other trading and available-for-sale debt securities 263 41 217 5 Derivative assets 110 49 24 37 Total assets 6,018 4,327 1,498 42 151 Derivative liabilities (668 ) (162 ) (468 ) (38 ) Net assets $ 5,350 $ 4,165 $ 1,030 $ 4 $ 151 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. December 31, 2015 Derivatives (in millions) Investments (net) Total Balance at beginning of period $ 5 $ (1 ) $ 4 Total pretax realized or unrealized gains (losses) included in earnings — 21 21 Purchases, sales, issuances and settlements: Purchases — 24 24 Sales — (1 ) (1 ) Settlements — (37 ) (37 ) Total gains included on the Consolidated Balance Sheet as regulatory assets or liabilities — 4 4 Balance at end of period $ 5 $ 10 $ 15 December 31, 2014 Derivatives (in millions) Investments (net) Total Balance at beginning of period $ 20 $ 13 $ 33 Total pretax realized or unrealized gains (losses) included in earnings — (7 ) (7 ) Purchases, sales, issuances and settlements: Purchases — 50 50 Sales (15 ) — (15 ) Settlements — (54 ) (54 ) Net transfers In (Out) of Level 3 due to observability of inputs — 6 6 Total losses included on the Consolidated Balance Sheet as regulatory assets or liabilities — (9 ) (9 ) Balance at end of period $ 5 $ (1 ) $ 4 Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding $ — $ (14 ) $ (14 ) DUKE ENERGY CAROLINAS The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,094 $ 1,922 $ — $ — $ 172 Nuclear decommissioning trust fund debt securities 944 246 698 — Other available-for-sale debt securities 3 — — 3 Total assets 3,041 2,168 698 3 172 Derivative liabilities (45 ) — (45 ) — Net assets $ 2,996 $ 2,168 $ 653 $ 3 $ 172 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,162 $ 2,005 $ 6 $ — $ 151 Nuclear decommissioning trust fund debt securities 870 138 732 — Other trading and available-for-sale debt securities 3 — — 3 Total assets 3,035 2,143 738 3 151 Derivative liabilities (19 ) — (19 ) — Net assets $ 3,016 $ 2,143 $ 719 $ 3 $ 151 The following tables provide a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. There was no change to the Level 3 balance during the year ended December 31, 2015. December 31, 2014 Derivatives (in millions) Investments (net) Total Balance at beginning of period $ 3 $ (2 ) $ 1 Settlements — 2 2 Balance at end of period $ 3 $ — $ 3 PROGRESS ENERGY The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,496 $ 1,496 $ — $ — Nuclear decommissioning trust fund debt securities 1,283 426 857 — Other available-for-sale debt securities 63 18 45 — Derivative assets 11 — 11 — Total assets 2,853 1,940 913 — Derivative liabilities (322 ) — (322 ) — Net assets $ 2,531 $ 1,940 $ 591 $ — December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,488 $ 1,488 $ — $ — Nuclear decommissioning trust fund debt securities 1,029 510 519 — Other trading and available-for-sale debt securities 58 15 43 — Derivative assets 4 — 4 — Total assets 2,579 2,013 566 — Derivative liabilities (373 ) — (373 ) — Net assets $ 2,206 $ 2,013 $ 193 $ — DUKE ENERGY PROGRESS The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,178 $ 1,178 $ — $ — Nuclear decommissioning trust fund debt securities and other 860 141 719 — Other available-for-sale debt securities and other 1 1 — — Derivative assets 2 — 2 — Total assets 2,041 1,320 721 — Derivative liabilities (98 ) — (98 ) — Net assets $ 1,943 $ 1,320 $ 623 $ — December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,171 $ 1,171 $ — $ — Nuclear decommissioning trust fund debt securities and other 540 151 389 — Total assets 1,711 1,322 389 — Derivative liabilities (132 ) — (132 ) — Net assets $ 1,579 $ 1,322 $ 257 $ — DUKE ENERGY FLORIDA The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 318 $ 318 $ — $ — Nuclear decommissioning trust fund debt securities and other 423 285 138 — Other available-for-sale debt securities and other 51 6 45 — Derivative assets 7 — 7 — Total assets 799 609 190 — Derivative liabilities (216 ) — (216 ) — Net assets (liabilities) $ 583 $ 609 $ (26 ) $ — December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 317 $ 317 $ — $ — Nuclear decommissioning trust fund debt securities and other 489 359 130 — Other trading and available-for-sale debt securities and other 44 — 44 — Derivative assets 4 — 4 — Total assets 854 676 178 — Derivative liabilities (241 ) — (241 ) — Net assets (liabilities) $ 613 $ 676 $ (63 ) $ — DUKE ENERGY OHIO The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which are disclosed in Note 14 . December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 3 $ — $ — $ 3 Derivative liabilities (7 ) — (7 ) — Net assets (liabilities) $ (4 ) $ — $ (7 ) $ 3 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 49 $ 20 $ 9 $ 20 Derivative liabilities (181 ) (117 ) (26 ) (38 ) Net assets (liabilities) $ (132 ) $ (97 ) $ (17 ) $ (18 ) The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2015 2014 Balance at beginning of period $ (18 ) $ (4 ) Total pretax realized or unrealized gains (losses) included in earnings 21 (9 ) Purchases, sales, issuances and settlements: Purchases 5 1 Settlements (5 ) (13 ) Net transfers In (Out) of Level 3 due to observability of inputs — 6 Total gains included on the Consolidated Balance Sheet as regulatory assets or liabilities — 1 Balance at end of period $ 3 $ (18 ) DUKE ENERGY INDIANA The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other available-for-sale equity securities $ 71 $ 71 $ — $ — Other available-for-sale debt securities and other 30 2 28 — Derivative assets 7 — — 7 Net assets (liabilities) $ 108 $ 73 $ 28 $ 7 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other trading and available-for-sale equity securities $ 71 $ 71 $ — $ — Other trading and available-for-sale debt securities and other 30 — 30 — Derivative assets 14 — — 14 Net assets (liabilities) $ 115 $ 71 $ 30 $ 14 The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2015 2014 Balance at beginning of period $ 14 $ 12 Total pretax realized or unrealized gains included in earnings — 3 Purchases, sales, issuances and settlements: Purchases 19 49 Settlements (30 ) (41 ) Total gains (losses) included on the Consolidated Balance Sheet as regulatory assets or liabilities 4 (9 ) Balance at end of period $ 7 $ 14 QUANTITATIVE INFORMATION ABOUT UNOBSERVABLE INPUTS The following table includes quantitative information about the Duke Energy Registrants' derivatives classified as Level 3. December 31, 2015 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Financial transmission rights (FTRs) $ 10 RTO auction pricing FTR price – per Megawatt-Hour (MWh) $ (0.74 ) - 7.29 Duke Energy Ohio FTRs $ 3 RTO auction pricing FTR price – per MWh $ 0.67 - 2.53 Duke Energy Indiana FTRs $ 7 RTO auction pricing FTR price – per MWh $ (0.74 ) - 7.29 December 31, 2014 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Natural gas contracts $ (5 ) Discounted cash flow Forward natural gas curves – price per Million British Thermal Unit (MMBtu) $ 2.12 - 4.35 FTRs 14 RTO auction pricing FTR price – per MWh (1.92 ) - 9.86 Electricity contracts (1 ) Discounted cash flow Forward electricity curves – price per MWh 25.16 - 51.75 Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves – price per MW day 21.00 - 109.00 Reserves (11 ) Bid-ask spreads, implied volatility, probability of default Total Level 3 derivatives $ (1 ) Duke Energy Ohio Electricity contracts $ (6 ) Discounted cash flow Forward electricity curves – price per MWh $ 25.25 - 51.75 Natural gas contracts (5 ) Discounted cash flow Forward natural gas curves – price per MMBtu 2.12 - 4.35 Reserves (7 ) Bid-ask spreads, implied volatility, probability of default Total Level 3 derivatives $ (18 ) Duke Energy Indiana FTRs $ 14 RTO auction pricing FTR price – per MWh $ (1.92 ) - 9.86 OTHER FAIR VALUE DISCLOSURES The fair value and book value of long-term debt, including current maturities, is summarized in the following table. Estimates determined are not necessarily indicative of amounts that could have been settled in current markets. Fair value of long-term debt uses Level 2 measurements. December 31, 2015 December 31, 2014 (in millions) Book Value Fair Value Book Value Fair Value Duke Energy $ 39,569 $ 42,537 $ 39,868 $ 44,566 Duke Energy Carolinas 8,367 9,156 8,353 9,626 Progress Energy 14,464 15,856 14,668 16,951 Duke Energy Progress 6,518 6,757 6,170 6,696 Duke Energy Florida 4,266 4,908 4,823 5,767 Duke Energy Ohio 1,598 1,724 1,760 1,970 Duke Energy Indiana 3,768 4,219 3,769 4,456 At both December 31, 2015 and December 31, 2014 , fair value of cash and cash equivalents, accounts and notes receivable, accounts payable, notes payable and commercial paper, and non-recourse notes payable of variable interest entities are not materially different from their carrying amounts because of the short-term nature of these instruments and/or because the stated rates approximate market rates.

Variable Interest Entities

Variable Interest Entities	12 Months Ended
	Dec. 31, 2015
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 most significant activities of the VIE that impact its economic performance and (ii) what party has rights to receive benefits or is obligated to absorb losses that are significant to the VIE. The analysis of the party that consolidates a VIE is a continual reassessment. No financial support was provided to any of the consolidated VIEs during the years ended December 31, 2015 , 2014 and 2013, or is expected to be provided in the future, that was not previously contractually required. CONSOLIDATED VIEs The following tables summarize the impact of VIEs consolidated by Duke Energy and the Subsidiary Registrants on the Consolidated Balance Sheets. December 31, 2015 Duke Energy Duke Duke Duke Energy Energy Energy Carolinas Progress Florida (in millions) DERF DEPR (c) DEFR (c) CRC Renewables Other Total ASSETS Current Assets Cash and Cash Equivalents $ — $ — $ — $ — $ — $ 2 $ 2 Restricted receivables of variable interest entities (net of allowance for doubtful accounts) 596 349 309 454 19 21 1,748 Other — — — — 138 4 142 Investments and Other Assets Other — — — — 70 — 70 Property, Plant and Equipment Property, plant and equipment, cost (a) — — — — 2,015 20 2,035 Accumulated depreciation and amortization — — — — (321 ) (6 ) (327 ) Total assets $ 596 $ 349 $ 309 $ 454 $ 1,921 $ 41 $ 3,670 LIABILITIES AND EQUITY Current Liabilities Accounts payable — — — — 35 — 35 Taxes accrued 5 3 — — 5 1 14 Current maturities of long-term debt — — — — 108 17 125 Other — — — — 15 2 17 Long-Term Debt (b) 425 254 225 325 968 — 2,197 Deferred Credits and Other Liabilities Deferred income taxes — — — — 289 — 289 Asset retirement obligations — — — — 35 — 35 Other — — — — 33 — 33 Total liabilities $ 430 $ 257 $ 225 $ 325 $ 1,488 $ 20 $ 2,745 Net assets of consolidated variable interest entities $ 166 $ 92 $ 84 $ 129 $ 433 $ 21 $ 925 December 31, 2014 Duke Energy Duke Duke Duke Energy Energy Energy Carolinas Progress Florida (in millions) DERF DEPR (c) DEFR (c) CRC Renewables Other Total ASSETS Current Assets Restricted receivables of variable interest entities (net of allowance for doubtful accounts) $ 647 $ 436 $ 305 $ 547 $ 20 $ 18 $ 1,973 Other — — — — 68 6 74 Investments and Other Assets Other — — — — 25 25 50 Property, Plant and Equipment Property, plant and equipment, cost (a) — — — — 1,855 18 1,873 Accumulated depreciation and amortization — — — — (250 ) (5 ) (255 ) Regulatory Assets and Deferred Debits Other — — — — 34 2 36 Total assets $ 647 $ 436 $ 305 $ 547 $ 1,752 $ 64 $ 3,751 LIABILITIES AND EQUITY Current Liabilities Accounts payable — — — 3 — 3 Taxes accrued — — — 6 — 6 Current maturities of long-term debt — — — 68 16 84 Other — — — 16 5 21 Long-Term Debt (b) 400 300 225 325 967 17 2,234 Deferred Credits and Other Liabilities Deferred income taxes — — — 283 — 283 Asset retirement obligations — — — 29 — 29 Other — — — 34 4 38 Total liabilities $ 400 $ 300 $ 225 $ 325 $ 1,406 $ 42 $ 2,698 Net assets of consolidated variable interest entities $ 247 $ 136 $ 80 $ 222 $ 346 $ 22 $ 1,053 (a) Restricted as collateral for non-recourse debt of VIEs. (b) Non-recourse to the general assets of the applicable registrant. (c) The amount for Progress Energy is equal to the total amount for Duke Energy Progress and Duke Energy Florida. The obligations of these VIEs are non-recourse to Duke Energy, Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida. These entities have no requirement to provide liquidity to, purchase assets of or guarantee performance of these VIEs unless noted in the following paragraphs. 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. On a daily basis, DERF, DEPR and DEFR buy certain accounts receivable arising from the sale of electricity and/or related services from their parent companies. DERF, DEPR and DEFR are wholly owned limited liability companies with separate legal existence from their parents and their assets are not generally available to creditors of their parent companies. DERF, DEPR and DEFR borrow amounts under credit facilities to buy the receivables. Borrowing availability is limited to the amount of qualified receivables sold, which is generally expected to be in excess of the credit facilities. The credit facilities are reflected on the Consolidated Balance Sheets as Long-Term Debt. The secured credit facilities were not structured to meet the criteria for sale accounting treatment under the accounting guidance for transfers and servicing of financial assets. 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. The following table outlines amounts and expiration dates of the credit facilities. DERF DEPR DEFR Credit facility amount (in millions) $ 425 $ 300 $ 225 Expiration date December 2018 February 2019 March 2017 CRC On a revolving basis, Duke Energy Ohio and Duke Energy Indiana sell to CRC certain accounts receivable arising from the sale of electricity and related services. The receivables sold are securitized by CRC through a $325 million credit facility managed by two unrelated third parties. 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. The credit facility expires in December 2018 and is reflected on Duke Energy's Consolidated Balance Sheets as Long-Term Debt. The proceeds Duke Energy Ohio and Duke Energy Indiana receive from the sale of receivables to CRC are 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 . There were no infusions to CRC during the years ended December 31, 2015 and 2014 . CRC is considered a VIE because (i) equity capitalization is insufficient to support its operations, (ii) power to direct the most significant activities that impact economic performance of the entity are not performed by the equity holder, Cinergy, and (iii) deficiencies in net worth of CRC are not funded by Cinergy, but by Duke Energy. The most significant activity of CRC relates to the decisions made with respect to the management of delinquent receivables. Duke Energy consolidates CRC as it makes these decisions. Neither Duke Energy Ohio nor Duke Energy Indiana consolidate CRC. Renewables Certain of Duke Energy’s renewable energy facilities are VIEs due to long-term fixed price power purchase agreements. These fixed price agreements effectively transfer commodity price risk to the buyer of the power. Certain other 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. For certain VIEs, assets are restricted and cannot be pledged as collateral or sold to third parties without prior approval of debt holders. The most significant activities that impact the economic performance of these renewable energy facilities were decisions associated with siting, negotiating purchase power agreements, engineering, procurement and construction and decisions associated with ongoing operations and maintenance-related activities. Duke Energy consolidates the entities as it makes all of these decisions. NON-CONSOLIDATED VIEs The tables below show VIEs not consolidated and how these entities impact the Consolidated Balance Sheets. December 31, 2015 Duke Energy Duke Duke Energy Energy (in millions) Renewables Other Total Ohio Indiana Receivables $ — $ — $ — $ 47 $ 60 Investments in equity method unconsolidated affiliates 235 152 387 — — Total assets $ 235 $ 152 $ 387 $ 47 $ 60 Other current liabilities — 3 3 — — Deferred credits and other liabilities — 14 14 — — Total liabilities $ — $ 17 $ 17 $ — $ — Net assets (liabilities) $ 235 $ 135 $ 370 $ 47 $ 60 December 31, 2014 Duke Energy Duke Duke Energy Energy (in millions) Renewables Other Total Ohio Indiana Receivables $ — $ — $ — $ 91 $ 113 Investments in equity method unconsolidated affiliates 150 38 188 — — Intangibles — — — — — Investments and other assets — 4 4 — — Total assets $ 150 $ 42 $ 192 $ 91 $ 113 Other current liabilities — 3 3 — — Deferred credits and other liabilities — 14 14 — — Total liabilities $ — $ 17 $ 17 $ — $ — Net assets $ 150 $ 25 $ 175 $ 91 $ 113 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 Deferred credits and other liabilities. For more information on various guarantees, refer to Note 7 , "Guarantees and Indemnifications." Renewables Duke Energy has investments in various renewable energy project entities. Some of these entities are VIEs due to long-term fixed price power purchase agreements. These fixed price agreements effectively transfer commodity price risk to the buyer of the power. 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 Duke Energy holds a 50 percent equity interest in Duke-American Transmission Company, LLC (DATC). DATC is considered a VIE due to insufficient equity at risk to permit DATC to finance its own activities without additional subordinated financial support. The activities that most significantly impact DATC’s economic performance are the 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 and, therefore, Duke Energy does not consolidate. Duke Energy has a 40 percent equity interest and a 7.5 percent equity interest in ACP and Sabal Trail, respectively. These entities are considered VIEs as their equity is not sufficient to permit the entities to finance their activities without additional subordinated financial support. The activity that most significantly impacts the economic performance of both ACP and Sabal Trail is construction. Duke Energy does not control these activities and therefore does not consolidate ACP or Sabal Trail. OVEC Duke Energy Ohio’s 9 percent ownership interest in OVEC is considered a non-consolidated VIE. Through its ownership interest in OVEC, Duke Energy Ohio has a contractual arrangement to buy power from OVEC’s power plants through June 2040. Proceeds from the sale of power by OVEC to its power purchase agreement counterparties are designed to be sufficient to meet its operating expenses, fixed costs, debt amortization and interest expense, as well as earn a return on equity. Accordingly, the value of this contract is subject to variability due to fluctuations in power prices and changes in OVEC’s costs of business, including costs associated with its 2,256 MW of coal-fired generation capacity. Proposed environmental rulemaking could increase the costs of OVEC, which would be passed through to Duke Energy Ohio. In 2014, Duke Energy Ohio recorded a $94 million impairment related to OVEC. CRC See discussion under Consolidated VIEs for additional information related to CRC. Amounts included in Receivables in the above table for Duke Energy Ohio and Duke Energy Indiana reflect their retained interest in receivables sold to CRC. These subordinated notes held by Duke Energy Ohio and Duke Energy Indiana are stated at fair value. Carrying values of retained interests are determined by allocating carrying value of the receivables between assets sold and interests retained based on relative fair value. The allocated bases of the subordinated notes are not materially different than their face value because (i) the receivables generally turnover in less than two months, (ii) credit losses are reasonably predictable due to the broad customer base and lack of significant concentration and (iii) the equity in CRC is subordinate to all retained interests and thus would absorb losses first. The hypothetical effect on fair value of the retained interests assuming both a 10 percent and a 20 percent unfavorable variation in credit losses or discount rates is not material due to the short turnover of receivables and historically low credit loss history. Interest accrues to Duke Energy Ohio and Duke Energy Indiana on the retained interests using the acceptable yield method. This method generally approximates the stated rate on the notes since the allocated basis and the face value are nearly equivalent. An impairment charge is recorded against the carrying value of both retained interests and purchased beneficial interest whenever it is determined that an other-than-temporary impairment has occurred. Key assumptions used in estimating fair value are detailed in the following table. Duke Energy Ohio Duke Energy Indiana 2015 2014 2015 2014 Anticipated credit loss ratio 0.6 % 0.6 % 0.3 % 0.3 % Discount rate 1.2 % 1.2 % 1.2 % 1.2 % Receivable turnover rate 12.9 % 12.8 % 10.6 % 10.5 % The following table shows the gross and net receivables sold. Duke Energy Ohio Duke Energy Indiana (in millions) 2015 2014 2015 2014 Receivables sold $ 233 $ 273 $ 260 $ 310 Less: Retained interests 47 91 60 113 Net receivables sold $ 186 $ 182 $ 200 $ 197 The following table shows sales and cash flows related to receivables sold. Duke Energy Ohio Duke Energy Indiana Years Ended December 31, Years Ended December 31, (in millions) 2015 2014 2013 2015 2014 2013 Sales Receivables sold $ 1,963 $ 2,246 $ 2,251 $ 2,627 $ 2,913 $ 2,985 Loss recognized on sale 9 11 12 11 11 11 Cash Flows Cash proceeds from receivables sold 1,995 2,261 2,220 2,670 2,932 2,944 Collection fees received 1 1 1 1 1 1 Return received on retained interests 3 4 5 5 6 6 Cash flows from the sales of receivables are reflected within Cash Flows From Operating Activities on Duke Energy Ohio’s and Duke Energy Indiana’s Consolidated Statements of Cash Flows. Collection fees received in connection with servicing transferred accounts receivable are included in Operation, maintenance and other on Duke Energy Ohio’s and Duke Energy Indiana’s Consolidated Statements of Operations and Comprehensive Income. The loss recognized on sales of receivables is calculated monthly by multiplying receivables sold during the month by the required discount. The required discount is derived monthly utilizing a three-year weighted average formula that considers charge-off history, late charge history and turnover history on the sold receivables, as well as a component for the time value of money. The discount rate, or component for the time value of money, is the prior month-end LIBOR plus a fixed rate of 1.00 percent .

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2015
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 stock 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 stock 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, were exercised or settled. Duke Energy’s participating securities are restricted stock units that are entitled to dividends declared on Duke Energy common shares during the restricted stock unit’s vesting periods. The following table presents Duke Energy’s basic and diluted EPS calculations and reconciles the weighted average number of common stock outstanding to the diluted weighted average number of common stock outstanding. Years Ended December 31, (in millions, except per share amounts) 2015 2014 2013 Income from continuing operations attributable to Duke Energy common stockholders excluding impact of participating securities $ 2,791 $ 2,446 $ 2,565 Weighted average shares outstanding – basic 694 707 706 Weighted average shares outstanding – diluted 694 707 706 Earnings per share from continuing operations attributable to Duke Energy common stockholders Basic $ 4.02 3.46 3.64 Diluted $ 4.02 3.46 3.63 Potentially dilutive items excluded from the calculation (a) 2 2 2 Dividends declared per common share $ 3.24 3.15 3.09 (a) Performance stock awards and certain stock options were not included in the dilutive securities calculation because either the performance measures related to the awards had not been met or the option exercise prices were greater than the average market price of the common shares during the presented periods. On April 6, 2015, Duke Energy entered into agreements with each of Goldman, Sachs & Co. and JPMorgan Chase Bank, National Association (the Dealers) to repurchase a total of $1.5 billion of Duke Energy common stock under an accelerated stock repurchase program (the ASR). Duke Energy made payments of $750 million to each of the Dealers and was delivered 16.6 million shares, with a total fair value of $1.275 billion , which represented approximately 85 percent of the total number of shares of Duke Energy common stock expected to be repurchased under the ASR. The $225 million unsettled portion met the criteria to be accounted for as a forward contract indexed to Duke Energy's stock and qualified as an equity instrument. The company recorded the $1.5 billion payment as a reduction to common stock as of April 6, 2015. In June 2015, the Dealers delivered 3.2 million additional shares to Duke Energy to complete the ASR. Approximately 19.8 million shares, in total, were delivered to Duke Energy and retired under the ASR at an average price of $75.75 per share. The final number of shares repurchased was based upon the average of the daily volume weighted average stock prices of Duke Energy’s common stock during the term of the program, less a discount.

Severance

Severance	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Severance	SEVERANCE During 2015, Duke Energy developed targeted cost-savings initiatives aimed at reducing operating and maintenance expense. The initiatives include efforts to reduce costs through standardization of processes and systems, leveraging technology and workforce optimization throughout the company in order to achieve sustainable cost reductions. In conjunction with these initiatives, voluntary and involuntary severance benefits were extended to a total of approximately 900 employees. The following table presents the direct and allocated severance and related expenses recorded by the Duke Energy Registrants associated with these initiatives. Amounts are included within Operation, maintenance and other on the Consolidated Statements of Operations. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Year Ended December 31, 2015 $ 142 $ 93 $ 36 $ 28 $ 8 $ 2 $ 6 In conjunction with the 2012 merger with Progress Energy, Duke Energy and Progress Energy offered a voluntary severance plan to certain eligible employees. As of December 31, 2015, all plan participants have separated from the company. The following table presents direct and allocated severance and related expenses recorded by the Duke Energy Registrants associated with this plan. Amounts are included within Operation, maintenance and other on the Consolidated Statements of Operations. Amounts for 2014 and 2015 were not material. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy (a) Carolinas Energy Progress Florida Ohio Indiana Year Ended December 31, 2013 $ 34 $ 8 $ 19 $ 14 $ 5 $ 2 $ 2 (a) Includes $5 million of accelerated stock award expense and $2 million of COBRA and health care reimbursement expense. During 2013, in conjunction with the retirement of Crystal River Unit 3, severance benefits were made available to certain impacted unionized and non-unionized employees, to the extent that those employees did not find job opportunities at other locations. For the year ended December 31, 2013, Duke Energy Florida deferred $26 million of severance costs as a regulatory asset. Severance costs accrued in 2014 and 2015 related to this plan were not material. As of December 31, 2015, all plan participants have separated from the company. Refer to Note 4 for further discussion regarding Crystal River Unit 3. The table below presents the severance liability for past and ongoing severance plans including the plans described above. Amounts for Duke Energy Indiana and Duke Energy Ohio are not material. Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Balance at December 31, 2014 $ 28 $ 2 $ 18 $ 1 $ 17 Provision/Adjustments 144 80 20 20 — Cash Reductions (36 ) (4 ) (15 ) (2 ) (13 ) Balance at December 31, 2015 $ 136 $ 78 $ 23 $ 19 $ 4

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION The Duke Energy Corporation 2015 Long-Term Incentive Plan (the 2015 Plan) provides for the grant of stock-based compensation awards to employees and outside directors. The 2015 Plan reserves 10 million shares of common stock for issuance. Duke Energy has historically issued new shares upon exercising or vesting of share-based awards. However, Duke Energy may use a combination of new share issuances and open market repurchases for share-based awards that are exercised or vest in the future. Duke Energy has not determined with certainty the amount of such new share issuances or open market repurchases. The 2015 Plan supersedes the 2010 Long-Term Incentive Plan, as amended (the 2010 Plan), and the Progress Energy, Inc. 2007 Equity Incentive Plan (the Progress Plan). No additional grants will be made from the 2010 Plan and Progress Plan. The following table summarizes the total expense recognized by the Duke Energy Registrants, net of tax, for stock-based compensation. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy $ 38 $ 38 $ 52 Duke Energy Carolinas 14 12 13 Progress Energy 14 14 23 Duke Energy Progress 9 9 14 Duke Energy Florida 5 5 9 Duke Energy Ohio 2 5 4 Duke Energy Indiana 4 3 4 Duke Energy's pretax stock-based compensation costs, the tax benefit associated with stock-based compensation expense, and stock-based compensation costs capitalized are included in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Restricted stock unit awards $ 38 $ 39 $ 49 Performance awards 23 22 34 Stock options — — 2 Pretax stock-based compensation cost $ 61 $ 61 $ 85 Tax benefit associated with stock-based compensation expense $ 23 $ 23 $ 33 Stock-based compensation costs capitalized 3 4 3 STOCK OPTIONS Stock options are granted with a maximum option term of 10 years and with an exercise price not less than the market price of Duke Energy's common stock on the grant date. Stock options outstanding at December 31, 2015, were not exercisable and the aggregate intrinsic value was not material. The following table summarizes information about stock options outstanding. Weighted Average Stock Options Exercise Price Weighted Average (in thousands) (per share) Remaining Life Outstanding at December 31, 2014 373 $ 64 Exercised (270 ) 62 Outstanding at December 31, 2015 (a) 103 69 7 years, 2 months (a) Outstanding stock options all vested on January 1, 2016. The following table summarizes additional information related to stock options exercised and granted. Years Ended December 31, 2015 2014 2013 Intrinsic value of options exercised (in millions) $ 5 $ 6 $ 26 Tax benefit related to options exercised (in millions) 2 2 10 Cash received from options exercised (in millions) 17 25 9 Stock options granted (in thousands) (a) — — 310 (a) Stock options granted in 2013 were expensed immediately. RESTRICTED STOCK UNIT AWARDS Restricted stock unit awards generally vest over periods from immediate to three years . Fair value amounts are based on the market price of Duke Energy's common stock on the grant date. The following table includes information related to restricted stock unit awards. Years Ended December 31, 2015 2014 2013 Shares awarded (in thousands) 524 557 612 Fair value (in millions) $ 41 $ 40 $ 42 The following table summarizes information about restricted stock unit awards outstanding. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2014 1,080 $ 69 Granted 524 79 Vested (602 ) 68 Forfeited (49 ) 73 Outstanding at December 31, 2015 953 75 Restricted stock unit awards expected to vest 924 75 The total grant date fair value of shares vested during the years ended December 31, 2015 , 2014 and 2013 was $41 million , $52 million and $50 million , respectively. At December 31, 2015 , Duke Energy had $19 million of unrecognized compensation cost, which is expected to be recognized over a weighted average period of one year, eleven months . PERFORMANCE AWARDS Stock-based performance awards generally vest over three years if performance targets are met. Performance awards granted in 2015, 2014 and 2013 contain market conditions based on the total shareholder return (TSR) of Duke Energy stock relative to a predefined peer group (relative TSR). These awards are valued using a path-dependent model that incorporates expected relative TSR into the fair value determination of Duke Energy’s performance-based share awards. The model uses three-year historical volatilities and correlations for all companies in the predefined peer group, including Duke Energy, to simulate Duke Energy’s relative TSR as of the end of the performance period. For each simulation, Duke Energy’s relative TSR associated with the simulated stock price at the end of the performance period plus expected dividends within the period results in a value per share for the award portfolio. The average of these simulations is the expected portfolio value per share. Actual life to date results of Duke Energy’s relative TSR for each grant are incorporated within the model. For performance awards granted in 2015, the model used a risk-fee interest rate of 1.0 percent , which reflects the yield on three-year Treasury bonds as of the grant date, and an expected volatility of 13.6 percent based on Duke Energy's historical volatility over three years using daily stock prices. The following table includes information related to stock-based performance awards. Years Ended December 31, 2015 2014 2013 Shares awarded (in thousands) 642 542 633 Fair value (in millions) $ 26 $ 19 $ 28 The following table summarizes information about stock-based performance awards outstanding and assumes payout at the maximum level. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2014 1,627 $ 42 Granted 642 41 Vested (271 ) 51 Forfeited (301 ) 38 Outstanding at December 31, 2015 1,697 40 Stock-based performance awards expected to vest 1,301 40 The total grant date fair value of shares vested during the years ended December 31, 2015 , 2014 and 2013 was $26 million , $27 million and $42 million , respectively. At December 31, 2015 , Duke Energy had $22 million of unrecognized compensation cost, which is expected to be recognized over a weighted average period of one year, two months .

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2015
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, non-contributory defined benefit retirement plans. The plans cover most U.S. employees using a cash balance formula. Under a cash balance formula, a plan participant accumulates a retirement benefit consisting of pay credits based upon a percentage of current eligible earnings based on age, or age and years of service, and interest credits. Certain employees are covered under plans that use a final average earnings formula. Under these average earnings formulas, a plan participant accumulates a retirement benefit equal to the sum of percentages of their (i) highest three-year or four-year average earnings, (ii) highest three-year or four-year average earnings in excess of covered compensation per year of participation (maximum of 35 years ), and/or (iii) highest three-year average earnings times years of participation in excess of 35 years . Duke Energy also maintains, and the Subsidiary Registrants participate in, non-qualified, non-contributory defined benefit retirement plans which cover certain executives. As of January 1, 2014, the qualified and non-qualified non-contributory defined benefit plans are closed to new and rehired non-union and certain unionized employees. Duke Energy uses a December 31 measurement date for its defined benefit retirement plan assets and obligations. Net periodic benefit costs disclosed in the tables below represent the cost of the respective benefit plan for the periods presented. 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 cost 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 cost for employees of Duke Energy’s shared services affiliate that provide support to the Subsidiary Registrants. These allocated amounts are included in the governance and shared service costs discussed in Note 13 . Duke Energy’s policy is to fund amounts on an actuarial basis to provide assets sufficient to meet benefit payments to be paid to plan participants. The following table includes information related to the Duke Energy Registrants’ contributions to its U.S. qualified defined benefit pension plans. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Anticipated Contributions: 2016 $ 145 $ 43 $ 43 $ 24 $ 20 $ 4 $ 9 Contributions Made: 2015 $ 302 $ 91 $ 83 $ 42 $ 40 $ 8 $ 19 2014 — — — — — — — 2013 250 — 250 63 133 — — QUALIFIED PENSION PLANS Components of Net Periodic Pension Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 159 $ 50 $ 44 $ 23 $ 20 $ 4 $ 10 Interest cost on projected benefit obligation 324 83 104 48 54 18 27 Expected return on plan assets (516 ) (139 ) (171 ) (79 ) (87 ) (26 ) (42 ) Amortization of actuarial loss 166 39 65 33 31 7 13 Amortization of prior service (credit) cost (15 ) (7 ) (3 ) (2 ) (1 ) — 1 Other 8 2 3 1 1 — 1 Net periodic pension costs (a)(b) $ 126 $ 28 $ 42 $ 24 $ 18 $ 3 $ 10 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 135 $ 41 $ 40 $ 21 $ 20 $ 4 $ 9 Interest cost on projected benefit obligation 344 85 112 54 57 20 29 Expected return on plan assets (511 ) (132 ) (173 ) (85 ) (85 ) (27 ) (41 ) Amortization of actuarial loss 150 36 68 32 32 4 13 Amortization of prior service credit (15 ) (8 ) (3 ) (2 ) (1 ) — — Other 8 2 3 1 1 — 1 Net periodic pension costs (a)(b) $ 111 $ 24 $ 47 $ 21 $ 24 $ 1 $ 11 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 167 $ 49 $ 60 $ 22 $ 30 $ 6 $ 11 Interest cost on projected benefit obligation 320 80 116 50 53 21 28 Expected return on plan assets (549 ) (148 ) (199 ) (94 ) (87 ) (31 ) (46 ) Amortization of actuarial loss 244 60 101 46 49 13 24 Amortization of prior service (credit) cost (11 ) (6 ) (4 ) (1 ) (2 ) — 1 Other 7 2 2 1 1 — 1 Net periodic pension costs (a)(b) $ 178 $ 37 $ 76 $ 24 $ 44 $ 9 $ 19 (a) Duke Energy amounts exclude $9 million , $10 million , and $12 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $4 million , $5 million , and $6 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase $ 173 $ 65 $ 18 $ 14 $ 4 $ 14 $ 11 Accumulated other comprehensive loss (income) Deferred income tax expense $ 6 — 5 — — — — Actuarial losses arising during the year 4 — — — — — — Amortization of prior year service credit 1 — — — — — — Amortization of prior year actuarial losses (11 ) — (4 ) — — — — Transfer with the disposal group 3 Reclassification of actuarial losses to regulatory assets (6 ) — — — — — — Net amount recognized in accumulated other comprehensive income $ (3 ) $ — $ 1 $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase (decrease) $ 112 $ 30 $ (73 ) $ (17 ) $ 11 $ 17 $ 4 Accumulated other comprehensive (income) loss Deferred income tax expense $ (10 ) $ — $ (2 ) $ — $ — $ — $ — Actuarial losses arising during the year 29 — — — — — — Prior year service credit arising during the year — — — — — — — Amortization of prior year actuarial losses (9 ) — — — — — — Reclassification of actuarial losses to regulatory assets (1 ) — — — — — — Net amount recognized in accumulated other comprehensive income $ 9 $ — $ (2 ) $ — $ — $ — $ — Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 8,107 $ 2,053 $ 2,557 $ 1,187 $ 1,335 $ 469 $ 673 Obligation transferred with the Disposal Group (83 ) — — — — — — Service cost 159 50 44 23 20 4 10 Interest cost 324 83 104 48 54 18 27 Actuarial gain (241 ) (53 ) (111 ) (46 ) (62 ) (9 ) (15 ) Transfers — 8 4 7 (3 ) 8 — Plan amendments (6 ) — — — — — (4 ) Benefits paid (533 ) (146 ) (147 ) (76 ) (68 ) (37 ) (42 ) Obligation at measurement date $ 7,727 $ 1,995 $ 2,451 $ 1,143 $ 1,276 $ 453 $ 649 Accumulated Benefit Obligation at measurement date $ 7,606 $ 1,993 $ 2,414 $ 1,143 $ 1,240 $ 442 $ 628 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 8,498 $ 2,300 $ 2,722 $ 1,321 $ 1,363 $ 456 $ 681 Plan assets transferred with the Disposal Group (81 ) — — — — — — Employer contributions 302 91 83 42 40 8 19 Actual return on plan assets (50 ) (10 ) (22 ) (10 ) (11 ) (2 ) (3 ) Benefits paid (533 ) (146 ) (147 ) (76 ) (68 ) (37 ) (42 ) Transfers — 8 4 7 (3 ) 8 — Plan assets at measurement date $ 8,136 $ 2,243 $ 2,640 $ 1,284 $ 1,321 $ 433 $ 655 Funded status of plan $ 409 $ 248 $ 189 $ 141 $ 45 $ (20 ) $ 6 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 7,510 $ 1,875 $ 2,739 $ 1,172 $ 1,233 $ 442 $ 632 Service cost 135 41 40 21 20 4 9 Interest cost 344 85 112 54 57 20 29 Actuarial loss (a) 618 132 211 98 105 41 41 Transfers — 37 (375 ) (61 ) (9 ) (6 ) — Plan amendments (4 ) (1 ) — — — (1 ) — Benefits paid (496 ) (116 ) (170 ) (97 ) (71 ) (31 ) (38 ) Obligation at measurement date $ 8,107 $ 2,053 $ 2,557 $ 1,187 $ 1,335 $ 469 $ 673 Accumulated Benefit Obligation at measurement date $ 7,966 $ 2,052 $ 2,519 $ 1,187 $ 1,297 $ 459 $ 645 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 8,142 $ 2,162 $ 2,944 $ 1,330 $ 1,299 $ 448 $ 654 Actual return on plan assets 852 217 300 149 144 45 65 Benefits paid (496 ) (116 ) (170 ) (97 ) (71 ) (31 ) (38 ) Transfers — 37 (352 ) (61 ) (9 ) (6 ) — Plan assets at measurement date $ 8,498 $ 2,300 $ 2,722 $ 1,321 $ 1,363 $ 456 $ 681 Funded status of plan $ 391 $ 247 $ 165 $ 134 $ 28 $ (13 ) $ 8 (a) Includes an increase in benefit obligation of $180 million as a result of changes in Duke Energy's mortality assumptions. Amounts Recognized in the Consolidated Balance Sheets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Prefunded pension (a) $ 474 $ 252 $ 232 $ 145 $ 84 $ 1 $ 6 Noncurrent pension liability (b) $ 65 $ 4 $ 43 $ 4 $ 39 $ 21 $ — Net asset recognized $ 409 $ 248 $ 189 $ 141 $ 45 $ (20 ) $ 6 Regulatory assets $ 1,884 $ 472 $ 771 $ 360 $ 410 $ 79 $ 162 Accumulated other comprehensive (income) loss Deferred income tax asset $ (45 ) $ — $ (6 ) $ — $ — $ — $ — Prior service credit (4 ) — — — — — — Net actuarial loss 130 — 17 — — — — Net amounts recognized in accumulated other comprehensive loss (c) $ 81 $ — $ 11 $ — $ — $ — $ — Amounts to be recognized in net periodic pension costs in the next year Unrecognized net actuarial loss $ 132 $ 31 $ 59 $ 25 $ 31 $ 4 $ 11 Unrecognized prior service credit (16 ) (8 ) (3 ) (2 ) (1 ) — — December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Prefunded pension (a) $ 441 $ 247 $ 165 $ 134 $ 28 $ — $ 8 Noncurrent pension liability (b) $ 50 $ — $ — $ — $ — $ 13 $ — Net asset recognized $ 391 $ 247 $ 165 $ 134 $ 28 $ (13 ) $ 8 Regulatory assets $ 1,711 $ 407 $ 753 $ 346 $ 406 $ 65 $ 151 Accumulated other comprehensive (income) loss Deferred income tax asset $ (51 ) $ — $ (11 ) $ — $ — $ — $ — Prior service credit (5 ) — — — — — — Net actuarial loss 140 — 21 — — — — Net amounts recognized in accumulated other comprehensive loss (c) $ 84 $ — $ 10 $ — $ — $ — $ — (a) Included in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets. (c) Excludes accumulated other comprehensive income of $13 million and $22 million as of December 31, 2015 and 2014 , respectively, net of tax, associated with a Brazilian retirement plan. Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2015 Duke Duke Duke Progress Energy Energy (in millions) Energy Energy Florida Ohio Projected benefit obligation $ 1,216 $ 611 $ 611 $ 307 Accumulated benefit obligation 1,158 575 575 298 Fair value of plan assets 1,151 574 574 289 December 31, 2014 Duke Duke Energy (in millions) Energy Ohio Projected benefit obligation $ 702 $ 315 Accumulated benefit obligation 672 306 Fair value of plan assets 652 302 Assumptions Used for Pension Benefits Accounting The discount rate used to determine the current year pension obligation and following year’s pension expense is based on a bond selection-settlement portfolio approach. This approach develops a discount rate by selecting a portfolio of high quality corporate bonds that generate sufficient cash flow to provide for projected benefit payments of the plan. The selected bond portfolio is derived from a universe of non-callable corporate bonds rated Aa quality or higher. After the bond portfolio is selected, a single interest rate is determined that equates the present value of the plan’s projected benefit payments discounted at this rate with the market value of the bonds selected. The average remaining service period of active covered employees is seven years for Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana. The following tables present the assumptions or range of assumptions used for pension benefit accounting. December 31, 2015 2014 2013 Benefit Obligations Discount rate 4.40% 4.10% 4.70% Salary increase 4.00 % - 4.40% 4.00 % - 4.40% 4.00 % - 4.40% Net Periodic Benefit Cost Discount rate 4.10% 4.70% 4.10% Salary increase 4.00 % - 4.40% 4.00 % - 4.40% 4.00 % - 4.30% Expected long-term rate of return on plan assets 6.50% 6.75% 7.75% Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Years ending December 31, 2016 $ 628 $ 189 $ 164 $ 91 $ 71 $ 35 $ 48 2017 639 199 167 92 73 35 47 2018 640 203 169 92 75 34 47 2019 643 202 171 91 77 34 47 2020 641 201 174 92 80 35 47 2021 – 2025 3,053 906 869 438 420 171 230 NON-QUALIFIED PENSION PLANS Components of Net Periodic Pension Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ — $ 1 $ — $ — $ — $ — Interest cost on projected benefit obligation 13 1 4 1 2 — — Amortization of actuarial loss 6 — 2 1 2 — 1 Amortization of prior service credit (1 ) — (1 ) — — — — Net periodic pension costs $ 21 $ 1 $ 6 $ 2 $ 4 $ — $ 1 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ — $ 1 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 14 1 5 1 2 — — Amortization of actuarial loss 3 — 2 — — — — Amortization of prior service credit (1 ) — (1 ) — — — — Net periodic pension costs $ 19 $ 1 $ 7 $ 2 $ 2 $ — $ — Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ — $ 1 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 13 1 7 1 1 — — Amortization of actuarial loss 5 — 3 1 1 — — Amortization of prior service credit (1 ) — (1 ) — — — — Net periodic pension costs $ 20 $ 1 $ 10 $ 3 $ 2 $ — $ — Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net (decrease) increase $ (13 ) $ 2 $ (16 ) $ (1 ) $ (15 ) $ — $ (1 ) Accumulated other comprehensive (income) loss Deferred income tax benefit $ (7 ) $ — $ (5 ) $ — $ — $ — $ — Amortization of prior service credit 1 — — — — — — Actuarial gains arising during the year 17 — 13 — — — — Net amount recognized in accumulated other comprehensive loss (income) $ 11 $ — $ 8 $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase $ 44 $ 1 $ 14 $ 4 $ 19 $ 1 $ 2 Regulatory liabilities, net decrease $ (7 ) $ — $ — $ — $ — $ — $ — Accumulated other comprehensive (income) loss Deferred income tax benefit $ 4 $ — $ 5 $ — $ — $ — $ — Actuarial gains arising during the year (9 ) — (11 ) — — — — Net amount recognized in accumulated other comprehensive loss (income) $ (5 ) $ — $ (6 ) $ — $ — $ — $ — Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Service cost 3 — 1 — — — — Interest cost 13 1 4 1 2 — — Actuarial losses (gains) 10 1 (1 ) — (14 ) — — Transfers 4 — — — — — — Benefits paid (26 ) (2 ) (8 ) (3 ) (3 ) — — Obligation at measurement date $ 341 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Accumulated Benefit Obligation at measurement date $ 336 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Change in Fair Value of Plan Assets Plan assets at prior measurement date — — — — — — — Benefits paid (26 ) (2 ) (8 ) (3 ) (3 ) — — Employer contributions 26 2 8 3 3 — — Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 304 $ 15 $ 140 $ 34 $ 39 $ 3 $ 5 Service cost 3 — 1 1 — — — Interest cost 14 1 5 1 2 — — Actuarial losses (a) 43 2 11 2 20 1 1 Settlements — — — — — — — Plan amendments — — — — — — — Transfers — — (32 ) — 4 — — Benefits paid (27 ) (2 ) (9 ) (3 ) (4 ) — (1 ) Obligation at measurement date $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Accumulated Benefit Obligation at measurement date $ 333 $ 15 $ 116 $ 35 $ 61 $ 4 $ 5 Change in Fair Value of Plan Assets Plan assets at prior measurement date — — — — — — — Benefits paid (27 ) (2 ) (9 ) (3 ) (4 ) — (1 ) Employer contributions 27 2 9 3 4 — 1 Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — (a) Includes an increase in benefit obligation of $21 million as a result of changes in Duke Energy's mortality assumptions. Amounts Recognized in the Consolidated Balance Sheets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current pension liability (a) $ 27 $ 2 $ 8 $ 3 $ 3 $ — $ — Noncurrent pension liability (b) 314 14 104 30 43 4 5 Total accrued pension liability $ 341 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Regulatory assets $ 76 $ 7 $ 16 $ 6 $ 10 $ 1 $ 1 Accumulated other comprehensive (income) loss Deferred income tax liability $ (3 ) $ — $ (3 ) $ — $ — $ — $ — Net actuarial loss 9 — 9 — — — — Net amounts recognized in accumulated other comprehensive income $ 6 $ — $ 6 $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss $ 8 $ — $ 1 $ — $ — $ — $ — Unrecognized prior service credit (1 ) — — — — — — December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current pension liability (a) $ 27 $ 2 $ 8 $ 3 $ 4 $ — $ — Noncurrent pension liability (b) 310 14 108 32 57 4 5 Total accrued pension liability $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Regulatory assets $ 89 $ 5 $ 32 $ 7 $ 25 $ 1 $ 2 Regulatory liabilities $ — $ — $ — $ — $ — $ — $ — Accumulated other comprehensive (income) loss Deferred income tax asset $ 4 $ — $ 2 $ — $ — $ — $ — Prior service credit (1 ) — — — — — — Net actuarial gain (8 ) — (4 ) — — — — Net amounts recognized in accumulated other comprehensive loss $ (5 ) $ — $ (2 ) $ — $ — $ — $ — (a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets. Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Projected benefit obligation $ 341 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Accumulated benefit obligation 336 16 112 33 46 4 5 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Projected benefit obligation $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Accumulated benefit obligation 333 15 116 35 61 4 5 Assumptions Used for Pension Benefits Accounting The discount rate used to determine the current year pension obligation and following year’s pension expense is based on a bond selection-settlement portfolio approach. This approach develops a discount rate by selecting a portfolio of high quality corporate bonds that generate sufficient cash flow to provide for projected benefit payments of the plan. The selected bond portfolio is derived from a universe of non-callable corporate bonds rated Aa quality or higher. After the bond portfolio is selected, a single interest rate is determined that equates the present value of the plan’s projected benefit payments discounted at this rate with the market value of the bonds selected. The average remaining service period of active covered employees is 10 years for Duke Energy and Progress Energy, seven years for Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, 12 years for Duke Energy Progress and 17 years for Duke Energy Florida. The following tables present the assumptions used for pension benefit accounting. December 31, 2015 2014 2013 Benefit Obligations Discount rate 4.40 % 4.10 % 4.70 % Salary increase 4.40 % 4.40 % 4.40 % Net Periodic Benefit Cost Discount rate 4.10 % 4.70 % 4.10 % Salary increase 4.40 % 4.40 % 4.30 % Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Years ending December 31, 2016 $ 28 $ 2 $ 8 $ 3 $ 3 $ — $ — 2017 29 2 8 3 3 — — 2018 25 2 8 3 3 — — 2019 26 2 8 3 3 — — 2020 25 2 8 3 3 — 1 2021 - 2025 126 9 38 12 16 1 2 OTHER POST-RETIREMENT BENEFIT PLANS Duke Energy provides, and the Subsidiary Registrants participate in, some health care and life insurance benefits for retired employees on a contributory and non-contributory basis. Employees are eligible for these benefits if they have met age and service requirements at retirement, as defined in the plans. The health care benefits include medical, dental, and prescription drug coverage and are subject to certain limitations, such as deductibles and co-payments. Duke Energy did not make any pre-funding contributions to its other post-retirement benefit plans during the years ended December 31, 2015 , 2014 or 2013 . Components of Net Periodic Other Post-Retirement Benefit Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 6 $ 1 $ 1 $ 1 $ 1 $ — $ 1 Interest cost on accumulated post-retirement benefit obligation 36 9 15 8 7 2 4 Expected return on plan assets (13 ) (8 ) — — — (1 ) (1 ) Amortization of actuarial loss (gain) 16 (2 ) 28 18 10 (2 ) (2 ) Amortization of prior service credit (140 ) (14 ) (102 ) (68 ) (35 ) — — Net periodic post-retirement benefit costs (a)(b) $ (95 ) $ (14 ) $ (58 ) $ (41 ) $ (17 ) $ (1 ) $ 2 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 10 $ 2 $ 4 $ 1 $ 3 $ — $ 1 Interest cost on accumulated post-retirement benefit obligation 49 12 22 11 12 2 5 Expected return on plan assets (13 ) (9 ) — — — — (1 ) Amortization of actuarial loss (gain) 39 3 42 31 10 (2 ) — Amortization of prior service credit (125 ) (11 ) (95 ) (73 ) (21 ) — — Net periodic post-retirement benefit costs (a)(b) $ (40 ) $ (3 ) $ (27 ) $ (30 ) $ 4 $ — $ 5 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 24 $ 2 $ 18 $ 9 $ 7 $ 1 $ 1 Interest cost on accumulated post-retirement benefit obligation 68 13 41 22 16 2 5 Expected return on plan assets (14 ) (11 ) — — — (1 ) (1 ) Amortization of actuarial loss (gain) 52 3 57 34 16 (1 ) 1 Amortization of prior service credit (41 ) (7 ) (30 ) (20 ) (6 ) (1 ) — Net periodic post-retirement benefit costs (a)(b) $ 89 $ — $ 86 $ 45 $ 33 $ — $ 6 (a) Duke Energy amounts exclude $10 million , $9 million , and $8 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $3 million , $2 million , and $2 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase (decrease) $ 1 $ — $ 1 $ — $ 1 $ — $ (7 ) Regulatory liabilities, net increase (decrease) $ (92 ) $ (8 ) $ (71 ) $ (36 ) $ (35 ) $ 2 $ (8 ) Accumulated other comprehensive (income) loss Deferred income tax benefit $ 2 $ — $ (1 ) $ — $ — $ — $ — Actuarial losses (gains) arising during the year (5 ) — 2 — — — — Transfer with the disposal group (3 ) — — — — — — Amortization of prior year prior service credit 3 — (1 ) — — — — Net amount recognized in accumulated other comprehensive income $ (3 ) $ — $ — $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase (decrease) $ 162 $ 34 $ 129 $ 97 $ (4 ) $ — $ (7 ) Regulatory liabilities, net increase (decrease) $ 249 $ 76 $ 122 $ 61 $ 61 $ (2 ) $ 14 Accumulated other comprehensive (income) loss Deferred income tax benefit $ 1 $ — $ 1 $ — $ — $ — $ — Actuarial losses (gains) arising during the year 1 — (2 ) — — — — Prior year service credit arising during the year (6 ) — — — — — — Amortization of prior year prior service credit 2 — — — — — — Net amount recognized in accumulated other comprehensive income $ (2 ) $ — $ (1 ) $ — $ — $ — $ — Reconciliation of Funded Status to Accrued Other Post-Retirement Benefit Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 916 $ 220 $ 379 $ 207 $ 170 $ 39 $ 96 Service cost 6 1 1 1 1 — 1 Interest cost 36 9 15 8 7 2 4 Plan participants' contributions 20 4 7 4 3 1 2 Actuarial (gains) losses (39 ) (18 ) (1 ) (13 ) 11 (3 ) 1 Transfers — 2 — — — — — Plan amendments (9 ) — — — — (1 ) (4 ) Benefits paid (100 ) (18 ) (47 ) (19 ) (28 ) (3 ) (13 ) Obligation transferred with the Disposal Group (3 ) — — — — — — Accrued retiree drug subsidy 1 — — — — — — Accumulated post-retirement benefit obligation at measurement date $ 828 $ 200 $ 354 $ 188 $ 164 $ 35 $ 87 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 227 $ 145 $ — $ (1 ) $ — $ 8 $ 23 Actual return on plan assets (1 ) (1 ) 1 1 1 — (1 ) Benefits paid (100 ) (18 ) (47 ) (19 ) (28 ) (3 ) (13 ) Employer contributions 62 4 39 15 25 2 8 Plan participants' contributions 20 4 7 4 3 1 2 Plan assets at measurement date $ 208 $ 134 $ — $ — $ 1 $ 8 $ 19 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 1,106 $ 265 $ 533 $ 233 $ 253 $ 42 $ 118 Service cost 10 2 4 1 3 — 1 Interest cost 49 12 22 11 12 2 5 Plan participants' contributions 25 10 8 4 4 — 2 Actuarial gains (a) (87 ) (35 ) (19 ) (21 ) — — (20 ) Transfers — 1 (48 ) (2 ) — (1 ) — Plan amendments (85 ) (4 ) (77 ) — (78 ) (1 ) — Benefits paid (103 ) (31 ) (44 ) (19 ) (24 ) (3 ) (10 ) Accrued retiree drug subsidy 1 — — — — — — Accumulated post-retirement benefit obligation at measurement date $ 916 $ 220 $ 379 $ 207 $ 170 $ 39 $ 96 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 214 $ 143 $ — $ — $ — $ 8 $ 18 Actual return on plan assets 18 12 — — — — 2 Benefits paid (103 ) (31 ) (44 ) (19 ) (24 ) (3 ) (10 ) Transfers — (1 ) — — — — — Employer contributions 73 12 36 14 20 3 11 Plan participants' contributions 25 10 8 4 4 — 2 Plan assets at measurement date $ 227 $ 145 $ — $ (1 ) $ — $ 8 $ 23 (a) Includes an increase in benefit obligation of $7 million as a result of changes in Duke Energy's mortality assumptions. Amounts Recognized in the Consolidated Balance Sheets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current post-retirement liability (a) $ 37 $ — $ 31 $ 16 $ 15 $ 2 $ — Noncurrent post-retirement liability (b) 583 66 323 172 149 25 68 Total accrued post-retirement liability $ 620 $ 66 $ 354 $ 188 $ 164 $ 27 $ 68 Regulatory assets $ 1 $ — $ 1 $ — $ 1 $ — $ 57 Regulatory liabilities $ 288 $ 68 $ 51 $ 25 $ 26 $ 21 $ 83 Accumulated other comprehensive (income) loss Deferred income tax liability $ 7 $ — $ — $ — $ — $ — $ — Prior service credit (6 ) — (1 ) — — — — Net actuarial gain (13 ) — — — — — — Net amounts recognized in accumulated other comprehensive income $ (12 ) $ — $ (1 ) $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss (gain) $ 6 $ (3 ) $ 22 $ 13 $ 9 $ (2 ) $ (2 ) Unrecognized prior service credit (142 ) (14 ) (103 ) (68 ) (35 ) — (1 ) December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current post-retirement liability (a) $ 35 $ — $ 29 $ 16 $ 14 $ 2 $ — Noncurrent post-retirement liability (b) 654 75 350 192 156 29 73 Total accrued post-retirement liability $ 689 $ 75 $ 379 $ 208 $ 170 $ 31 $ 73 Regulatory assets $ — $ — $ — $ — $ — $ — $ 64 Regulatory liabilities $ 380 $ 76 $ 122 $ 61 $ 61 $ 19 $ 91 Accumulated other comprehensive (income) loss Deferred income tax liability $ 5 $ — $ 1 $ — $ — $ — $ — Prior service credit (9 ) — — — — — — Net actuarial gain (5 ) — (2 ) — — — — Net amounts recognized in accumulated other comprehensive income $ (9 ) $ — $ (1 ) $ — $ — $ — $ — (a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets. Assumptions Used for Other Post-Retirement Benefits Accounting The discount rate used to determine the current year other post-retirement benefits obligation and following year’s other post-retirement benefits expense is based on a bond selection-settlement portfolio approach. This approach develops a discount rate by selecting a portfolio of high quality corporate bonds that generate sufficient cash flow to provide for projected benefit payments of the plan. The selected bond portfolio is derived from a universe of non-callable corporate bonds rated Aa quality or higher. After the bond portfolio is selected, a single interest rate is determined that equates present value of the plan’s projected benefit payments discounted at this rate with the market value of the bonds selected. The following tables present the assumptions used for other post-retirement benefits accounting. December 31, 2015 2014 2013 Benefit Obligations Discount rate 4.40 % 4.10 % 4.70 % Net Periodic Benefit Cost Discount rate 4.10 % 4.70 % 4.10 % Expected long-term rate of return on plan assets 6.50 % 6.75 % 7.75 % Assumed tax rate 35 % 35 % 35 % Assumed Health Care Cost Trend Rate December 31, 2015 2014 Health care cost trend rate assumed for next year 7.50 % 6.75 % Rate to which the cost trend is assumed to

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Income Tax Expense Components of Income Tax Expense Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ — $ 216 $ (193 ) $ (56 ) $ 1 $ (18 ) $ (86 ) State (12 ) 14 1 (4 ) (7 ) (1 ) (12 ) Foreign 99 — — — — — — Total current income taxes 87 230 (192 ) (60 ) (6 ) (19 ) (98 ) Deferred income taxes Federal 1,089 345 694 334 290 96 245 State 181 57 27 27 58 5 17 Foreign (17 ) — — — — — — Total deferred income taxes (a) 1,253 402 721 361 348 101 262 Investment tax credit amortization (14 ) (5 ) (7 ) (7 ) — (1 ) (1 ) Income tax expense from continuing operations 1,326 627 522 294 342 81 163 Tax expense (benefit) from discontinued operations 19 — (1 ) — — 22 — Total income tax expense included in Consolidated Statements of Operations $ 1,345 $ 627 $ 521 $ 294 $ 342 $ 103 $ 163 (a) Includes benefits of net operating loss (NOL) carryforwards and utilization of NOL and tax credit carryforwards of $264 million at Duke Energy, $15 million at Duke Energy Carolinas, $119 million at Progress Energy, $21 million at Duke Energy Progress, $84 million at Duke Energy Florida, $3 million at Duke Energy Ohio and $45 million at Duke Energy Indiana. Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ — $ 161 $ (466 ) $ (184 ) $ (53 ) $ (73 ) $ (112 ) State 56 51 (8 ) 14 1 3 1 Foreign 144 — — — — — — Total current income taxes 200 212 (474 ) (170 ) (52 ) (70 ) (111 ) Deferred income taxes Federal 1,517 407 938 436 350 113 294 State 35 (25 ) 84 25 52 1 15 Foreign (67 ) — — — — — — Total deferred income taxes (a)(b) 1,485 382 1,022 461 402 114 309 Investment tax credit amortization (16 ) (6 ) (8 ) (6 ) (1 ) (1 ) (1 ) Income tax expense from continuing operations 1,669 588 540 285 349 43 197 Tax benefit from discontinued operations (295 ) — (4 ) — — (300 ) — Total income tax expense (benefit) included in Consolidated Statements of Operations $ 1,374 $ 588 $ 536 $ 285 $ 349 $ (257 ) $ 197 (a) There were no benefits of NOL carryforwards. (b) Includes utilization of NOL and tax credit carryforwards of $1,544 million at Duke Energy, $345 million at Duke Energy Carolinas, $530 million at Progress Energy, $291 million at Duke Energy Progress, $64 million at Duke Energy Florida, $56 million at Duke Energy Ohio and $141 million at Duke Energy Indiana. Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ (141 ) $ 49 $ (221 ) $ (70 ) $ (143 ) $ (24 ) $ (88 ) State (40 ) 11 (37 ) (10 ) (13 ) (4 ) 7 Foreign 151 — — — — — — Total current income taxes (30 ) 60 (258 ) (80 ) (156 ) (28 ) (81 ) Deferred income taxes Federal 1,092 464 555 316 326 65 276 State 144 75 84 59 44 6 29 Foreign 14 — — — — — — Total deferred income taxes (a) 1,250 539 639 375 370 71 305 Investment tax credit amortization (15 ) (5 ) (8 ) (7 ) (1 ) — (1 ) Income tax expense from continuing operations 1,205 594 373 288 213 43 223 Tax expense (benefit) from discontinued operations 29 — (26 ) — — 32 — Total income tax expense included in Consolidated Statements of Operations $ 1,234 $ 594 $ 347 $ 288 $ 213 $ 75 $ 223 (a) Includes benefits of NOL carryforwards of $808 million at Duke Energy, $458 million at Progress Energy, $64 million at Duke Energy Progress, $301 million at Duke Energy Florida and $179 million at Duke Energy Indiana. Duke Energy Income from Continuing Operations before Income Taxes Years Ended December 31, (in millions) 2015 2014 2013 Domestic $ 3,828 $ 3,600 $ 3,183 Foreign 309 534 612 Income from continuing operations before income taxes $ 4,137 $ 4,134 $ 3,795 Statutory Rate Reconciliation The following tables present a reconciliation of income tax expense at the U.S. federal statutory tax rate to the actual tax expense from continuing operations. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,448 $ 598 $ 555 $ 302 $ 330 $ 81 $ 168 State income tax, net of federal income tax effect 109 46 18 15 33 2 2 Tax differential on foreign earnings (27 ) — — — — — — AFUDC equity income (58 ) (34 ) (19 ) (17 ) (3 ) (1 ) (4 ) Renewable energy production tax credits (72 ) — (1 ) — — — — Audit adjustment (22 ) — (23 ) 1 (24 ) — — Tax true-up 2 2 (3 ) (4 ) 2 (5 ) (9 ) Other items, net (54 ) 15 (5 ) (3 ) 4 4 6 Income tax expense from continuing operations $ 1,326 $ 627 $ 522 $ 294 $ 342 $ 81 $ 163 Effective tax rate 32.1 % 36.7 % 32.9 % 34.2 % 36.3 % 35.2 % 34.0 % Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,447 $ 581 $ 497 $ 263 $ 314 $ 39 $ 195 State income tax, net of federal income tax effect 59 17 49 25 34 3 10 Tax differential on foreign earnings (a) (110 ) — — — — — — AFUDC equity income (47 ) (32 ) (9 ) (9 ) — (1 ) (5 ) Renewable energy production tax credits (67 ) — — — — — — International tax dividend (b) 373 — — — — — — Other items, net 14 22 3 6 1 2 (3 ) Income tax expense (benefit) from continuing operations $ 1,669 $ 588 $ 540 $ 285 $ 349 $ 43 $ 197 Effective tax rate 40.4 % 35.4 % 38.0 % 37.9 % 38.9 % 38.9 % 35.5 % (a) Includes a $57 million benefit as a result of the merger of two Chilean subsidiaries and a change in income tax rates in various countries primarily relating to Peru. (b) During 2014, Duke Energy declared a taxable dividend of foreign earnings in the form of notes payable that was expected to result in the repatriation of approximately $2.7 billion of cash held, and expected to be generated, by International Energy over a period of up to eight years. In 2015, approximately $1.5 billion was remitted. As a result of the decision to repatriate cumulative historical undistributed foreign earnings Duke Energy recorded U.S. income tax expense of approximately $373 million in 2014. Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,328 $ 549 $ 361 $ 276 $ 188 $ 39 $ 203 State income tax, net of federal income tax effect 66 56 31 31 20 2 23 Tax differential on foreign earnings (49 ) — — — — — — AFUDC equity income (55 ) (32 ) (18 ) (15 ) (3 ) — (5 ) Renewable energy production tax credits (62 ) — — — — — — Other items, net (23 ) 21 (1 ) (4 ) 8 2 2 Income tax expense from continuing operations $ 1,205 $ 594 $ 373 $ 288 $ 213 $ 43 $ 223 Effective tax rate 31.8 % 37.8 % 36.2 % 36.5 % 39.6 % 39.1 % 38.4 % Valuation allowances have been established for certain foreign and state NOL carryforwards and state income tax credits that reduce deferred tax assets to an amount that will be realized on a more-likely-than-not basis. The net change in the total valuation allowance is included in Tax differential on foreign earnings and State income tax, net of federal income tax effect in the above tables. Undistributed Foreign Earnings As of December 31, 2015, Duke Energy’s intention was to indefinitely reinvest undistributed earnings generated by Duke Energy's foreign subsidiaries. As a result, no U.S. tax is recorded on such earnings of approximately $250 million . The amount of unrecognized deferred tax liability related to undistributed earnings was approximately $12 million . On February 18, 2016, Duke Energy announced it had initiated a process to divest the International Energy business segment, excluding the investment in NMC. See Note 2 for further information. Accordingly, Duke Energy no longer intends to indefinitely reinvest the undistributed foreign earnings of International Energy and will therefore record U.S. taxes related to International Energy's undistributed foreign earnings during the first quarter of 2016. DEFERRED TAXES Net Deferred Income Tax Liability Components December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Deferred credits and other liabilities $ 245 $ 38 $ 115 $ 25 $ 66 $ 29 $ 5 Capital lease obligations 63 9 — — — — 2 Pension, post-retirement and other employee benefits 580 46 186 92 82 24 40 Progress Energy merger purchase accounting adjustments (a) 1,009 — — — — — — Tax credits and NOL carryforwards 3,719 170 997 163 177 25 215 Investments and other assets — — — — — 3 — Other 206 20 48 2 46 37 20 Valuation allowance (160 ) — (38 ) — — — — Total deferred income tax assets 5,662 283 1,308 282 371 118 282 Investments and other assets (1,584 ) (1,057 ) (412 ) (228 ) (201 ) — (7 ) Accelerated depreciation rates (13,070 ) (4,429 ) (4,169 ) (2,325 ) (1,868 ) (1,356 ) (1,797 ) Regulatory assets and deferred debits, net (3,633 ) (943 ) (1,517 ) (756 ) (762 ) (169 ) (135 ) Total deferred income tax liabilities (18,287 ) (6,429 ) (6,098 ) (3,309 ) (2,831 ) (1,525 ) (1,939 ) Net deferred income tax liabilities $ (12,625 ) $ (6,146 ) $ (4,790 ) $ (3,027 ) $ (2,460 ) $ (1,407 ) $ (1,657 ) (a) Primarily related to capital lease obligations and debt fair value adjustments. The following table presents the expiration of tax credits and NOL carryforwards. December 31, 2015 (in millions) Amount Expiration Year Investment tax credits $ 864 2029 — 2035 Alternative minimum tax credits 1,121 Indefinite Federal NOL carryforwards 484 2030 — 2033 State NOL carryforwards and credits (a) 299 2016 — 2035 Foreign NOL carryforwards (b) 100 2026 — 2034 Foreign Tax Credits 851 2024 Total tax credits and NOL carryforwards $ 3,719 (a) A valuation allowance of $81 million has been recorded on the state Net Operating Loss carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (b) A valuation allowance of $79 million has been recorded on the foreign Net Operating Loss carryforwards, as presented in the Net Deferred Income Tax Liability Components table. December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Deferred credits and other liabilities $ 188 $ 53 $ 108 $ 28 $ 78 $ (8 ) $ 12 Capital lease obligations 63 10 — — — — 2 Pension, post-retirement and other employee benefits 546 4 188 96 93 17 43 Progress Energy merger purchase accounting adjustments (a) 1,124 — — — — — — Tax credits and NOL carryforwards 3,540 157 980 91 252 38 260 Investments and other assets — — — — — 14 — Other — 12 — 55 — 35 11 Valuation allowance (184 ) — (13 ) (1 ) — — — Total deferred income tax assets 5,277 236 1,263 269 423 96 328 Investments and other assets (1,625 ) (1,051 ) (427 ) (232 ) (245 ) — (4 ) Accelerated depreciation rates (11,715 ) (4,046 ) (3,284 ) (2,030 ) (1,252 ) (1,660 ) (1,603 ) Regulatory assets and deferred debits, net (3,694 ) (953 ) (1,602 ) (809 ) (792 ) (141 ) (106 ) Other (44 ) — (151 ) — (246 ) — — Total deferred income tax liabilities (17,078 ) (6,050 ) (5,464 ) (3,071 ) (2,535 ) (1,801 ) (1,713 ) Net deferred income tax liabilities $ (11,801 ) $ (5,814 ) $ (4,201 ) $ (2,802 ) $ (2,112 ) $ (1,705 ) $ (1,385 ) (a) Primarily related to capital lease obligations and debt fair value adjustments. On July 23, 2013, HB 998 was signed into law. HB 998 reduces the North Carolina corporate income tax rate from a statutory 6.9 percent to 6.0 percent in January 2014 with a further reduction to 5.0 percent in January 2015. Duke Energy recorded a net reduction of approximately $145 million to its North Carolina deferred tax liability in the third quarter of 2013. The significant majority of this deferred tax liability reduction was offset by recording a regulatory liability pending NCUC determination of the disposition of the amounts related to Duke Energy Carolinas and Duke Energy Progress. The impact of HB 998 did not have a significant impact on the financial position, results of operation, or cash flows of Duke Energy, Duke Energy Carolinas, Progress Energy or Duke Energy Progress. On August 6, 2015, pursuant to N.C. Gen. Stat. 105-130.3C, the North Carolina Department of Revenue announced the North Carolina corporate income tax rate would be reduced from a statutory rate of 5.0 percent to 4.0 percent beginning January 1, 2016. Duke Energy recorded a net reduction of approximately $95 million to its North Carolina deferred tax liability in the third quarter of 2015. The significant majority of this deferred tax liability reduction was offset by recording a regulatory liability pending NCUC determination of the disposition of amounts related to Duke Energy Carolinas and Duke Energy Progress. The impact did not have a significant impact on the financial position, results of operation, or cash flows of Duke Energy, Duke Energy Carolinas, Progress Energy or Duke Energy Progress. Balance Sheet Classification of Deferred Taxes As discussed in Note 1, the FASB issued revised accounting guidance for the Balance Sheet classification of deferred taxes. As shown in the table below, all deferred tax assets and liabilities are presented as noncurrent as of December 31, 2015. However, for December 31, 2014, the revised guidance was not applied. As a result, a portion of deferred tax assets and liabilities is shown as current at December 31, 2014. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Investments and Other Assets: Other 80 — — — — — — Deferred Credits and Other Liabilities: Deferred income taxes (12,705 ) (6,146 ) (4,790 ) (3,027 ) (2,460 ) (1,407 ) (1,657 ) Net deferred income tax liabilities $ (12,625 ) $ (6,146 ) $ (4,790 ) $ (3,027 ) $ (2,460 ) $ (1,407 ) $ (1,657 ) December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current Assets: Other $ 1,593 $ 3 $ 558 $ 106 $ 340 $ 60 $ 206 Investments and Other Assets: Other 29 — — — — — — Current Liabilities: Other — (5 ) — — — — — Deferred Credits and Other Liabilities: Deferred income taxes (13,423 ) (5,812 ) (4,759 ) (2,908 ) (2,452 ) (1,765 ) (1,591 ) Net deferred income tax liabilities $ (11,801 ) $ (5,814 ) $ (4,201 ) $ (2,802 ) $ (2,112 ) $ (1,705 ) $ (1,385 ) UNRECOGNIZED TAX BENEFITS The following tables present changes to unrecognized tax benefits. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Indiana Unrecognized tax benefits – January 1 $ 213 $ 160 $ 32 $ 23 $ 8 $ 1 Unrecognized tax benefits increases (decreases) Gross increases – tax positions in prior periods — — 1 1 — — Gross decreases – tax positions in prior periods (48 ) (45 ) — — — — Decreases due to settlements (45 ) (43 ) — — — — Reduction due to lapse of statute of limitations (32 ) — (32 ) (21 ) (8 ) — Total changes (125 ) (88 ) (31 ) (20 ) (8 ) — Unrecognized tax benefits – December 31 $ 88 $ 72 $ 1 $ 3 $ — $ 1 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Indiana Unrecognized tax benefits – January 1 $ 230 $ 171 $ 32 $ 22 $ 8 $ 1 Unrecognized tax benefits (decreases) increases Gross increases – tax positions in prior periods — — 1 1 — — Gross decreases – tax positions in prior periods (2 ) — — — — — Decreases due to settlements (15 ) (11 ) (1 ) — — — Total changes (17 ) (11 ) — 1 — — Unrecognized tax benefits – December 31 $ 213 $ 160 $ 32 $ 23 $ 8 $ 1 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Unrecognized tax benefits – January 1 $ 540 $ 271 $ 131 $ 67 $ 44 $ 36 $ 32 Unrecognized tax benefits increases (decreases) Gross decreases – tax positions in prior periods (231 ) (100 ) (86 ) (45 ) (37 ) (36 ) (31 ) Decreases due to settlements (66 ) — — — — — — Reduction due to lapse of statute of limitations (13 ) — (13 ) — 1 — — Total changes (310 ) (100 ) (99 ) (45 ) (36 ) (36 ) (31 ) Unrecognized tax benefits – December 31 $ 230 $ 171 $ 32 $ 22 $ 8 $ — $ 1 The following table includes additional information regarding the Duke Energy Registrants' unrecognized tax benefits. It is reasonably possible that Duke Energy could reflect an approximate $65 million reduction and Duke Energy Carolinas could reflect an approximate $63 million reduction in unrecognized tax benefits within the next 12 months. All other Duke Energy Registrants do not anticipate a material increase or decrease in unrecognized tax benefits within the next 12 months. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Amount that if recognized, would affect the effective tax rate or regulatory liability (a) $ 62 $ 54 $ 2 $ 3 $ 1 $ — $ 2 Amount that if recognized, would be recorded as a component of discontinued operations 4 — — — — — — (a) Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida and Duke Energy Indiana are unable to estimate the specific amounts that would affect the effective tax rate versus the regulatory liability. OTHER TAX MATTERS The following tables include interest recognized in the Consolidated Statements of Operations and the Consolidated Balance Sheets. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Net interest income recognized related to income taxes $ 12 $ — $ 2 $ 2 $ 1 $ — $ 1 Net interest expense recognized related to income taxes — 1 — — — — — Interest receivable related to income taxes 3 — — — — — 3 Interest payable related to income taxes — 14 — 1 — — — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Net interest income recognized related to income taxes $ 6 $ — 3 — 1 4 $ 4 Net interest expense recognized related to income taxes — 1 — 1 — — — Interest receivable related to income taxes — — — — — — 2 Interest payable related to income taxes 13 13 5 3 5 — — Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Net interest income recognized related to income taxes $ 2 $ 2 $ 6 $ 7 $ — 4 1 Interest payable related to income taxes 27 8 10 2 7 — — Duke Energy and its subsidiaries are no longer subject to U.S. federal examination for years before 2008. The years 2008 through 2011 are in Appeals. The IRS is currently auditing the federal income tax returns for years 2012 through 2014. With few exceptions, Duke Energy and its subsidiaries are no longer subject to state, local or non-U.S. income tax examinations by tax authorities for years before 2004.

Other Income and Expenses, Net

Other Income and Expenses, Net	12 Months Ended
	Dec. 31, 2015
Other Income and Expenses [Abstract]
Other Income and Expenses, Net	OTHER INCOME AND EXPENSES, NET The components of Other income and expenses, net on the Consolidated Statements of Operations are as follows. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 38 $ 2 $ 4 $ 2 $ 2 $ 4 $ 6 Foreign exchange losses (4 ) — — — — — — AFUDC equity 164 96 54 47 7 3 11 Post in-service equity returns 73 60 13 13 — — — Nonoperating income (expense), other 36 2 26 9 15 (1 ) (6 ) Other income and expense, net $ 307 $ 160 $ 97 $ 71 $ 24 $ 6 $ 11 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 57 $ 4 $ 3 $ — $ 2 $ 8 $ 6 Foreign exchange gains 3 — — — — — — AFUDC equity 135 91 26 25 — 4 14 Post in-service equity returns 89 71 17 17 — — — Nonoperating income (expense), other 67 6 31 9 18 (2 ) 2 Other income and expense, net $ 351 $ 172 $ 77 $ 51 $ 20 $ 10 $ 22 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 26 $ 1 $ 7 $ 1 $ 3 $ 5 $ 6 Foreign exchange losses (18 ) — — — — — — AFUDC equity 157 91 50 42 8 1 15 Post in-service equity returns 39 32 7 7 — — — Nonoperating income (expense), other 58 (4 ) 30 7 19 (4 ) (3 ) Other income and expense, net $ 262 $ 120 $ 94 $ 57 $ 30 $ 2 $ 18

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS For information on subsequent events related to significant accounting policies, acquisitions and dispositions, business segments, regulatory matters, commitments and contingencies, debt and credit facilities, asset retirement obligations, derivatives and hedging and income taxes see Notes 1, 2, 3, 4, 5, 6, 9, 14 and 22, respectively.

Quarterly Financial Data (Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Data (Unaudited)	QUARTERLY FINANCIAL DATA (UNAUDITED) DUKE ENERGY Quarterly EPS amounts may not sum to the full-year total due to changes in the weighted average number of common shares outstanding and rounding. First Second Third Fourth (in millions, except per share data) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 6,065 $ 5,589 $ 6,483 $ 5,322 $ 23,459 Operating income 1,456 1,246 1,688 977 5,367 Income from continuing operations 776 604 940 491 2,811 Income (loss) from discontinued operations, net of tax 91 (57 ) (5 ) (9 ) 20 Net income 867 547 935 482 2,831 Net income attributable to Duke Energy Corporation 864 543 932 477 2,816 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 1.09 $ 0.87 $ 1.36 $ 0.70 $ 4.02 Diluted $ 1.09 $ 0.87 $ 1.36 $ 0.70 $ 4.02 Income (loss) from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ 0.13 $ (0.09 ) $ (0.01 ) $ (0.01 ) $ 0.03 Diluted $ 0.13 $ (0.09 ) $ (0.01 ) $ (0.01 ) $ 0.03 Net income attributable to Duke Energy Corporation common stockholders Basic $ 1.22 $ 0.78 $ 1.35 $ 0.69 $ 4.05 Diluted $ 1.22 $ 0.78 $ 1.35 $ 0.69 $ 4.05 2014 Operating revenues $ 6,263 $ 5,708 $ 6,395 $ 5,559 $ 23,925 Operating income 1,362 1,289 1,619 988 5,258 Income from continuing operations 750 726 891 98 2,465 (Loss) Income from discontinued operations, net of tax (843 ) (113 ) 378 2 (576 ) Net (loss) income (93 ) 613 1,269 100 1,889 Net (loss) income attributable to Duke Energy Corporation (97 ) 609 1,274 97 1,883 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 1.05 $ 1.02 $ 1.25 $ 0.14 $ 3.46 Diluted $ 1.05 $ 1.02 $ 1.25 $ 0.14 $ 3.46 (Loss) Income from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ (1.19 ) $ (0.16 ) $ 0.55 $ — $ (0.80 ) Diluted $ (1.19 ) $ (0.16 ) $ 0.55 $ — $ (0.80 ) Net (loss) income attributable to Duke Energy Corporation common stockholders Basic $ (0.14 ) $ 0.86 $ 1.80 $ 0.14 $ 2.66 Diluted $ (0.14 ) $ 0.86 $ 1.80 $ 0.14 $ 2.66 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (21 ) $ (22 ) $ (24 ) $ (30 ) $ (97 ) Edwardsport Settlement (see Note 4) — — (90 ) (3 ) (93 ) Ash Basin Settlement and Penalties (see Note 5) — — (7 ) (7 ) (14 ) State Tax Adjustment related to Midwest Generation Sale — (41 ) — — (41 ) Cost Savings Initiatives (see Note 19) — — — (142 ) (142 ) Total $ (21 ) $ (63 ) $ (121 ) $ (182 ) $ (387 ) 2014 Costs to Achieve, Mergers $ (55 ) $ (61 ) $ (56 ) $ (33 ) $ (205 ) Midwest Generation Impairment (1,287 ) — 477 (39 ) (849 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (102 ) (102 ) International Tax Adjustment (see Note 22) — — — (373 ) (373 ) Asset Impairment (94 ) — — — (94 ) Total $ (1,436 ) $ (61 ) $ 421 $ (547 ) $ (1,623 ) DUKE ENERGY CAROLINAS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 1,901 $ 1,707 $ 2,061 $ 1,560 $ 7,229 Operating income 515 483 666 296 1,960 Net income 292 265 383 141 1,081 2014 Operating revenues $ 2,000 $ 1,755 $ 1,938 $ 1,658 $ 7,351 Operating income 509 438 630 318 1,895 Net income 286 270 377 139 1,072 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (9 ) $ (11 ) $ (11 ) $ (16 ) $ (47 ) Ash Basin Settlement and Penalties (see Note 5) — — (1 ) (7 ) (8 ) Cost Savings Initiatives (see Note 19) — — — (93 ) (93 ) Total $ (9 ) $ (11 ) $ (12 ) $ (116 ) $ (148 ) 2014 Costs to Achieve, Mergers $ (29 ) $ (38 ) $ (25 ) $ (17 ) $ (109 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (72 ) (72 ) Total $ (29 ) $ (38 ) $ (25 ) $ (89 ) $ (181 ) PROGRESS ENERGY First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 2,536 $ 2,476 $ 2,929 $ 2,336 $ 10,277 Operating income 549 504 756 351 2,160 Income from continuing operations 264 217 452 132 1,065 Net income 263 217 451 131 1,062 Net income attributable to Parent 260 215 448 128 1,051 2014 Operating revenues $ 2,541 $ 2,421 $ 2,863 $ 2,341 $ 10,166 Operating income 477 488 665 388 2,018 Income from continuing operations 204 207 330 139 880 Net income 203 202 330 139 874 Net income attributable to Parent 202 202 329 136 869 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (8 ) $ (8 ) $ (8 ) $ (10 ) $ (34 ) Ash Basin Settlement and Penalties (see Note 5) — — (6 ) — (6 ) Cost Savings Initiatives (see Note 19) — — — (36 ) (36 ) Total $ (8 ) $ (8 ) $ (14 ) $ (46 ) $ (76 ) 2014 Costs to Achieve, Mergers $ (19 ) $ (12 ) $ (21 ) $ (13 ) $ (65 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (30 ) (30 ) Total $ (19 ) $ (12 ) $ (21 ) $ (43 ) $ (95 ) DUKE ENERGY PROGRESS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 1,449 $ 1,193 $ 1,488 $ 1,160 $ 5,290 Operating income 316 184 394 130 1,024 Net income 183 85 229 69 566 2014 Operating revenues $ 1,422 $ 1,191 $ 1,367 $ 1,196 $ 5,176 Operating income 258 212 285 180 935 Net income 133 101 157 76 467 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (5 ) $ (5 ) $ (6 ) $ (6 ) $ (22 ) Ash Basin Settlement and Penalties (see Note 5) — — (6 ) — (6 ) Cost Savings Initiatives (see Note 19) — — — (28 ) (28 ) Total $ (5 ) $ (5 ) $ (12 ) $ (34 ) $ (56 ) 2014 Costs to Achieve, Mergers $ (14 ) $ (3 ) $ (15 ) $ (10 ) $ (42 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (30 ) (30 ) Total $ (14 ) $ (3 ) $ (15 ) $ (40 ) $ (72 ) DUKE ENERGY FLORIDA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 1,086 $ 1,281 $ 1,436 $ 1,174 $ 4,977 Operating income 227 315 357 216 1,115 Net income 113 165 216 105 599 2014 Operating revenues $ 1,116 $ 1,225 $ 1,491 $ 1,143 $ 4,975 Operating income 219 276 378 205 1,078 Net income 108 142 205 93 548 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (3 ) $ (3 ) $ (3 ) $ (4 ) $ (13 ) Cost Savings Initiatives (see Note 19) — — — (8 ) (8 ) Total $ (3 ) $ (3 ) $ (3 ) $ (12 ) $ (21 ) 2014 Costs to Achieve, Mergers $ (5 ) $ (9 ) $ (6 ) $ (3 ) $ (23 ) DUKE ENERGY OHIO First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 586 $ 405 $ 462 $ 452 $ 1,905 Operating income 111 43 76 73 303 Income (loss) from discontinued operations, net of tax 90 (65 ) (2 ) — 23 Net income (loss) 149 (52 ) 32 43 172 2014 Operating revenues $ 575 $ 412 $ 446 $ 480 $ 1,913 Operating (loss) income (7 ) 60 58 76 187 (Loss) Income from discontinued operations, net of tax (875 ) (135 ) 413 34 (563 ) Net (loss) income (890 ) (107 ) 439 63 (495 ) The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (1 ) $ (1 ) $ (1 ) $ (1 ) $ (4 ) Cost Savings Initiatives (see Note 19) — — — (2 ) (2 ) Total $ (1 ) $ (1 ) $ (1 ) $ (3 ) $ (6 ) 2014 Costs to Achieve, Mergers $ (2 ) $ (4 ) $ (3 ) $ (2 ) $ (11 ) Midwest Generation Impairment (1,318 ) — 477 (39 ) (880 ) Asset Impairment (94 ) — — — (94 ) Total $ (1,414 ) $ (4 ) $ 474 $ (41 ) $ (985 ) DUKE ENERGY INDIANA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 788 $ 686 $ 749 $ 667 $ 2,890 Operating income 210 146 117 171 644 Net income 108 68 46 94 316 2014 Operating revenues $ 845 $ 748 $ 790 $ 792 $ 3,175 Operating income 215 178 182 130 705 Net income 113 87 101 58 359 The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (2 ) $ (1 ) $ (2 ) $ (2 ) $ (7 ) Edwardsport Settlement (see Note 4) — — (90 ) (3 ) (93 ) Cost Savings Initiatives (see Note 19) — — — (6 ) (6 ) Total $ (2 ) $ (1 ) $ (92 ) $ (11 ) $ (106 ) 2014 Costs to Achieve, Mergers $ (2 ) $ (5 ) $ (3 ) $ (2 ) $ (12 )

Summary of Significant Accoun34

Summary of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2015
Policy Text Block [Line Items]
Nature of Operations and Basis of Consolidation	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.) and Latin America primarily through its direct and indirect subsidiaries. Duke Energy’s subsidiaries include its subsidiary registrants, Duke Energy Carolinas, LLC (Duke Energy Carolinas); Progress Energy, Inc. (Progress Energy); Duke Energy Progress, LLC (formerly Duke Energy Progress, Inc.) (Duke Energy Progress); Duke Energy Florida, LLC (formerly Duke Energy Florida, Inc.) (Duke Energy Florida); Duke Energy Ohio, Inc. (Duke Energy Ohio) and Duke Energy Indiana, Inc. (subsequently Duke Energy Indiana, LLC) (Duke Energy Indiana). When discussing Duke Energy’s consolidated financial information, it necessarily includes the results of its six separate subsidiary registrants (collectively referred to as the Subsidiary Registrants), which, along with Duke Energy, are collectively referred to as the Duke Energy Registrants (Duke Energy Registrants). The information in these combined notes relate to each of the Duke Energy Registrants as noted in the Index to the Combined Notes to Consolidated Financial Statements. However, none of the registrants makes any representations as to information related solely to Duke Energy or the subsidiaries of Duke Energy other than itself. These Consolidated Financial Statements include, after eliminating intercompany transactions and balances, the accounts of the Duke Energy Registrants and subsidiaries where the respective Duke Energy Registrants have control. These Consolidated Financial Statements also reflect the Duke Energy Registrants’ proportionate share of certain jointly owned generation and transmission facilities. 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. Substantially all of Duke Energy Carolinas’ operations qualify for regulatory accounting. Progress Energy is a public utility holding company headquartered in Raleigh, North Carolina, subject to regulation by the FERC. Progress Energy conducts operations through its wholly owned subsidiaries, Duke Energy Progress and Duke Energy Florida. Substantially all of Progress Energy’s operations qualify for regulatory accounting. 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. Substantially all of Duke Energy Progress’ operations qualify for regulatory accounting. On August 1, 2015, Duke Energy Progress, a North Carolina corporation, converted into a North Carolina limited liability company. 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. Substantially all of Duke Energy Florida’s operations qualify for regulatory accounting. On August 1, 2015, Duke Energy Florida, a Florida corporation, converted into a Florida limited liability company. 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 also conducts competitive auctions for retail electricity supply in Ohio whereby recovery of the energy price is from retail customers and recorded in Operating Revenues on the Consolidated Statements of Operations and Comprehensive Income. Operations in Kentucky are conducted through its wholly owned subsidiary, Duke Energy Kentucky, Inc. (Duke Energy Kentucky). References herein to Duke Energy Ohio 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. On April 2, 2015, Duke Energy completed the sale of its nonregulated Midwest generation business, which sold power into wholesale energy markets, to a subsidiary of Dynegy Inc. (Dynegy). For further information about the sale of the Midwest Generation business, refer to Note 2 "Acquisitions and Dispositions." Substantially all of Duke Energy Ohio's operations that remain after the sale qualify for regulatory accounting. 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. Substantially all of Duke Energy Indiana’s operations qualify for regulatory accounting. On January 1, 2016, Duke Energy Indiana, an Indiana corporation, converted into an Indiana limited liability company. Certain prior year amounts have been reclassified to conform to the current year presentation.
Use of Estimates	Use of Estimates In preparing financial statements that conform to generally accepted accounting principles (GAAP) in the U.S., the Duke Energy Registrants must make estimates and assumptions that affect the reported amounts of assets and liabilities, the reported amounts of revenues and expenses and the disclosure of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates.
Regulatory Accounting	Regulatory Accounting The majority of the Duke Energy Registrants’ operations are subject to price regulation for the sale of electricity and gas by state utility commissions or FERC. When prices are set on the basis of specific costs of the regulated operations and an effective franchise is in place such that sufficient gas or electric services can be sold to recover those costs, the Duke Energy Registrants apply regulatory accounting. Regulatory accounting changes the timing of the recognition of costs or revenues relative to a company that does not apply regulatory accounting. As a result, Regulatory assets and Regulatory liabilities are recognized on the Consolidated Balance Sheets. Regulatory assets and liabilities are amortized consistent with the treatment of the related cost in the ratemaking process. See Note 4 for further information. Regulatory accounting rules also require recognition of a disallowance (also called "impairment") loss if it becomes probable that part of the cost of a plant under construction (or a recently completed plant or an abandoned plant) will be disallowed for ratemaking purposes and a reasonable estimate of the amount of the disallowance can be made. Other disallowances can require judgments on allowed future rate recovery. When it becomes probable that regulated generation, transmission or distribution assets will be abandoned, the cost of the asset is removed from plant in service. The value that may be retained as a regulatory asset on the balance sheet for the abandoned property is dependent upon amounts that may be recovered through regulated rates, including any return. As such, an impairment charge could be offset by the establishment of a regulatory asset if rate recovery is probable. The impairment for a disallowance of costs for regulated plants under construction, recently completed or abandoned is based on discounted cash flows.
Regulated Fuel Costs and Purchased Power	Regulated Fuel Costs and Purchased Power The Duke Energy Registrants utilize cost-tracking mechanisms, commonly referred to as fuel adjustment clauses. These clauses allow for the recovery of fuel and fuel-related costs and portions of purchased power costs through surcharges on customer rates. The difference between the costs incurred and the surcharge revenues is recorded either as an adjustment to Operating Revenues – Regulated electric or Operating Expenses – Fuel used in electric generation on the Consolidated Statements of Operations with an off-setting impact on regulatory assets or liabilities.
Cash and Cash Equivalents	Cash and Cash Equivalents All highly liquid investments with maturities of three months or less at the date of acquisition are considered cash equivalents. At December 31, 2015 , $534 million of Duke Energy’s total cash and cash equivalents is held by entities domiciled in foreign jurisdictions. During the fourth quarter of 2014, Duke Energy declared a taxable dividend of historical foreign earnings in the form of notes payable that will result in the repatriation of approximately $2.7 billion in cash held and expected to be generated by International Energy over a period of up to eight years . Approximately $1.5 billion was remitted in 2015. See Note 22 to the Consolidated Financial Statements, “Income Taxes,” for additional information.
Restricted Cash	Restricted Cash The Duke Energy Registrants have restricted cash related primarily to collateral assets, escrow deposits and variable interest entities (VIEs). Restricted cash balances are reflected in Other within Current Assets and in Other within Investments and Other Assets on the Consolidated Balance Sheets. At December 31, 2015 and 2014 , Duke Energy had restricted cash totaling $108 million and $298 million , respectively.
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. Reserves are established for excess and obsolete inventory. Inventory reserves were not material at December 31, 2015 and 2014. The components of inventory are presented in the tables below.
Investments in Debt and Equity Securities	Investments in Debt and Equity Securities The Duke Energy Registrants classify investments into two categories – trading and available-for-sale. Both categories are recorded at fair value on the Consolidated Balance Sheets. Realized and unrealized gains and losses on trading securities are included in earnings. For certain investments of regulated operations such as the Nuclear Decommissioning Trust Fund (NDTF), realized and unrealized gains and losses (including any other-than-temporary impairments) on available-for-sale securities are recorded as a regulatory asset or liability. Otherwise, unrealized gains and losses are included in Accumulated Other Comprehensive Income (AOCI), unless other-than-temporarily impaired. Other-than-temporary impairments for equity securities and the credit loss portion of debt securities of nonregulated operations are included in earnings. Investments in debt and equity securities are classified as either current or noncurrent based on management’s intent and ability to sell these securities, taking into consideration current market liquidity. See Note 15 for further information.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill Duke Energy, Progress Energy and Duke Energy Ohio perform annual goodwill impairment tests as of August 31 each year at the reporting unit level, which is determined to be an operating segment or one level below. Duke Energy, Progress Energy and Duke Energy Ohio update these tests between annual tests if events or circumstances occur that would more likely than not reduce the fair value of a reporting unit below its carrying value. Intangible Assets Intangible assets are included in Other in Investments and Other Assets on the Consolidated Balance Sheets. Generally, intangible assets are amortized using an amortization method that reflects the pattern in which the economic benefits of the intangible asset are consumed, or on a straight-line basis if that pattern is not readily determinable. Amortization of intangibles is reflected in Depreciation and amortization on the Consolidated Statements of Operations. Intangible assets are subject to impairment testing and if impaired, the carrying value is accordingly reduced. Emission allowances permit the holder of the allowance to emit certain gaseous byproducts of fossil fuel combustion, including sulfur dioxide (SO 2 ) and nitrogen oxide (NO X ). Allowances are issued by the U.S. Environmental Protection Agency (EPA) at zero cost and may also be bought and sold via third-party transactions. Allowances allocated to or acquired by the Duke Energy Registrants are held primarily for consumption. Carrying amounts for emission allowances are based on the cost to acquire the allowances or, in the case of a business combination, on the fair value assigned in the allocation of the purchase price of the acquired business. Emission allowances are expensed to Fuel used in electric generation and purchased power – regulated on the Consolidated Statements of Operations. Renewable energy certificates are used to measure compliance with renewable energy standards and are held primarily for consumption. See Note 11 for further information.
Long-Lived Asset Impairments	Long-Lived Asset Impairments The Duke Energy Registrants evaluate long-lived assets, excluding goodwill, for impairment when circumstances indicate the carrying value of those assets may not be recoverable. An impairment exists when a long-lived asset’s carrying value exceeds the estimated undiscounted cash flows expected to result from the use and eventual disposition of the asset. The estimated cash flows may be based on alternative expected outcomes that are probability weighted. If the carrying value of the long-lived asset is not recoverable based on these estimated future undiscounted cash flows, the carrying value of the asset is written-down to its then-current estimated fair value and an impairment charge is recognized. The Duke Energy Registrants assess fair value of long-lived assets using various methods, including recent comparable third-party sales, internally developed discounted cash flow analysis and analysis from outside advisers. Significant changes in commodity prices, the condition of an asset or management’s interest in selling the asset are generally viewed as triggering events to reassess cash flows.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at the lower of depreciated historical cost net of any disallowances or fair value, if impaired. The Duke Energy Registrants capitalize all construction-related direct labor and material costs, as well as indirect construction costs such as general engineering, taxes and financing costs. See “Allowance for Funds Used During Construction (AFUDC) and Interest Capitalized” for information on capitalized financing costs. Costs of renewals and betterments that extend the useful life of property, plant and equipment are also capitalized. The cost of repairs, replacements and major maintenance projects, which do not extend the useful life or increase the expected output of the asset, are expensed as incurred. Depreciation is generally computed over the estimated useful life of the asset using the composite straight-line method. Depreciation studies are conducted periodically to update composite rates and are approved by state utility commissions and/or the FERC when required. The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows. In general, when the Duke Energy Registrants retire regulated property, plant and equipment, original cost plus the cost of retirement, less salvage value, is charged to accumulated depreciation. However, when it becomes probable a regulated asset will be retired substantially in advance of its original expected useful life or is abandoned, the cost of the asset and the corresponding accumulated depreciation is recognized as a separate asset. If the asset is still in operation, the net amount is classified as Generation facilities to be retired, net on the Consolidated Balance Sheets. If the asset is no longer operating, the net amount is classified in Regulatory Assets on the Consolidated Balance Sheets. The carrying value of the asset is based on historical cost if the Duke Energy Registrants are allowed to recover the remaining net book value and a return equal to at least the incremental borrowing rate. If not, an impairment is recognized to the extent the net book value of the asset exceeds the present value of future revenues discounted at the incremental borrowing rate. When the Duke Energy Registrants sell entire regulated operating units, or retire or sell nonregulated properties, the original cost and accumulated depreciation and amortization balances are removed from Property, Plant and Equipment on the Consolidated Balance Sheets. Any gain or loss is recorded in earnings, unless otherwise required by the applicable regulatory body. See Note 10 for further information.
Nuclear Fuel	Nuclear Fuel Nuclear fuel is classified as Property, Plant and Equipment on the Consolidated Balance Sheets, except for Duke Energy Florida. Refer to Note 4, “Regulatory Matters,” for additional information on Crystal River Unit 3 investments, including nuclear fuel. Nuclear fuel in the front-end fuel processing phase is considered work in progress and not amortized until placed in service. Amortization of nuclear fuel is included within Fuel used in electric generation and purchased power – regulated in the Consolidated Statements of Operations. Amortization is recorded using the units-of-production method.
Allowance for Funds Used During Construction (AFUDC) and Interest Capitalized	Allowance for Funds Used During Construction and Interest Capitalized For regulated operations, the debt and equity costs of financing the construction of property, plant and equipment are reflected as AFUDC and capitalized as a component of the cost of property, plant and equipment. AFUDC equity is reported on the Consolidated Statements of Operations as non-cash income in Other income and expenses, net. AFUDC debt is reported as a non-cash offset to Interest Expense. After construction is completed, the Duke Energy Registrants are permitted to recover these costs through their inclusion in rate base and the corresponding subsequent depreciation or amortization of those regulated assets. AFUDC equity, a permanent difference for income taxes, reduces the effective tax rate when capitalized and increases the effective tax rate when depreciated or amortized. See Note 22 for additional information. For nonregulated operations, interest is capitalized during the construction phase with an offsetting non-cash credit to Interest Expense on the Consolidated Statements of Operations.
Asset Retirement Obligations	Asset Retirement Obligations Asset retirement obligations are recognized for legal obligations associated with the retirement of property, plant and equipment. Substantially all asset retirement obligations are related to regulated operations. When recording an asset retirement obligation, the present value of the projected liability is recognized in the period in which it is incurred, if a reasonable estimate of fair value can be made. The liability is accreted over time. For operating plants, the present value of the liability is added to the cost of the associated asset and depreciated over the remaining life of the asset. For retired plants, the present value of the liability is recorded as a regulatory asset. The present value of the initial obligation and subsequent updates are based on discounted cash flows, which include estimates regarding timing of future cash flows, selection of discount rates and cost escalation rates, among other factors. These estimates are subject to change. Depreciation expense is adjusted prospectively for any changes to the carrying amount of the associated asset. The Duke Energy Registrants receive amounts to fund the cost of the asset retirement obligation for regulated operations through a combination of regulated revenues and earnings on the NDTF. As a result, amounts recovered in regulated revenues, earnings on the NDTF, accretion expense and depreciation of the associated asset are all deferred as a regulatory asset or liability. Obligations for nuclear decommissioning are based on-site-specific cost studies. Duke Energy Carolinas and Duke Energy Progress assume prompt dismantlement of the nuclear facilities after operations are ceased. Duke Energy Florida assumes Crystal River Unit 3 will be placed into a safe storage configuration until eventual dismantlement is completed by 2074. Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida also assume that spent fuel will be stored on-site until such time that it can be transferred to a U.S. Department of Energy (DOE) facility. Obligations for closure of ash basins are based upon discounted cash flows of estimated costs for site specific plans, if known, or probability weightings of the potential closure methods if the closure plans are under development and multiple closure options are being considered and evaluated on a site-by-site basis. See Note 9 for additional information
Revenue Recognition and Unbilled Revenue	Revenue Recognition and Unbilled Revenue Revenues on sales of electricity and 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 delivered but not yet billed. Unbilled revenues can vary significantly from period to period as a result of seasonality, weather, customer usage patterns, customer mix, average price in effect for customer classes, timing of rendering customer bills and meter reading schedules. Unbilled revenues are included within Receivables and Restricted receivables of variable interest entities on the Consolidated Balance Sheets
Derivatives and Hedging	Derivatives and Hedging Derivative and non-derivative instruments may be used in connection with commodity price, interest rate and foreign currency risk management activities, including swaps, futures, forwards and options. All derivative instruments, except those that qualify for the normal purchase/normal sale (NPNS) exception, are recorded on the Consolidated Balance Sheets at fair value. Qualifying derivative instruments may be designated as either cash flow hedges or fair value hedges. Other derivative instruments (undesignated contracts) either have not been designated or do not qualify as hedges. The effective portion of the change in the fair value of cash flow hedges is recorded in AOCI. The effective portion of the change in the fair value of a fair value hedge is offset in net income by changes in the hedged item. For activity subject to regulatory accounting, gains and losses on derivative contracts are reflected as regulatory assets or liabilities and not as other comprehensive income or current period income. As a result, changes in fair value of these derivatives have no immediate earnings impact. Formal documentation, including transaction type and risk management strategy, is maintained for all contracts accounted for as a hedge. At inception and at least every three months thereafter, the hedge contract is assessed to see if it is highly effective in offsetting changes in cash flows or fair values of hedged items. See Note 14 for further information.
Captive Insurance Reserves	Captive Insurance Reserves Duke Energy has captive insurance subsidiaries that provide coverage, on an indemnity basis, to the Subsidiary Registrants as well as certain third parties, on a limited basis, for various business risks and losses, such as property, workers’ compensation and general liability. Liabilities include provisions for estimated losses incurred but not yet reported (IBNR), as well as estimated provisions for known claims. IBNR reserve estimates are primarily based upon historical loss experience, industry data and other actuarial assumptions. Reserve estimates are adjusted in future periods as actual losses differ from experience. Duke Energy, through its captive insurance entities, also has reinsurance coverage with third parties for certain losses above a per occurrence and/or aggregate retention. Receivables for reinsurance coverage are recognized when realization is deemed probable.
Unamortized Debt Premium, Discount and Expense	Unamortized Debt Premium, Discount and Expense Premiums, discounts and expenses incurred with the issuance of outstanding long-term debt are amortized over the term of the debt issue. Call premiums and unamortized expenses associated with refinancing higher-cost debt obligations in the regulated operations are amortized. Amortization expense is recorded as Interest Expense in the Consolidated Statements of Operations and is reflected as Depreciation, amortization and accretion within Net cash provided by operating activities on the Consolidated Statements of Cash Flows. During 2015, Duke Energy retrospectively adopted revised accounting guidance related to the presentation of debt issuance costs. Unamortized debt issuance cost are presented as a reduction of the debt amount and included in Long-Term Debt on the Consolidated Balance Sheets presented. See discussion of New Accounting Standards below for further information.
Loss Contingencies and Environmental Liabilities	Loss Contingencies and Environmental Liabilities Contingent losses are recorded when it is probable a loss has occurred and can be reasonably estimated. When a range of the probable loss exists and no amount within the range is a better estimate than any other amount, the minimum amount in the range is recorded. Unless otherwise required by GAAP, legal fees are expensed as incurred. Environmental liabilities are recorded on an undiscounted basis when environmental remediation or other liabilities become probable and can be reasonably estimated. Environmental expenditures related to past operations that do not generate current or future revenues are expensed. Environmental expenditures related to operations that generate current or future revenues are expensed or capitalized, as appropriate. Certain environmental expenditures receive regulatory accounting treatment and are recorded as regulatory assets. See Notes 4 and 5 for further information.
Pension and Other Post-Retirement Benefit Plans	Pension and Other Post-Retirement Benefit Plans Duke Energy maintains qualified, non-qualified and other post-retirement benefit plans. Eligible employees of the Subsidiary Registrants participate in the respective qualified, non-qualified and other post-retirement benefit plans and the Subsidiary Registrants are allocated their proportionate share of benefit costs. See Note 21 for further information, including significant accounting policies associated with these plans.
Severance and Special Termination Benefits	Severance and Special Termination Benefits Duke Energy has a severance plan under which, in general, the longer a terminated employee worked prior to termination the greater the amount of severance benefits. A liability for involuntary severance is recorded once an involuntary severance plan is committed to by management if involuntary severances are probable and can be reasonably estimated. For involuntary severance benefits incremental to its ongoing severance plan benefits, the fair value of the obligation is expensed at the communication date if there are no future service requirements, or over the required future service period. From time to time, Duke Energy offers special termination benefits under voluntary severance programs. Special termination benefits are recorded immediately upon employee acceptance absent a significant retention period. Otherwise, the cost is recorded over the remaining service period. Employee acceptance of voluntary severance benefits is determined by management based on the facts and circumstances of the benefits being offered. See Note 19 for further information.
Guarantees	Guarantees Liabilities are recognized at the time of issuance or material modification of a guarantee for the estimated fair value of the obligation it assumes. Fair value is estimated using a probability-weighted approach. The obligation is reduced over the term of the guarantee or related contract in a systematic and rational method as risk is reduced. Any additional contingent loss for guarantee contracts subsequent to the initial recognition of a liability is accounted for and recognized at the time a loss is probable and can be reasonably estimated. See Note 7 for further information.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation represents costs related to stock-based awards granted to employees and Duke Energy Board of Directors (Board of Directors) members. Duke Energy recognizes stock-based compensation based upon the estimated fair value of awards, net of estimated forfeitures at the date of issuance. The recognition period for these costs begins at either the applicable service inception date or grant date and continues throughout the requisite service period, or, for certain share-based awards, until the employee becomes retirement eligible, if earlier. Compensation cost is recognized as expense or capitalized as a component of property, plant and equipment. See Note 20 for further information.
Income Taxes	Income Taxes Duke Energy and its subsidiaries file a consolidated federal income tax return and other state and foreign jurisdictional returns. The Subsidiary Registrants entered into a tax-sharing agreement with Duke Energy. Income taxes recorded represent amounts the Subsidiary Registrants would incur as separate C-Corporations. Deferred income taxes have been provided for temporary differences between GAAP and tax bases of assets and liabilities because the differences create taxable or tax-deductible amounts for future periods. Deferred taxes are not provided on translation gains and losses when earnings of a foreign operation are expected to be indefinitely reinvested. Investment tax credits (ITC) associated with regulated operations are deferred and amortized as a reduction of income tax expense over the estimated useful lives of the related properties. Positions taken or expected to be taken on tax returns, including the decision to exclude certain income or transactions from a return, are recognized in the financial statements when it is more likely than not the tax position can be sustained based solely on the technical merits of the position. The largest amount of tax benefit that is greater than 50 percent likely of being effectively settled is recorded. Management considers a tax position effectively settled when: (i) the taxing authority has completed its examination procedures, including all appeals and administrative reviews; (ii) the Duke Energy Registrants do not intend to appeal or litigate the tax position included in the completed examination; and (iii) it is remote the taxing authority would examine or re-examine the tax position. The amount of a tax return position that is not recognized in the financial statements is disclosed as an unrecognized tax benefit. If these unrecognized tax benefits are later recognized, then there will be a decrease in income taxes payable, an income tax refund or a reclassification between deferred and current taxes payable. If the portion of tax benefits that has been recognized changes and those tax benefits are subsequently unrecognized, then the previously recognized tax benefits may impact the financial statements through increasing income taxes payable, reducing income tax refunds receivable or changing deferred taxes. Changes in assumptions on tax benefits may also impact interest expense or interest income and may result in the recognition of tax penalties. Tax-related interest and penalties are recorded in Interest Expense and Other Income and Expenses, net, in the Consolidated Statements of Operations. See Note 22 for further information.
Accounting for Renewable Energy Tax Credits and Cash Grants	Accounting for Renewable Energy Tax Credits and Cash Grants When Duke Energy receives ITC or cash grants on wind or solar facilities, it reduces the basis of the property recorded on the Consolidated Balance Sheets by the amount of the ITC or cash grant and, therefore, the ITC or grant benefit is recognized through reduced depreciation expense. Additionally, certain tax credits and government grants result in an initial tax depreciable base in excess of the book carrying value by an amount equal to one half of the ITC or government grant. Deferred tax benefits are recorded as a reduction to income tax expense in the period that the basis difference is created.
Excise Taxes	Excise Taxes Certain excise taxes levied by state or local governments are required to be paid even if not collected from the customer. These taxes are recognized on a gross basis. Otherwise, the taxes are accounted for net. Excise taxes accounted for on a gross basis as both operating revenues and property and other taxes in the Consolidated Statements of Operations were as follows.
Foreign Currency Transaction	Foreign Currency Translation The local currencies of most of Duke Energy’s foreign operations have been determined to be their functional currencies. However, certain foreign operations’ functional currency has been determined to be the U.S. dollar, based on an assessment of the economic circumstances of the foreign operation . Assets and liabilities of foreign operations whose functional currency is not the U.S. dollar are translated into U.S. dollars at the exchange rates in effect at period end. Translation adjustments resulting from changes in exchange rates are included in AOCI. Revenue and expense accounts are translated at average exchange rates during the year. Remeasurement gains and losses arising from balances and transactions denominated in currencies other than the local currency are included in the results of operations when they occur.
Dividend Restrictions and Unappropriated Retained Earnings	Dividend Restrictions and Unappropriated Retained Earnings Duke Energy does not have any legal, regulatory or other restrictions on paying common stock dividends to shareholders. However, as further described in Note 4 , due to conditions established by regulators in conjunction with merger transaction approvals, Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio and Duke Energy Indiana have restrictions on paying dividends or otherwise advancing funds to Duke Energy. At December 31, 2015 and 2014 , an insignificant amount of Duke Energy’s consolidated Retained earnings balance represents undistributed earnings of equity method investments.
New Accounting Standards	New Accounting Standards The new accounting standards that were adopted for 2015 , 2014 and 2013 had no material impact on the presentation or results of operations, cash flows or financial position of the Duke Energy Registrants. The following accounting standards were adopted by the Duke Energy Registrants during 2015. Reporting Discontinued Operations. In April 2014, the Financial Accounting Standards Board (FASB) issued revised accounting guidance for reporting discontinued operations. A discontinued operation would be either (i) a component of an entity or a group of components of an entity that represents a separate major line of business or major geographical area of operations that either has been disposed of or is part of a single coordinated plan to be classified as held for sale or (ii) a business that, upon acquisition, meets the criteria to be classified as held for sale. For Duke Energy, the revised accounting guidance is effective on a prospective basis for qualified disposals of components or classifications as held for sale that occurred after January 1, 2015. Under the standard, the guidance is not effective for a component classified as held for sale before the effective date even if the disposal occurs after the effective date of the guidance. Duke Energy has not reported any discontinued operations under the revised accounting guidance. Balance Sheet Classification of Deferred Taxes. In November 2015, the FASB issued revised accounting guidance for the Balance Sheet classification of deferred taxes. The core principle of this revised accounting guidance is that all deferred tax assets and liabilities should be classified as noncurrent. For Duke Energy, this revised accounting guidance was adopted prospectively for December 31, 2015. The Balance Sheet as of December 31, 2014, does not reflect this reclassification of current deferred tax assets and liabilities. See Note 22 for further information on the impact from adoption of this accounting standard. Balance Sheet Presentation of Debt Issuance Costs. In April and August 2015, the FASB issued revised accounting guidance for the presentation of debt issuance costs. The core principle of this revised accounting guidance is that debt issuance costs are not assets, but adjustments to the carrying cost of debt. For Duke Energy, this revised accounting guidance was adopted retrospectively to December 31, 2014. The implementation of this accounting standard resulted in a reduction of Other within Regulatory Assets and Deferred Debits and in Long-Term Debt of $170 million and $152 million on the Consolidated Balance Sheets as of December 31, 2015 and 2014, respectively. Fair Value Disclosures for Certain Investments. In May 2015, the FASB issued revised accounting guidance for investments in certain entities that use net asset value per share (or its equivalent) as a ‘practical expedient’ to determine fair value. The core principle of this revised accounting guidance is that the valuation of investments using the ‘practical expedient’ should not be categorized within the fair value hierarchy (i.e., as Level 1, 2 or 3). The ‘practical expedient’ applies to investments in investment companies for which there is not a readily determinable fair value (market quote) or the investment is not in a mutual fund with a publicly available net asset value. For Duke Energy, this revised accounting guidance was adopted retrospectively. The implementation of this guidance is reflected in Note 16 : Fair Value Measurements and Note 21 : Employee Benefit Plans. The following new accounting standards have been issued, but have not yet been adopted by the Duke Energy Registrants, as of December 31, 2015 . 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. For the Duke Energy Registrants, this guidance is effective for interim and annual periods beginning January 1, 2018, although it can be early adopted for annual periods beginning as early as January 1, 2017. The guidance can be applied retroactively to all prior reporting periods presented or retrospectively with a cumulative effect as of the initial date of application. Duke Energy is currently evaluating the requirements. The ultimate impact of the new standard has not yet been determined. 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 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 to the balance sheet as of January 1, 2018. This guidance is expected to have minimal impact on Duke Energy’s Statement of Comprehensive Income as changes in the fair value of most of Duke Energy's available-for-sale equity securities are deferred as regulatory assets or liabilities.
Duke Energy Ohio [Member]
Policy Text Block [Line Items]
Revenue Recognition and Unbilled Revenue	Additionally, Duke Energy Ohio and Duke Energy Indiana sell, on a revolving basis, nearly all of their retail accounts receivable, including receivables for unbilled revenues, to an affiliate, Cinergy Receivables Company, LLC (CRC) and account for the transfers of receivables as sales. Accordingly, the receivables sold are not reflected on the Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana. See Note 17 for further information.
Duke Energy Indiana [Member]
Policy Text Block [Line Items]
Revenue Recognition and Unbilled Revenue	Additionally, Duke Energy Ohio and Duke Energy Indiana sell, on a revolving basis, nearly all of their retail accounts receivable, including receivables for unbilled revenues, to an affiliate, Cinergy Receivables Company, LLC (CRC) and account for the transfers of receivables as sales. Accordingly, the receivables sold are not reflected on the Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana. See Note 17 for further information.

Summary of Significant Accoun35

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Organization And Basis Of Presentation [Line Items]
Schedule of Current and Noncurrent Assets and Liabilities	The following table provides detail of amounts included in Other within Current Assets or Current Liabilities on the Consolidated Balance Sheets. December 31, (in millions) Location 2015 2014 Duke Energy Accrued compensation Current Liabilities $ 621 $ 638 Duke Energy Carolinas Accrued compensation Current Liabilities $ 213 $ 216 Collateral liabilities Current Liabilities 141 128 Progress Energy Income taxes receivable Current Assets $ 129 $ 718 Customer deposits Current Liabilities 373 360 Derivative liabilities Current Liabilities 201 271 Duke Energy Progress Income taxes receivable Current Assets $ 111 $ 272 Customer deposits Current Liabilities 141 135 Accrued compensation Current Liabilities 108 116 Derivative liabilities Current Liabilities 76 108 Duke Energy Florida Income taxes receivable Current Assets $ — $ 177 Customer deposits Current Liabilities 232 225 Derivative liabilities Current Liabilities 125 163 Duke Energy Ohio Income taxes receivable Current Assets $ 59 $ 40 Other receivable Current Assets 33 39 Accrued litigation reserve Current Liabilities 80 — Collateral Liabilities Current Liabilities 48 $ 42 Duke Energy Indiana Income taxes receivable Current Assets $ — $ 98 Collateral liabilities Current Liabilities 44 43
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 for the years ended December 31, 2014 and 2013. Years ended December 31, 2014 2013 Duke Progress Duke Progress (in millions) Energy Energy Energy Energy Income from Continuing Operations $ 2,465 $ 880 2,590 659 Income from Continuing Operations Attributable to Noncontrolling Interests 14 5 16 3 Income from Continuing Operations Attributable to Duke Energy Corporation $ 2,451 $ 875 $ 2,574 $ 656 (Loss) Income From Discontinued Operations, net of tax $ (576 ) $ (6 ) 86 16 Loss from Discontinued Operations Attributable to Noncontrolling Interests, net of tax (8 ) — (5 ) — (Loss) Income From Discontinued Operations Attributable to Duke Energy Corporation, net of tax $ (568 ) $ (6 ) $ 91 $ 16 Net Income $ 1,889 $ 874 $ 2,676 $ 675 Net Income Attributable to Noncontrolling Interests 6 5 11 3 Net Income Attributable to Duke Energy Corporation $ 1,883 $ 869 $ 2,665 $ 672
Components Of Inventory	The components of inventory are presented in the tables below. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Materials and supplies $ 2,389 $ 785 $ 1,133 $ 776 $ 357 $ 81 $ 301 Coal held for electric generation 1,114 451 370 192 178 16 267 Oil, gas and other fuel held for electric generation 307 40 248 120 128 8 2 Total inventory $ 3,810 $ 1,276 $ 1,751 $ 1,088 $ 663 $ 105 $ 570 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Materials and supplies $ 2,102 $ 719 $ 981 $ 676 $ 305 $ 67 $ 258 Coal held for electric generation 997 362 329 150 178 21 275 Oil, gas and other fuel held for electric generation 360 43 280 140 140 9 4 Total inventory $ 3,459 $ 1,124 $ 1,590 $ 966 $ 623 $ 97 $ 537
Schedule Of Property, Plant And Equipment	The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows. Years Ended December 31, 2015 2014 2013 Duke Energy 2.9 % 2.8 % 2.8 % Duke Energy Carolinas 2.8 % 2.7 % 2.8 % Progress Energy 2.6 % 2.5 % 2.5 % Duke Energy Progress 2.6 % 2.5 % 2.5 % Duke Energy Florida 2.7 % 2.7 % 2.4 % Duke Energy Ohio 2.7 % 2.3 % 3.3 % Duke Energy Indiana 3.0 % 3.0 % 2.8 % The following tables summarize the property, plant and equipment for Duke Energy and its subsidiary registrants. December 31, 2015 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Land $ 1,466 $ 407 $ 719 $ 392 $ 327 $ 118 $ 108 Plant – Regulated Electric generation, distribution and transmission 8 - 100 87,593 33,623 36,422 22,888 13,534 4,429 13,118 Natural gas transmission and distribution 12 - 67 2,322 — — — — 2,322 — Other buildings and improvements 15 - 100 1,480 477 621 294 322 204 179 Plant – Nonregulated Electric generation, distribution and transmission 1 - 30 3,348 — — — — — — Other buildings and improvements 5 - 50 2,363 — — — — — — Nuclear fuel 3,194 1,827 1,367 1,367 — — — Equipment 3 - 38 1,791 368 530 398 132 344 173 Construction in process 4,525 1,860 1,827 1,118 709 180 214 Other 2 - 60 4,744 836 1,180 856 319 153 215 Total property, plant and equipment (a)(d) 112,826 39,398 42,666 27,313 15,343 7,750 14,007 Total accumulated depreciation – regulated (b)(c)(d) (35,367 ) (13,521 ) (14,867 ) (10,141 ) (4,720 ) (2,507 ) (4,484 ) Total accumulated depreciation – nonregulated (c)(d) (2,298 ) — — — — — — Generation facilities to be retired, net 548 — 548 548 — — — Total net property, plant and equipment $ 75,709 $ 25,877 $ 28,347 $ 17,720 $ 10,623 $ 5,243 $ 9,523 (a) Includes capitalized leases of $1,470 million , $40 million , $302 million , $144 million , $158 million , $96 million , and $39 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, and Duke Energy Indiana, respectively, primarily within Plant - Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $85 million , $7 million and $78 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,621 million , $976 million , $645 million and $645 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $58 million , $11 million , $27 million and $7 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $2,033 million and accumulated depreciation of consolidated VIEs of $327 million at Duke Energy. December 31, 2014 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Land $ 1,459 $ 403 $ 704 $ 380 $ 324 $ 114 $ 108 Plant – Regulated Electric generation, distribution and transmission 2 - 138 82,206 31,751 33,672 20,616 13,056 3,956 11,911 Natural gas transmission and distribution 12 - 67 2,230 — — — — 2,230 — Other buildings and improvements 9 - 100 1,445 465 607 286 318 200 173 Plant – Nonregulated Electric generation, distribution and transmission 1- 30 2,380 — — — — — — Other buildings and improvements 5 - 50 2,498 — — — — — — Nuclear fuel 2,865 1,676 1,190 1,190 — — — Equipment 3 - 34 1,762 341 506 388 118 330 166 Construction in process 4,519 2,081 1,215 908 307 97 481 Other 5 - 80 3,497 655 756 439 310 214 195 Total property, plant and equipment (a)(d) 104,861 37,372 38,650 24,207 14,433 7,141 13,034 Total accumulated depreciation – regulated (b)(c)(d) (32,628 ) (12,700 ) (13,506 ) (9,021 ) (4,478 ) (2,213 ) (4,219 ) Total accumulated depreciation – nonregulated (c)(d) (2,196 ) — — — — — — Generation facilities to be retired, net 9 — — — — 9 — Total net property, plant and equipment $ 70,046 $ 24,672 $ 25,144 $ 15,186 $ 9,955 $ 4,937 $ 8,815 (a) Includes capitalized leases of $1,548 million , $40 million , $315 million , $146 million , $169 million , $98 million , and $30 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, and Duke Energy Indiana, respectively, primarily in regulated plant. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $72 million , $5 million and $67 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,408 million , $847 million , $561 million and $561 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $52 million , $8 million , $25 million and $6 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $1,873 million and accumulated depreciation of consolidated VIEs of $257 million at Duke Energy.
Schedule of Allowance for Doubtful Accounts	Allowances for doubtful accounts are presented in the following table. December 31, (in millions) 2015 2014 2013 Allowance for Doubtful Accounts Duke Energy $ 18 17 30 Duke Energy Carolinas 3 3 3 Progress Energy 6 8 14 Duke Energy Progress 4 7 10 Duke Energy Florida 2 2 4 Duke Energy Ohio 2 2 2 Duke Energy Indiana 1 1 1 Allowance for Doubtful Accounts – VIEs Duke Energy $ 53 51 43 Duke Energy Carolinas 7 6 6 Progress Energy 8 8 — Duke Energy Progress 5 5 — Duke Energy Florida 3 3 —
Schedule of Excise Taxes	Excise taxes accounted for on a gross basis as both operating revenues and property and other taxes in the Consolidated Statements of Operations were as follows. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy $ 396 $ 498 $ 602 Duke Energy Carolinas 31 94 164 Progress Energy 229 263 304 Duke Energy Progress 16 56 115 Duke Energy Florida 213 207 189 Duke Energy Ohio 102 103 105 Duke Energy Indiana 34 38 29
Unbilled Revenues [Member]
Organization And Basis Of Presentation [Line Items]
Schedule Of Unbilled Revenues Within Receivables and Restricted Receivables	Unbilled revenues are included within Receivables and Restricted receivables of variable interest entities on the Consolidated Balance Sheets as shown in the following table. This table excludes amounts included in assets held for sale (AHFS) at December 31, 2014. December 31, (in millions) 2015 2014 Duke Energy $ 748 $ 827 Duke Energy Carolinas 283 295 Progress Energy 172 217 Duke Energy Progress 102 135 Duke Energy Florida 70 82 Duke Energy Ohio 3 — Duke Energy Indiana 31 27 Additionally, Duke Energy Ohio and Duke Energy Indiana sell, on a revolving basis, nearly all of their retail accounts receivable, including receivables for unbilled revenues, to an affiliate, Cinergy Receivables Company, LLC (CRC) and account for the transfers of receivables as sales. Accordingly, the receivables sold are not reflected on the Consolidated Balance Sheets of Duke Energy Ohio and Duke Energy Indiana. See Note 17 for further information. These receivables for unbilled revenues are shown in the table below. December 31, (in millions) 2015 2014 Duke Energy Ohio $ 71 $ 79 Duke Energy Indiana 97 112

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Schedule of purchase price allocation	The ownership interests in generating assets acquired are subject to rate-setting authority of the FERC, NCUC and PSCSC and accordingly, the assets are recorded at historical cost. The assets acquired are presented in the following table. (in millions) Inventory $ 56 Net property, plant and equipment 845 Total assets 901 Acquisition adjustment, recorded within property, plant and equipment 350 Total purchase price $ 1,251
Generation Facilities of Disposal Group	The following table presents information at the time of the sale related to the Duke Energy Ohio generation plants included in the Disposal Group. Total MW Owned MW Ownership Facility Plant Type Primary Fuel Location Capacity (d) Capacity (d) Interest Stuart (a)(c) Fossil Steam Coal OH 2,308 900 39 % Zimmer (a) Fossil Steam Coal OH 1,300 605 46.5 % Hanging Rock Combined Cycle Gas OH 1,226 1,226 100 % Miami Fort (Units 7 and 8) (b) Fossil Steam Coal OH 1,020 652 64 % Conesville (a)(c) Fossil Steam Coal OH 780 312 40 % Washington Combined Cycle Gas OH 617 617 100 % Fayette Combined Cycle Gas PA 614 614 100 % Killen (b)(c) Fossil Steam Coal OH 600 198 33 % Lee Combustion Turbine Gas IL 568 568 100 % Dick's Creek Combustion Turbine Gas OH 136 136 100 % Miami Fort Combustion Turbine Oil OH 56 56 100 % Total Midwest Generation 9,225 5,884 (a) Jointly owned with American Electric Power Generation Resources and The Dayton Power and Light Company. (b) Jointly owned with The Dayton Power and Light Company. (c) Not operated by Duke Energy Ohio. (d) Total MW capacity is based on summer capacity.
Income Statement Disclosures	The following table presents the results of discontinued operations. Duke Energy Years Ended December 31, (in millions) 2015 2014 2013 Operating Revenues $ 543 $ 1,748 $ 1,885 Loss on disposition (a) (45 ) (929 ) — Income (loss) before income taxes (b) $ 59 $ (818 ) $ 141 Income tax expense (benefit) 26 (294 ) 56 Income (loss) from discontinued operations of the Disposal Group 33 (524 ) 85 Other, net of tax (c) (13 ) (52 ) 1 Income (Loss) From Discontinued Operations, net of tax $ 20 $ (576 ) $ 86 (a) The Loss on disposition includes impairments recorded to adjust the carrying amount of the assets to the estimated fair value of the business, based on the selling price to Dynegy less cost to sell. (b) The Income (loss) before income taxes includes the pretax impact of an $81 million charge for the settlement agreement reached in a lawsuit related to the Disposal Group for the year ended December 31, 2015. Refer to Note 5 for further information related to the lawsuit. (c) Relates to discontinued operations of businesses not related to the Disposal Group. Amounts include indemnifications provided for certain legal, tax and environmental matters, and foreign currency translation adjustments. Duke Energy Ohio Years Ended December 31, (in millions) 2015 2014 2013 Operating Revenues $ 412 $ 1,299 $ 1,503 Loss on disposition (a) (52 ) (959 ) — Income (loss) before income taxes (b) $ 44 $ (863 ) $ 67 Income tax expense (benefit) 21 (300 ) 32 Income (Loss) From Discontinued Operations, net of tax $ 23 $ (563 ) $ 35 (a) The Loss on disposition includes impairments recorded to adjust the carrying amount of the assets to the estimated fair value of the business, based on the selling price to Dynegy less cost to sell. (b) The Income (loss) before income taxes includes the pretax impact of an $81 million charge for the settlement agreement reached in a lawsuit related to the Disposal Group for the year ended December 31, 2015, respectively. Refer to Note 5 for further information related to the lawsuit.

Business Segments (Tables)

Business Segments (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting Information [Line Items]
Business Segment Data	The following table summarizes the net loss for Other for each of these entities. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas $ (95 ) $ (79 ) $ (97 ) Progress Energy (159 ) (190 ) (241 ) Duke Energy Progress (32 ) (31 ) (46 ) Duke Energy Florida (16 ) (19 ) (24 ) Duke Energy Indiana (10 ) (11 ) (16 ) Year Ended December 31, 2015 Total Regulated International Commercial Reportable (in millions) Utilities Energy Portfolio Segments Other Eliminations Total Unaffiliated Revenues $ 22,024 $ 1,088 $ 301 $ 23,413 $ 46 $ — $ 23,459 Intersegment Revenues 38 — — 38 77 (115 ) — Total Revenues $ 22,062 $ 1,088 $ 301 $ 23,451 $ 123 $ (115 ) $ 23,459 Interest Expense $ 1,097 $ 85 $ 44 $ 1,226 $ 393 $ (6 ) $ 1,613 Depreciation and amortization 2,814 92 104 3,010 134 — 3,144 Equity in earnings of unconsolidated affiliates (4 ) 74 (3 ) 67 2 — 69 Income tax expense (benefit) 1,647 74 (92 ) 1,629 (303 ) — 1,326 Segment income (loss) (a)(b)(c)(d) 2,893 225 4 3,122 (322 ) (4 ) 2,796 Add back noncontrolling interest component 15 Income from discontinued operations, net of tax (e) 20 Net income $ 2,831 Capital investments expenditures and acquisitions $ 6,974 $ 45 $ 1,131 $ 8,150 $ 213 $ — $ 8,363 Segment Assets 111,562 3,271 4,010 118,843 2,125 188 121,156 (a) Regulated Utilities includes an after-tax charge of $58 million related to the Edwardsport settlement. Refer to Note 4 for further information. (b) Commercial Portfolio includes state tax expense of $41 million , resulting from changes to state apportionment factors due to the sale of the Disposal Group, that does not qualify for discontinued operations. Refer to Note 2 for further information related to the sale. (c) Other includes $60 million of after-tax costs to achieve mergers. (d) Other includes an after-tax charge of $77 million related to cost savings initiatives. Refer to Note 19 for further information related to the cost savings initiatives. (e) Includes after-tax impact of $53 million for the settlement agreement reached in a lawsuit related to the Disposal Group. Refer to Note 5 for further information related to the lawsuit. Year Ended December 31, 2014 Total Regulated International Commercial Reportable (in millions) Utilities Energy Portfolio Segments Other Eliminations Total Unaffiliated Revenues $ 22,228 $ 1,417 $ 255 $ 23,900 $ 25 $ — $ 23,925 Intersegment Revenues 43 — — 43 80 (123 ) — Total Revenues $ 22,271 $ 1,417 $ 255 $ 23,943 $ 105 $ (123 ) $ 23,925 Interest Expense $ 1,093 $ 93 $ 58 $ 1,244 $ 400 $ (22 ) $ 1,622 Depreciation and amortization 2,759 97 92 2,948 118 — 3,066 Equity in earnings of unconsolidated affiliates (3 ) 120 10 127 3 — 130 Income tax expense (benefit) (a) 1,628 449 (171 ) 1,906 (237 ) — 1,669 Segment income (loss) (b)(c)(d) 2,795 55 (55 ) 2,795 (334 ) (10 ) 2,451 Add back noncontrolling interest component 14 Loss from discontinued operations, net of tax (576 ) Net income $ 1,889 Capital investments expenditures and acquisitions $ 4,744 $ 67 $ 555 $ 5,366 $ 162 $ — $ 5,528 Segment Assets 106,574 5,093 6,278 117,945 2,423 189 120,557 (a) International Energy includes a tax adjustment of $373 million related to deferred tax impact resulting from the decision to repatriate all cumulative historical undistributed foreign earnings. See Note 22 for additional information. (b) Commercial Portfolio recorded a $94 million pretax impairment charge related to OVEC. (c) Other includes costs to achieve mergers. (d) Regulated Utilities includes an increase in the litigation reserve related to the criminal investigation of the Dan River coal ash spill. See Note 5 for additional information. Year Ended December 31, 2013 Total Regulated International Commercial Reportable (in millions) Utilities Energy Portfolio Segments Other Eliminations Total Unaffiliated Revenues (a)(b)(c) $ 20,871 $ 1,546 $ 254 $ 22,671 $ 85 $ — $ 22,756 Intersegment Revenues 39 — 6 45 90 (135 ) — Total Revenues $ 20,910 $ 1,546 $ 260 $ 22,716 $ 175 $ (135 ) $ 22,756 Interest Expense $ 986 $ 86 $ 61 $ 1,133 $ 416 $ (6 ) $ 1,543 Depreciation and amortization 2,323 100 110 2,533 135 — 2,668 Equity in earnings of unconsolidated affiliates (1 ) 110 7 116 6 — 122 Income tax expense (benefit) 1,522 166 (148 ) 1,540 (335 ) — 1,205 Segment income (loss) (a)(b)(c)(d)(e)(f)(g) 2,504 408 (88 ) 2,824 (238 ) (12 ) 2,574 Add back noncontrolling interest component 16 Income from discontinued operations, net of tax 86 Net income $ 2,676 Capital investments expenditures and acquisitions $ 5,049 $ 67 $ 268 $ 5,384 $ 223 $ — $ 5,607 Segment Assets 99,884 4,998 6,955 111,837 2,754 188 114,779 (a) In May 2013, the PUCO approved a Duke Energy Ohio settlement agreement that provides for a net annual increase in electric distribution revenues beginning in May 2013. This rate increase impacts Regulated Utilities. (b) In June 2013, NCUC approved a Duke Energy Progress settlement agreement that included an increase in rates in the first year beginning in June 2013. This rate increase impacts Regulated Utilities. (c) In September 2013, Duke Energy Carolinas implemented revised customer rates approved by the NCUC and the PSCSC. These rate increases impact Regulated Utilities. (d) Regulated Utilities recorded an impairment charge related to Duke Energy Florida's Crystal River Unit 3. See Note 4 for additional information. (e) Regulated Utilities recorded an impairment charge related to the letter Duke Energy Progress filed with the NRC requesting the NRC to suspend its review activities associated with the combined construction and operating license (COL) at the Harris site. Regulated Utilities also recorded an impairment charge related to the write-off of the wholesale portion of the Levy investments at Duke Energy Florida in accordance with the 2013 Settlement. See Note 4 for additional information. (f) Other includes costs to achieve mergers. (g) Other includes gain from the sale of Duke Energy's ownership interest in DukeNet. See Note 12 for additional information on the sale of DukeNet.
Schedule Of Revenue And Long-Lived Assets, By Geographical Area	Geographical Information (in millions) U.S. Latin America (a) Consolidated 2015 Consolidated revenues $ 22,371 $ 1,088 $ 23,459 Consolidated long-lived assets 87,552 2,012 89,564 2014 Consolidated revenues $ 22,508 $ 1,417 $ 23,925 Consolidated long-lived assets 80,709 2,458 83,167 2013 Consolidated revenues $ 21,211 $ 1,545 $ 22,756 Consolidated long-lived assets 78,581 2,781 81,362 (a) Change in amounts of long-lived assets in Latin America includes foreign currency translation adjustments on property, plant and equipment and other long-lived asset balances.
Schedule of Revenue, By Products and Services	Products and Services The following table summarizes revenues of the reportable segments by type. Retail Wholesale Retail Wholesale Total (in millions) Electric Electric Natural Gas Natural Gas Other Revenues 2015 Regulated Utilities $ 18,695 $ 2,014 $ 546 $ — $ 807 $ 22,062 International Energy — 1,025 — 63 — 1,088 Commercial Portfolio — 260 — — 41 301 Total Reportable Segments $ 18,695 $ 3,299 $ 546 $ 63 $ 848 $ 23,451 2014 Regulated Utilities $ 19,007 $ 1,879 $ 571 $ — $ 814 $ 22,271 International Energy — 1,326 — 91 — 1,417 Commercial Portfolio — 255 — — — 255 Total Reportable Segments $ 19,007 $ 3,460 $ 571 $ 91 $ 814 $ 23,943 2013 Regulated Utilities $ 17,837 $ 1,720 $ 506 $ — $ 847 $ 20,910 International Energy — 1,447 — 99 — 1,546 Commercial Portfolio — 260 — — — 260 Total Reportable Segments $ 17,837 $ 3,427 $ 506 $ 99 $ 847 $ 22,716
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Business Segment Data	Year Ended December 31, 2015 Total Regulated Commercial Reportable (in millions) Utilities Portfolio Segments Other Eliminations Total Unaffiliated revenues $ 1,872 $ 14 $ 1,886 $ 19 $ — $ 1,905 Intersegment revenues 1 — 1 — (1 ) — Total revenues $ 1,873 $ 14 $ 1,887 $ 19 $ (1 ) $ 1,905 Interest expense $ 78 $ — $ 78 $ 1 $ — $ 79 Depreciation and amortization 226 — 226 1 — 227 Income tax expense (benefit) 105 (5 ) 100 (19 ) — 81 Segment income (loss) 191 (8 ) 183 (33 ) (1 ) 149 Income from discontinued operations, net of tax 23 Net income $ 172 Capital expenditures $ 399 $ — $ 399 $ — $ — $ 399 Segment assets 7,050 — 7,050 55 (8 ) 7,097 Year Ended December 31, 2014 Total Regulated Commercial Reportable (in millions) Utilities Portfolio Segments Other Eliminations Total Unaffiliated revenues $ 1,894 $ 19 $ 1,913 $ — $ — $ 1,913 Intersegment revenues 1 — 1 — (1 ) — Total revenues $ 1,895 $ 19 $ 1,914 $ — $ (1 ) $ 1,913 Interest expense $ 81 $ 5 $ 86 $ — $ — $ 86 Depreciation and amortization 211 2 213 1 — 214 Income tax expense (benefit) 117 (67 ) 50 (7 ) — 43 Segment income (loss) (a) 202 (121 ) 81 (13 ) — 68 Income from discontinued operations, net of tax (563 ) Net loss $ (495 ) Capital expenditures $ 300 $ 22 $ 322 $ — $ — $ 322 Segment assets 6,902 3,187 10,089 134 (230 ) 9,993 (a) Commercial Portfolio recorded a $94 million pretax impairment charge related to OVEC. Year Ended December 31, 2013 Total Regulated Commercial Reportable (in millions) Utilities Portfolio Segments Other Eliminations Total Total revenues $ 1,765 $ 40 $ 1,805 $ — $ — $ 1,805 Interest expense $ 74 $ — $ 74 $ — $ — $ 74 Depreciation and amortization 200 13 213 — — 213 Income tax expense (benefit) 91 (36 ) 55 (12 ) — 43 Segment income (loss) 151 (65 ) 86 (19 ) — 67 Income from discontinued operations, net of tax 35 Net income $ 102 Capital expenditures $ 375 $ 58 $ 433 $ — $ — $ 433 Segment assets 6,649 4,170 10,819 99 (155 ) 10,763

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2015
Public Utilities, General Disclosures [Line Items]
Schedule of Regulatory Assets	December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Assets Asset retirement obligations – coal ash $ 1,992 $ 840 $ 1,152 $ 1,152 $ — $ — $ — Asset retirement obligations – nuclear and other 1,025 67 730 432 298 — — Accrued pension and OPEB 2,015 412 812 354 458 132 217 Retired generation facilities 1,659 58 1,545 152 1,393 — 56 Debt fair value adjustment 1,305 — — — — — — Net regulatory asset related to income taxes 1,144 614 354 141 213 64 111 Hedge costs and other deferrals 628 103 490 217 273 7 28 DSM/EE 330 106 203 193 10 21 — Grid Modernization 76 — — — — 76 — Vacation accrual 213 86 46 46 — 6 12 Deferred fuel and purchased power 246 50 182 138 44 9 5 Nuclear deferral 296 141 155 43 112 — — Post-in-service carrying costs and deferred operating expenses 494 124 121 28 93 21 228 Gasification services agreement buyout 55 — — — — — 55 Transmission expansion obligation 70 — — — — 74 — MGP 115 — — — — 115 — Other 494 263 109 66 42 36 66 Total regulatory assets 12,157 2,864 5,899 2,962 2,936 561 778 Less: current portion 1,115 399 491 287 203 49 93 Total noncurrent regulatory assets $ 11,042 $ 2,465 $ 5,408 $ 2,675 $ 2,733 $ 512 $ 685 The following tables present the regulatory assets and liabilities recorded on the Consolidated Balance Sheets. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Assets Asset retirement obligations – coal ash $ 2,555 $ 1,120 $ 1,394 $ 1,386 $ 8 $ 4 $ 37 Asset retirement obligations – nuclear and other 838 104 487 195 292 — — Accrued pension and OPEB 2,151 479 807 366 441 139 220 Retired generation facilities 509 49 409 179 230 — 51 Debt fair value adjustment 1,191 — — — — — — Net regulatory asset related to income taxes 1,075 564 318 106 212 55 120 Nuclear asset securitizable balance, net 1,237 — 1,237 — 1,237 — — Hedge costs and other deferrals 571 127 410 171 239 7 27 Demand side management (DSM)/Energy efficiency (EE) 340 80 250 237 13 10 — Grid Modernization 68 — — — — 68 — Vacation accrual 192 79 38 38 — 5 10 Deferred fuel and purchased power 151 21 129 93 36 1 — Nuclear deferral 245 107 138 62 76 — — Post-in-service carrying costs and deferred operating expenses 383 97 38 38 — 21 227 Gasification services agreement buyout 32 — — — — — 32 Transmission expansion obligation 72 — — — — 72 — Manufactured gas plant (MGP) 104 — — — — 104 — NCEMPA deferrals 21 — 21 21 — — — East Bend deferrals 16 — — — — 16 — Other 499 244 121 82 39 31 94 Total regulatory assets 12,250 3,071 5,797 2,974 2,823 533 818 Less: current portion 877 305 362 264 98 36 102 Total noncurrent regulatory assets $ 11,373 $ 2,766 $ 5,435 $ 2,710 $ 2,725 $ 497 $ 716
Schedule Of Regulatory Liabilities	December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Liabilities Costs of removal $ 5,329 $ 2,413 $ 2,078 $ 1,725 $ 353 $ 222 $ 616 Amounts to be refunded to customers 71 — — — — — 71 Storm reserve 150 24 125 — 125 1 — Accrued pension and OPEB 288 68 51 25 26 21 83 Deferred fuel and purchased power 311 55 255 58 197 1 — Other 506 281 164 155 8 12 46 Total regulatory liabilities 6,655 2,841 2,673 1,963 709 257 816 Less: current portion 400 39 286 85 200 12 62 Total noncurrent regulatory liabilities $ 6,255 $ 2,802 $ 2,387 $ 1,878 $ 509 $ 245 $ 754 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory Liabilities Costs of removal $ 5,221 $ 2,420 $ 1,975 $ 1,692 $ 283 $ 222 $ 613 Amounts to be refunded to customers 166 — 70 — 70 — 96 Storm reserve 150 25 125 — 125 — — Accrued pension and OPEB 379 76 121 61 60 19 91 Deferred fuel and purchased power 37 6 23 23 — — 8 Other 444 217 171 127 44 10 42 Total regulatory liabilities 6,397 2,744 2,485 1,903 582 251 850 Less: current portion 204 34 106 71 35 10 54 Total noncurrent regulatory liabilities $ 6,193 $ 2,710 $ 2,379 $ 1,832 $ 547 $ 241 $ 796
Schedule of Potential Plant Retirements	The table below contains the net carrying value of generating facilities planned for retirement or included in recent IRPs as evaluated for potential retirement due to a lack of requisite environmental control equipment. Dollar amounts in the table below are included in Net property, plant and equipment on the Consolidated Balance Sheets. December 31, 2015 Duke Duke Duke Energy Energy Energy Florida (b) Indiana (c) Capacity (in MW) 1,821 873 948 Remaining net book value (in millions) (a) $ 352 $ 131 $ 221 (a) Remaining net book value amounts presented exclude any capitalized asset retirement costs related to closure of ash basins. (b) Includes Crystal River Units 1 and 2. Progress Energy amounts are equal to Duke Energy Florida amounts. (c) Includes Wabash River Units 2 through 6 and Gallagher Units 2 and 4. Wabash River Unit 6 is being evaluated for potential conversion to natural gas. Duke Energy Indiana committed to retire or convert the Wabash River Units 2 through 6 by June 2018 in conjunction with a settlement agreement associated with the Edwardsport air permit. 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 proposed settlement of Edwardsport IGCC matters.
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Schedule of MISO Exit Fee Obligations	The following table provides a reconciliation of the beginning and ending balance of Duke Energy Ohio’s recorded obligations related to its withdrawal from MISO. As of December 31, 2015 , $72 million is recorded as a Regulatory asset on Duke Energy Ohio's Consolidated Balance Sheets. Provisions/ Cash (in millions) December 31, 2014 Adjustments Reductions December 31, 2015 Duke Energy Ohio $ 94 $ 3 $ (5 ) $ 92

Commitments and Contingencies (

Commitments and Contingencies (Table)	12 Months Ended
	Dec. 31, 2015
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 $ 74 Duke Energy Carolinas 22 Duke Energy Ohio 42 Duke Energy Indiana 7
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 Consolidated Balance Sheets in Other within Deferred Credits and Other 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. December 31, (in millions) 2015 2014 Reserves for Legal Matters Duke Energy $ 166 $ 323 Duke Energy Carolinas 11 72 Progress Energy 54 93 Duke Energy Progress 6 37 Duke Energy Florida 31 36 Duke Energy Ohio 80 —
Schedule of Purchase Power Obligations	The following table presents executory purchased power contracts with terms exceeding one year, excluding contracts classified as leases. Minimum Purchase Amount at December 31, 2015 Contract (in millions) Expiration 2016 2017 2018 2019 2020 Thereafter Total Duke Energy Progress (a) 2019-2031 $ 54 $ 60 $ 61 $ 62 $ 49 $ 363 $ 649 Duke Energy Florida (b) 2021-2043 305 345 360 377 394 1,591 3,372 Duke Energy Ohio (c)(d) 2017-2018 236 195 59 — — — 490 (a) Contracts represent between 15 percent and 100 percent of net plant output. (b) Contracts represent between 80 percent and 100 percent of net plant output. (c) Contracts represent between 1 percent and 11 percent of net plant output. (d) Excludes purchase power agreement with OVEC. See Note 17 for additional information.
Schedule of Operating Lease Rent Expense	The following table presents rental expense for operating leases. These amounts are included in Operation, maintenance and other on the Consolidated Statements of Operations. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy $ 318 $ 355 $ 321 Duke Energy Carolinas 41 41 39 Progress Energy 230 257 225 Duke Energy Progress 149 161 153 Duke Energy Florida 81 96 72 Duke Energy Ohio 13 17 14 Duke Energy Indiana 20 21 22
Schedule of Future Minimum Rental Payments for Operating Leases	The following table presents future minimum lease payments under operating leases, which at inception had a non-cancelable term of more than one year. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana 2016 $ 219 $ 41 $ 132 $ 66 $ 66 $ 13 $ 20 2017 182 33 111 63 48 9 15 2018 161 24 108 61 47 6 12 2019 146 21 102 56 46 4 8 2020 127 16 93 48 45 3 5 Thereafter 864 51 622 365 257 5 8 Total $ 1,699 $ 186 $ 1,168 $ 659 $ 509 $ 40 $ 68
Schedule of Future Minimum Lease Payments for Capital Leases	The following table presents future minimum lease payments under capital leases. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana 2016 $ 173 $ 6 $ 46 $ 20 $ 26 $ 7 $ 3 2017 171 6 46 21 25 1 1 2018 180 6 46 21 25 5 2 2019 178 6 45 22 25 1 1 2020 182 5 46 21 25 — 1 Thereafter 1,176 30 367 272 95 1 43 Minimum annual payments 2,060 59 596 377 221 15 51 Less: amount representing interest (724 ) (35 ) (295 ) (230 ) (65 ) (2 ) (38 ) Total $ 1,336 $ 24 $ 301 $ 147 $ 156 $ 13 $ 13
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 Deferred Credits and Other Liabilities on the Consolidated Balance Sheets. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Balance at December 31, 2012 $ 75 $ 12 $ 33 $ 14 $ 19 $ 15 $ 8 Provisions/adjustments 26 — 4 (1 ) 5 20 1 Cash reductions (22 ) (1 ) (10 ) (5 ) (5 ) (8 ) (2 ) Balance at December 31, 2013 79 11 27 8 19 27 7 Provisions/adjustments 32 (1 ) 1 4 (3 ) 28 4 Cash reductions (14 ) — (11 ) (7 ) (4 ) (1 ) (1 ) Balance at December 31, 2014 97 10 17 5 12 54 10 Provisions/adjustments 9 1 4 — 4 1 5 Cash reductions (9 ) (1 ) (4 ) (2 ) (2 ) (1 ) (3 ) Balance at December 31, 2015 $ 97 $ 10 $ 17 $ 3 $ 14 $ 54 $ 12

Debt and Credit Facilities (Tab

Debt and Credit Facilities (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Schedule of Debt	The following tables show short-term obligations classified as long-term debt. December 31, 2015 Duke Duke Duke Duke Duke Energy Energy Energy Energy (in millions) Energy Carolinas Progress Ohio Indiana Tax-exempt bonds $ 347 $ 35 $ — $ 27 $ 285 Commercial paper (a) 625 300 150 25 150 Total $ 972 $ 335 $ 150 $ 52 $ 435 December 31, 2014 Duke Duke Duke Duke Energy Energy Energy (in millions) Energy Carolinas Ohio Indiana Tax-exempt bonds $ 347 $ 35 $ 27 $ 285 Commercial paper 475 300 25 150 Secured debt (b) 200 — — — Total $ 1,022 $ 335 $ 52 $ 435 (a) Progress Energy amounts are equal to Duke Energy Progress amounts. (b) In December 2015, Duke Energy used cash held by the lender to repay debt. Instrument had a term of less than one year with the right to extend the maturity date for additional one-year periods with a final maturity date no later than December 2026. The following tables summarize outstanding debt. December 31, 2015 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Unsecured debt, maturing 2016 - 2073 4.99 % $ 13,392 $ 1,152 $ 3,850 $ — $ 150 $ 765 $ 740 Secured debt, maturing 2016 - 2037 2.57 % 2,635 425 479 254 225 — — First mortgage bonds, maturing 2016 - 2045 (a) 4.74 % 18,980 6,161 9,750 5,975 3,775 750 2,319 Capital leases, maturing 2016 - 2051 (b) 5.38 % 1,336 24 300 144 156 13 14 Tax-exempt bonds, maturing 2017 - 2041 (c) 2.59 % 1,053 355 48 48 — 77 572 Notes payable and commercial paper (d) 0.88 % 4,258 — — — — — — Money pool/intercompany borrowings — 300 1,458 359 813 128 150 Fair value hedge carrying value adjustment 6 6 — — — — — Unamortized debt discount and premium, net (e) 1,712 (17 ) (28 ) (16 ) (8 ) (28 ) (8 ) Unamortized debt issuance costs (f) (170 ) (39 ) (85 ) (37 ) (32 ) (4 ) (19 ) Total debt 4.25 % $ 43,202 $ 8,367 $ 15,772 $ 6,727 $ 5,079 $ 1,701 $ 3,768 Short-term notes payable and commercial paper (3,633 ) — — — — — — Short-term money pool/intercompany borrowings — — (1,308 ) (209 ) (813 ) (103 ) — Current maturities of long-term debt (g) (2,074 ) (356 ) (315 ) (2 ) (13 ) (106 ) (547 ) Total long-term debt (g) $ 37,495 $ 8,011 $ 14,149 $ 6,516 $ 4,253 $ 1,492 $ 3,221 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $114 million and $731 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds or letters of credit. (d) Includes $625 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that back-stop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for commercial paper was 15 days. (e) Duke Energy includes $1,798 million in purchase accounting adjustments related to the merger with Progress Energy. (f) Duke Energy includes $59 million in purchase accounting adjustments primarily related to the merger with Progress Energy. (g) Refer to Note 17 for additional information on amounts from consolidated VIEs. December 31, 2014 Weighted Average Duke Duke Duke Duke Duke Interest Duke Energy Progress Energy Energy Energy Energy (in millions) Rate Energy Carolinas Energy Progress Florida Ohio Indiana Unsecured debt, maturing 2015 - 2073 4.92 % $ 12,937 $ 1,155 $ 3,850 $ — $ 150 $ 773 $ 742 Secured debt, maturing 2016 - 2037 2.50 % 2,806 400 525 300 225 — — First mortgage bonds, maturing 2015 - 2044 (a) 4.76 % 19,180 6,161 9,800 5,475 4,325 900 2,319 Capital leases, maturing 2015 - 2051 (b) 5.30 % 1,428 27 314 146 168 20 16 Tax-exempt bonds, maturing 2015 - 2041 (c) 2.13 % 1,296 355 291 291 — 77 573 Notes payable and commercial paper (d) 0.70 % 2,989 — — — — — — Money pool/intercompany borrowings — 300 835 — 84 516 221 Fair value hedge carrying value adjustment 8 8 — — — — — Unamortized debt discount and premium, net (e) 1,890 (15 ) (26 ) (11 ) (8 ) (29 ) (9 ) Unamortized debt issuance costs (152 ) (38 ) (86 ) (31 ) (37 ) (6 ) (22 ) Total debt 4.29 % $ 42,382 $ 8,353 $ 15,503 $ 6,170 $ 4,907 $ 2,251 $ 3,840 Short-term notes payable and commercial paper (2,514 ) — — — — — — Short-term money pool/intercompany borrowings — — (835 ) — (84 ) (491 ) (71 ) Current maturities of long-term debt (f) (2,807 ) (507 ) (1,507 ) (945 ) (562 ) (157 ) (5 ) Total long-term debt (f) $ 37,061 $ 7,846 $ 13,161 $ 5,225 $ 4,261 $ 1,603 $ 3,764 (a) Substantially all electric utility property is mortgaged under mortgage bond indentures. (b) Duke Energy includes $129 million and $787 million of capital lease purchase accounting adjustments related to Duke Energy Progress and Duke Energy Florida, respectively, related to power purchase agreements that are not accounted for as capital leases in their respective financial statements because of grandfathering provisions in GAAP. (c) Substantially all tax-exempt bonds are secured by first mortgage bonds or letters of credit. (d) Includes $475 million that was classified as Long-Term Debt on the Consolidated Balance Sheets due to the existence of long-term credit facilities that back-stop these commercial paper balances, along with Duke Energy’s ability and intent to refinance these balances on a long-term basis. The weighted average days to maturity for commercial paper was 27 days. (e) Duke Energy includes $1,975 million in purchase accounting adjustments related to the merger with Progress Energy. (f) Refer to Note 17 for additional information on amounts from consolidated VIEs. The following table shows the significant components of Current maturities of long-term debt on the Consolidated Balance Sheets. The Duke Energy Registrants currently anticipate satisfying these obligations with cash on hand and proceeds from additional borrowings. (in millions) Maturity Date Interest Rate December 31, 2015 Unsecured Debt Progress Energy (Parent) January 2016 5.625 % $ 300 Duke Energy Indiana June 2016 6.05 % 325 Duke Energy (Parent) November 2016 2.150 % 500 First Mortgage Bonds Duke Energy Indiana July 2016 0.670 % 150 Duke Energy Carolinas December 2016 1.750 % 350 Other 449 Current maturities of long-term debt $ 2,074
Schedule of Maturities of Long-term Debt	The following table shows the annual maturities of long-term debt for the next five years and thereafter. Amounts presented exclude short-term notes payable and commercial paper and money pool borrowings for the Subsidiary Registrants. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy (a) Carolinas Energy Progress Florida Ohio Indiana 2016 $ 2,074 $ 356 $ 315 $ 2 $ 13 $ 106 $ 547 2017 2,468 115 923 446 482 1 2 2018 3,441 1,629 510 — 512 5 3 2019 3,022 5 1,667 855 14 552 63 2020 2,091 755 415 152 265 25 653 Thereafter 24,616 5,507 10,634 5,063 2,980 909 2,500 Total long-term debt, including current maturities $ 37,712 $ 8,367 $ 14,464 $ 6,518 $ 4,266 $ 1,598 $ 3,768 (a) Excludes $1,857 million in purchase accounting adjustments related to the merger with Progress Energy.
Schedule of Long-term Debt Instruments	The following tables summarize significant debt issuances (in millions). Year Ended December 31, 2015 Duke Duke Duke Maturity Interest Duke Energy Energy Energy Issuance Date Date Rate Energy (Parent) Carolinas Progress Unsecured Debt November 2015 (a)(b) April 2024 3.750 % $ 400 $ 400 $ — $ — November 2015 (a)(b) December 2045 4.800 % 600 600 — — First Mortgage Bonds March 2015 (c) June 2045 3.750 % 500 — 500 — August 2015 (a)(d) August 2025 3.250 % 500 — — 500 August 2015 (a)(d) August 2045 4.200 % 700 — — 700 Total issuances $ 2,700 $ 1,000 $ 500 $ 1,200 (a) Proceeds were used to repay short-term money pool and commercial paper borrowing issued to fund a portion of the NCEMPA acquisition, see Note 2 for further information. (b) Proceeds were used to refinance at maturity $300 million of unsecured notes at Progress Energy due January 2016. (c) Proceeds were used to redeem at maturity $500 million of first mortgage bonds due October 2015. (d) Proceeds were used to refinance at maturity $400 million of first mortgage bonds due December 2015. Year Ended December 31, 2014 Duke Duke Duke Maturity Interest Duke Energy Energy Energy Issuance Date Date Rate Energy (Parent) Progress Florida Unsecured Debt April 2014 (a) April 2024 3.750 % $ 600 $ 600 $ — $ — April 2014 (a)(b) April 2017 0.613 % 400 400 — — June 2014 (c) May 2019 11.970 % 108 — — — June 2014 (c) May 2021 13.680 % 110 — — — Secured Debt March 2014 (d) March 2017 0.863 % 225 — — 225 July 2014 (e) July 2036 5.340 % 129 — — — First Mortgage Bonds March 2014 (f) March 2044 4.375 % 400 — 400 — March 2014 (f)(g) March 2017 0.435 % 250 — 250 — November 2014 (h) December 2044 4.150 % 500 — 500 — November 2014 (g)(h) November 2017 0.432 % 200 — 200 — Total issuances $ 2,922 $ 1,000 $ 1,350 $ 225 (a) Proceeds were used to redeem $402 million of tax-exempt bonds at Duke Energy Ohio, the repayment of outstanding commercial paper and for general corporate purposes. See Note 13 for additional information related to the redemption of Duke Energy Ohio's tax-exempt bonds. (b) The debt is floating rate based on three-month London Interbank Offered Rate (LIBOR) plus a fixed credit spread of 38 basis points. (c) Proceeds were used to repay $196 million of debt for International Energy and for general corporate purposes. The interest rates include country specific risk premiums. (d) Relates to the securitization of accounts receivable at a subsidiary of Duke Energy Florida. Proceeds were used to repay short-term borrowings under the intercompany money pool borrowing arrangement and for general corporate purposes. See Note 17 for further details. (e) Proceeds were used to fund a portion of Duke Energy's prior investment in the existing Wind Star renewables portfolio. (f) Proceeds were used to repay short-term borrowings under the intercompany money pool borrowing arrangement and for general corporate purposes. (g) The debt is floating rate based on three-month LIBOR plus a fixed credit spread of 20 basis points. (h) Proceeds were used to redeem $450 million of tax-exempt bonds, repay short-term borrowings under the intercompany money pool borrowing arrangement and for general corporate purposes.
Schedule Of Line Of Credit Facilities	The table below includes the current borrowing sublimits and available capacity under the Master Credit Facility. December 31, 2015 Duke Duke Duke Duke Duke Duke Duke Energy Energy Energy Energy Energy Energy (in millions) Energy (Parent) Carolinas Progress Florida Ohio Indiana Facility size (a) $ 7,500 $ 3,475 $ 800 $ 1,000 $ 1,200 $ 425 $ 600 Reduction to backstop issuances Commercial paper (b) (3,138 ) (1,531 ) (300 ) (333 ) (709 ) (115 ) (150 ) Outstanding letters of credit (72 ) (65 ) (4 ) (2 ) (1 ) — — Tax-exempt bonds (116 ) — (35 ) — — — (81 ) Coal ash set-aside (c) (500 ) — (250 ) (250 ) — — — Available capacity $ 3,674 $ 1,879 $ 211 $ 415 $ 490 $ 310 $ 369 (a) Represents the sublimit of each borrower. (b) Duke Energy issued $625 million of commercial paper and loaned the proceeds through the money pool to Duke Energy Carolinas, Duke Energy Progress, Duke Energy Ohio and Duke Energy Indiana. The balances are classified as Long-Term Debt Payable to Affiliated Companies in the Consolidated Balance Sheets. (c) On May 14, 2015, the United States District Court for the Eastern District of North Carolina approved the separate Plea Agreements entered into by Duke Energy Carolinas, Duke Energy Progress and DEBS, a wholly owned subsidiary of Duke Energy, in connection with the investigation initiated by the USDOJ. Duke Energy Carolinas and Duke Energy Progress are required to each maintain $250 million of available capacity under the Master Credit Facility as security to meet their obligations under the Plea Agreements, in addition to certain other conditions. See Note 5 for further details.

Guarantees and Indemnificatio41

Guarantees and Indemnifications (Tables)	12 Months Ended
	Dec. 31, 2015
Guarantor Obligations [Line Items]
Schedule of Guarantor Obligations	The following table includes the liabilities recognized for the guarantees discussed above. These amounts are primarily recorded in Other within Deferred Credits and other Liabilities on the Consolidated Balance Sheets. As current estimates change, additional losses related to guarantees and indemnifications to third parties, which could be material, may be recorded by the Duke Energy Registrants in the future. December 31, 2015 2014 Duke Energy $ 21 $ 28 Progress Energy 7 13 Duke Energy Florida 7 7

Joint Ownership of Generating42

Joint Ownership of Generating and Transmission Facilities (Tables)	12 Months Ended
	Dec. 31, 2015
Jointly Owned Utility Plant Interests [Line Items]
Schedule Joint Ownership of Generating and Transmission Facilities	The following table presents the Duke Energy Registrants' interest of jointly owned plant or facilities and amounts included on the Consolidated Balance Sheets. All facilities are operated by the Duke Energy Registrants and are included in the Regulated Utilities segment unless otherwise noted. December 31, 2015 Construction Ownership Property, Plant Accumulated Work in Interest and Equipment Depreciation Progress Duke Energy Carolinas Catawba Nuclear Station (units 1 and 2) (a) 19.25 % $ 926 $ 567 $ 9 Duke Energy Florida Intercession City Plant (unit 11) (b) 24 15 — Duke Energy Ohio Transmission facilities (c) Various 85 50 1 Duke Energy Indiana Gibson Station (unit 5) (d) 50.05 % 329 151 5 Vermillion (e) 62.5 % 153 108 — Transmission and local facilities (d) Various 4,094 1,688 — International Energy Brazil – Canoas I and II (f) 47.2 % 160 57 — (a) Jointly owned with North Carolina Municipal Power Agency Number One, NCEMC and Piedmont Municipal Power Agency. (b) Jointly owned with Georgia Power Company (GPC). GPC has exclusive rights to the output of the unit during the months of June through September and pays all fuel and water costs during this period. Duke Energy Florida pays all fuel and water costs during the remaining months. Other costs are allocated 66.67 percent to Duke Energy Florida and the remainder to GPC. (c) Jointly owned with America Electric Power Generation Resources and The Dayton Power and Light Company. (d) Jointly owned with Wabash Valley Power Association, Inc. (WVPA) and Indiana Municipal Power Agency. (e) Jointly owned with WVPA. (f) Jointly owned with Companhia Brasileira de Aluminio and included in the International segment.

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation [Line Items]
Schedule of Asset Retirement Obligations by Category	The following table presents the AROs recorded on the Consolidated Balance Sheets. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Decommissioning of Nuclear Power Facilities $ 5,072 $ 1,730 $ 3,093 $ 2,349 $ 744 $ — $ — Closure of Ash Impoundments 4,958 2,161 2,196 2,188 7 94 507 Other (a) 234 27 80 30 51 31 18 Total Asset retirement obligation $ 10,264 $ 3,918 $ 5,369 $ 4,567 $ 802 $ 125 $ 525 (a) Includes obligations related to asbestos removal and the closure of certain landfills at fossil generation facilities. Duke Energy Ohio also includes AROs related to the retirement of natural gas mains. Duke Energy also includes AROs related to the removal of renewable energy generation assets.
Public Utilities General Disclosures	The following table presents the fair value of NDTF assets legally restricted for purposes of settling asset retirement obligations associated with nuclear decommissioning. December 31, (in millions) 2015 2014 Duke Energy $ 4,670 $ 5,182 Duke Energy Carolinas 2,686 2,678 Duke Energy Progress (a) 1,984 1,701 Duke Energy Florida (a)(b) — 803 (a) Amounts for Progress Energy equal the sum of Duke Energy Progress and Duke Energy Florida. (b) Duke Energy Florida is actively decommissioning Crystal River Unit 3 and was granted an exemption from the NRC which allows for unrestricted use of the NDTF. Therefore, the entire balance of Duke Energy Florida’s NDTF may be applied towards license termination, spent fuel and site restoration costs incurred to decommission Crystal River Unit 3. The following table summarizes information about the most recent site-specific nuclear decommissioning cost studies. Decommissioning costs in the table below are presented in dollars of the year of the cost study and include costs to decommission plant components not subject to radioactive contamination. Annual Funding Decommissioning (in millions) Requirement (a) Costs (a)(b) Year of Cost Study Duke Energy $ 14 $ 8,130 2013 and 2014 Duke Energy Carolinas — 3,420 2013 Duke Energy Progress 14 3,550 2014 Duke Energy Florida — 1,160 2013 (a) Amounts for Progress Energy equal the sum of Duke Energy Progress and Duke Energy Florida. (b) Amounts include the Subsidiary Registrant's ownership interest in jointly owned reactors. Other joint owners are responsible for decommissioning costs related to their interest in the reactors. The following table includes the current expiration of nuclear operating licenses. Duke Energy Florida has requested the NRC terminate the operating license for Crystal River Unit 3 as it permanently ceased operation in February 2013. Refer to Note 4 for further information on decommissioning activity and transition to SAFSTOR. Unit Year of Expiration Duke Energy Carolinas Catawba Units 1 and 2 2043 McGuire Unit 1 2041 McGuire Unit 2 2043 Oconee Units 1 and 2 2033 Oconee Unit 3 2034 Duke Energy Progress Brunswick Unit 1 2036 Brunswick Unit 2 2034 Harris 2046 Robinson 2030
Rollforward Schedule of Asset Retirement Obligations	The following table presents changes in the liability associated with AROs. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Balance at December 31, 2013 4,958 1,594 2,570 1,737 833 28 30 Acquisitions 4 — — — — — — Accretion expense (a) 246 113 135 97 38 2 2 Liabilities settled (b) (68 ) — (68 ) — (68 ) — — Liabilities incurred in the current year (c) 3,500 1,717 1,783 1,783 — — — Revisions in estimates of cash flows (d) (174 ) 4 291 288 3 (3 ) — Balance at December 31, 2014 8,466 3,428 4,711 3,905 806 27 32 Acquisitions (e) 226 — 226 204 23 — — Accretion expense (a) 384 165 203 169 34 4 15 Liabilities settled (b) (422 ) (200 ) (195 ) (125 ) (70 ) (4 ) (23 ) Liabilities incurred in the current year (c) 1,016 178 282 282 — 116 418 Revisions in estimates of cash flows (f) 594 347 142 132 9 (18 ) 83 Balance at December 31, 2015 $ 10,264 $ 3,918 $ 5,369 $ 4,567 $ 802 $ 125 $ 525 (a) Substantially all accretion expense for the years ended December 31, 2015 and 2014 relates to Duke Energy’s regulated electric operations and has been deferred in accordance with regulatory accounting treatment. (b) For 2014, amounts relate to nuclear decommissioning of Crystal River Unit 3. For 2015, amounts primarily relate to ash impoundment closures and nuclear decommissioning of Crystal River Unit 3. (c) For 2014, amounts primarily relate to AROs recorded as a result of the Coal Ash Act and an agreement with the SCDHEC related to the W.S. Lee Steam Station. For 2015, amounts primarily relate to AROs recorded as a result of the EPA's rule for disposal of CCR. (d) Amounts for Progress Energy and Duke Energy Progress primarily relate to Duke Energy Progress' site-specific nuclear decommissioning cost studies. The Duke Energy amount also includes the impact of Duke Energy Progress' site-specific nuclear decommissioning cost studies on purchase accounting amounts. (e) Duke Energy Progress amount relates to the NCEMPA acquisition. See footnote 2 for additional information. (f) Primarily relates to the closure of ash impoundments.

Property, Plant and Equipment (

Property, Plant and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Public Utility, Property, Plant and Equipment [Line Items]
Schedule Of Property, Plant And Equipment	The composite weighted average depreciation rates, excluding nuclear fuel, are included in the table that follows. Years Ended December 31, 2015 2014 2013 Duke Energy 2.9 % 2.8 % 2.8 % Duke Energy Carolinas 2.8 % 2.7 % 2.8 % Progress Energy 2.6 % 2.5 % 2.5 % Duke Energy Progress 2.6 % 2.5 % 2.5 % Duke Energy Florida 2.7 % 2.7 % 2.4 % Duke Energy Ohio 2.7 % 2.3 % 3.3 % Duke Energy Indiana 3.0 % 3.0 % 2.8 % The following tables summarize the property, plant and equipment for Duke Energy and its subsidiary registrants. December 31, 2015 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Land $ 1,466 $ 407 $ 719 $ 392 $ 327 $ 118 $ 108 Plant – Regulated Electric generation, distribution and transmission 8 - 100 87,593 33,623 36,422 22,888 13,534 4,429 13,118 Natural gas transmission and distribution 12 - 67 2,322 — — — — 2,322 — Other buildings and improvements 15 - 100 1,480 477 621 294 322 204 179 Plant – Nonregulated Electric generation, distribution and transmission 1 - 30 3,348 — — — — — — Other buildings and improvements 5 - 50 2,363 — — — — — — Nuclear fuel 3,194 1,827 1,367 1,367 — — — Equipment 3 - 38 1,791 368 530 398 132 344 173 Construction in process 4,525 1,860 1,827 1,118 709 180 214 Other 2 - 60 4,744 836 1,180 856 319 153 215 Total property, plant and equipment (a)(d) 112,826 39,398 42,666 27,313 15,343 7,750 14,007 Total accumulated depreciation – regulated (b)(c)(d) (35,367 ) (13,521 ) (14,867 ) (10,141 ) (4,720 ) (2,507 ) (4,484 ) Total accumulated depreciation – nonregulated (c)(d) (2,298 ) — — — — — — Generation facilities to be retired, net 548 — 548 548 — — — Total net property, plant and equipment $ 75,709 $ 25,877 $ 28,347 $ 17,720 $ 10,623 $ 5,243 $ 9,523 (a) Includes capitalized leases of $1,470 million , $40 million , $302 million , $144 million , $158 million , $96 million , and $39 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, and Duke Energy Indiana, respectively, primarily within Plant - Regulated. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $85 million , $7 million and $78 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,621 million , $976 million , $645 million and $645 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $58 million , $11 million , $27 million and $7 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $2,033 million and accumulated depreciation of consolidated VIEs of $327 million at Duke Energy. December 31, 2014 Estimated Useful Duke Duke Duke Duke Duke Life Duke Energy Progress Energy Energy Energy Energy (in millions) (Years) Energy Carolinas Energy Progress Florida Ohio Indiana Land $ 1,459 $ 403 $ 704 $ 380 $ 324 $ 114 $ 108 Plant – Regulated Electric generation, distribution and transmission 2 - 138 82,206 31,751 33,672 20,616 13,056 3,956 11,911 Natural gas transmission and distribution 12 - 67 2,230 — — — — 2,230 — Other buildings and improvements 9 - 100 1,445 465 607 286 318 200 173 Plant – Nonregulated Electric generation, distribution and transmission 1- 30 2,380 — — — — — — Other buildings and improvements 5 - 50 2,498 — — — — — — Nuclear fuel 2,865 1,676 1,190 1,190 — — — Equipment 3 - 34 1,762 341 506 388 118 330 166 Construction in process 4,519 2,081 1,215 908 307 97 481 Other 5 - 80 3,497 655 756 439 310 214 195 Total property, plant and equipment (a)(d) 104,861 37,372 38,650 24,207 14,433 7,141 13,034 Total accumulated depreciation – regulated (b)(c)(d) (32,628 ) (12,700 ) (13,506 ) (9,021 ) (4,478 ) (2,213 ) (4,219 ) Total accumulated depreciation – nonregulated (c)(d) (2,196 ) — — — — — — Generation facilities to be retired, net 9 — — — — 9 — Total net property, plant and equipment $ 70,046 $ 24,672 $ 25,144 $ 15,186 $ 9,955 $ 4,937 $ 8,815 (a) Includes capitalized leases of $1,548 million , $40 million , $315 million , $146 million , $169 million , $98 million , and $30 million at Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio, and Duke Energy Indiana, respectively, primarily in regulated plant. The Progress Energy, Duke Energy Progress and Duke Energy Florida amounts are net of $72 million , $5 million and $67 million , respectively, of accumulated amortization of capitalized leases. (b) Includes $1,408 million , $847 million , $561 million and $561 million of accumulated amortization of nuclear fuel at Duke Energy, Duke Energy Carolinas, Progress Energy and Duke Energy Progress, respectively. (c) Includes accumulated amortization of capitalized leases of $52 million , $8 million , $25 million and $6 million at Duke Energy, Duke Energy Carolinas, Duke Energy Ohio and Duke Energy Indiana, respectively. (d) Includes gross property, plant and equipment cost of consolidated VIEs of $1,873 million and accumulated depreciation of consolidated VIEs of $257 million at Duke Energy.
Schedule Of Capitalized Interest	The following table presents capitalized interest, which includes the debt component of AFUDC. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy $ 98 $ 75 $ 89 Duke Energy Carolinas 38 38 41 Progress Energy 24 11 19 Duke Energy Progress 20 10 16 Duke Energy Florida 4 1 3 Duke Energy Ohio 10 10 11 Duke Energy Indiana 6 6 9

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill [Line Items]
Goodwill By Reportable Operating Segment	The following table presents goodwill by reportable operating segment for Duke Energy. Duke Energy Regulated International Commercial (in millions) Utilities Energy Portfolio Total Goodwill at December 31, 2014 (a) $ 15,950 $ 307 $ 64 $ 16,321 Foreign exchange and other changes — (36 ) — (36 ) Acquisitions — — 58 58 Goodwill at December 31, 2015 $ 15,950 $ 271 $ 122 $ 16,343
Schedule of Intangible Assets	The following tables show the carrying amount and accumulated amortization of intangible assets within Other on the Consolidated Balance Sheets of the Duke Energy Registrants at December 31, 2015 and 2014 . December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Emission allowances $ 20 $ 1 $ 6 $ 2 $ 4 $ — $ 14 Renewable energy certificates 116 30 80 80 — 5 — Gas, coal and power contracts 24 — — — — — 24 Wind development rights 115 — — — — — — Other 68 — — — — — — Total gross carrying amounts 343 31 86 82 4 5 38 Accumulated amortization – gas, coal and power contracts (16 ) — — — — — (16 ) Accumulated amortization – wind development rights (18 ) — — — — — — Accumulated amortization – other (24 ) — — — — — — Total accumulated amortization (58 ) — — — — — (16 ) Total intangible assets, net $ 285 $ 31 $ 86 $ 82 $ 4 $ 5 $ 22 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Emission allowances $ 23 $ 1 $ 7 $ 3 $ 4 $ — $ 16 Renewable energy certificates 97 25 69 69 — 3 — Gas, coal and power contracts 24 — — — — — 24 Wind development rights 97 — — — — — — Other 76 — — — — — — Total gross carrying amounts 317 26 76 72 4 3 40 Accumulated amortization – gas, coal and power contracts (15 ) — — — — — (15 ) Accumulated amortization – wind development rights (14 ) — — — — — — Accumulated amortization – other (25 ) — — — — — — Total accumulated amortization (54 ) — — — — — (15 ) Total intangible assets, net $ 263 $ 26 $ 76 $ 72 $ 4 $ 3 $ 25
Schedule of Amortization Expense	The following table presents amortization expense for gas, coal and power contracts, wind development rights and other intangible assets. December 31, (in millions) 2015 2014 2013 Duke Energy $ 4 $ 6 $ 13 Duke Energy Ohio — 2 8 Duke Energy Indiana 1 1 1
Schedule of Expected Amortization Expense	The amortization amounts discussed below are estimates and actual amounts may differ from these estimates due to such factors as changes in consumption patterns, sales or impairments of emission allowances or other intangible assets, delays in the in-service dates of wind assets, additional intangible acquisitions and other events. (in millions) 2016 2017 2018 2019 2020 Duke Energy $ 8 $ 8 $ 8 $ 7 $ 7 Duke Energy Indiana 2 2 2 2 2

Investments in Unconsolidated46

Investments in Unconsolidated Affiliates (Tables)	12 Months Ended
	Dec. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investments in Equity Method Unconsolidated Affiliates	The following table presents Duke Energy’s investments in unconsolidated affiliates accounted for under the equity method, as well as the respective equity in earnings, by segment. Years Ended December 31, 2015 2014 2013 Equity in Equity in Equity in (in millions) Investments earnings Investments earnings earnings Regulated Utilities $ 2 $ (4 ) $ 3 $ (3 ) $ (1 ) International Energy 39 74 69 120 110 Commercial Portfolio 433 (3 ) 258 10 7 Other 25 2 28 3 6 Total $ 499 $ 69 $ 358 $ 130 $ 122

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2015
Duke Energy Carolinas [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 914 $ 851 $ 927 Indemnification coverages (b) 24 21 22 JDA revenue (c) 51 133 121 JDA expense (c) 183 198 116 Progress Energy Corporate governance and shared services provided by Duke Energy (a) $ 712 $ 732 $ 290 Corporate governance and shared services provided to Duke Energy (d) — — 96 Indemnification coverages (b) 38 33 34 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Progress Corporate governance and shared service expenses (a) $ 403 $ 386 $ 266 Indemnification coverages (b) 16 17 20 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Florida Corporate governance and shared service expenses (a) $ 309 $ 346 $ 182 Indemnification coverages (b) 22 16 14 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 342 $ 316 $ 347 Indemnification coverages (b) 6 13 15 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 349 $ 384 $ 422 Indemnification coverages (b) 9 11 14 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These amounts are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power under the JDA are recorded in Operating Revenues on the 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 Consolidated Statements of Operations and Comprehensive Income. (d) In 2013, Progress Energy Service Company (PESC), a consolidated subsidiary of Progress Energy, charged a proportionate share of corporate governance and other costs to consolidated affiliates of Duke Energy. Corporate governance and other shared costs were primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These charges were recorded as an offset to Operation, maintenance and other in the Consolidated Statements of Operations and Comprehensive Income. Effective January 1, 2014, PESC was contributed to Duke Energy Corporate Services (DECS), a consolidated subsidiary of Duke Energy, and these costs were no longer charged out of Progress Energy. Progress Energy recorded a non-cash after-tax equity transfer related to the contribution of PESC to DECS in its Consolidated Statements of Changes in Common Stockholder's Equity.
Intercompany Income Tax Receivable	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 for the subsidiary registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana December 31, 2015 Intercompany income tax receivable $ 122 $ 120 $ 104 $ — $ 54 $ — Intercompany income tax payable — — — 96 — 47 December 31, 2014 Intercompany income tax receivable $ 43 $ 713 $ 267 $ 174 $ 39 $ 95
Progress Energy [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 914 $ 851 $ 927 Indemnification coverages (b) 24 21 22 JDA revenue (c) 51 133 121 JDA expense (c) 183 198 116 Progress Energy Corporate governance and shared services provided by Duke Energy (a) $ 712 $ 732 $ 290 Corporate governance and shared services provided to Duke Energy (d) — — 96 Indemnification coverages (b) 38 33 34 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Progress Corporate governance and shared service expenses (a) $ 403 $ 386 $ 266 Indemnification coverages (b) 16 17 20 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Florida Corporate governance and shared service expenses (a) $ 309 $ 346 $ 182 Indemnification coverages (b) 22 16 14 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 342 $ 316 $ 347 Indemnification coverages (b) 6 13 15 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 349 $ 384 $ 422 Indemnification coverages (b) 9 11 14 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These amounts are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power under the JDA are recorded in Operating Revenues on the 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 Consolidated Statements of Operations and Comprehensive Income. (d) In 2013, Progress Energy Service Company (PESC), a consolidated subsidiary of Progress Energy, charged a proportionate share of corporate governance and other costs to consolidated affiliates of Duke Energy. Corporate governance and other shared costs were primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These charges were recorded as an offset to Operation, maintenance and other in the Consolidated Statements of Operations and Comprehensive Income. Effective January 1, 2014, PESC was contributed to Duke Energy Corporate Services (DECS), a consolidated subsidiary of Duke Energy, and these costs were no longer charged out of Progress Energy. Progress Energy recorded a non-cash after-tax equity transfer related to the contribution of PESC to DECS in its Consolidated Statements of Changes in Common Stockholder's Equity.
Intercompany Income Tax Receivable	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 for the subsidiary registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana December 31, 2015 Intercompany income tax receivable $ 122 $ 120 $ 104 $ — $ 54 $ — Intercompany income tax payable — — — 96 — 47 December 31, 2014 Intercompany income tax receivable $ 43 $ 713 $ 267 $ 174 $ 39 $ 95
Duke Energy Progress [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 914 $ 851 $ 927 Indemnification coverages (b) 24 21 22 JDA revenue (c) 51 133 121 JDA expense (c) 183 198 116 Progress Energy Corporate governance and shared services provided by Duke Energy (a) $ 712 $ 732 $ 290 Corporate governance and shared services provided to Duke Energy (d) — — 96 Indemnification coverages (b) 38 33 34 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Progress Corporate governance and shared service expenses (a) $ 403 $ 386 $ 266 Indemnification coverages (b) 16 17 20 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Florida Corporate governance and shared service expenses (a) $ 309 $ 346 $ 182 Indemnification coverages (b) 22 16 14 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 342 $ 316 $ 347 Indemnification coverages (b) 6 13 15 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 349 $ 384 $ 422 Indemnification coverages (b) 9 11 14 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These amounts are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power under the JDA are recorded in Operating Revenues on the 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 Consolidated Statements of Operations and Comprehensive Income. (d) In 2013, Progress Energy Service Company (PESC), a consolidated subsidiary of Progress Energy, charged a proportionate share of corporate governance and other costs to consolidated affiliates of Duke Energy. Corporate governance and other shared costs were primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These charges were recorded as an offset to Operation, maintenance and other in the Consolidated Statements of Operations and Comprehensive Income. Effective January 1, 2014, PESC was contributed to Duke Energy Corporate Services (DECS), a consolidated subsidiary of Duke Energy, and these costs were no longer charged out of Progress Energy. Progress Energy recorded a non-cash after-tax equity transfer related to the contribution of PESC to DECS in its Consolidated Statements of Changes in Common Stockholder's Equity.
Intercompany Income Tax Receivable	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 for the subsidiary registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana December 31, 2015 Intercompany income tax receivable $ 122 $ 120 $ 104 $ — $ 54 $ — Intercompany income tax payable — — — 96 — 47 December 31, 2014 Intercompany income tax receivable $ 43 $ 713 $ 267 $ 174 $ 39 $ 95
Duke Energy Florida [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 914 $ 851 $ 927 Indemnification coverages (b) 24 21 22 JDA revenue (c) 51 133 121 JDA expense (c) 183 198 116 Progress Energy Corporate governance and shared services provided by Duke Energy (a) $ 712 $ 732 $ 290 Corporate governance and shared services provided to Duke Energy (d) — — 96 Indemnification coverages (b) 38 33 34 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Progress Corporate governance and shared service expenses (a) $ 403 $ 386 $ 266 Indemnification coverages (b) 16 17 20 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Florida Corporate governance and shared service expenses (a) $ 309 $ 346 $ 182 Indemnification coverages (b) 22 16 14 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 342 $ 316 $ 347 Indemnification coverages (b) 6 13 15 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 349 $ 384 $ 422 Indemnification coverages (b) 9 11 14 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These amounts are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power under the JDA are recorded in Operating Revenues on the 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 Consolidated Statements of Operations and Comprehensive Income. (d) In 2013, Progress Energy Service Company (PESC), a consolidated subsidiary of Progress Energy, charged a proportionate share of corporate governance and other costs to consolidated affiliates of Duke Energy. Corporate governance and other shared costs were primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These charges were recorded as an offset to Operation, maintenance and other in the Consolidated Statements of Operations and Comprehensive Income. Effective January 1, 2014, PESC was contributed to Duke Energy Corporate Services (DECS), a consolidated subsidiary of Duke Energy, and these costs were no longer charged out of Progress Energy. Progress Energy recorded a non-cash after-tax equity transfer related to the contribution of PESC to DECS in its Consolidated Statements of Changes in Common Stockholder's Equity.
Intercompany Income Tax Receivable	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 for the subsidiary registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana December 31, 2015 Intercompany income tax receivable $ 122 $ 120 $ 104 $ — $ 54 $ — Intercompany income tax payable — — — 96 — 47 December 31, 2014 Intercompany income tax receivable $ 43 $ 713 $ 267 $ 174 $ 39 $ 95
Duke Energy Ohio [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 914 $ 851 $ 927 Indemnification coverages (b) 24 21 22 JDA revenue (c) 51 133 121 JDA expense (c) 183 198 116 Progress Energy Corporate governance and shared services provided by Duke Energy (a) $ 712 $ 732 $ 290 Corporate governance and shared services provided to Duke Energy (d) — — 96 Indemnification coverages (b) 38 33 34 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Progress Corporate governance and shared service expenses (a) $ 403 $ 386 $ 266 Indemnification coverages (b) 16 17 20 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Florida Corporate governance and shared service expenses (a) $ 309 $ 346 $ 182 Indemnification coverages (b) 22 16 14 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 342 $ 316 $ 347 Indemnification coverages (b) 6 13 15 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 349 $ 384 $ 422 Indemnification coverages (b) 9 11 14 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These amounts are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power under the JDA are recorded in Operating Revenues on the 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 Consolidated Statements of Operations and Comprehensive Income. (d) In 2013, Progress Energy Service Company (PESC), a consolidated subsidiary of Progress Energy, charged a proportionate share of corporate governance and other costs to consolidated affiliates of Duke Energy. Corporate governance and other shared costs were primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These charges were recorded as an offset to Operation, maintenance and other in the Consolidated Statements of Operations and Comprehensive Income. Effective January 1, 2014, PESC was contributed to Duke Energy Corporate Services (DECS), a consolidated subsidiary of Duke Energy, and these costs were no longer charged out of Progress Energy. Progress Energy recorded a non-cash after-tax equity transfer related to the contribution of PESC to DECS in its Consolidated Statements of Changes in Common Stockholder's Equity.
Intercompany Income Tax Receivable	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 for the subsidiary registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana December 31, 2015 Intercompany income tax receivable $ 122 $ 120 $ 104 $ — $ 54 $ — Intercompany income tax payable — — — 96 — 47 December 31, 2014 Intercompany income tax receivable $ 43 $ 713 $ 267 $ 174 $ 39 $ 95
Duke Energy Indiana [Member]
Related Party Transaction [Line Items]
Related Party Transactions, Other Revenue and Expense	Material amounts related to transactions with related parties included in the Consolidated Statements of Operations and Comprehensive Income are presented in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy Carolinas Corporate governance and shared service expenses (a) $ 914 $ 851 $ 927 Indemnification coverages (b) 24 21 22 JDA revenue (c) 51 133 121 JDA expense (c) 183 198 116 Progress Energy Corporate governance and shared services provided by Duke Energy (a) $ 712 $ 732 $ 290 Corporate governance and shared services provided to Duke Energy (d) — — 96 Indemnification coverages (b) 38 33 34 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Progress Corporate governance and shared service expenses (a) $ 403 $ 386 $ 266 Indemnification coverages (b) 16 17 20 JDA revenue (c) 183 198 116 JDA expense (c) 51 133 121 Duke Energy Florida Corporate governance and shared service expenses (a) $ 309 $ 346 $ 182 Indemnification coverages (b) 22 16 14 Duke Energy Ohio Corporate governance and shared service expenses (a) $ 342 $ 316 $ 347 Indemnification coverages (b) 6 13 15 Duke Energy Indiana Corporate governance and shared service expenses (a) $ 349 $ 384 $ 422 Indemnification coverages (b) 9 11 14 (a) The Subsidiary Registrants are charged their proportionate share of corporate governance and other shared services costs, primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These amounts are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (b) The Subsidiary Registrants incur expenses related to certain indemnification coverages through Bison, Duke Energy’s wholly owned captive insurance subsidiary. These expenses are recorded in Operation, maintenance and other on the Consolidated Statements of Operations and Comprehensive Income. (c) Duke Energy Carolinas and Duke Energy Progress participate in a JDA which allows the collective dispatch of power plants between the service territories to reduce customer rates. Revenues from the sale of power under the JDA are recorded in Operating Revenues on the 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 Consolidated Statements of Operations and Comprehensive Income. (d) In 2013, Progress Energy Service Company (PESC), a consolidated subsidiary of Progress Energy, charged a proportionate share of corporate governance and other costs to consolidated affiliates of Duke Energy. Corporate governance and other shared costs were primarily related to human resources, employee benefits, legal and accounting fees, as well as other third-party costs. These charges were recorded as an offset to Operation, maintenance and other in the Consolidated Statements of Operations and Comprehensive Income. Effective January 1, 2014, PESC was contributed to Duke Energy Corporate Services (DECS), a consolidated subsidiary of Duke Energy, and these costs were no longer charged out of Progress Energy. Progress Energy recorded a non-cash after-tax equity transfer related to the contribution of PESC to DECS in its Consolidated Statements of Changes in Common Stockholder's Equity.
Intercompany Income Tax Receivable	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 for the subsidiary registrants. Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Carolinas Energy Progress Florida Ohio Indiana December 31, 2015 Intercompany income tax receivable $ 122 $ 120 $ 104 $ — $ 54 $ — Intercompany income tax payable — — — 96 — 47 December 31, 2014 Intercompany income tax receivable $ 43 $ 713 $ 267 $ 174 $ 39 $ 95

Derivatives and Hedging (Tables

Derivatives and Hedging (Tables)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Notional Amounts of Outstanding Derivative Positions	The following table shows notional amounts for derivatives related to interest rate risk. December 31, 2015 December 31, 2014 Duke Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Duke Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Energy Energy Florida Ohio Cash flow hedges (a) $ 700 $ — $ — $ — $ — $ — $ 750 $ — $ — $ — Undesignated contracts 1,827 400 500 250 250 27 277 250 250 27 Total notional amount $ 2,527 $ 400 $ 500 $ 250 $ 250 $ 27 $ 1,027 $ 250 $ 250 $ 27 (a) Duke Energy includes amounts related to consolidated Variable Interest Entities (VIEs) of $497 million and $541 million at December 31, 2015 and 2014 , respectively. The tables below show information relating to volumes of outstanding commodity derivatives. Amounts disclosed represent the absolute value of notional volumes of commodity contracts excluding NPNS. The Duke Energy Registrants have netted contractual amounts where offsetting purchase and sale contracts exist with identical delivery locations and times of delivery. Where all commodity positions are perfectly offset, no quantities are shown. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Energy Carolinas Energy Progress Florida Ohio Indiana Electricity (gigawatt-hours) 70 — — — — 34 36 Natural gas (millions of decatherms) 398 66 332 117 215 — — December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy Energy Carolinas Energy Progress Florida Ohio Indiana Electricity (gigawatt-hours) (a)(b) 25,370 — — — — 19,141 — Natural gas (millions of decatherms) (a) 676 35 328 116 212 313 — (a) Duke Energy Ohio includes amounts related to the Disposal Group. Refer to Note 2 for further information on the sale. (b) Amounts at Duke Energy Ohio include intercompany positions that eliminate at Duke Energy.
Location and Fair Value of Derivatives Recognized in the Consolidated Balance Sheets	The following tables show the fair value and balance sheet location of derivative instruments. Although derivatives subject to master netting arrangements are netted on the Consolidated Balance Sheets, the fair values presented below are shown gross and cash collateral on the derivatives has not been netted against the fair values shown. Derivative Assets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Not Designated as Hedging Instruments Current 12 — 1 — 1 3 7 Noncurrent 4 — 4 — 4 — — Total Derivative Assets – Commodity Contracts $ 16 $ — $ 5 $ — $ 5 $ 3 $ 7 Interest Rate Contracts Designated as Hedging Instruments Noncurrent $ 4 $ — $ — $ — $ — $ — $ — Not Designated as Hedging Instruments Current 6 — 6 2 2 — — Total Derivative Assets – Interest Rate Contracts $ 10 $ — $ 6 $ 2 $ 2 $ — $ — Total Derivative Assets $ 26 $ — $ 11 $ 2 $ 7 $ 3 $ 7 Derivative Liabilities December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Not Designated as Hedging Instruments Current $ 256 $ 32 $ 222 $ 77 $ 145 $ — $ — Noncurrent 100 8 92 16 71 — — Total Derivative Liabilities – Commodity Contracts $ 356 $ 40 $ 314 $ 93 $ 216 $ — $ — Interest Rate Contracts Designated as Hedging Instruments Current $ 11 $ — $ — $ — $ — $ — $ — Noncurrent 33 — — — — — — Not Designated as Hedging Instruments Current 4 — 3 — — 1 — Noncurrent 15 5 5 5 — 6 — Total Derivative Liabilities – Interest Rate Contracts $ 63 $ 5 $ 8 $ 5 $ — $ 7 $ — Total Derivative Liabilities $ 419 $ 45 $ 322 $ 98 $ 216 $ 7 $ — Derivative Assets December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Not Designated as Hedging Instruments Current Assets: Other $ 18 $ — $ — $ — $ — $ 1 $ 14 Current Assets: Assets held for sale 15 — — — — 28 — Investments and Other Assets: Other 3 — — — — — — Investments and Other Assets: Assets held for sale 15 — — — — 26 — Current Liabilities: Other 1 — — — — — — Current Liabilities: Assets held for sale 174 — — — — 175 — Deferred Credits and Other Liabilities: Other 2 — — — — — — Deferred Credits and Other Liabilities: Assets held for sale 111 — — — — 111 — Total Derivative Assets – Commodity Contracts $ 339 $ — $ — $ — $ — $ 341 $ 14 Interest Rate Contracts Designated as Hedging Instruments Investments and Other Assets: Other 10 — — — — — — Not Designated as Hedging Instruments Current Assets: Other 2 — 2 — 2 — — Total Derivative Assets – Interest Rate Contracts $ 12 $ — $ 2 $ — $ 2 $ — $ — Total Derivative Assets $ 351 $ — $ 2 $ — $ 2 $ 341 $ 14 Derivative Liabilities December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Commodity Contracts Designated as Hedging Instruments Current Liabilities: Other $ — $ — $ 1 $ 1 $ — $ — $ — Not Designated as Hedging Instruments Current Assets: Assets held for sale — — — — — 4 — Investments and Other Assets: Assets held for sale — — — — — 4 — Current Liabilities: Other 307 14 288 108 180 — — Current Liabilities: Assets held for sale 253 — — — — 252 — Deferred Credits and Other Liabilities: Other 91 5 80 23 57 — — Deferred Credits and Other Liabilities: Assets held for sale 208 — — — — 207 — Total Derivative Liabilities – Commodity Contracts $ 859 $ 19 $ 369 $ 132 $ 237 $ 467 $ — Interest Rate Contracts Designated as Hedging Instruments Current Liabilities: Other $ 13 $ — $ — $ — $ — $ — $ — Deferred Credits and Other Liabilities: Other 29 — — — — — — Not Designated as Hedging Instruments Current Liabilities: Other 1 — — — — 1 — Deferred Credits and Other Liabilities: Other 7 — 2 — 2 5 — Total Derivative Liabilities – Interest Rate Contracts $ 50 $ — $ 2 $ — $ 2 $ 6 $ — Total Derivative Liabilities $ 909 $ 19 $ 371 $ 132 $ 239 $ 473 $ —
Offsetting Assets	Derivative Assets December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current (a) Gross amounts recognized $ 210 $ — $ 2 $ — $ 2 $ 204 $ 14 Gross amounts offset (153 ) — (2 ) — (2 ) (179 ) — Net amounts subject to master netting 57 — — — — 25 14 Amounts not subject to master netting — — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 57 $ — $ — $ — $ — $ 25 $ 14 Noncurrent (b) Gross amounts recognized $ 136 $ — $ — $ — $ — $ 137 $ — Gross amounts offset (88 ) — — — — (114 ) — Net amounts subject to master netting 48 — — — — 23 — Amounts not subject to master netting 5 — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 53 $ — $ — $ — $ — $ 23 $ — (a) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Current Assets on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Assets held for sale within Current Assets on the Condensed Consolidated Balance Sheets. (b) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Investments and Other Assets on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Assets held for sale within Investments and Other Assets on the Condensed Consolidated Balance Sheets. The following tables present the line items on the Consolidated Balance Sheets where derivatives are reported. Substantially all of Duke Energy's outstanding derivative contracts are subject to enforceable master netting arrangements. The Gross amounts offset in the tables below show the effect of these netting arrangements on financial position, and include collateral posted to offset the net position. The amounts shown are calculated by counterparty. Accounts receivable or accounts payable may also be available to offset exposures in the event of bankruptcy. These amounts are not included in the tables below. Derivative Assets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current Gross amounts recognized $ 18 $ — $ 7 $ 2 $ 3 $ 3 $ 7 Gross amounts offset (3 ) — (2 ) — (2 ) — — Net amounts presented in Current Assets: Other $ 15 $ — $ 5 $ 2 $ 1 $ 3 $ 7 Noncurrent Gross amounts recognized $ 8 $ — $ 4 $ — $ 4 $ — $ — Gross amounts offset (4 ) — (4 ) — (4 ) — — Net amounts presented in Investments and Other Assets: Other $ 4 $ — $ — $ — $ — $ — $ —
Offsetting Liabilities	Derivative Liabilities December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current Gross amounts recognized $ 271 $ 32 $ 225 $ 77 $ 145 $ 1 $ — Gross amounts offset (22 ) — (21 ) (1 ) (20 ) — — Net amounts presented in Current Liabilities: Other $ 249 $ 32 $ 204 $ 76 $ 125 $ 1 $ — Noncurrent Gross amounts recognized $ 148 $ 13 $ 97 $ 21 $ 71 $ 6 $ — Gross amounts offset (16 ) — (15 ) — (15 ) — — Net amounts presented in Deferred Credits and Other Liabilities: Other $ 132 $ 13 $ 82 $ 21 $ 56 $ 6 $ — Derivative Liabilities December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current (c) Gross amounts recognized $ 573 $ 14 $ 289 $ 109 $ 180 $ 257 $ — Gross amounts offset (213 ) — (17 ) — (17 ) (222 ) — Net amounts subject to master netting 360 14 272 109 163 35 — Amounts not subject to master netting 1 — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 361 $ 14 $ 272 $ 109 $ 163 $ 35 $ — Noncurrent (d) Gross amounts recognized $ 319 $ 5 $ 82 $ 23 $ 59 $ 216 $ — Gross amounts offset (173 ) — (8 ) — (8 ) (193 ) — Net amounts subject to master netting 146 5 74 23 51 23 — Amounts not subject to master netting 16 — — — — — — Net amounts recognized on the Condensed Consolidated Balance Sheet $ 162 $ 5 $ 74 $ 23 $ 51 $ 23 $ — (c) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Current Liabilities on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Liabilities associated with assets held for sale within Current Liabilities on the Condensed Consolidated Balance Sheets. (d) Amounts for Duke Energy Registrants, except Duke Energy and Duke Energy Ohio, are included in Other within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets. Amounts for Duke Energy and Duke Energy Ohio are included in Other and Liabilities associated with assets held for sale within Deferred Credits and Other Liabilities on the Condensed Consolidated Balance Sheets.
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 Indiana were not material. December 31, 2015 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Aggregate fair value of derivatives in a net liability position $ 334 $ 45 $ 290 $ 93 $ 194 $ — Fair value of collateral already posted 30 — 30 — 30 — Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 304 45 260 93 164 — December 31, 2014 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio (a) Aggregate fair value of derivatives in a net liability position $ 845 $ 19 $ 370 $ 131 $ 239 $ 456 Fair value of collateral already posted 209 — 23 — 23 186 Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered 407 19 347 131 216 41 (a) Duke Energy Ohio includes amounts related to the Disposal Group for the year ended December 31, 2014. The Duke Energy Registrants have elected to offset cash collateral and fair values of derivatives. For amounts to be netted, the derivative must be executed with the same counterparty under the same master netting arrangement. Amounts disclosed below represent the receivables related to the right to reclaim cash collateral under master netting arrangements. December 31, 2015 December 31, 2014 (in millions) Receivables Receivables Duke Energy Amounts offset against net derivative positions $ 30 $ 145 Amounts not offset against net derivative positions — 64 Progress Energy Amounts offset against net derivative positions 30 23 Duke Energy Florida Amounts offset against net derivative positions 30 23 Duke Energy Ohio Amounts offset against net derivative positions — 122 Amounts not offset against net derivative positions — 64

Investments in Debt and Equit49

Investments in Debt and Equity Securities (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-For-Sale Investments	The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 179 $ — $ — $ 136 Equity securities 1,823 58 3,590 1,926 29 3,650 Corporate debt securities 7 8 432 14 2 454 Municipal bonds 5 1 185 5 — 184 U.S. government bonds 11 5 1,254 19 2 978 Other debt securities — 4 177 1 2 147 Total NDTF (c) $ 1,846 $ 76 $ 5,817 $ 1,965 $ 35 $ 5,549 Other Investments Cash and cash equivalents $ — $ — $ 29 $ — $ — $ 15 Equity securities 32 1 95 34 — 96 Corporate debt securities 1 3 92 1 1 58 Municipal bonds 3 1 74 3 1 76 U.S. government bonds — — 45 — — 27 Other debt securities — 2 62 1 1 80 Total Other Investments (a) $ 36 $ 7 $ 397 $ 39 $ 3 $ 352 Total Investments $ 1,882 $ 83 $ 6,214 $ 2,004 $ 38 $ 5,901 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts are considered other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) The increase in estimated fair value of the NDTF as of December 31, 2015 , is primarily due to NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets and the NDTF assets acquired in a settlement with FMJO. This is partially offset due to reimbursements from the NDTF for Duke Energy Florida's costs related to ongoing decommissioning activity of the Crystal River Unit 3 Nuclear Plant. Refer to Note 2 for further information.
Schedule of Maturity Dates for Debt Securities	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less 120 Due after one through five years 775 Due after five through 10 years 598 Due after 10 years 828 Total 2,321
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. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 193 $ 271 $ 209 Realized losses 98 105 65
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-For-Sale Investments	The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 34 $ — $ — $ 51 Equity securities 1,021 27 2,094 1,102 17 2,162 Corporate debt securities 3 5 292 8 2 316 Municipal bonds 1 — 33 1 — 62 U.S. government bonds 3 3 438 7 1 308 Other debt securities — 4 147 1 2 133 Total NDTF $ 1,028 $ 39 $ 3,038 $ 1,119 $ 22 $ 3,032 Other Investments Other debt securities $ — $ 1 $ 3 $ — $ 1 $ 3 Total Other Investments (a) $ — $ 1 $ 3 $ — $ 1 $ 3 Total Investments $ 1,028 $ 40 $ 3,041 $ 1,119 $ 23 $ 3,035 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.
Schedule of Maturity Dates for Debt Securities	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 13 Due after one through five years 187 Due after five through 10 years 275 Due after 10 years 438 Total $ 913
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. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 158 $ 109 $ 115 Realized losses 83 93 12
Progress Energy [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-For-Sale Investments	The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 145 $ — $ — $ 85 Equity securities 802 31 1,496 824 12 1,488 Corporate debt securities 4 3 140 6 — 138 Municipal bonds 4 1 152 4 — 122 U.S. government bonds 8 2 816 12 1 670 Other debt securities — — 30 — — 14 Total NDTF (c) $ 818 $ 37 $ 2,779 $ 846 $ 13 $ 2,517 Other Investments Cash and cash equivalents $ — $ — $ 18 $ — $ — $ 15 Municipal bonds 3 — 45 3 — 43 Total Other Investments (a) $ 3 $ — $ 63 $ 3 $ — $ 58 Total Investments $ 821 $ 37 $ 2,842 $ 849 $ 13 $ 2,575 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts are considered other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) The increase in estimated fair value of the NDTF as of December 31, 2015 , is primarily due to NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets and the NDTF assets acquired in a settlement with FMJO. This is partially offset due to reimbursements from the NDTF for Duke Energy Florida's costs related to ongoing decommissioning activity of the Crystal River Unit 3 Nuclear Plant. Refer to Note 2 for further information.
Schedule of Maturity Dates for Debt Securities	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 94 Due after one through five years 496 Due after five through 10 years 254 Due after 10 years 339 Total $ 1,183
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. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 33 $ 157 $ 90 Realized losses 13 11 46
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-For-Sale Investments	The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 110 $ — $ — $ 50 Equity securities 596 25 1,178 612 10 1,171 Corporate debt securities 3 2 96 5 — 97 Municipal bonds 4 1 150 4 — 120 U.S. government bonds 6 2 486 9 1 265 Other debt securities — — 18 — — 8 Total NDTF (c) $ 609 $ 30 $ 2,038 $ 630 $ 11 $ 1,711 Other Investments Cash and cash equivalents $ — $ — $ 1 $ — $ — $ — Total Other Investments (a) $ — $ — $ 1 $ — $ — $ — Total Investments $ 609 $ 30 $ 2,039 $ 630 $ 11 $ 1,711 (a) These amounts are recorded in Other with Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) As of December 31, 2015 , the estimated fair value of the NDTF includes NDTF assets acquired with the purchase of NCEMPA's ownership interest in certain generating assets. Refer to Note 2 for further information.
Schedule of Maturity Dates for Debt Securities	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 15 Due after one through five years 285 Due after five through 10 years 206 Due after 10 years 244 Total $ 750
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. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 26 $ 19 $ 58 Realized losses 11 5 26
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-For-Sale Investments	The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value NDTF Cash and cash equivalents $ — $ — $ 35 $ — $ — $ 35 Equity securities 206 6 318 212 2 317 Corporate debt securities 1 1 44 1 — 41 Municipal bonds — — 2 — — 2 U.S. government bonds 2 — 330 3 — 405 Other debt securities — — 12 — — 6 Total NDTF (c) $ 209 $ 7 $ 741 $ 216 $ 2 $ 806 Other Investments Cash and cash equivalents $ — $ — $ 6 $ — $ — $ 1 Municipal bonds 3 — 45 3 — 43 Total Other Investments (a) $ 3 $ — $ 51 $ 3 $ — $ 44 Total Investments $ 212 $ 7 $ 792 $ 219 $ 2 $ 850 (a) These amounts are recorded in Other with Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset. (c) The decrease in estimated fair value of the NDTF as of December 31, 2015 , is primarily due to reimbursements from the NDTF for costs related to ongoing decommissioning activity of the Crystal River Unit 3 Nuclear Plant, partially offset by the NDTF asset acquired in a settlement with FMJO. Refer to Note 2 for further information.
Schedule of Maturity Dates for Debt Securities	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 79 Due after one through five years 211 Due after five through 10 years 48 Due after 10 years 95 Total $ 433
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. Years Ended December 31, (in millions) 2015 2014 2013 Realized gains $ 7 $ 138 $ 32 Realized losses 2 5 20
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-For-Sale Investments	The following table presents the estimated fair value of investments in available-for-sale securities. December 31, 2015 December 31, 2014 Gross Gross Gross Gross Unrealized Unrealized Unrealized Unrealized Holding Holding Estimated Holding Holding Estimated (in millions) Gains Losses (b) Fair Value Gains Losses (b) Fair Value Other Investments Cash and cash equivalents $ — $ — $ 2 $ — $ — $ — Equity securities 27 — 71 28 — 71 Corporate debt securities — — 2 — — — Municipal bonds — 1 26 — 1 30 Total Other Investments (a) $ 27 $ 1 $ 101 $ 28 $ 1 $ 101 Total Investments $ 27 $ 1 $ 101 $ 28 $ 1 $ 101 (a) These amounts are recorded in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Substantially all these amounts represent other-than-temporary impairments on investments within Investment Trusts that have been recognized immediately as a regulatory asset.
Schedule of Maturity Dates for Debt Securities	The table below summarizes the maturity date for debt securities. (in millions) December 31, 2015 Due in one year or less $ 2 Due after one through five years 14 Due after five through 10 years 9 Due after 10 years 3 Total $ 28

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 3,590 $ 3,418 $ — $ — $ 172 Nuclear decommissioning trust fund debt securities 2,227 672 1,555 — Other available-for-sale equity securities 95 95 — — — Other available-for-sale debt securities 302 75 222 5 Derivative assets 26 — 16 10 Total assets 6,240 4,260 1,793 15 172 Derivative liabilities (419 ) — (419 ) — Net assets $ 5,821 $ 4,260 $ 1,374 $ 15 $ 172 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 3,650 $ 3,493 $ 6 $ — $ 151 Nuclear decommissioning trust fund debt securities 1,899 648 1,251 — Other trading and available-for-sale equity securities 96 96 — — — Other trading and available-for-sale debt securities 263 41 217 5 Derivative assets 110 49 24 37 Total assets 6,018 4,327 1,498 42 151 Derivative liabilities (668 ) (162 ) (468 ) (38 ) Net assets $ 5,350 $ 4,165 $ 1,030 $ 4 $ 151
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. December 31, 2015 Derivatives (in millions) Investments (net) Total Balance at beginning of period $ 5 $ (1 ) $ 4 Total pretax realized or unrealized gains (losses) included in earnings — 21 21 Purchases, sales, issuances and settlements: Purchases — 24 24 Sales — (1 ) (1 ) Settlements — (37 ) (37 ) Total gains included on the Consolidated Balance Sheet as regulatory assets or liabilities — 4 4 Balance at end of period $ 5 $ 10 $ 15 December 31, 2014 Derivatives (in millions) Investments (net) Total Balance at beginning of period $ 20 $ 13 $ 33 Total pretax realized or unrealized gains (losses) included in earnings — (7 ) (7 ) Purchases, sales, issuances and settlements: Purchases — 50 50 Sales (15 ) — (15 ) Settlements — (54 ) (54 ) Net transfers In (Out) of Level 3 due to observability of inputs — 6 6 Total losses included on the Consolidated Balance Sheet as regulatory assets or liabilities — (9 ) (9 ) Balance at end of period $ 5 $ (1 ) $ 4 Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding $ — $ (14 ) $ (14 )
Schedule of Long-term debt, including current	The fair value and book value of long-term debt, including current maturities, is summarized in the following table. Estimates determined are not necessarily indicative of amounts that could have been settled in current markets. Fair value of long-term debt uses Level 2 measurements. December 31, 2015 December 31, 2014 (in millions) Book Value Fair Value Book Value Fair Value Duke Energy $ 39,569 $ 42,537 $ 39,868 $ 44,566 Duke Energy Carolinas 8,367 9,156 8,353 9,626 Progress Energy 14,464 15,856 14,668 16,951 Duke Energy Progress 6,518 6,757 6,170 6,696 Duke Energy Florida 4,266 4,908 4,823 5,767 Duke Energy Ohio 1,598 1,724 1,760 1,970 Duke Energy Indiana 3,768 4,219 3,769 4,456
Quantitative Information Table - Level 3	The following table includes quantitative information about the Duke Energy Registrants' derivatives classified as Level 3. December 31, 2015 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Financial transmission rights (FTRs) $ 10 RTO auction pricing FTR price – per Megawatt-Hour (MWh) $ (0.74 ) - 7.29 Duke Energy Ohio FTRs $ 3 RTO auction pricing FTR price – per MWh $ 0.67 - 2.53 Duke Energy Indiana FTRs $ 7 RTO auction pricing FTR price – per MWh $ (0.74 ) - 7.29 December 31, 2014 Fair Value Investment Type (in millions) Valuation Technique Unobservable Input Range Duke Energy Natural gas contracts $ (5 ) Discounted cash flow Forward natural gas curves – price per Million British Thermal Unit (MMBtu) $ 2.12 - 4.35 FTRs 14 RTO auction pricing FTR price – per MWh (1.92 ) - 9.86 Electricity contracts (1 ) Discounted cash flow Forward electricity curves – price per MWh 25.16 - 51.75 Commodity capacity option contracts 2 Discounted cash flow Forward capacity option curves – price per MW day 21.00 - 109.00 Reserves (11 ) Bid-ask spreads, implied volatility, probability of default Total Level 3 derivatives $ (1 ) Duke Energy Ohio Electricity contracts $ (6 ) Discounted cash flow Forward electricity curves – price per MWh $ 25.25 - 51.75 Natural gas contracts (5 ) Discounted cash flow Forward natural gas curves – price per MMBtu 2.12 - 4.35 Reserves (7 ) Bid-ask spreads, implied volatility, probability of default Total Level 3 derivatives $ (18 ) Duke Energy Indiana FTRs $ 14 RTO auction pricing FTR price – per MWh $ (1.92 ) - 9.86
Duke Energy Carolinas [Member]
Fair Value Disclosures [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,094 $ 1,922 $ — $ — $ 172 Nuclear decommissioning trust fund debt securities 944 246 698 — Other available-for-sale debt securities 3 — — 3 Total assets 3,041 2,168 698 3 172 Derivative liabilities (45 ) — (45 ) — Net assets $ 2,996 $ 2,168 $ 653 $ 3 $ 172 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Not categorized Nuclear decommissioning trust fund equity securities $ 2,162 $ 2,005 $ 6 $ — $ 151 Nuclear decommissioning trust fund debt securities 870 138 732 — Other trading and available-for-sale debt securities 3 — — 3 Total assets 3,035 2,143 738 3 151 Derivative liabilities (19 ) — (19 ) — Net assets $ 3,016 $ 2,143 $ 719 $ 3 $ 151
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following tables provide a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. There was no change to the Level 3 balance during the year ended December 31, 2015. December 31, 2014 Derivatives (in millions) Investments (net) Total Balance at beginning of period $ 3 $ (2 ) $ 1 Settlements — 2 2 Balance at end of period $ 3 $ — $ 3
Progress Energy [Member]
Fair Value Disclosures [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,496 $ 1,496 $ — $ — Nuclear decommissioning trust fund debt securities 1,283 426 857 — Other available-for-sale debt securities 63 18 45 — Derivative assets 11 — 11 — Total assets 2,853 1,940 913 — Derivative liabilities (322 ) — (322 ) — Net assets $ 2,531 $ 1,940 $ 591 $ — December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,488 $ 1,488 $ — $ — Nuclear decommissioning trust fund debt securities 1,029 510 519 — Other trading and available-for-sale debt securities 58 15 43 — Derivative assets 4 — 4 — Total assets 2,579 2,013 566 — Derivative liabilities (373 ) — (373 ) — Net assets $ 2,206 $ 2,013 $ 193 $ —
Duke Energy Progress [Member]
Fair Value Disclosures [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,178 $ 1,178 $ — $ — Nuclear decommissioning trust fund debt securities and other 860 141 719 — Other available-for-sale debt securities and other 1 1 — — Derivative assets 2 — 2 — Total assets 2,041 1,320 721 — Derivative liabilities (98 ) — (98 ) — Net assets $ 1,943 $ 1,320 $ 623 $ — December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 1,171 $ 1,171 $ — $ — Nuclear decommissioning trust fund debt securities and other 540 151 389 — Total assets 1,711 1,322 389 — Derivative liabilities (132 ) — (132 ) — Net assets $ 1,579 $ 1,322 $ 257 $ —
Duke Energy Florida [Member]
Fair Value Disclosures [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 318 $ 318 $ — $ — Nuclear decommissioning trust fund debt securities and other 423 285 138 — Other available-for-sale debt securities and other 51 6 45 — Derivative assets 7 — 7 — Total assets 799 609 190 — Derivative liabilities (216 ) — (216 ) — Net assets (liabilities) $ 583 $ 609 $ (26 ) $ — December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Nuclear decommissioning trust fund equity securities $ 317 $ 317 $ — $ — Nuclear decommissioning trust fund debt securities and other 489 359 130 — Other trading and available-for-sale debt securities and other 44 — 44 — Derivative assets 4 — 4 — Total assets 854 676 178 — Derivative liabilities (241 ) — (241 ) — Net assets (liabilities) $ 613 $ 676 $ (63 ) $ —
Duke Energy Ohio [Member]
Fair Value Disclosures [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which are disclosed in Note 14 . December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 3 $ — $ — $ 3 Derivative liabilities (7 ) — (7 ) — Net assets (liabilities) $ (4 ) $ — $ (7 ) $ 3 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Derivative assets $ 49 $ 20 $ 9 $ 20 Derivative liabilities (181 ) (117 ) (26 ) (38 ) Net assets (liabilities) $ (132 ) $ (97 ) $ (17 ) $ (18 )
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2015 2014 Balance at beginning of period $ (18 ) $ (4 ) Total pretax realized or unrealized gains (losses) included in earnings 21 (9 ) Purchases, sales, issuances and settlements: Purchases 5 1 Settlements (5 ) (13 ) Net transfers In (Out) of Level 3 due to observability of inputs — 6 Total gains included on the Consolidated Balance Sheet as regulatory assets or liabilities — 1 Balance at end of period $ 3 $ (18 )
Duke Energy Indiana [Member]
Fair Value Disclosures [Line Items]
Fair Value Measurement Amounts For Assets And Liabilities	The following tables provide recorded balances for assets and liabilities measured at fair value on a recurring basis on the Consolidated Balance Sheets. Derivative amounts in the table below exclude cash collateral, which is disclosed in Note 14 . See Note 15 for additional information related to investments by major security type. December 31, 2015 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other available-for-sale equity securities $ 71 $ 71 $ — $ — Other available-for-sale debt securities and other 30 2 28 — Derivative assets 7 — — 7 Net assets (liabilities) $ 108 $ 73 $ 28 $ 7 December 31, 2014 (in millions) Total Fair Value Level 1 Level 2 Level 3 Other trading and available-for-sale equity securities $ 71 $ 71 $ — $ — Other trading and available-for-sale debt securities and other 30 — 30 — Derivative assets 14 — — 14 Net assets (liabilities) $ 115 $ 71 $ 30 $ 14
Reconciliation Of Assets And Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs	The following table provides a reconciliation of beginning and ending balances of assets and liabilities measured at fair value using Level 3 measurements. Derivatives (net) Years Ended December 31, (in millions) 2015 2014 Balance at beginning of period $ 14 $ 12 Total pretax realized or unrealized gains included in earnings — 3 Purchases, sales, issuances and settlements: Purchases 19 49 Settlements (30 ) (41 ) Total gains (losses) included on the Consolidated Balance Sheet as regulatory assets or liabilities 4 (9 ) Balance at end of period $ 7 $ 14

Variable Interest Entities (Tab

Variable Interest Entities (Tables)	12 Months Ended
	Dec. 31, 2015
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	The following table outlines amounts and expiration dates of the credit facilities. DERF DEPR DEFR Credit facility amount (in millions) $ 425 $ 300 $ 225 Expiration date December 2018 February 2019 March 2017 The following tables summarize the impact of VIEs consolidated by Duke Energy and the Subsidiary Registrants on the Consolidated Balance Sheets. December 31, 2015 Duke Energy Duke Duke Duke Energy Energy Energy Carolinas Progress Florida (in millions) DERF DEPR (c) DEFR (c) CRC Renewables Other Total ASSETS Current Assets Cash and Cash Equivalents $ — $ — $ — $ — $ — $ 2 $ 2 Restricted receivables of variable interest entities (net of allowance for doubtful accounts) 596 349 309 454 19 21 1,748 Other — — — — 138 4 142 Investments and Other Assets Other — — — — 70 — 70 Property, Plant and Equipment Property, plant and equipment, cost (a) — — — — 2,015 20 2,035 Accumulated depreciation and amortization — — — — (321 ) (6 ) (327 ) Total assets $ 596 $ 349 $ 309 $ 454 $ 1,921 $ 41 $ 3,670 LIABILITIES AND EQUITY Current Liabilities Accounts payable — — — — 35 — 35 Taxes accrued 5 3 — — 5 1 14 Current maturities of long-term debt — — — — 108 17 125 Other — — — — 15 2 17 Long-Term Debt (b) 425 254 225 325 968 — 2,197 Deferred Credits and Other Liabilities Deferred income taxes — — — — 289 — 289 Asset retirement obligations — — — — 35 — 35 Other — — — — 33 — 33 Total liabilities $ 430 $ 257 $ 225 $ 325 $ 1,488 $ 20 $ 2,745 Net assets of consolidated variable interest entities $ 166 $ 92 $ 84 $ 129 $ 433 $ 21 $ 925 December 31, 2014 Duke Energy Duke Duke Duke Energy Energy Energy Carolinas Progress Florida (in millions) DERF DEPR (c) DEFR (c) CRC Renewables Other Total ASSETS Current Assets Restricted receivables of variable interest entities (net of allowance for doubtful accounts) $ 647 $ 436 $ 305 $ 547 $ 20 $ 18 $ 1,973 Other — — — — 68 6 74 Investments and Other Assets Other — — — — 25 25 50 Property, Plant and Equipment Property, plant and equipment, cost (a) — — — — 1,855 18 1,873 Accumulated depreciation and amortization — — — — (250 ) (5 ) (255 ) Regulatory Assets and Deferred Debits Other — — — — 34 2 36 Total assets $ 647 $ 436 $ 305 $ 547 $ 1,752 $ 64 $ 3,751 LIABILITIES AND EQUITY Current Liabilities Accounts payable — — — 3 — 3 Taxes accrued — — — 6 — 6 Current maturities of long-term debt — — — 68 16 84 Other — — — 16 5 21 Long-Term Debt (b) 400 300 225 325 967 17 2,234 Deferred Credits and Other Liabilities Deferred income taxes — — — 283 — 283 Asset retirement obligations — — — 29 — 29 Other — — — 34 4 38 Total liabilities $ 400 $ 300 $ 225 $ 325 $ 1,406 $ 42 $ 2,698 Net assets of consolidated variable interest entities $ 247 $ 136 $ 80 $ 222 $ 346 $ 22 $ 1,053 (a) Restricted as collateral for non-recourse debt of VIEs. (b) Non-recourse to the general assets of the applicable registrant. (c) The amount for Progress Energy is equal to the total amount for Duke Energy Progress and Duke Energy Florida.
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	The tables below show VIEs not consolidated and how these entities impact the Consolidated Balance Sheets. December 31, 2015 Duke Energy Duke Duke Energy Energy (in millions) Renewables Other Total Ohio Indiana Receivables $ — $ — $ — $ 47 $ 60 Investments in equity method unconsolidated affiliates 235 152 387 — — Total assets $ 235 $ 152 $ 387 $ 47 $ 60 Other current liabilities — 3 3 — — Deferred credits and other liabilities — 14 14 — — Total liabilities $ — $ 17 $ 17 $ — $ — Net assets (liabilities) $ 235 $ 135 $ 370 $ 47 $ 60 December 31, 2014 Duke Energy Duke Duke Energy Energy (in millions) Renewables Other Total Ohio Indiana Receivables $ — $ — $ — $ 91 $ 113 Investments in equity method unconsolidated affiliates 150 38 188 — — Intangibles — — — — — Investments and other assets — 4 4 — — Total assets $ 150 $ 42 $ 192 $ 91 $ 113 Other current liabilities — 3 3 — — Deferred credits and other liabilities — 14 14 — — Total liabilities $ — $ 17 $ 17 $ — $ — Net assets $ 150 $ 25 $ 175 $ 91 $ 113
Cinergy Receivables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Schedule Of Variable Interest Entities	Key assumptions used in estimating fair value are detailed in the following table. Duke Energy Ohio Duke Energy Indiana 2015 2014 2015 2014 Anticipated credit loss ratio 0.6 % 0.6 % 0.3 % 0.3 % Discount rate 1.2 % 1.2 % 1.2 % 1.2 % Receivable turnover rate 12.9 % 12.8 % 10.6 % 10.5 % The following table shows the gross and net receivables sold. Duke Energy Ohio Duke Energy Indiana (in millions) 2015 2014 2015 2014 Receivables sold $ 233 $ 273 $ 260 $ 310 Less: Retained interests 47 91 60 113 Net receivables sold $ 186 $ 182 $ 200 $ 197 The following table shows sales and cash flows related to receivables sold. Duke Energy Ohio Duke Energy Indiana Years Ended December 31, Years Ended December 31, (in millions) 2015 2014 2013 2015 2014 2013 Sales Receivables sold $ 1,963 $ 2,246 $ 2,251 $ 2,627 $ 2,913 $ 2,985 Loss recognized on sale 9 11 12 11 11 11 Cash Flows Cash proceeds from receivables sold 1,995 2,261 2,220 2,670 2,932 2,944 Collection fees received 1 1 1 1 1 1 Return received on retained interests 3 4 5 5 6 6

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2015
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 stock outstanding to the diluted weighted average number of common stock outstanding. Years Ended December 31, (in millions, except per share amounts) 2015 2014 2013 Income from continuing operations attributable to Duke Energy common stockholders excluding impact of participating securities $ 2,791 $ 2,446 $ 2,565 Weighted average shares outstanding – basic 694 707 706 Weighted average shares outstanding – diluted 694 707 706 Earnings per share from continuing operations attributable to Duke Energy common stockholders Basic $ 4.02 3.46 3.64 Diluted $ 4.02 3.46 3.63 Potentially dilutive items excluded from the calculation (a) 2 2 2 Dividends declared per common share $ 3.24 3.15 3.09 (a) Performance stock awards and certain stock options were not included in the dilutive securities calculation because either the performance measures related to the awards had not been met or the option exercise prices were greater than the average market price of the common shares during the presented periods.

Severance (Tables)

Severance (Tables)	12 Months Ended
	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Schedule of Severance Expense	The following table presents direct and allocated severance and related expenses recorded by the Duke Energy Registrants associated with this plan. Amounts are included within Operation, maintenance and other on the Consolidated Statements of Operations. Amounts for 2014 and 2015 were not material. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy (a) Carolinas Energy Progress Florida Ohio Indiana Year Ended December 31, 2013 $ 34 $ 8 $ 19 $ 14 $ 5 $ 2 $ 2 (a) Includes $5 million of accelerated stock award expense and $2 million of COBRA and health care reimbursement expense. The following table presents the direct and allocated severance and related expenses recorded by the Duke Energy Registrants associated with these initiatives. Amounts are included within Operation, maintenance and other on the Consolidated Statements of Operations. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Year Ended December 31, 2015 $ 142 $ 93 $ 36 $ 28 $ 8 $ 2 $ 6
Schedule of Severance Liability	The table below presents the severance liability for past and ongoing severance plans including the plans described above. Amounts for Duke Energy Indiana and Duke Energy Ohio are not material. Duke Duke Duke Duke Energy Progress Energy Energy (in millions) Energy Carolinas Energy Progress Florida Balance at December 31, 2014 $ 28 $ 2 $ 18 $ 1 $ 17 Provision/Adjustments 144 80 20 20 — Cash Reductions (36 ) (4 ) (15 ) (2 ) (13 ) Balance at December 31, 2015 $ 136 $ 78 $ 23 $ 19 $ 4

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Schedule Of Total Stock-Based Compensation Expense, net of tax	The following table summarizes the total expense recognized by the Duke Energy Registrants, net of tax, for stock-based compensation. Years Ended December 31, (in millions) 2015 2014 2013 Duke Energy $ 38 $ 38 $ 52 Duke Energy Carolinas 14 12 13 Progress Energy 14 14 23 Duke Energy Progress 9 9 14 Duke Energy Florida 5 5 9 Duke Energy Ohio 2 5 4 Duke Energy Indiana 4 3 4
Schedule Of Stock-Based Compensation Expense	Duke Energy's pretax stock-based compensation costs, the tax benefit associated with stock-based compensation expense, and stock-based compensation costs capitalized are included in the following table. Years Ended December 31, (in millions) 2015 2014 2013 Restricted stock unit awards $ 38 $ 39 $ 49 Performance awards 23 22 34 Stock options — — 2 Pretax stock-based compensation cost $ 61 $ 61 $ 85 Tax benefit associated with stock-based compensation expense $ 23 $ 23 $ 33 Stock-based compensation costs capitalized 3 4 3
Schedule of Share-based Compensation, Stock Options, Activity	The following table summarizes information about stock options outstanding. Weighted Average Stock Options Exercise Price Weighted Average (in thousands) (per share) Remaining Life Outstanding at December 31, 2014 373 $ 64 Exercised (270 ) 62 Outstanding at December 31, 2015 (a) 103 69 7 years, 2 months (a) Outstanding stock options all vested on January 1, 2016.
Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Exercises	The following table summarizes additional information related to stock options exercised and granted. Years Ended December 31, 2015 2014 2013 Intrinsic value of options exercised (in millions) $ 5 $ 6 $ 26 Tax benefit related to options exercised (in millions) 2 2 10 Cash received from options exercised (in millions) 17 25 9 Stock options granted (in thousands) (a) — — 310 (a) Stock options granted in 2013 were expensed immediately.
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	The following table includes information related to restricted stock unit awards. Years Ended December 31, 2015 2014 2013 Shares awarded (in thousands) 524 557 612 Fair value (in millions) $ 41 $ 40 $ 42 The following table summarizes information about restricted stock unit awards outstanding. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2014 1,080 $ 69 Granted 524 79 Vested (602 ) 68 Forfeited (49 ) 73 Outstanding at December 31, 2015 953 75 Restricted stock unit awards expected to vest 924 75
Schedule of Performance Awards	The following table includes information related to stock-based performance awards. Years Ended December 31, 2015 2014 2013 Shares awarded (in thousands) 642 542 633 Fair value (in millions) $ 26 $ 19 $ 28
Schedule of Nonvested Performance-based Units Activity	The following table summarizes information about stock-based performance awards outstanding and assumes payout at the maximum level. Weighted Average Shares Grant Date Fair Value (in thousands) (per share) Outstanding at December 31, 2014 1,627 $ 42 Granted 642 41 Vested (271 ) 51 Forfeited (301 ) 38 Outstanding at December 31, 2015 1,697 40 Stock-based performance awards expected to vest 1,301 40

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension Plan Contributions	Duke Energy’s policy is to fund amounts on an actuarial basis to provide assets sufficient to meet benefit payments to be paid to plan participants. The following table includes information related to the Duke Energy Registrants’ contributions to its U.S. qualified defined benefit pension plans. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Anticipated Contributions: 2016 $ 145 $ 43 $ 43 $ 24 $ 20 $ 4 $ 9 Contributions Made: 2015 $ 302 $ 91 $ 83 $ 42 $ 40 $ 8 $ 19 2014 — — — — — — — 2013 250 — 250 63 133 — —
Employee Savings Plan Matching Contributions	The following table includes pretax employer matching contributions made by Duke Energy and expensed by the Subsidiary Registrants. Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Years ended December 31, 2015 (a) $ 159 $ 54 $ 48 $ 34 $ 13 $ 3 $ 7 2014 (a) 143 47 43 30 14 3 7 2013 134 45 45 25 14 3 7 (a) For 2014 and 2015, amounts include the additional employer contribution of 4 percent of eligible pay per pay period for employees not eligible to participate in a defined benefit plan.
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value and Allocation of Plan Assets	The following tables provide the fair value measurement amounts for the Duke Energy Master Retirement Trust qualified pension and other post-retirement assets. December 31, 2015 Total Fair Not (in millions) Value Level 1 Level 2 Level 3 Categorized (b) Equity securities $ 2,160 $ 1,470 $ 2 $ — 688 Corporate debt securities 4,362 — 4,362 — — Short-term investment funds 404 192 212 — — Partnership interests 185 — — — 185 Hedge funds 210 — — — 210 Real estate limited partnerships 118 — — — 118 U.S. government securities 748 — 748 — — Guaranteed investment contracts 31 — — 31 — Governments bonds – foreign 34 — 34 — — Cash 10 10 — — — Government and commercial mortgage backed securities 9 — 9 — — Net pending transactions and other investments (28 ) (36 ) 8 — — Total assets (a) $ 8,243 $ 1,636 $ 5,375 $ 31 $ 1,201 (a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana were allocated approximately 28 percent , 32 percent , 15 percent , 16 percent , 5 percent and 8 percent , respectively, of the Duke Energy Master Retirement Trust assets at December 31, 2015 . Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages. (b) Certain investments are not categorized. These investments are measured based on the fair value of the underlying investments but may not be readily redeemable at that fair value. December 31, 2014 Total Fair Not (in millions) Value Level 1 Level 2 Level 3 Categorized (b) Equity securities $ 2,346 $ 1,625 $ 3 $ — $ 718 Corporate debt securities 4,349 — 4,348 1 — Short-term investment funds 333 171 162 — — Partnership interests 298 — — — 298 Hedge funds 146 — — — 146 Real estate limited partnerships 104 — — — 104 U.S. government securities 917 — 916 1 — Guaranteed investment contracts 32 — — 32 — Governments bonds – foreign 44 — 44 — — Cash 30 30 — — — Government and commercial mortgage backed securities 9 — 9 — — Net pending transactions and other investments 10 (10 ) 20 — — Total assets (a) $ 8,618 $ 1,816 $ 5,502 $ 34 $ 1,266 (a) Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida, Duke Energy Ohio and Duke Energy Indiana were allocated approximately 28 percent , 31 percent , 15 percent , 16 percent , 5 percent and 8 percent , respectively, of the Duke Energy Master Retirement Trust assets at December 31, 2014 . Accordingly, all amounts included in the table above are allocable to the Subsidiary Registrants using these percentages. (b) Certain investments are not categorized. These investments are measured based on the fair value of the underlying investments but may not be readily redeemable at that fair value. The following table includes the target asset allocations by asset class at December 31, 2015 and the actual asset allocations for the Duke Energy Master Retirement Trust. Actual Allocation at December 31, Target Allocation 2015 2014 U.S. equity securities 10 % 11 % 10 % Non-U.S. equity securities 8 % 8 % 8 % Global equity securities 10 % 10 % 10 % Global private equity securities 3 % 2 % 3 % Debt securities 63 % 63 % 63 % Hedge funds 2 % 2 % 3 % Real estate and cash 2 % 2 % 1 % Other global securities 2 % 2 % 2 % Total 100 % 100 % 100 %
Master Trust Level 3 Rollforward	The following table provides a reconciliation of beginning and ending balances of assets of master trusts measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3). (in millions) 2015 2014 Balance at January 1 $ 34 $ 37 Sales (2 ) (4 ) Total gains (losses) and other, net (1 ) 1 Balance at December 31 $ 31 $ 34
Voluntary Employee Beneficiary Association [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value and Allocation of Plan Assets	The following table presents target and actual asset allocations for VEBA I at December 31, 2015 . Actual Allocation at Target December 31, Allocation 2015 2014 U.S. equity securities 30 % 29 % 29 % Debt securities 45 % 28 % 28 % Cash 25 % 43 % 43 % Total 100 % 100 % 100 % The following tables provide the fair value measurement amounts for VEBA I other post-retirement assets. December 31, 2015 Total Fair (in millions) Value Level 1 Level 2 Level 3 Cash and cash equivalents $ 18 — $ 18 — Equity securities 12 — 12 — Debt securities 12 — 12 — Total assets $ 42 — $ 42 — December 31, 2014 Total Fair (in millions) Value Level 1 Level 2 Level 3 Cash and cash equivalents $ 21 — $ 21 — Equity securities 14 — 14 — Debt securities 13 — 13 — Total assets $ 48 — $ 48 —
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Components of Net Periodic Pension Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 159 $ 50 $ 44 $ 23 $ 20 $ 4 $ 10 Interest cost on projected benefit obligation 324 83 104 48 54 18 27 Expected return on plan assets (516 ) (139 ) (171 ) (79 ) (87 ) (26 ) (42 ) Amortization of actuarial loss 166 39 65 33 31 7 13 Amortization of prior service (credit) cost (15 ) (7 ) (3 ) (2 ) (1 ) — 1 Other 8 2 3 1 1 — 1 Net periodic pension costs (a)(b) $ 126 $ 28 $ 42 $ 24 $ 18 $ 3 $ 10 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 135 $ 41 $ 40 $ 21 $ 20 $ 4 $ 9 Interest cost on projected benefit obligation 344 85 112 54 57 20 29 Expected return on plan assets (511 ) (132 ) (173 ) (85 ) (85 ) (27 ) (41 ) Amortization of actuarial loss 150 36 68 32 32 4 13 Amortization of prior service credit (15 ) (8 ) (3 ) (2 ) (1 ) — — Other 8 2 3 1 1 — 1 Net periodic pension costs (a)(b) $ 111 $ 24 $ 47 $ 21 $ 24 $ 1 $ 11 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 167 $ 49 $ 60 $ 22 $ 30 $ 6 $ 11 Interest cost on projected benefit obligation 320 80 116 50 53 21 28 Expected return on plan assets (549 ) (148 ) (199 ) (94 ) (87 ) (31 ) (46 ) Amortization of actuarial loss 244 60 101 46 49 13 24 Amortization of prior service (credit) cost (11 ) (6 ) (4 ) (1 ) (2 ) — 1 Other 7 2 2 1 1 — 1 Net periodic pension costs (a)(b) $ 178 $ 37 $ 76 $ 24 $ 44 $ 9 $ 19 (a) Duke Energy amounts exclude $9 million , $10 million , and $12 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $4 million , $5 million , and $6 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.
Amounts Recognized in AOCI and Regulatory Assets and Liabilities	Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase $ 173 $ 65 $ 18 $ 14 $ 4 $ 14 $ 11 Accumulated other comprehensive loss (income) Deferred income tax expense $ 6 — 5 — — — — Actuarial losses arising during the year 4 — — — — — — Amortization of prior year service credit 1 — — — — — — Amortization of prior year actuarial losses (11 ) — (4 ) — — — — Transfer with the disposal group 3 Reclassification of actuarial losses to regulatory assets (6 ) — — — — — — Net amount recognized in accumulated other comprehensive income $ (3 ) $ — $ 1 $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase (decrease) $ 112 $ 30 $ (73 ) $ (17 ) $ 11 $ 17 $ 4 Accumulated other comprehensive (income) loss Deferred income tax expense $ (10 ) $ — $ (2 ) $ — $ — $ — $ — Actuarial losses arising during the year 29 — — — — — — Prior year service credit arising during the year — — — — — — — Amortization of prior year actuarial losses (9 ) — — — — — — Reclassification of actuarial losses to regulatory assets (1 ) — — — — — — Net amount recognized in accumulated other comprehensive income $ 9 $ — $ (2 ) $ — $ — $ — $ —
Reconciliation of Funded Status to Net Amount Recognized	Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 8,107 $ 2,053 $ 2,557 $ 1,187 $ 1,335 $ 469 $ 673 Obligation transferred with the Disposal Group (83 ) — — — — — — Service cost 159 50 44 23 20 4 10 Interest cost 324 83 104 48 54 18 27 Actuarial gain (241 ) (53 ) (111 ) (46 ) (62 ) (9 ) (15 ) Transfers — 8 4 7 (3 ) 8 — Plan amendments (6 ) — — — — — (4 ) Benefits paid (533 ) (146 ) (147 ) (76 ) (68 ) (37 ) (42 ) Obligation at measurement date $ 7,727 $ 1,995 $ 2,451 $ 1,143 $ 1,276 $ 453 $ 649 Accumulated Benefit Obligation at measurement date $ 7,606 $ 1,993 $ 2,414 $ 1,143 $ 1,240 $ 442 $ 628 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 8,498 $ 2,300 $ 2,722 $ 1,321 $ 1,363 $ 456 $ 681 Plan assets transferred with the Disposal Group (81 ) — — — — — — Employer contributions 302 91 83 42 40 8 19 Actual return on plan assets (50 ) (10 ) (22 ) (10 ) (11 ) (2 ) (3 ) Benefits paid (533 ) (146 ) (147 ) (76 ) (68 ) (37 ) (42 ) Transfers — 8 4 7 (3 ) 8 — Plan assets at measurement date $ 8,136 $ 2,243 $ 2,640 $ 1,284 $ 1,321 $ 433 $ 655 Funded status of plan $ 409 $ 248 $ 189 $ 141 $ 45 $ (20 ) $ 6 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 7,510 $ 1,875 $ 2,739 $ 1,172 $ 1,233 $ 442 $ 632 Service cost 135 41 40 21 20 4 9 Interest cost 344 85 112 54 57 20 29 Actuarial loss (a) 618 132 211 98 105 41 41 Transfers — 37 (375 ) (61 ) (9 ) (6 ) — Plan amendments (4 ) (1 ) — — — (1 ) — Benefits paid (496 ) (116 ) (170 ) (97 ) (71 ) (31 ) (38 ) Obligation at measurement date $ 8,107 $ 2,053 $ 2,557 $ 1,187 $ 1,335 $ 469 $ 673 Accumulated Benefit Obligation at measurement date $ 7,966 $ 2,052 $ 2,519 $ 1,187 $ 1,297 $ 459 $ 645 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 8,142 $ 2,162 $ 2,944 $ 1,330 $ 1,299 $ 448 $ 654 Actual return on plan assets 852 217 300 149 144 45 65 Benefits paid (496 ) (116 ) (170 ) (97 ) (71 ) (31 ) (38 ) Transfers — 37 (352 ) (61 ) (9 ) (6 ) — Plan assets at measurement date $ 8,498 $ 2,300 $ 2,722 $ 1,321 $ 1,363 $ 456 $ 681 Funded status of plan $ 391 $ 247 $ 165 $ 134 $ 28 $ (13 ) $ 8 (a) Includes an increase in benefit obligation of $180 million as a result of changes in Duke Energy's mortality assumptions.
Amounts Recognized in the Consolidated Balance Sheet	Amounts Recognized in the Consolidated Balance Sheets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Prefunded pension (a) $ 474 $ 252 $ 232 $ 145 $ 84 $ 1 $ 6 Noncurrent pension liability (b) $ 65 $ 4 $ 43 $ 4 $ 39 $ 21 $ — Net asset recognized $ 409 $ 248 $ 189 $ 141 $ 45 $ (20 ) $ 6 Regulatory assets $ 1,884 $ 472 $ 771 $ 360 $ 410 $ 79 $ 162 Accumulated other comprehensive (income) loss Deferred income tax asset $ (45 ) $ — $ (6 ) $ — $ — $ — $ — Prior service credit (4 ) — — — — — — Net actuarial loss 130 — 17 — — — — Net amounts recognized in accumulated other comprehensive loss (c) $ 81 $ — $ 11 $ — $ — $ — $ — Amounts to be recognized in net periodic pension costs in the next year Unrecognized net actuarial loss $ 132 $ 31 $ 59 $ 25 $ 31 $ 4 $ 11 Unrecognized prior service credit (16 ) (8 ) (3 ) (2 ) (1 ) — — December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Prefunded pension (a) $ 441 $ 247 $ 165 $ 134 $ 28 $ — $ 8 Noncurrent pension liability (b) $ 50 $ — $ — $ — $ — $ 13 $ — Net asset recognized $ 391 $ 247 $ 165 $ 134 $ 28 $ (13 ) $ 8 Regulatory assets $ 1,711 $ 407 $ 753 $ 346 $ 406 $ 65 $ 151 Accumulated other comprehensive (income) loss Deferred income tax asset $ (51 ) $ — $ (11 ) $ — $ — $ — $ — Prior service credit (5 ) — — — — — — Net actuarial loss 140 — 21 — — — — Net amounts recognized in accumulated other comprehensive loss (c) $ 84 $ — $ 10 $ — $ — $ — $ — (a) Included in Other within Investments and Other Assets on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets. (c) Excludes accumulated other comprehensive income of $13 million and $22 million as of December 31, 2015 and 2014 , respectively, net of tax, associated with a Brazilian retirement plan.
Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets	December 31, 2014 Duke Duke Energy (in millions) Energy Ohio Projected benefit obligation $ 702 $ 315 Accumulated benefit obligation 672 306 Fair value of plan assets 652 302 Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2015 Duke Duke Duke Progress Energy Energy (in millions) Energy Energy Florida Ohio Projected benefit obligation $ 1,216 $ 611 $ 611 $ 307 Accumulated benefit obligation 1,158 575 575 298 Fair value of plan assets 1,151 574 574 289
Assumptions Used for Pension Benefits Accounting	The following tables present the assumptions or range of assumptions used for pension benefit accounting. December 31, 2015 2014 2013 Benefit Obligations Discount rate 4.40% 4.10% 4.70% Salary increase 4.00 % - 4.40% 4.00 % - 4.40% 4.00 % - 4.40% Net Periodic Benefit Cost Discount rate 4.10% 4.70% 4.10% Salary increase 4.00 % - 4.40% 4.00 % - 4.40% 4.00 % - 4.30% Expected long-term rate of return on plan assets 6.50% 6.75% 7.75%
Expected Benefit Payments	Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Years ending December 31, 2016 $ 628 $ 189 $ 164 $ 91 $ 71 $ 35 $ 48 2017 639 199 167 92 73 35 47 2018 640 203 169 92 75 34 47 2019 643 202 171 91 77 34 47 2020 641 201 174 92 80 35 47 2021 – 2025 3,053 906 869 438 420 171 230
Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Components of Net Periodic Pension Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ — $ 1 $ — $ — $ — $ — Interest cost on projected benefit obligation 13 1 4 1 2 — — Amortization of actuarial loss 6 — 2 1 2 — 1 Amortization of prior service credit (1 ) — (1 ) — — — — Net periodic pension costs $ 21 $ 1 $ 6 $ 2 $ 4 $ — $ 1 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ — $ 1 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 14 1 5 1 2 — — Amortization of actuarial loss 3 — 2 — — — — Amortization of prior service credit (1 ) — (1 ) — — — — Net periodic pension costs $ 19 $ 1 $ 7 $ 2 $ 2 $ — $ — Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 3 $ — $ 1 $ 1 $ — $ — $ — Interest cost on projected benefit obligation 13 1 7 1 1 — — Amortization of actuarial loss 5 — 3 1 1 — — Amortization of prior service credit (1 ) — (1 ) — — — — Net periodic pension costs $ 20 $ 1 $ 10 $ 3 $ 2 $ — $ —
Amounts Recognized in AOCI and Regulatory Assets and Liabilities	Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net (decrease) increase $ (13 ) $ 2 $ (16 ) $ (1 ) $ (15 ) $ — $ (1 ) Accumulated other comprehensive (income) loss Deferred income tax benefit $ (7 ) $ — $ (5 ) $ — $ — $ — $ — Amortization of prior service credit 1 — — — — — — Actuarial gains arising during the year 17 — 13 — — — — Net amount recognized in accumulated other comprehensive loss (income) $ 11 $ — $ 8 $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase $ 44 $ 1 $ 14 $ 4 $ 19 $ 1 $ 2 Regulatory liabilities, net decrease $ (7 ) $ — $ — $ — $ — $ — $ — Accumulated other comprehensive (income) loss Deferred income tax benefit $ 4 $ — $ 5 $ — $ — $ — $ — Actuarial gains arising during the year (9 ) — (11 ) — — — — Net amount recognized in accumulated other comprehensive loss (income) $ (5 ) $ — $ (6 ) $ — $ — $ — $ —
Reconciliation of Funded Status to Net Amount Recognized	Reconciliation of Funded Status to Net Amount Recognized Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Service cost 3 — 1 — — — — Interest cost 13 1 4 1 2 — — Actuarial losses (gains) 10 1 (1 ) — (14 ) — — Transfers 4 — — — — — — Benefits paid (26 ) (2 ) (8 ) (3 ) (3 ) — — Obligation at measurement date $ 341 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Accumulated Benefit Obligation at measurement date $ 336 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Change in Fair Value of Plan Assets Plan assets at prior measurement date — — — — — — — Benefits paid (26 ) (2 ) (8 ) (3 ) (3 ) — — Employer contributions 26 2 8 3 3 — — Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Obligation at prior measurement date $ 304 $ 15 $ 140 $ 34 $ 39 $ 3 $ 5 Service cost 3 — 1 1 — — — Interest cost 14 1 5 1 2 — — Actuarial losses (a) 43 2 11 2 20 1 1 Settlements — — — — — — — Plan amendments — — — — — — — Transfers — — (32 ) — 4 — — Benefits paid (27 ) (2 ) (9 ) (3 ) (4 ) — (1 ) Obligation at measurement date $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Accumulated Benefit Obligation at measurement date $ 333 $ 15 $ 116 $ 35 $ 61 $ 4 $ 5 Change in Fair Value of Plan Assets Plan assets at prior measurement date — — — — — — — Benefits paid (27 ) (2 ) (9 ) (3 ) (4 ) — (1 ) Employer contributions 27 2 9 3 4 — 1 Plan assets at measurement date $ — $ — $ — $ — $ — $ — $ — (a) Includes an increase in benefit obligation of $21 million as a result of changes in Duke Energy's mortality assumptions.
Amounts Recognized in the Consolidated Balance Sheet	Amounts Recognized in the Consolidated Balance Sheets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current pension liability (a) $ 27 $ 2 $ 8 $ 3 $ 3 $ — $ — Noncurrent pension liability (b) 314 14 104 30 43 4 5 Total accrued pension liability $ 341 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Regulatory assets $ 76 $ 7 $ 16 $ 6 $ 10 $ 1 $ 1 Accumulated other comprehensive (income) loss Deferred income tax liability $ (3 ) $ — $ (3 ) $ — $ — $ — $ — Net actuarial loss 9 — 9 — — — — Net amounts recognized in accumulated other comprehensive income $ 6 $ — $ 6 $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss $ 8 $ — $ 1 $ — $ — $ — $ — Unrecognized prior service credit (1 ) — — — — — — December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current pension liability (a) $ 27 $ 2 $ 8 $ 3 $ 4 $ — $ — Noncurrent pension liability (b) 310 14 108 32 57 4 5 Total accrued pension liability $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Regulatory assets $ 89 $ 5 $ 32 $ 7 $ 25 $ 1 $ 2 Regulatory liabilities $ — $ — $ — $ — $ — $ — $ — Accumulated other comprehensive (income) loss Deferred income tax asset $ 4 $ — $ 2 $ — $ — $ — $ — Prior service credit (1 ) — — — — — — Net actuarial gain (8 ) — (4 ) — — — — Net amounts recognized in accumulated other comprehensive loss $ (5 ) $ — $ (2 ) $ — $ — $ — $ — (a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.
Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets	Information for Plans with Accumulated Benefit Obligation in Excess of Plan Assets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Projected benefit obligation $ 341 $ 16 $ 112 $ 33 $ 46 $ 4 $ 5 Accumulated benefit obligation 336 16 112 33 46 4 5 December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Projected benefit obligation $ 337 $ 16 $ 116 $ 35 $ 61 $ 4 $ 5 Accumulated benefit obligation 333 15 116 35 61 4 5
Assumptions Used for Pension Benefits Accounting	The following tables present the assumptions used for pension benefit accounting. December 31, 2015 2014 2013 Benefit Obligations Discount rate 4.40 % 4.10 % 4.70 % Salary increase 4.40 % 4.40 % 4.40 % Net Periodic Benefit Cost Discount rate 4.10 % 4.70 % 4.10 % Salary increase 4.40 % 4.40 % 4.30 %
Expected Benefit Payments	Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Years ending December 31, 2016 $ 28 $ 2 $ 8 $ 3 $ 3 $ — $ — 2017 29 2 8 3 3 — — 2018 25 2 8 3 3 — — 2019 26 2 8 3 3 — — 2020 25 2 8 3 3 — 1 2021 - 2025 126 9 38 12 16 1 2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Components of Net Periodic Pension Costs	Components of Net Periodic Other Post-Retirement Benefit Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 6 $ 1 $ 1 $ 1 $ 1 $ — $ 1 Interest cost on accumulated post-retirement benefit obligation 36 9 15 8 7 2 4 Expected return on plan assets (13 ) (8 ) — — — (1 ) (1 ) Amortization of actuarial loss (gain) 16 (2 ) 28 18 10 (2 ) (2 ) Amortization of prior service credit (140 ) (14 ) (102 ) (68 ) (35 ) — — Net periodic post-retirement benefit costs (a)(b) $ (95 ) $ (14 ) $ (58 ) $ (41 ) $ (17 ) $ (1 ) $ 2 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 10 $ 2 $ 4 $ 1 $ 3 $ — $ 1 Interest cost on accumulated post-retirement benefit obligation 49 12 22 11 12 2 5 Expected return on plan assets (13 ) (9 ) — — — — (1 ) Amortization of actuarial loss (gain) 39 3 42 31 10 (2 ) — Amortization of prior service credit (125 ) (11 ) (95 ) (73 ) (21 ) — — Net periodic post-retirement benefit costs (a)(b) $ (40 ) $ (3 ) $ (27 ) $ (30 ) $ 4 $ — $ 5 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Service cost $ 24 $ 2 $ 18 $ 9 $ 7 $ 1 $ 1 Interest cost on accumulated post-retirement benefit obligation 68 13 41 22 16 2 5 Expected return on plan assets (14 ) (11 ) — — — (1 ) (1 ) Amortization of actuarial loss (gain) 52 3 57 34 16 (1 ) 1 Amortization of prior service credit (41 ) (7 ) (30 ) (20 ) (6 ) (1 ) — Net periodic post-retirement benefit costs (a)(b) $ 89 $ — $ 86 $ 45 $ 33 $ — $ 6 (a) Duke Energy amounts exclude $10 million , $9 million , and $8 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006. (b) Duke Energy Ohio amounts exclude $3 million , $2 million , and $2 million for the years ended December 2015, 2014, and 2013, respectively, of regulatory asset amortization resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.
Amounts Recognized in AOCI and Regulatory Assets and Liabilities	Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase (decrease) $ 1 $ — $ 1 $ — $ 1 $ — $ (7 ) Regulatory liabilities, net increase (decrease) $ (92 ) $ (8 ) $ (71 ) $ (36 ) $ (35 ) $ 2 $ (8 ) Accumulated other comprehensive (income) loss Deferred income tax benefit $ 2 $ — $ (1 ) $ — $ — $ — $ — Actuarial losses (gains) arising during the year (5 ) — 2 — — — — Transfer with the disposal group (3 ) — — — — — — Amortization of prior year prior service credit 3 — (1 ) — — — — Net amount recognized in accumulated other comprehensive income $ (3 ) $ — $ — $ — $ — $ — $ — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Regulatory assets, net increase (decrease) $ 162 $ 34 $ 129 $ 97 $ (4 ) $ — $ (7 ) Regulatory liabilities, net increase (decrease) $ 249 $ 76 $ 122 $ 61 $ 61 $ (2 ) $ 14 Accumulated other comprehensive (income) loss Deferred income tax benefit $ 1 $ — $ 1 $ — $ — $ — $ — Actuarial losses (gains) arising during the year 1 — (2 ) — — — — Prior year service credit arising during the year (6 ) — — — — — — Amortization of prior year prior service credit 2 — — — — — — Net amount recognized in accumulated other comprehensive income $ (2 ) $ — $ (1 ) $ — $ — $ — $ —
Reconciliation of Funded Status to Net Amount Recognized	Reconciliation of Funded Status to Accrued Other Post-Retirement Benefit Costs Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 916 $ 220 $ 379 $ 207 $ 170 $ 39 $ 96 Service cost 6 1 1 1 1 — 1 Interest cost 36 9 15 8 7 2 4 Plan participants' contributions 20 4 7 4 3 1 2 Actuarial (gains) losses (39 ) (18 ) (1 ) (13 ) 11 (3 ) 1 Transfers — 2 — — — — — Plan amendments (9 ) — — — — (1 ) (4 ) Benefits paid (100 ) (18 ) (47 ) (19 ) (28 ) (3 ) (13 ) Obligation transferred with the Disposal Group (3 ) — — — — — — Accrued retiree drug subsidy 1 — — — — — — Accumulated post-retirement benefit obligation at measurement date $ 828 $ 200 $ 354 $ 188 $ 164 $ 35 $ 87 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 227 $ 145 $ — $ (1 ) $ — $ 8 $ 23 Actual return on plan assets (1 ) (1 ) 1 1 1 — (1 ) Benefits paid (100 ) (18 ) (47 ) (19 ) (28 ) (3 ) (13 ) Employer contributions 62 4 39 15 25 2 8 Plan participants' contributions 20 4 7 4 3 1 2 Plan assets at measurement date $ 208 $ 134 $ — $ — $ 1 $ 8 $ 19 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Change in Projected Benefit Obligation Accumulated post-retirement benefit obligation at prior measurement date $ 1,106 $ 265 $ 533 $ 233 $ 253 $ 42 $ 118 Service cost 10 2 4 1 3 — 1 Interest cost 49 12 22 11 12 2 5 Plan participants' contributions 25 10 8 4 4 — 2 Actuarial gains (a) (87 ) (35 ) (19 ) (21 ) — — (20 ) Transfers — 1 (48 ) (2 ) — (1 ) — Plan amendments (85 ) (4 ) (77 ) — (78 ) (1 ) — Benefits paid (103 ) (31 ) (44 ) (19 ) (24 ) (3 ) (10 ) Accrued retiree drug subsidy 1 — — — — — — Accumulated post-retirement benefit obligation at measurement date $ 916 $ 220 $ 379 $ 207 $ 170 $ 39 $ 96 Change in Fair Value of Plan Assets Plan assets at prior measurement date $ 214 $ 143 $ — $ — $ — $ 8 $ 18 Actual return on plan assets 18 12 — — — — 2 Benefits paid (103 ) (31 ) (44 ) (19 ) (24 ) (3 ) (10 ) Transfers — (1 ) — — — — — Employer contributions 73 12 36 14 20 3 11 Plan participants' contributions 25 10 8 4 4 — 2 Plan assets at measurement date $ 227 $ 145 $ — $ (1 ) $ — $ 8 $ 23 (a) Includes an increase in benefit obligation of $7 million as a result of changes in Duke Energy's mortality assumptions.
Amounts Recognized in the Consolidated Balance Sheet	Amounts Recognized in the Consolidated Balance Sheets December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current post-retirement liability (a) $ 37 $ — $ 31 $ 16 $ 15 $ 2 $ — Noncurrent post-retirement liability (b) 583 66 323 172 149 25 68 Total accrued post-retirement liability $ 620 $ 66 $ 354 $ 188 $ 164 $ 27 $ 68 Regulatory assets $ 1 $ — $ 1 $ — $ 1 $ — $ 57 Regulatory liabilities $ 288 $ 68 $ 51 $ 25 $ 26 $ 21 $ 83 Accumulated other comprehensive (income) loss Deferred income tax liability $ 7 $ — $ — $ — $ — $ — $ — Prior service credit (6 ) — (1 ) — — — — Net actuarial gain (13 ) — — — — — — Net amounts recognized in accumulated other comprehensive income $ (12 ) $ — $ (1 ) $ — $ — $ — $ — Amounts to be recognized in net periodic pension expense in the next year Unrecognized net actuarial loss (gain) $ 6 $ (3 ) $ 22 $ 13 $ 9 $ (2 ) $ (2 ) Unrecognized prior service credit (142 ) (14 ) (103 ) (68 ) (35 ) — (1 ) December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current post-retirement liability (a) $ 35 $ — $ 29 $ 16 $ 14 $ 2 $ — Noncurrent post-retirement liability (b) 654 75 350 192 156 29 73 Total accrued post-retirement liability $ 689 $ 75 $ 379 $ 208 $ 170 $ 31 $ 73 Regulatory assets $ — $ — $ — $ — $ — $ — $ 64 Regulatory liabilities $ 380 $ 76 $ 122 $ 61 $ 61 $ 19 $ 91 Accumulated other comprehensive (income) loss Deferred income tax liability $ 5 $ — $ 1 $ — $ — $ — $ — Prior service credit (9 ) — — — — — — Net actuarial gain (5 ) — (2 ) — — — — Net amounts recognized in accumulated other comprehensive income $ (9 ) $ — $ (1 ) $ — $ — $ — $ — (a) Included in Other within Current Liabilities on the Consolidated Balance Sheets. (b) Included in Accrued pension and other post-retirement benefit costs on the Consolidated Balance Sheets.
Assumptions Used for Pension Benefits Accounting	The following tables present the assumptions used for other post-retirement benefits accounting. December 31, 2015 2014 2013 Benefit Obligations Discount rate 4.40 % 4.10 % 4.70 % Net Periodic Benefit Cost Discount rate 4.10 % 4.70 % 4.10 % Expected long-term rate of return on plan assets 6.50 % 6.75 % 7.75 % Assumed tax rate 35 % 35 % 35 %
Assumed Health Care Cost Trend Rate	Assumed Health Care Cost Trend Rate December 31, 2015 2014 Health care cost trend rate assumed for next year 7.50 % 6.75 % Rate to which the cost trend is assumed to decline (the ultimate trend rate) 4.75 % 4.75 % Year that rate reaches ultimate trend 2023 2023
Sensitivity to Changes in Assumed Health Care Cost Trend Rates	Sensitivity to Changes in Assumed Health Care Cost Trend Rates Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana 1-Percentage Point Increase Effect on total service and interest costs $ 2 $ — $ 1 $ 1 $ — $ — $ — Effect on post-retirement benefit obligation 29 7 12 6 6 1 3 1-Percentage Point Decrease Effect on total service and interest costs (1 ) — (1 ) (1 ) — — — Effect on post-retirement benefit obligation (26 ) (6 ) (11 ) (6 ) (5 ) (1 ) (3 )
Expected Benefit Payments	Expected Benefit Payments Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Years ending December 31, 2016 $ 76 $ 16 $ 31 $ 16 $ 15 $ 4 $ 10 2017 76 17 31 16 15 3 10 2018 74 18 30 16 14 3 9 2019 73 18 29 15 14 3 9 2020 71 18 29 15 13 3 8 2021 – 2025 312 80 129 68 60 14 33

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Line Items]
Schedule of Components of Income Tax Expense (Benefit)	Components of Income Tax Expense Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ — $ 216 $ (193 ) $ (56 ) $ 1 $ (18 ) $ (86 ) State (12 ) 14 1 (4 ) (7 ) (1 ) (12 ) Foreign 99 — — — — — — Total current income taxes 87 230 (192 ) (60 ) (6 ) (19 ) (98 ) Deferred income taxes Federal 1,089 345 694 334 290 96 245 State 181 57 27 27 58 5 17 Foreign (17 ) — — — — — — Total deferred income taxes (a) 1,253 402 721 361 348 101 262 Investment tax credit amortization (14 ) (5 ) (7 ) (7 ) — (1 ) (1 ) Income tax expense from continuing operations 1,326 627 522 294 342 81 163 Tax expense (benefit) from discontinued operations 19 — (1 ) — — 22 — Total income tax expense included in Consolidated Statements of Operations $ 1,345 $ 627 $ 521 $ 294 $ 342 $ 103 $ 163 (a) Includes benefits of net operating loss (NOL) carryforwards and utilization of NOL and tax credit carryforwards of $264 million at Duke Energy, $15 million at Duke Energy Carolinas, $119 million at Progress Energy, $21 million at Duke Energy Progress, $84 million at Duke Energy Florida, $3 million at Duke Energy Ohio and $45 million at Duke Energy Indiana. Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ — $ 161 $ (466 ) $ (184 ) $ (53 ) $ (73 ) $ (112 ) State 56 51 (8 ) 14 1 3 1 Foreign 144 — — — — — — Total current income taxes 200 212 (474 ) (170 ) (52 ) (70 ) (111 ) Deferred income taxes Federal 1,517 407 938 436 350 113 294 State 35 (25 ) 84 25 52 1 15 Foreign (67 ) — — — — — — Total deferred income taxes (a)(b) 1,485 382 1,022 461 402 114 309 Investment tax credit amortization (16 ) (6 ) (8 ) (6 ) (1 ) (1 ) (1 ) Income tax expense from continuing operations 1,669 588 540 285 349 43 197 Tax benefit from discontinued operations (295 ) — (4 ) — — (300 ) — Total income tax expense (benefit) included in Consolidated Statements of Operations $ 1,374 $ 588 $ 536 $ 285 $ 349 $ (257 ) $ 197 (a) There were no benefits of NOL carryforwards. (b) Includes utilization of NOL and tax credit carryforwards of $1,544 million at Duke Energy, $345 million at Duke Energy Carolinas, $530 million at Progress Energy, $291 million at Duke Energy Progress, $64 million at Duke Energy Florida, $56 million at Duke Energy Ohio and $141 million at Duke Energy Indiana. Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current income taxes Federal $ (141 ) $ 49 $ (221 ) $ (70 ) $ (143 ) $ (24 ) $ (88 ) State (40 ) 11 (37 ) (10 ) (13 ) (4 ) 7 Foreign 151 — — — — — — Total current income taxes (30 ) 60 (258 ) (80 ) (156 ) (28 ) (81 ) Deferred income taxes Federal 1,092 464 555 316 326 65 276 State 144 75 84 59 44 6 29 Foreign 14 — — — — — — Total deferred income taxes (a) 1,250 539 639 375 370 71 305 Investment tax credit amortization (15 ) (5 ) (8 ) (7 ) (1 ) — (1 ) Income tax expense from continuing operations 1,205 594 373 288 213 43 223 Tax expense (benefit) from discontinued operations 29 — (26 ) — — 32 — Total income tax expense included in Consolidated Statements of Operations $ 1,234 $ 594 $ 347 $ 288 $ 213 $ 75 $ 223 (a) Includes benefits of NOL carryforwards of $808 million at Duke Energy, $458 million at Progress Energy, $64 million at Duke Energy Progress, $301 million at Duke Energy Florida and $179 million at Duke Energy Indiana.
Schedule of Income before Income Tax, Domestic and Foreign	Duke Energy Income from Continuing Operations before Income Taxes Years Ended December 31, (in millions) 2015 2014 2013 Domestic $ 3,828 $ 3,600 $ 3,183 Foreign 309 534 612 Income from continuing operations before income taxes $ 4,137 $ 4,134 $ 3,795
Summary of Effective Tax Rates	The following tables present a reconciliation of income tax expense at the U.S. federal statutory tax rate to the actual tax expense from continuing operations. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,448 $ 598 $ 555 $ 302 $ 330 $ 81 $ 168 State income tax, net of federal income tax effect 109 46 18 15 33 2 2 Tax differential on foreign earnings (27 ) — — — — — — AFUDC equity income (58 ) (34 ) (19 ) (17 ) (3 ) (1 ) (4 ) Renewable energy production tax credits (72 ) — (1 ) — — — — Audit adjustment (22 ) — (23 ) 1 (24 ) — — Tax true-up 2 2 (3 ) (4 ) 2 (5 ) (9 ) Other items, net (54 ) 15 (5 ) (3 ) 4 4 6 Income tax expense from continuing operations $ 1,326 $ 627 $ 522 $ 294 $ 342 $ 81 $ 163 Effective tax rate 32.1 % 36.7 % 32.9 % 34.2 % 36.3 % 35.2 % 34.0 % Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,447 $ 581 $ 497 $ 263 $ 314 $ 39 $ 195 State income tax, net of federal income tax effect 59 17 49 25 34 3 10 Tax differential on foreign earnings (a) (110 ) — — — — — — AFUDC equity income (47 ) (32 ) (9 ) (9 ) — (1 ) (5 ) Renewable energy production tax credits (67 ) — — — — — — International tax dividend (b) 373 — — — — — — Other items, net 14 22 3 6 1 2 (3 ) Income tax expense (benefit) from continuing operations $ 1,669 $ 588 $ 540 $ 285 $ 349 $ 43 $ 197 Effective tax rate 40.4 % 35.4 % 38.0 % 37.9 % 38.9 % 38.9 % 35.5 % (a) Includes a $57 million benefit as a result of the merger of two Chilean subsidiaries and a change in income tax rates in various countries primarily relating to Peru. (b) During 2014, Duke Energy declared a taxable dividend of foreign earnings in the form of notes payable that was expected to result in the repatriation of approximately $2.7 billion of cash held, and expected to be generated, by International Energy over a period of up to eight years. In 2015, approximately $1.5 billion was remitted. As a result of the decision to repatriate cumulative historical undistributed foreign earnings Duke Energy recorded U.S. income tax expense of approximately $373 million in 2014. Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Income tax expense, computed at the statutory rate of 35 percent $ 1,328 $ 549 $ 361 $ 276 $ 188 $ 39 $ 203 State income tax, net of federal income tax effect 66 56 31 31 20 2 23 Tax differential on foreign earnings (49 ) — — — — — — AFUDC equity income (55 ) (32 ) (18 ) (15 ) (3 ) — (5 ) Renewable energy production tax credits (62 ) — — — — — — Other items, net (23 ) 21 (1 ) (4 ) 8 2 2 Income tax expense from continuing operations $ 1,205 $ 594 $ 373 $ 288 $ 213 $ 43 $ 223 Effective tax rate 31.8 % 37.8 % 36.2 % 36.5 % 39.6 % 39.1 % 38.4 %
Schedule of Deferred Tax Assets and Liabilities	December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Deferred credits and other liabilities $ 188 $ 53 $ 108 $ 28 $ 78 $ (8 ) $ 12 Capital lease obligations 63 10 — — — — 2 Pension, post-retirement and other employee benefits 546 4 188 96 93 17 43 Progress Energy merger purchase accounting adjustments (a) 1,124 — — — — — — Tax credits and NOL carryforwards 3,540 157 980 91 252 38 260 Investments and other assets — — — — — 14 — Other — 12 — 55 — 35 11 Valuation allowance (184 ) — (13 ) (1 ) — — — Total deferred income tax assets 5,277 236 1,263 269 423 96 328 Investments and other assets (1,625 ) (1,051 ) (427 ) (232 ) (245 ) — (4 ) Accelerated depreciation rates (11,715 ) (4,046 ) (3,284 ) (2,030 ) (1,252 ) (1,660 ) (1,603 ) Regulatory assets and deferred debits, net (3,694 ) (953 ) (1,602 ) (809 ) (792 ) (141 ) (106 ) Other (44 ) — (151 ) — (246 ) — — Total deferred income tax liabilities (17,078 ) (6,050 ) (5,464 ) (3,071 ) (2,535 ) (1,801 ) (1,713 ) Net deferred income tax liabilities $ (11,801 ) $ (5,814 ) $ (4,201 ) $ (2,802 ) $ (2,112 ) $ (1,705 ) $ (1,385 ) (a) Primarily related to capital lease obligations and debt fair value adjustments. Net Deferred Income Tax Liability Components December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Deferred credits and other liabilities $ 245 $ 38 $ 115 $ 25 $ 66 $ 29 $ 5 Capital lease obligations 63 9 — — — — 2 Pension, post-retirement and other employee benefits 580 46 186 92 82 24 40 Progress Energy merger purchase accounting adjustments (a) 1,009 — — — — — — Tax credits and NOL carryforwards 3,719 170 997 163 177 25 215 Investments and other assets — — — — — 3 — Other 206 20 48 2 46 37 20 Valuation allowance (160 ) — (38 ) — — — — Total deferred income tax assets 5,662 283 1,308 282 371 118 282 Investments and other assets (1,584 ) (1,057 ) (412 ) (228 ) (201 ) — (7 ) Accelerated depreciation rates (13,070 ) (4,429 ) (4,169 ) (2,325 ) (1,868 ) (1,356 ) (1,797 ) Regulatory assets and deferred debits, net (3,633 ) (943 ) (1,517 ) (756 ) (762 ) (169 ) (135 ) Total deferred income tax liabilities (18,287 ) (6,429 ) (6,098 ) (3,309 ) (2,831 ) (1,525 ) (1,939 ) Net deferred income tax liabilities $ (12,625 ) $ (6,146 ) $ (4,790 ) $ (3,027 ) $ (2,460 ) $ (1,407 ) $ (1,657 ) (a) Primarily related to capital lease obligations and debt fair value adjustments.
Summary of Tax Credit Carryforwards	The following table presents the expiration of tax credits and NOL carryforwards. December 31, 2015 (in millions) Amount Expiration Year Investment tax credits $ 864 2029 — 2035 Alternative minimum tax credits 1,121 Indefinite Federal NOL carryforwards 484 2030 — 2033 State NOL carryforwards and credits (a) 299 2016 — 2035 Foreign NOL carryforwards (b) 100 2026 — 2034 Foreign Tax Credits 851 2024 Total tax credits and NOL carryforwards $ 3,719 (a) A valuation allowance of $81 million has been recorded on the state Net Operating Loss carryforwards, as presented in the Net Deferred Income Tax Liability Components table. (b) A valuation allowance of $79 million has been recorded on the foreign Net Operating Loss carryforwards, as presented in the Net Deferred Income Tax Liability Components table.
Schedule of Balance Sheet Classification of Deferred Tax Assets and Liabilities	As discussed in Note 1, the FASB issued revised accounting guidance for the Balance Sheet classification of deferred taxes. As shown in the table below, all deferred tax assets and liabilities are presented as noncurrent as of December 31, 2015. However, for December 31, 2014, the revised guidance was not applied. As a result, a portion of deferred tax assets and liabilities is shown as current at December 31, 2014. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Investments and Other Assets: Other 80 — — — — — — Deferred Credits and Other Liabilities: Deferred income taxes (12,705 ) (6,146 ) (4,790 ) (3,027 ) (2,460 ) (1,407 ) (1,657 ) Net deferred income tax liabilities $ (12,625 ) $ (6,146 ) $ (4,790 ) $ (3,027 ) $ (2,460 ) $ (1,407 ) $ (1,657 ) December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Current Assets: Other $ 1,593 $ 3 $ 558 $ 106 $ 340 $ 60 $ 206 Investments and Other Assets: Other 29 — — — — — — Current Liabilities: Other — (5 ) — — — — — Deferred Credits and Other Liabilities: Deferred income taxes (13,423 ) (5,812 ) (4,759 ) (2,908 ) (2,452 ) (1,765 ) (1,591 ) Net deferred income tax liabilities $ (11,801 ) $ (5,814 ) $ (4,201 ) $ (2,802 ) $ (2,112 ) $ (1,705 ) $ (1,385 )
Schedule of Unrecognized Tax Benefits Roll Forward	The following tables present changes to unrecognized tax benefits. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Indiana Unrecognized tax benefits – January 1 $ 213 $ 160 $ 32 $ 23 $ 8 $ 1 Unrecognized tax benefits increases (decreases) Gross increases – tax positions in prior periods — — 1 1 — — Gross decreases – tax positions in prior periods (48 ) (45 ) — — — — Decreases due to settlements (45 ) (43 ) — — — — Reduction due to lapse of statute of limitations (32 ) — (32 ) (21 ) (8 ) — Total changes (125 ) (88 ) (31 ) (20 ) (8 ) — Unrecognized tax benefits – December 31 $ 88 $ 72 $ 1 $ 3 $ — $ 1 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Indiana Unrecognized tax benefits – January 1 $ 230 $ 171 $ 32 $ 22 $ 8 $ 1 Unrecognized tax benefits (decreases) increases Gross increases – tax positions in prior periods — — 1 1 — — Gross decreases – tax positions in prior periods (2 ) — — — — — Decreases due to settlements (15 ) (11 ) (1 ) — — — Total changes (17 ) (11 ) — 1 — — Unrecognized tax benefits – December 31 $ 213 $ 160 $ 32 $ 23 $ 8 $ 1 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Unrecognized tax benefits – January 1 $ 540 $ 271 $ 131 $ 67 $ 44 $ 36 $ 32 Unrecognized tax benefits increases (decreases) Gross decreases – tax positions in prior periods (231 ) (100 ) (86 ) (45 ) (37 ) (36 ) (31 ) Decreases due to settlements (66 ) — — — — — — Reduction due to lapse of statute of limitations (13 ) — (13 ) — 1 — — Total changes (310 ) (100 ) (99 ) (45 ) (36 ) (36 ) (31 ) Unrecognized tax benefits – December 31 $ 230 $ 171 $ 32 $ 22 $ 8 $ — $ 1
Schedule of Unrecognized Tax Benefits	The following table includes additional information regarding the Duke Energy Registrants' unrecognized tax benefits. It is reasonably possible that Duke Energy could reflect an approximate $65 million reduction and Duke Energy Carolinas could reflect an approximate $63 million reduction in unrecognized tax benefits within the next 12 months. All other Duke Energy Registrants do not anticipate a material increase or decrease in unrecognized tax benefits within the next 12 months. December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Amount that if recognized, would affect the effective tax rate or regulatory liability (a) $ 62 $ 54 $ 2 $ 3 $ 1 $ — $ 2 Amount that if recognized, would be recorded as a component of discontinued operations 4 — — — — — — (a) Duke Energy, Duke Energy Carolinas, Progress Energy, Duke Energy Progress, Duke Energy Florida and Duke Energy Indiana are unable to estimate the specific amounts that would affect the effective tax rate versus the regulatory liability.
Summary of Income Tax Contingencies	The following tables include interest recognized in the Consolidated Statements of Operations and the Consolidated Balance Sheets. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Net interest income recognized related to income taxes $ 12 $ — $ 2 $ 2 $ 1 $ — $ 1 Net interest expense recognized related to income taxes — 1 — — — — — Interest receivable related to income taxes 3 — — — — — 3 Interest payable related to income taxes — 14 — 1 — — — Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Net interest income recognized related to income taxes $ 6 $ — 3 — 1 4 $ 4 Net interest expense recognized related to income taxes — 1 — 1 — — — Interest receivable related to income taxes — — — — — — 2 Interest payable related to income taxes 13 13 5 3 5 — — Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Net interest income recognized related to income taxes $ 2 $ 2 $ 6 $ 7 $ — 4 1 Interest payable related to income taxes 27 8 10 2 7 — —

Other Income and Expenses, Net

Other Income and Expenses, Net (Tables)	12 Months Ended
	Dec. 31, 2015
Component Of Other Income Expense Nonoperating [Line Items]
Schedule of Other Income and Expenses, Net	The components of Other income and expenses, net on the Consolidated Statements of Operations are as follows. Year Ended December 31, 2015 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 38 $ 2 $ 4 $ 2 $ 2 $ 4 $ 6 Foreign exchange losses (4 ) — — — — — — AFUDC equity 164 96 54 47 7 3 11 Post in-service equity returns 73 60 13 13 — — — Nonoperating income (expense), other 36 2 26 9 15 (1 ) (6 ) Other income and expense, net $ 307 $ 160 $ 97 $ 71 $ 24 $ 6 $ 11 Year Ended December 31, 2014 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 57 $ 4 $ 3 $ — $ 2 $ 8 $ 6 Foreign exchange gains 3 — — — — — — AFUDC equity 135 91 26 25 — 4 14 Post in-service equity returns 89 71 17 17 — — — Nonoperating income (expense), other 67 6 31 9 18 (2 ) 2 Other income and expense, net $ 351 $ 172 $ 77 $ 51 $ 20 $ 10 $ 22 Year Ended December 31, 2013 Duke Duke Duke Duke Duke Duke Energy Progress Energy Energy Energy Energy (in millions) Energy Carolinas Energy Progress Florida Ohio Indiana Interest income $ 26 $ 1 $ 7 $ 1 $ 3 $ 5 $ 6 Foreign exchange losses (18 ) — — — — — — AFUDC equity 157 91 50 42 8 1 15 Post in-service equity returns 39 32 7 7 — — — Nonoperating income (expense), other 58 (4 ) 30 7 19 (4 ) (3 ) Other income and expense, net $ 262 $ 120 $ 94 $ 57 $ 30 $ 2 $ 18

Quarterly Financial Data (Una58

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	Quarterly EPS amounts may not sum to the full-year total due to changes in the weighted average number of common shares outstanding and rounding. First Second Third Fourth (in millions, except per share data) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 6,065 $ 5,589 $ 6,483 $ 5,322 $ 23,459 Operating income 1,456 1,246 1,688 977 5,367 Income from continuing operations 776 604 940 491 2,811 Income (loss) from discontinued operations, net of tax 91 (57 ) (5 ) (9 ) 20 Net income 867 547 935 482 2,831 Net income attributable to Duke Energy Corporation 864 543 932 477 2,816 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 1.09 $ 0.87 $ 1.36 $ 0.70 $ 4.02 Diluted $ 1.09 $ 0.87 $ 1.36 $ 0.70 $ 4.02 Income (loss) from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ 0.13 $ (0.09 ) $ (0.01 ) $ (0.01 ) $ 0.03 Diluted $ 0.13 $ (0.09 ) $ (0.01 ) $ (0.01 ) $ 0.03 Net income attributable to Duke Energy Corporation common stockholders Basic $ 1.22 $ 0.78 $ 1.35 $ 0.69 $ 4.05 Diluted $ 1.22 $ 0.78 $ 1.35 $ 0.69 $ 4.05 2014 Operating revenues $ 6,263 $ 5,708 $ 6,395 $ 5,559 $ 23,925 Operating income 1,362 1,289 1,619 988 5,258 Income from continuing operations 750 726 891 98 2,465 (Loss) Income from discontinued operations, net of tax (843 ) (113 ) 378 2 (576 ) Net (loss) income (93 ) 613 1,269 100 1,889 Net (loss) income attributable to Duke Energy Corporation (97 ) 609 1,274 97 1,883 Earnings per share: Income from continuing operations attributable to Duke Energy Corporation common stockholders Basic $ 1.05 $ 1.02 $ 1.25 $ 0.14 $ 3.46 Diluted $ 1.05 $ 1.02 $ 1.25 $ 0.14 $ 3.46 (Loss) Income from discontinued operations attributable to Duke Energy Corporation common stockholders Basic $ (1.19 ) $ (0.16 ) $ 0.55 $ — $ (0.80 ) Diluted $ (1.19 ) $ (0.16 ) $ 0.55 $ — $ (0.80 ) Net (loss) income attributable to Duke Energy Corporation common stockholders Basic $ (0.14 ) $ 0.86 $ 1.80 $ 0.14 $ 2.66 Diluted $ (0.14 ) $ 0.86 $ 1.80 $ 0.14 $ 2.66
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (21 ) $ (22 ) $ (24 ) $ (30 ) $ (97 ) Edwardsport Settlement (see Note 4) — — (90 ) (3 ) (93 ) Ash Basin Settlement and Penalties (see Note 5) — — (7 ) (7 ) (14 ) State Tax Adjustment related to Midwest Generation Sale — (41 ) — — (41 ) Cost Savings Initiatives (see Note 19) — — — (142 ) (142 ) Total $ (21 ) $ (63 ) $ (121 ) $ (182 ) $ (387 ) 2014 Costs to Achieve, Mergers $ (55 ) $ (61 ) $ (56 ) $ (33 ) $ (205 ) Midwest Generation Impairment (1,287 ) — 477 (39 ) (849 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (102 ) (102 ) International Tax Adjustment (see Note 22) — — — (373 ) (373 ) Asset Impairment (94 ) — — — (94 ) Total $ (1,436 ) $ (61 ) $ 421 $ (547 ) $ (1,623 )
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY CAROLINAS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 1,901 $ 1,707 $ 2,061 $ 1,560 $ 7,229 Operating income 515 483 666 296 1,960 Net income 292 265 383 141 1,081 2014 Operating revenues $ 2,000 $ 1,755 $ 1,938 $ 1,658 $ 7,351 Operating income 509 438 630 318 1,895 Net income 286 270 377 139 1,072
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (9 ) $ (11 ) $ (11 ) $ (16 ) $ (47 ) Ash Basin Settlement and Penalties (see Note 5) — — (1 ) (7 ) (8 ) Cost Savings Initiatives (see Note 19) — — — (93 ) (93 ) Total $ (9 ) $ (11 ) $ (12 ) $ (116 ) $ (148 ) 2014 Costs to Achieve, Mergers $ (29 ) $ (38 ) $ (25 ) $ (17 ) $ (109 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (72 ) (72 ) Total $ (29 ) $ (38 ) $ (25 ) $ (89 ) $ (181 )
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	PROGRESS ENERGY First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 2,536 $ 2,476 $ 2,929 $ 2,336 $ 10,277 Operating income 549 504 756 351 2,160 Income from continuing operations 264 217 452 132 1,065 Net income 263 217 451 131 1,062 Net income attributable to Parent 260 215 448 128 1,051 2014 Operating revenues $ 2,541 $ 2,421 $ 2,863 $ 2,341 $ 10,166 Operating income 477 488 665 388 2,018 Income from continuing operations 204 207 330 139 880 Net income 203 202 330 139 874 Net income attributable to Parent 202 202 329 136 869
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (8 ) $ (8 ) $ (8 ) $ (10 ) $ (34 ) Ash Basin Settlement and Penalties (see Note 5) — — (6 ) — (6 ) Cost Savings Initiatives (see Note 19) — — — (36 ) (36 ) Total $ (8 ) $ (8 ) $ (14 ) $ (46 ) $ (76 ) 2014 Costs to Achieve, Mergers $ (19 ) $ (12 ) $ (21 ) $ (13 ) $ (65 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (30 ) (30 ) Total $ (19 ) $ (12 ) $ (21 ) $ (43 ) $ (95 )
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY PROGRESS First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 1,449 $ 1,193 $ 1,488 $ 1,160 $ 5,290 Operating income 316 184 394 130 1,024 Net income 183 85 229 69 566 2014 Operating revenues $ 1,422 $ 1,191 $ 1,367 $ 1,196 $ 5,176 Operating income 258 212 285 180 935 Net income 133 101 157 76 467
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (5 ) $ (5 ) $ (6 ) $ (6 ) $ (22 ) Ash Basin Settlement and Penalties (see Note 5) — — (6 ) — (6 ) Cost Savings Initiatives (see Note 19) — — — (28 ) (28 ) Total $ (5 ) $ (5 ) $ (12 ) $ (34 ) $ (56 ) 2014 Costs to Achieve, Mergers $ (14 ) $ (3 ) $ (15 ) $ (10 ) $ (42 ) Coal Ash Plea Agreements Reserve (see Note 5) — — — (30 ) (30 ) Total $ (14 ) $ (3 ) $ (15 ) $ (40 ) $ (72 )
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY FLORIDA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 1,086 $ 1,281 $ 1,436 $ 1,174 $ 4,977 Operating income 227 315 357 216 1,115 Net income 113 165 216 105 599 2014 Operating revenues $ 1,116 $ 1,225 $ 1,491 $ 1,143 $ 4,975 Operating income 219 276 378 205 1,078 Net income 108 142 205 93 548
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (3 ) $ (3 ) $ (3 ) $ (4 ) $ (13 ) Cost Savings Initiatives (see Note 19) — — — (8 ) (8 ) Total $ (3 ) $ (3 ) $ (3 ) $ (12 ) $ (21 ) 2014 Costs to Achieve, Mergers $ (5 ) $ (9 ) $ (6 ) $ (3 ) $ (23 )
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY OHIO First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 586 $ 405 $ 462 $ 452 $ 1,905 Operating income 111 43 76 73 303 Income (loss) from discontinued operations, net of tax 90 (65 ) (2 ) — 23 Net income (loss) 149 (52 ) 32 43 172 2014 Operating revenues $ 575 $ 412 $ 446 $ 480 $ 1,913 Operating (loss) income (7 ) 60 58 76 187 (Loss) Income from discontinued operations, net of tax (875 ) (135 ) 413 34 (563 ) Net (loss) income (890 ) (107 ) 439 63 (495 )
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (1 ) $ (1 ) $ (1 ) $ (1 ) $ (4 ) Cost Savings Initiatives (see Note 19) — — — (2 ) (2 ) Total $ (1 ) $ (1 ) $ (1 ) $ (3 ) $ (6 ) 2014 Costs to Achieve, Mergers $ (2 ) $ (4 ) $ (3 ) $ (2 ) $ (11 ) Midwest Generation Impairment (1,318 ) — 477 (39 ) (880 ) Asset Impairment (94 ) — — — (94 ) Total $ (1,414 ) $ (4 ) $ 474 $ (41 ) $ (985 )
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Schedule Of Quarterly Financial Information	DUKE ENERGY INDIANA First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Operating revenues $ 788 $ 686 $ 749 $ 667 $ 2,890 Operating income 210 146 117 171 644 Net income 108 68 46 94 316 2014 Operating revenues $ 845 $ 748 $ 790 $ 792 $ 3,175 Operating income 215 178 182 130 705 Net income 113 87 101 58 359
Schedule Of Unusual Or Infrequently Occurring Items	The following table includes unusual or infrequently occurring items in each quarter during the two most recently completed fiscal years. All amounts discussed below are pretax. First Second Third Fourth (in millions) Quarter Quarter Quarter Quarter Total 2015 Costs to Achieve, Mergers $ (2 ) $ (1 ) $ (2 ) $ (2 ) $ (7 ) Edwardsport Settlement (see Note 4) — — (90 ) (3 ) (93 ) Cost Savings Initiatives (see Note 19) — — — (6 ) (6 ) Total $ (2 ) $ (1 ) $ (92 ) $ (11 ) $ (106 ) 2014 Costs to Achieve, Mergers $ (2 ) $ (5 ) $ (3 ) $ (2 ) $ (12 )

Summary of Significant Accoun59

Summary of Significant Accounting Policies (Narrative)(Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended			96 Months Ended
	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2022
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	$ 209		$ 30	$ 209
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			170	152
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	2,036		857	2,036	$ 1,501
Restricted Cash [Abstract]
Restricted cash	298		108	298
Duke Energy Carolinas [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	13		13	13	23
Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Annual Reduction In Excise Taxes				160
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	23		30	23
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	42		44	42	58
Duke Energy Progress [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	9		15	9	21
Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Annual Reduction In Excise Taxes				110
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	23		30	23
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	8		8	8	16
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Collateral Already Posted, Aggregate Fair Value	186			186
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	20		14	20	36
Duke Energy Indiana [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period	$ 6		9	$ 6	$ 15
International Energy [Member]
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents at end of period			534
Foreign Earnings Repatriated			$ 1,500
Restricted Cash [Abstract]
Cash Repatriation period			8 years
International Energy [Member] | Scenario, Forecast [Member]
Cash and Cash Equivalents [Abstract]
Foreign Earnings Repatriated						$ 2,700
Utility Franchise Tax Member [Member] | Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.22%
Utility Franchise Tax Member [Member] | Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.22%
Electricity Sales Tax Member [Member] | Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.00%
Electricity Sales Tax Member [Member] | Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate		3.00%
Current [Member] | Electricity Sales Tax Member [Member] | Duke Energy Carolinas [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate	7.00%
Current [Member] | Electricity Sales Tax Member [Member] | Duke Energy Progress [Member] | State [Member]
Organization And Basis Of Presentation [Line Items]
Statutory Tax Rate	7.00%

Summary of Significant Accoun60

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Other Assets and Liabilities)(Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Organization And Basis Of Presentation [Line Items]
Other current receivables	$ 703	$ 791
Collateral assets	30	209
Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	621	638
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Other current receivables	142	129
Duke Energy Carolinas [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued compensation	213	216
Collateral liabilities	141	128
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Other current receivables	151	129
Collateral assets	30	23
Progress Energy [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	129	718
Progress Energy [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	373	360
Derivative liabilities	201	271
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Other current receivables	87	43
Duke Energy Progress [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	111	272
Duke Energy Progress [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	141	135
Accrued compensation	108	116
Derivative liabilities	76	108
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Other current receivables	60	84
Collateral assets	30	23
Duke Energy Florida [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable		177
Duke Energy Florida [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Customer deposits	232	225
Derivative liabilities	125	163
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Other current receivables	66	93
Collateral assets		186
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable	59	40
Other current receivables	33	39
Duke Energy Ohio [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Accrued litigation reserve	80
Collateral liabilities	48	42
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Other current receivables	96	87
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Organization And Basis Of Presentation [Line Items]
Income taxes receivable		98
Duke Energy Indiana [Member] | Current Liabilities, Other [Member]
Organization And Basis Of Presentation [Line Items]
Collateral liabilities	$ 44	$ 43

Summary of Significant Accoun61

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Amounts Attributable to Controlling Interests) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization And Basis Of Presentation [Line Items]
Income (Loss) from Continuing Operations	$ 491	$ 940	$ 604	$ 776	$ 98	$ 891	$ 726	$ 750	$ 2,811	$ 2,465	$ 2,590
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interests									15	14	16
Income (Loss) from Continuing Operations Attributable to Parent									2,796	2,451	2,574
Income (Loss) From Discontinued Operations, net of tax	(9)	(5)	(57)	91	2	378	(113)	(843)	20	(576)	86
Loss from Discontinued Operations Attributable to Noncontrolling Interest, net of tax										(8)	(5)
(Loss) Income from Discontinued Operations Attributable to Parent, net of tax										(568)	91
Net income	482	935	547	867	100	1,269	613	(93)	2,831	1,889	2,676
Net Income Attributable to Noncontrolling Interest									15	6	11
Net Income (Loss) Attributable to Parent	477	932	543	864	97	1,274	609	(97)	2,816	1,883	2,665
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Income (Loss) from Continuing Operations	132	452	217	264	139	330	207	204	1,065	880	659
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interests										5	3
Income (Loss) from Continuing Operations Attributable to Parent										875	656
Income (Loss) From Discontinued Operations, net of tax									(3)	(6)	16
(Loss) Income from Discontinued Operations Attributable to Parent, net of tax										(6)	16
Net income	131	451	217	263	139	330	202	203	1,062	874	675
Net Income Attributable to Noncontrolling Interest									11	5	3
Net Income (Loss) Attributable to Parent	$ 128	$ 448	$ 215	$ 260	$ 136	$ 329	$ 202	$ 202	$ 1,051	$ 869	$ 672

Summary of Significant Accoun62

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Inventory)(Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Public Utilities, Inventory [Line Items]
Materials and supplies	$ 2,389	$ 2,102
Coal held for electric generation	1,114	997
Oil, gas and other fuel held for electric generation	307	360
Public Utilities, Inventory	3,810	3,459
Duke Energy Carolinas [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	785	719
Coal held for electric generation	451	362
Oil, gas and other fuel held for electric generation	40	43
Public Utilities, Inventory	1,276	1,124
Progress Energy [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	1,133	981
Coal held for electric generation	370	329
Oil, gas and other fuel held for electric generation	248	280
Public Utilities, Inventory	1,751	1,590
Duke Energy Progress [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	776	676
Coal held for electric generation	192	150
Oil, gas and other fuel held for electric generation	120	140
Public Utilities, Inventory	1,088	966
Duke Energy Florida [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	357	305
Coal held for electric generation	178	178
Oil, gas and other fuel held for electric generation	128	140
Public Utilities, Inventory	663	623
Duke Energy Ohio [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	81	67
Coal held for electric generation	16	21
Oil, gas and other fuel held for electric generation	8	9
Public Utilities, Inventory	105	97
Duke Energy Indiana [Member]
Public Utilities, Inventory [Line Items]
Materials and supplies	301	258
Coal held for electric generation	267	275
Oil, gas and other fuel held for electric generation	2	4
Public Utilities, Inventory	$ 570	$ 537

Summary of Significant Accoun63

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Property, Plant and Equipment)(Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.90%	2.80%	2.80%
Duke Energy Carolinas [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.80%	2.70%	2.80%
Progress Energy [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.60%	2.50%	2.50%
Duke Energy Progress [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.60%	2.50%	2.50%
Duke Energy Florida [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.70%	2.70%	2.40%
Duke Energy Ohio [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	2.70%	2.30%	3.30%
Duke Energy Indiana [Member]
Public Utility, Property, Plant and Equipment [Line Items]
Weighted-average depreciation rate	3.00%	3.00%	2.80%

Summary of Significant Accoun64

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Unbilled Revenues)(Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	$ 748	$ 827
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	283	295
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	172	217
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	102	135
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	70	82
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	3
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	31	27
Cinergy Receivables [Member] | Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	71	79
Cinergy Receivables [Member] | Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	$ 97	$ 112

Summary of Significant Accoun65

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Allowance for Doubtful Accounts)(Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	$ 18	$ 17	$ 30
Restricted receivables, allowance for doubtful accounts	53	51	43
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	3	3	3
Restricted receivables, allowance for doubtful accounts	7	6	6
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	6	8	14
Restricted receivables, allowance for doubtful accounts	8	8
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	4	7	10
Restricted receivables, allowance for doubtful accounts	5	5
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	2	2	4
Restricted receivables, allowance for doubtful accounts	3	3
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	2	2	2
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Receivables, allowance for doubtful accounts	$ 1	$ 1	$ 1

Summary of Significant Accoun66

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Excise Taxes)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 396	$ 498	$ 602
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	31	94	164
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	229	263	304
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	16	56	115
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	213	207	189
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	102	103	105
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 34	$ 38	$ 29

Acquisitions and Dispositions67

Acquisitions and Dispositions (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2016
Business Acquisition [Line Items]
Asset retirement obligations assumed	$ 226	$ 4
Subsequent Event [Member] | International Energy [Member]
Business Acquisition [Line Items]
Segment Carrying Value			$ 2,700
Piedmont Natural Gas [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 4,900
Business Acquisition, Share Price	$ 60
Long-term debt assumed	$ 1,900
Forward starting interest rate swaps, notional	900
Bridge Facility	4,900
Acquiree Termination Fee	125
Acquirer Termination Fee	250
Duke Energy Progress [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	1,249
Asset retirement obligations assumed	204
Duke Energy Progress [Member] | NCEMPA Generating Assets [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	1,250
Acquisition adjustment, recorded within property, plant and equipment	350
Nuclear decommissioning trust fund assets transferred	287
Asset retirement obligations assumed	204
Duke Energy Ohio [Member] | Midwest Generation Business [Member]
Business Acquisition [Line Items]
Proceeds from sale of business	$ 2,800

Acquisitions and Dispositions68

Acquisitions and Dispositions (Purchase Price Allocation) (Details) - Duke Energy Progress [Member] - NCEMPA Generating Assets [Member] $ in Millions	Dec. 31, 2015USD ($)
Significant Acquisitions and Disposals [Line Items]
Inventory	$ 56
Net property, plant and equipment	845
Total assets	901
Acquisition adjustment, recorded within property, plant and equipment	350
Total purchase price	$ 1,251

Acquisitions and Dispositions A

Acquisitions and Dispositions Acquisitions and Dispositions (Plants in Disposal Group) (Details) - Duke Energy Ohio [Member]	3 Months Ended
	Mar. 31, 2015MW
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	9,225
Owned Average MW Capacity	5,884
Stuart [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	2,308
Owned Average MW Capacity	900
Jointly Owned Utility Plant, Proportionate Ownership Share	39.00%
Zimmer [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,300
Owned Average MW Capacity	605
Jointly Owned Utility Plant, Proportionate Ownership Share	46.50%
Hanging Rock [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,226
Owned Average MW Capacity	1,226
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Miami Fort Station Units 7 And 8 [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	1,020
Owned Average MW Capacity	652
Jointly Owned Utility Plant, Proportionate Ownership Share	64.00%
Conesville [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	780
Owned Average MW Capacity	312
Jointly Owned Utility Plant, Proportionate Ownership Share	40.00%
Washington [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	617
Owned Average MW Capacity	617
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Fayette [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	614
Owned Average MW Capacity	614
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Killen [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	600
Owned Average MW Capacity	198
Jointly Owned Utility Plant, Proportionate Ownership Share	33.00%
Lee [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	568
Owned Average MW Capacity	568
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Dicks Creek [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	136
Owned Average MW Capacity	136
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%
Miami Fort [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total Average MW Capacity	56
Owned Average MW Capacity	56
Jointly Owned Utility Plant, Proportionate Ownership Share	100.00%

Acquisitions and Dispositions70

Acquisitions and Dispositions Acquisitions and Dispositions (Assets Held For Sale) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Acquisitions and Disposals [Line Items]
Charge for settlement agreement									$ 53
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Income tax expense (benefit)									19	$ (295)	$ 29
Income (Loss) From Discontinued Operations, net of tax	$ (9)	$ (5)	$ (57)	$ 91	$ 2	$ 378	$ (113)	$ (843)	20	(576)	86
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Current assets					364					364
Current liabilities					262					262
Midwest Generation Business [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Operating Revenues									543	1,748	1,885
Loss on disposition									(45)	(929)
Income (loss) before income taxes									59	(818)	141
Income tax expense (benefit)									26	(294)	56
Income (Loss) From Discontinued Operations, net of tax									33	(524)	85
Other Disposal Groups [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Income (Loss) From Discontinued Operations, net of tax									(13)	(52)	1
Duke Energy Ohio [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Income tax expense (benefit)									22	(300)	32
Income (Loss) From Discontinued Operations, net of tax		$ (2)	$ (65)	$ 90	34	$ 413	$ (135)	$ (875)	23	(563)	35
Disposal Group, Including Discontinued Operation, Balance Sheet Disclosures [Abstract]
Current assets					316					316
Current liabilities					$ 246					246
Duke Energy Ohio [Member] | Midwest Generation Business [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Operating Revenues									412	1,299	1,503
Loss on disposition									(52)	(959)
Income (loss) before income taxes									44	(863)	67
Income tax expense (benefit)									21	$ (300)	$ 32
Antitrust Lawsuit [Member]
Significant Acquisitions and Disposals [Line Items]
Charge for settlement agreement									81
Antitrust Lawsuit [Member] | Duke Energy Ohio [Member]
Significant Acquisitions and Disposals [Line Items]
Charge for settlement agreement									$ 81

Business Segments (Narrative) (

Business Segments (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)segment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Segment Reporting Information [Line Items]
Interest expense	$ 1,613	$ 1,622	$ 1,543
Duke Energy Carolinas [Member]
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Interest expense	$ 412	407	359
Progress Energy [Member]
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Interest expense	$ 670	675	680
Duke Energy Progress [Member]
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Interest expense	$ 235	234	201
Duke Energy Progress [Member] | North Carolina Electric Membership Corporation [Member]
Segment Reporting Information [Line Items]
Entity-wide revenue, major customer, percentage	10.00%
Duke Energy Florida [Member]
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Interest expense	$ 198	201	180
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Interest expense	$ 79	86	74
Duke Energy Indiana [Member]
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Interest expense	$ 176	171	170
Other Segment [Member] | Progress Energy [Member]
Segment Reporting Information [Line Items]
Interest expense	$ 240	$ 241	$ 300
National Methanol Company [Member] | International Energy [Member]
Segment Reporting Information [Line Items]
Equity method investment, ownership percentage	25.00%

Business Segments (Business Seg

Business Segments (Business Segment Data) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	$ 5,322	$ 6,483	$ 5,589	$ 6,065	$ 5,559	$ 6,395	$ 5,708	$ 6,263	$ 23,459	$ 23,925	$ 22,756
Interest expense									1,613	1,622	1,543
Depreciation and amortization									3,144	3,066	2,668
Equity in earnings (losses) of unconsolidated affiliates									69	130	122
Income tax expense (benefit) from continuing operations									1,326	1,669	1,205
Segment income									2,796	2,451	2,574
Add back noncontrolling interests component									15	14	16
Income (Loss) From Discontinued Operations, net of tax	(9)	(5)	(57)	91	2	378	(113)	(843)	20	(576)	86
Net income (loss)	482	935	547	867	100	1,269	613	(93)	2,831	1,889	2,676
Net Income (Loss) Attributable to Parent	477	932	543	864	97	1,274	609	(97)	2,816	1,883	2,665
Deferred foreign taxes									(17)	(67)	14
Impairment charges									120	81	399
Current State and Local Tax Expense (Benefit)									(12)	56	(40)
Costs to achieve mergers	30	24	22	21	33	56	61	55	97	205
Charge for settlement agreement									53
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									8,363	5,528	5,607
Assets	121,156				120,557				121,156	120,557	114,779
Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues	452	462	405	586	480	446	412	575	1,905	1,913	1,805
Interest expense									79	86	74
Depreciation and amortization									227	214	213
Income tax expense (benefit) from continuing operations									81	43	43
Segment income									149	68	67
Income (Loss) From Discontinued Operations, net of tax		(2)	(65)	90	34	413	(135)	(875)	23	(563)	35
Net income (loss)	43	32	(52)	149	63	439	(107)	(890)	172	(495)	102
Net Income (Loss) Attributable to Parent									172	(495)	102
Impairment charges										94	5
Current State and Local Tax Expense (Benefit)									(1)	3	(4)
Costs to achieve mergers	1	$ 1	$ 1	$ 1	2	$ 3	$ 4	$ 2	4	11
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									399	322	433
Assets	7,097				9,993				7,097	9,993	10,763
Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									(115)	(123)	(135)
Interest expense									(6)	(22)	(6)
Segment income									(4)	(10)	(12)
Segment Reporting Information Assets [Abstract]
Assets	188				189				188	189	188
Intersegment Eliminations [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									(1)	(1)
Segment income									(1)
Segment Reporting Information Assets [Abstract]
Assets	(8)				(230)				(8)	(230)	(155)
Other VIEs [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges										94
Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									22,024	22,228	20,871
Equity in earnings (losses) of unconsolidated affiliates									(4)	(3)	(1)
Regulated Utilities [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									1,872	1,894
Regulated Utilities [Member] | Operating Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									22,062	22,271	20,910
Interest expense									1,097	1,093	986
Depreciation and amortization									2,814	2,759	2,323
Equity in earnings (losses) of unconsolidated affiliates									(4)	(3)	(1)
Income tax expense (benefit) from continuing operations									1,647	1,628	1,522
Segment income									2,893	2,795	2,504
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									6,974	4,744	5,049
Assets	111,562				106,574				111,562	106,574	99,884
Regulated Utilities [Member] | Operating Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									1,873	1,895	1,765
Interest expense									78	81	74
Depreciation and amortization									226	211	200
Income tax expense (benefit) from continuing operations									105	117	91
Segment income									191	202	151
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									399	300	375
Assets	7,050				6,902				7,050	6,902	6,649
Regulated Utilities [Member] | Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									(38)	(43)	(39)
Regulated Utilities [Member] | Intersegment Eliminations [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									(1)	(1)
Commercial Portfolio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges										94
Current State and Local Tax Expense (Benefit)									41
Commercial Portfolio [Member] | Other VIEs [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges										94
International Energy [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									1,088	1,417	1,546
Equity in earnings (losses) of unconsolidated affiliates									74	120	110
Deferred foreign taxes										373
International Energy [Member] | Operating Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									1,088	1,417	1,546
Interest expense									85	93	86
Depreciation and amortization									92	97	100
Equity in earnings (losses) of unconsolidated affiliates									74	120	110
Income tax expense (benefit) from continuing operations									74	449	166
Segment income									225	55	408
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									45	67	67
Assets	3,271				5,093				3,271	5,093	4,998
Commercial Power [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									301	255	254
Equity in earnings (losses) of unconsolidated affiliates									(3)	10	7
Commercial Power [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									14	19
Commercial Power [Member] | Operating Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									301	255	260
Interest expense									44	58	61
Depreciation and amortization									104	92	110
Equity in earnings (losses) of unconsolidated affiliates									(3)	10	7
Income tax expense (benefit) from continuing operations									(92)	(171)	(148)
Segment income									4	(55)	(88)
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									1,131	555	268
Assets	4,010				6,278				4,010	6,278	6,955
Commercial Power [Member] | Operating Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									14	19	40
Interest expense										5
Depreciation and amortization										2	13
Income tax expense (benefit) from continuing operations									(5)	(67)	(36)
Segment income									(8)	(121)	(65)
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions										22	58
Assets					3,187					3,187	4,170
Commercial Power [Member] | Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues											(6)
Total Reportable Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									23,413	23,900	22,671
Total Reportable Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									1,886	1,913
Total Reportable Segments [Member] | Operating Segments [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									23,451	23,943	22,716
Interest expense									1,226	1,244	1,133
Depreciation and amortization									3,010	2,948	2,533
Equity in earnings (losses) of unconsolidated affiliates									67	127	116
Income tax expense (benefit) from continuing operations									1,629	1,906	1,540
Segment income									3,122	2,795	2,824
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									8,150	5,366	5,384
Assets	118,843				117,945				118,843	117,945	111,837
Total Reportable Segments [Member] | Operating Segments [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									1,887	1,914	1,805
Interest expense									78	86	74
Depreciation and amortization									226	213	213
Income tax expense (benefit) from continuing operations									100	50	55
Segment income									183	81	86
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									399	322	433
Assets	7,050				10,089				7,050	10,089	10,819
Total Reportable Segments [Member] | Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									(38)	(43)	(45)
Total Reportable Segments [Member] | Intersegment Eliminations [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									(1)	(1)
Other Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									46	25	85
Other Segment [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									19
Other Segment [Member] | Intersegment Eliminations [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									(77)	(80)	(90)
Other Segment [Member] | Corporate, Non-Segment [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									123	105	175
Interest expense									393	400	416
Depreciation and amortization									134	118	135
Equity in earnings (losses) of unconsolidated affiliates									2	3	6
Income tax expense (benefit) from continuing operations									(303)	(237)	(335)
Segment income									(322)	(334)	(238)
Costs to achieve mergers									60
Cost Savings Initiative, Net of tax									77
Segment Reporting Information Assets [Abstract]
Capital investments, expenditures and acquisitions									213	162	223
Assets	2,125				2,423				2,125	2,423	2,754
Other Segment [Member] | Corporate, Non-Segment [Member] | Duke Energy Ohio [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Operating revenues									19
Interest expense									1
Depreciation and amortization									1	1
Income tax expense (benefit) from continuing operations									(19)	(7)	(12)
Segment income									(33)	(13)	(19)
Segment Reporting Information Assets [Abstract]
Assets	$ 55				$ 134				55	$ 134	$ 99
Edwardsport IGCC Plant [Member] | Regulated Utilities [Member]
Segment Reporting Information, Profit (Loss) [Abstract]
Impairment charges									$ 58

Business Segments (Schedule of

Business Segments (Schedule of Revenue and Long-Lived Assets, By Geographical Area) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated revenue	$ 5,322	$ 6,483	$ 5,589	$ 6,065	$ 5,559	$ 6,395	$ 5,708	$ 6,263	$ 23,459	$ 23,925	$ 22,756
Consolidated long-lived assets	89,564				83,167				89,564	83,167	81,362
U.S. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated revenue									22,371	22,508	21,211
Consolidated long-lived assets	87,552				80,709				87,552	80,709	78,581
Latin America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated revenue									1,088	1,417	1,545
Consolidated long-lived assets	$ 2,012				$ 2,458				$ 2,012	$ 2,458	$ 2,781

Business Segments (Schedule o74

Business Segments (Schedule of Revenue, By Products and Services) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Operating revenues	$ 5,322	$ 6,483	$ 5,589	$ 6,065	$ 5,559	$ 6,395	$ 5,708	$ 6,263	$ 23,459	$ 23,925	$ 22,756
Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									22,024	22,228	20,871
International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									1,088	1,417	1,546
Commercial Power [Member]
Segment Reporting Information [Line Items]
Operating revenues									301	255	254
Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues									23,413	23,900	22,671
Retail Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues									18,695	19,007	17,837
Retail Electric [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									18,695	19,007	17,837
Wholesale Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues									3,299	3,460	3,427
Wholesale Electric [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									2,014	1,879	1,720
Wholesale Electric [Member] | International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									1,025	1,326	1,447
Wholesale Electric [Member] | Commercial Power [Member]
Segment Reporting Information [Line Items]
Operating revenues									260	255	260
Retail Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues									546	571	506
Retail Gas [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									546	571	506
Wholesale Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues									63	91	99
Wholesale Gas [Member] | International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									63	91	99
Other Revenues [Member]
Segment Reporting Information [Line Items]
Operating revenues									848	814	847
Other Revenues [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									807	814	847
Other Revenues [Member] | Commercial Power [Member]
Segment Reporting Information [Line Items]
Operating revenues									41
Operating Segments [Member] | Regulated Utilities [Member]
Segment Reporting Information [Line Items]
Operating revenues									22,062	22,271	20,910
Operating Segments [Member] | International Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues									1,088	1,417	1,546
Operating Segments [Member] | Commercial Power [Member]
Segment Reporting Information [Line Items]
Operating revenues									301	255	260
Operating Segments [Member] | Total Reportable Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues									$ 23,451	$ 23,943	$ 22,716

Business Segments (Schedule o75

Business Segments (Schedule of Segment Reporting Information, by Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Segment income	$ 2,796	$ 2,451	$ 2,574
Duke Energy Carolinas [Member] | Other Segment [Member]
Segment Reporting Information [Line Items]
Segment income	(95)	(79)	(97)
Progress Energy [Member]
Segment Reporting Information [Line Items]
Segment income		875	656
Progress Energy [Member] | Other Segment [Member]
Segment Reporting Information [Line Items]
Segment income	(159)	(190)	(241)
Duke Energy Progress [Member] | Other Segment [Member]
Segment Reporting Information [Line Items]
Segment income	(32)	(31)	(46)
Duke Energy Florida [Member] | Other Segment [Member]
Segment Reporting Information [Line Items]
Segment income	(16)	(19)	(24)
Duke Energy Indiana [Member] | Other Segment [Member]
Segment Reporting Information [Line Items]
Segment income	$ (10)	$ (11)	$ (16)

Regulatory Matters (Narrative)

Regulatory Matters (Narrative) (Details)	Dec. 30, 2014USD ($)	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Jun. 30, 2014USD ($)	Jun. 30, 2013USD ($)	Dec. 31, 2015USD ($)MW	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Public Utilities, General Disclosures [Line Items]
Other Liabilities		$ 1,706,000,000					$ 1,706,000,000	$ 1,675,000,000
Accounts Payable, Current		2,400,000,000					2,400,000,000	2,271,000,000
Decommissioning cost study estimate		8,130,000,000					8,130,000,000
Restructuring Reserve		136,000,000					136,000,000	28,000,000
Regulatory assets, current		$ 877,000,000					$ 877,000,000	1,115,000,000
Net Asset Percentage Limit		25.00%					25.00%
Impairment charges							$ 120,000,000	81,000,000	$ 399,000,000
Other Nonoperating Income (Expense)							307,000,000	351,000,000	262,000,000
Net property, plant and equipment		$ 75,709,000,000					75,709,000,000	70,046,000,000
Regulated Revenue							21,379,000,000	21,550,000,000	20,329,000,000
Regulatory assets, noncurrent		11,373,000,000					11,373,000,000	11,042,000,000
Regulatory liabilities, noncurrent		6,255,000,000					6,255,000,000	6,193,000,000
Regulatory assets		12,250,000,000					12,250,000,000	12,157,000,000
Capital expenditures							6,766,000,000	5,384,000,000	5,526,000,000
Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		509,000,000					509,000,000	1,659,000,000
Nuclear asset securitizable balance, net [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		1,237,000,000					1,237,000,000
Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		245,000,000					245,000,000	296,000,000
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment		$ 352,000,000					$ 352,000,000
Capacity (in MW) | MW							1,821
Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		40.00%					40.00%
Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		7.50%					7.50%
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Other Liabilities		$ 621,000,000					$ 621,000,000	642,000,000
Accounts Payable, Current		753,000,000					753,000,000	709,000,000
Restructuring Reserve		78,000,000					78,000,000	2,000,000
Regulatory assets, current		305,000,000					305,000,000	399,000,000
Impairment charges							1,000,000	3,000,000
Other Nonoperating Income (Expense)							160,000,000	172,000,000	120,000,000
Net property, plant and equipment		25,877,000,000					25,877,000,000	24,672,000,000
Regulatory assets, noncurrent		2,766,000,000					2,766,000,000	2,465,000,000
Regulatory liabilities, noncurrent		2,802,000,000					2,802,000,000	2,710,000,000
Regulatory assets		3,071,000,000					3,071,000,000	2,864,000,000
Capital expenditures							1,933,000,000	1,879,000,000	1,695,000,000
Duke Energy Carolinas [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		49,000,000					49,000,000	58,000,000
Duke Energy Carolinas [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		107,000,000					$ 107,000,000	141,000,000
Duke Energy Carolinas [Member] | Minimum [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period							5 years
Duke Energy Carolinas [Member] | Maximum [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period							10 years
Duke Energy Carolinas [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							10.20%
Duke Energy Carolinas [Member] | FERC Complaint [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage							8.49%
Duke Energy Carolinas [Member] | William State Lee III Nuclear Station [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment		471,000,000					$ 471,000,000
Duke Energy Carolinas [Member] | NCEMC [Member] | William States Lee Combined Cycle Facility [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC		$ 600,000,000					$ 600,000,000
Joint owner ownership percentage		13.00%					13.00%
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Other Liabilities		$ 45,000,000					$ 45,000,000	89,000,000
Accounts Payable, Current		399,000,000					399,000,000	481,000,000
Restructuring Reserve		19,000,000					19,000,000	1,000,000
Regulatory assets, current		264,000,000					264,000,000	287,000,000
Payments to Acquire Businesses, Gross							1,249,000,000
Impairment charges							5,000,000	(18,000,000)	22,000,000
Other Nonoperating Income (Expense)							71,000,000	51,000,000	57,000,000
Net property, plant and equipment		17,720,000,000					17,720,000,000	15,186,000,000
Regulatory assets, noncurrent		2,710,000,000					2,710,000,000	2,675,000,000
Regulatory liabilities, noncurrent		1,878,000,000					1,878,000,000	1,832,000,000
Regulatory assets		2,974,000,000					2,974,000,000	2,962,000,000
Capital expenditures							$ 1,669,000,000	1,241,000,000	1,567,000,000
Duke Energy Progress [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period							10 years
Regulatory assets		179,000,000					$ 179,000,000	152,000,000
Duke Energy Progress [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		62,000,000					$ 62,000,000	43,000,000
Duke Energy Progress [Member] | Maximum [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period							10 years
Duke Energy Progress [Member] | FERC Mitigation [Member]
Public Utilities, General Disclosures [Line Items]
Impairment charges					$ (18,000,000)
Duke Energy Progress [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							10.80%
Duke Energy Progress [Member] | FERC Complaint [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage							8.49%
Duke Energy Progress [Member] | Western Carolinas Modernization Plan [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		1,100,000,000					$ 1,100,000,000
Duke Energy Progress [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment		548,000,000					$ 548,000,000
Capacity (in MW) | MW							376
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Public Utilities, General Disclosures [Line Items]
Impairment charges						$ 22,000,000
Regulatory assets, noncurrent		48,000,000					$ 48,000,000
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Other Liabilities		146,000,000					146,000,000	158,000,000
Accounts Payable, Current		322,000,000					322,000,000	365,000,000
Restructuring Reserve		4,000,000					4,000,000	17,000,000
Regulatory assets, current		98,000,000					98,000,000	203,000,000
Payments to Acquire Businesses, Gross							166,000,000
Impairment charges							7,000,000	2,000,000	358,000,000
Other Nonoperating Income (Expense)							24,000,000	20,000,000	30,000,000
Net property, plant and equipment		10,623,000,000					10,623,000,000	9,955,000,000
Regulatory assets, noncurrent		2,725,000,000					2,725,000,000	2,733,000,000
Regulatory liabilities, noncurrent		509,000,000					509,000,000	547,000,000
Regulatory assets		2,823,000,000					2,823,000,000	2,936,000,000
Capital expenditures							1,029,000,000	699,000,000	915,000,000
Duke Energy Florida [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		230,000,000					230,000,000	1,393,000,000
Duke Energy Florida [Member] | Nuclear asset securitizable balance, net [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		1,237,000,000					1,237,000,000
Duke Energy Florida [Member] | Nuclear Deferral [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		76,000,000					76,000,000	112,000,000
Duke Energy Florida [Member] | FPSC [Member] | Removal Costs [Member]
Public Utilities, General Disclosures [Line Items]
Amount of reduction to carrying amount of regulatory liabilities									114,000,000
Duke Energy Florida [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission							$ (14,100,000)
Approved return on equity percentage amount by state commission							10.80%
Public Utilities, Requested Return on Equity, Percentage							10.00%
Customer Refundable Fees, Refund Payments		14,100,000
Duke Energy Florida [Member] | FERC Complaint 3 [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							8.69%
Duke Energy Florida [Member] | 2013 FPSC Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							10.50%
Duke Energy Florida [Member] | 2013 FPSC Settlement Agreement [Member] | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							9.50%
Duke Energy Florida [Member] | 2013 FPSC Settlement Agreement [Member] | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							11.50%
Duke Energy Florida [Member] | 2012 FPSC Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission							$ 150,000,000
Total Customer Refunds To Be Paid							388,000,000
Customer Refund Liability, Current		70,000,000					70,000,000
Duke Energy Florida [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment		131,000,000					$ 131,000,000
Capacity (in MW) | MW							873
Duke Energy Florida [Member] | Crystal River Unit 3 [Member]
Public Utilities, General Disclosures [Line Items]
Decommissioning cost study estimate		1,180,000,000					$ 1,180,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | ISFSI Projects [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							7.35%
Regulatory assets, noncurrent		60,000,000					$ 60,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Acceleration of cash recovery through fuel clause							47,000,000
Impairment charges						295,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member] | Original Uprate Project [Member] [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets, noncurrent		169,000,000					169,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Impairment charges			$ 15,000,000
Amount of Regulatory Costs Not yet Approved		1,298,000,000					1,298,000,000
Regulatory assets, noncurrent		1,283,000,000					$ 1,283,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member] | 2013 FPSC Settlement Agreement [Member] | FPSC [Member] | Nuclear asset securitizable balance, net [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Noncurrent Asset, Amortization Period							20 years
Regulatory assets, noncurrent		1,283,000,000					$ 1,283,000,000
Duke Energy Florida [Member] | Levy Nuclear Station [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve		25,000,000					25,000,000
Duke Energy Florida [Member] | Levy Nuclear Station [Member] | FPSC [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission							0
Duke Energy Florida [Member] | Levy Nuclear Station [Member] | 2013 FPSC Settlement Agreement [Member]
Public Utilities, General Disclosures [Line Items]
Impairment charges						$ 65,000,000
Net unrecovered investment		183,000,000					183,000,000
Net property, plant and equipment		105,000,000					105,000,000
Regulatory assets, noncurrent		78,000,000					78,000,000
Duke Energy Florida [Member] | Citrus County Station [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC		1,500,000,000					1,500,000,000
Duke Energy Florida [Member] | Suwannee Station [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost of new utility plant, including AFUDC		197,000,000					197,000,000
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Other Liabilities		165,000,000					165,000,000	166,000,000
Accounts Payable, Current		207,000,000					207,000,000	209,000,000
Regulatory assets, current		$ 36,000,000					$ 36,000,000	49,000,000
Limit of Total Capital		30.00%					30.00%
Impairment charges								94,000,000	5,000,000
Other Nonoperating Income (Expense)							$ 6,000,000	10,000,000	2,000,000
Net property, plant and equipment		$ 5,243,000,000					5,243,000,000	4,937,000,000
Regulated Revenue							1,331,000,000	1,316,000,000	1,258,000,000
Regulatory assets, noncurrent		497,000,000					497,000,000	512,000,000
Regulatory liabilities, noncurrent		245,000,000					245,000,000	241,000,000
Regulatory assets		533,000,000					533,000,000	561,000,000
Capital expenditures							$ 399,000,000	322,000,000	434,000,000
Duke Energy Ohio [Member] | Natural Gas Rate Case [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							9.84%
Duke Energy Ohio [Member] | Mgp Remediation [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Approved rate increase (decrease) amount by state commission							$ 56,000,000
Duke Energy Ohio [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							12.38%
Duke Energy Ohio [Member] | FERC Complaint 1 [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							11.38%
Percentage Recovered Through Future Rate Case							30.00%
Duke Energy Ohio [Member] | Accelerated Natural Gas Service Line Replacement Rider | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital and operations and maintenance cost							$ 320,000,000
Duke Energy Ohio [Member] | Energy Efficiency and Peak Demand Reduction Program [Member] | PUCO [Member]
Public Utilities, General Disclosures [Line Items]
Regulated Revenue		20,000,000		$ (23,000,000)
Duke Energy Ohio [Member] | RTO Realignment [Member]
Public Utilities, General Disclosures [Line Items]
Restructuring Reserve		$ 92,000,000					$ 92,000,000	94,000,000
Approved MVP Proposals		17					17
MISO estimate of Duke Energy Ohio's MVP obligation							$ 2,700,000,000
Regulatory assets		$ 72,000,000					$ 72,000,000
Duke Energy Ohio [Member] | Dayton Power and Light [Member] | East Bend Station [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage	31.00%
Capital expenditures	$ 12,400,000
Duke Energy Kentucky [Member]
Public Utilities, General Disclosures [Line Items]
Required Equity Capital Structure Percent		35.00%					35.00%
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Other Liabilities		$ 65,000,000					$ 65,000,000	90,000,000
Accounts Payable, Current		189,000,000					189,000,000	179,000,000
Regulatory assets, current		102,000,000					102,000,000	93,000,000
Impairment charges							88,000,000
Other Nonoperating Income (Expense)							11,000,000	22,000,000	18,000,000
Net property, plant and equipment		9,523,000,000					9,523,000,000	8,815,000,000
Regulatory assets, noncurrent		716,000,000					716,000,000	685,000,000
Regulatory liabilities, noncurrent		754,000,000					754,000,000	796,000,000
Regulatory assets		818,000,000					818,000,000	778,000,000
Capital expenditures							690,000,000	625,000,000	$ 545,000,000
Duke Energy Indiana [Member] | Retired Generation Facilities [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory assets		51,000,000					$ 51,000,000	$ 56,000,000
Duke Energy Indiana [Member] | FERC Transmission Rates [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							12.38%
Duke Energy Indiana [Member] | FERC Transmission Rates [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Approved return on equity percentage amount by state commission							0.50%
Duke Energy Indiana [Member] | FERC Complaint 2 [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage							8.67%
Duke Energy Indiana [Member] | FERC Complaint 2 [Member] | Federal Energy Regulatory Commission [Member]
Public Utilities, General Disclosures [Line Items]
Public Utilities, Requested Return on Equity, Percentage							10.32%
Duke Energy Indiana [Member] | Grid Infrastructure Improvement Plan [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		1,900,000,000					$ 1,900,000,000
Duke Energy Indiana [Member] | Revised Grid Infrastructure Improvement Plan [Member]
Public Utilities, General Disclosures [Line Items]
Estimated capital cost		1,800,000,000					1,800,000,000
Duke Energy Indiana [Member] | Edwardsport IGCC Plant [Member] | IGCC Rider Proceeding [Member] | IURC [Member]
Public Utilities, General Disclosures [Line Items]
Amount of Impairment to Carrying Amount of Regulatory Assets		80,300,000					80,300,000
Other Liabilities		7,200,000					7,200,000
Legal Fees							5,500,000
Accounts Payable, Current		5,500,000					$ 5,500,000
Regulatory Noncurrent Asset, Amortization Period							8 years
Impairment charges							$ 87,500,000
Other Nonoperating Income (Expense)							5,500,000
Public Utilities, Requested Rate Increase (Decrease), Amended, Amount							(87,500,000)
Regulatory assets		128,000,000					128,000,000
Duke Energy Indiana [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment		$ 221,000,000					$ 221,000,000
Capacity (in MW) | MW							948
Dominion Resources [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		45.00%					45.00%
Piedmont Natural Gas [Member] | Atlantic Coast Pipeline (ACP) [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		10.00%					10.00%
Spectra Energy [Member] | Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		59.50%					59.50%
NextEra [Member] | Sabal Trail Transmission Pipeline [Member]
Public Utilities, General Disclosures [Line Items]
Joint owner ownership percentage		33.00%					33.00%

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Regulatory Assets Liabilities [Line Items]
Regulatory assets	$ 12,250	$ 12,157
Regulatory assets, current	877	1,115
Regulatory assets, noncurrent	11,373	11,042
Regulatory liabilities	6,655	6,397
Regulatory liabilities - current	400	204
Regulatory liabilities, noncurrent	6,255	6,193
Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	5,329	5,221
Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	71	166
Storm Reserve [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	150	150
Accrued Pension And Other Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	288	379
Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	311	37
Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	506	444
Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,555	1,992
Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	838	1,025
Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,151	2,015
Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	509	1,659
Debt Fair Value Adjustment [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,191	1,305
Net Regulatory Asset Related To Income Taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,075	1,144
Nuclear asset securitizable balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,237
Hedge Cost and Other Deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	571	628
Demand Side Management And Energy Efficiency [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	340	330
Grid Modernization [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	68	76
Vacation Accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	192	213
Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	151	246
Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	245	296
Post-In-Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	383	494
Gasification Services Agreement Buyout Costs [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	32	55
Transmission Expansion Obligation [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	72	70
Manufactured Gas Plant Environmental Reserve [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	104	115
NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21
East Bend deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	16
Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	499	494
Duke Energy Carolinas [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	3,071	2,864
Regulatory assets, current	305	399
Regulatory assets, noncurrent	2,766	2,465
Regulatory liabilities	2,841	2,744
Regulatory liabilities - current	39	34
Regulatory liabilities, noncurrent	2,802	2,710
Duke Energy Carolinas [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	2,413	2,420
Duke Energy Carolinas [Member] | Storm Reserve [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	24	25
Duke Energy Carolinas [Member] | Accrued Pension And Other Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	68	76
Duke Energy Carolinas [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	55	6
Duke Energy Carolinas [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	281	217
Duke Energy Carolinas [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,120	840
Duke Energy Carolinas [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	104	67
Duke Energy Carolinas [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	479	412
Duke Energy Carolinas [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	49	58
Duke Energy Carolinas [Member] | Net Regulatory Asset Related To Income Taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	564	614
Duke Energy Carolinas [Member] | Hedge Cost and Other Deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	127	103
Duke Energy Carolinas [Member] | Demand Side Management And Energy Efficiency [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	80	106
Duke Energy Carolinas [Member] | Vacation Accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	79	86
Duke Energy Carolinas [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21	50
Duke Energy Carolinas [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	107	141
Duke Energy Carolinas [Member] | Post-In-Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	97	124
Duke Energy Carolinas [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	244	263
Progress Energy [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	5,797	5,899
Regulatory assets, current	362	491
Regulatory assets, noncurrent	5,435	5,408
Regulatory liabilities	2,673	2,485
Regulatory liabilities - current	286	106
Regulatory liabilities, noncurrent	2,387	2,379
Progress Energy [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	2,078	1,975
Progress Energy [Member] | Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities		70
Progress Energy [Member] | Storm Reserve [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	125	125
Progress Energy [Member] | Accrued Pension And Other Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	51	121
Progress Energy [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	255	23
Progress Energy [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	164	171
Progress Energy [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,394	1,152
Progress Energy [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	487	730
Progress Energy [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	807	812
Progress Energy [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	409	1,545
Progress Energy [Member] | Net Regulatory Asset Related To Income Taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	318	354
Progress Energy [Member] | Nuclear asset securitizable balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,237
Progress Energy [Member] | Hedge Cost and Other Deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	410	490
Progress Energy [Member] | Demand Side Management And Energy Efficiency [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	250	203
Progress Energy [Member] | Vacation Accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	38	46
Progress Energy [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	129	182
Progress Energy [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	138	155
Progress Energy [Member] | Post-In-Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	38	121
Progress Energy [Member] | NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21
Progress Energy [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	121	109
Duke Energy Progress [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,974	2,962
Regulatory assets, current	264	287
Regulatory assets, noncurrent	2,710	2,675
Regulatory liabilities	1,963	1,903
Regulatory liabilities - current	85	71
Regulatory liabilities, noncurrent	1,878	1,832
Duke Energy Progress [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	1,725	1,692
Duke Energy Progress [Member] | Accrued Pension And Other Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	25	61
Duke Energy Progress [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	58	23
Duke Energy Progress [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	155	127
Duke Energy Progress [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,386	1,152
Duke Energy Progress [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	195	432
Duke Energy Progress [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	366	354
Duke Energy Progress [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	179	152
Duke Energy Progress [Member] | Net Regulatory Asset Related To Income Taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	106	141
Duke Energy Progress [Member] | Hedge Cost and Other Deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	171	217
Duke Energy Progress [Member] | Demand Side Management And Energy Efficiency [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	237	193
Duke Energy Progress [Member] | Vacation Accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	38	46
Duke Energy Progress [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	93	138
Duke Energy Progress [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	62	43
Duke Energy Progress [Member] | Post-In-Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	38	28
Duke Energy Progress [Member] | NCEMPA deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21
Duke Energy Progress [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	82	66
Duke Energy Florida [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	2,823	2,936
Regulatory assets, current	98	203
Regulatory assets, noncurrent	2,725	2,733
Regulatory liabilities	709	582
Regulatory liabilities - current	200	35
Regulatory liabilities, noncurrent	509	547
Duke Energy Florida [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	353	283
Duke Energy Florida [Member] | Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities		70
Duke Energy Florida [Member] | Storm Reserve [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	125	125
Duke Energy Florida [Member] | Accrued Pension And Other Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	26	60
Duke Energy Florida [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	197
Duke Energy Florida [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	8	44
Duke Energy Florida [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	8
Duke Energy Florida [Member] | Asset retirement obligations - nuclear and other [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	292	298
Duke Energy Florida [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	441	458
Duke Energy Florida [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	230	1,393
Duke Energy Florida [Member] | Net Regulatory Asset Related To Income Taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	212	213
Duke Energy Florida [Member] | Nuclear asset securitizable balance, net [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1,237
Duke Energy Florida [Member] | Hedge Cost and Other Deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	239	273
Duke Energy Florida [Member] | Demand Side Management And Energy Efficiency [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	13	10
Duke Energy Florida [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	36	44
Duke Energy Florida [Member] | Nuclear Deferral [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	76	112
Duke Energy Florida [Member] | Post-In-Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		93
Duke Energy Florida [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	39	42
Duke Energy Ohio [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	533	561
Regulatory assets, current	36	49
Regulatory assets, noncurrent	497	512
Regulatory liabilities	257	251
Regulatory liabilities - current	12	10
Regulatory liabilities, noncurrent	245	241
Duke Energy Ohio [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	222	222
Duke Energy Ohio [Member] | Storm Reserve [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	1
Duke Energy Ohio [Member] | Accrued Pension And Other Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	21	19
Duke Energy Ohio [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	1
Duke Energy Ohio [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	12	10
Duke Energy Ohio [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	4
Duke Energy Ohio [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	139	132
Duke Energy Ohio [Member] | Net Regulatory Asset Related To Income Taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	55	64
Duke Energy Ohio [Member] | Hedge Cost and Other Deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	7	7
Duke Energy Ohio [Member] | Demand Side Management And Energy Efficiency [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	10	21
Duke Energy Ohio [Member] | Grid Modernization [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	68	76
Duke Energy Ohio [Member] | Vacation Accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	5	6
Duke Energy Ohio [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	1	9
Duke Energy Ohio [Member] | Post-In-Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	21	21
Duke Energy Ohio [Member] | Gasification Services Agreement Buyout Costs [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	0
Duke Energy Ohio [Member] | Transmission Expansion Obligation [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	72	74
Duke Energy Ohio [Member] | Manufactured Gas Plant Environmental Reserve [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	104	115
Duke Energy Ohio [Member] | East Bend deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	16
Duke Energy Ohio [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	31	36
Duke Energy Indiana [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	818	778
Regulatory assets, current	102	93
Regulatory assets, noncurrent	716	685
Regulatory liabilities	816	850
Regulatory liabilities - current	62	54
Regulatory liabilities, noncurrent	754	796
Duke Energy Indiana [Member] | Costs of Removal [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	616	613
Duke Energy Indiana [Member] | Amounts To Be Refunded to Customers [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	71	96
Duke Energy Indiana [Member] | Accrued Pension And Other Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	83	91
Duke Energy Indiana [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities		8
Duke Energy Indiana [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory liabilities	46	42
Duke Energy Indiana [Member] | Asset retirement obligations - coal ash [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	37
Duke Energy Indiana [Member] | Accrued Pension And Post Retirement [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	220	217
Duke Energy Indiana [Member] | Retired Generation Facilities [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	51	56
Duke Energy Indiana [Member] | Net Regulatory Asset Related To Income Taxes [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	120	111
Duke Energy Indiana [Member] | Hedge Cost and Other Deferrals [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	27	28
Duke Energy Indiana [Member] | Vacation Accrual [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	10	12
Duke Energy Indiana [Member] | Deferred Fuel and Purchased Power [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets		5
Duke Energy Indiana [Member] | Post-In-Service Carrying Costs And Deferred Operating Expense [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	227	228
Duke Energy Indiana [Member] | Gasification Services Agreement Buyout Costs [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	32	55
Duke Energy Indiana [Member] | Other Regulatory Assets (Liabilities) [Member]
Regulatory Assets Liabilities [Line Items]
Regulatory assets	$ 94	$ 66

Regulatory Matters (Schedule 78

Regulatory Matters (Schedule of MISO Exit fees)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Restructuring Reserve [Roll Forward]
Balance, beginning of period	$ 28
Provision/adjustments	144
Cash reductions	(36)
Balance, end of period	136
Total regulatory assets	12,250	$ 12,157
Duke Energy Ohio [Member]
Restructuring Reserve [Roll Forward]
Total regulatory assets	533	$ 561
Duke Energy Ohio [Member] | RTO Realignment [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	94
Provision/adjustments	3
Cash reductions	(5)
Balance, end of period	92
Total regulatory assets	$ 72

Regulatory Matters (Schedule 79

Regulatory Matters (Schedule of Net Carrying Value Of Facilities As Well As the Remaining Non-current Regulatory Assets) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)MW	Dec. 31, 2014USD ($)
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 75,709	$ 70,046
Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	1,821
Net property, plant and equipment	$ 352
Duke Energy Carolinas [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	25,877	24,672
Progress Energy [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 28,347	25,144
Progress Energy [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	873
Net property, plant and equipment	$ 131
Duke Energy Progress [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 17,720	15,186
Duke Energy Progress [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	376
Net property, plant and equipment	$ 548
Duke Energy Florida [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 10,623	9,955
Duke Energy Florida [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	873
Net property, plant and equipment	$ 131
Duke Energy Ohio [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	5,243	4,937
Duke Energy Indiana [Member]
Public Utilities, General Disclosures [Line Items]
Net property, plant and equipment	$ 9,523	$ 8,815
Duke Energy Indiana [Member] | Generation Facilities To Be Retired [Member]
Public Utilities, General Disclosures [Line Items]
Capacity (in MW) | MW	948
Net property, plant and equipment	$ 221

Commitments and Contingencies80

Commitments and Contingencies (Narrative) (Details) T in Thousands	Feb. 08, 2016USD ($)	Aug. 10, 2011	Aug. 09, 2011	Dec. 31, 2015USD ($)plantClaimsprojectreactor	Dec. 31, 2014USD ($)	Dec. 31, 2000USD ($)	Aug. 18, 2014gal	Feb. 08, 2014Tgal
Insurance [Abstract]
Insured public liability limit per nuclear incident				$ 13,500,000,000
Excess nuclear liability program coverage				13,100,000,000
Pro rata assessment for each reactor owned for each incident exceeding public liability insurance				$ 127,000,000
Number of licensed nuclear reactors | reactor				103
Annual payment limit to pro rata assessments				$ 19,000,000
Industry aggregate limit				3,200,000,000
Sublimit for non-nuclear terrorist events				$ 1,830,000,000
Insurance Coverage Percentage Initial Weeks				100.00%
Accidental Outage Insurance Coverage Initial Weeks				365 days
Insurance Coverage Percentage Additional Weeks				80.00%
Accidental Outage Insurance Coverage Additional Weeks				770 days
Weeks of Sublimits for Accidental Outage Coverage				728 days
Sublimit accidental outage recovery				$ 328,000,000
Maximum Magnitude of Retroactive Premiums				10
Maximum Period for Retroactive Premium Assessment				6 years
Valuation and Qualifying Accounts [Abstract]
Charge for settlement agreement				$ 53,000,000
Progress Energy Merger Shareholder Litigation [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement Covered by Insurance				121,000,000
Payments for Legal Settlements				25,000,000
Litigation Settlement, Amount				$ 146,000,000
Brazil Expansion Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Obligation to expand installed generation capacity, percent		15.00%	15.00%
North Carolina Ash Basins [Member]
Valuation and Qualifying Accounts [Abstract]
Facilities with Ash Basins | plant				14
Ash Basins Fines and Restitution [Member] | USDOJ [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement, Expense				$ 68,000,000
Ash Basins Community Service and Mitigation [Member] | USDOJ [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement, Expense				34,000,000
Antitrust Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Charge for settlement agreement				81,000,000
Duke Energy Carolinas [Member]
Insurance [Abstract]
Primary nuclear liability program coverage				375,000,000
Max Retroactive Premium Assessments				159,000,000
Duke Energy Carolinas [Member] | McGuire Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses				1,500,000,000
Additional nuclear accident limit				1,250,000,000
Accidental outage insurance coverage policy limit				490,000,000
Duke Energy Carolinas [Member] | Catawba Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses				1,500,000,000
Dedicated additional nuclear accident limit				1,250,000,000
Additional Non Nuclear Accident Limit				750,000,000
Accidental outage insurance coverage policy limit				$ 490,000,000
Potential Obligation percentage				100.00%
Duke Energy Carolinas [Member] | Oconee Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses				$ 1,500,000,000
Additional nuclear accident limit				1,250,000,000
Additional Non Nuclear Accident Limit				750,000,000
Accidental outage insurance coverage policy limit				490,000,000
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Valuation and Qualifying Accounts [Abstract]
Minimum Master Credit Facility Balance required				250,000,000
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Environmental Remediation Expense					$ 24,000,000
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member] | Minimum [Member]
Valuation and Qualifying Accounts [Abstract]
Estimated amount of ash released, in tons | T								30
Estimated amount of ash basin water released, in gallons | gal								24,000,000
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member] | Maximum [Member]
Valuation and Qualifying Accounts [Abstract]
Estimated amount of ash released, in tons | T								39
Estimated amount of ash basin water released, in gallons | gal								27,000,000
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Operating Expense [Member] | USDOJ [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement, Expense					72,000,000
Duke Energy Carolinas [Member] | Groundwater Violation [Member]
Valuation and Qualifying Accounts [Abstract]
Charge for settlement agreement				$ 1,000,000
Duke Energy Carolinas [Member] | New Source Review Provisions Of Clean Air Act [Member]
Valuation and Qualifying Accounts [Abstract]
Maximum civil penalties per day for each violation						$ 37,500
Projects with Alleged NSR Violations | project				29
Number of Coal Plants with Alleged NSR Violations | plant				25
Loss contingency, pending claims, number | Claims				13
Remaining Number of Coal Units with Alleged NSR Violations | plant				13
Number of Retired Coal Plants | plant				11
Litigation Settlement, Amount				$ 4,000,000
Civil Penalty Assessed				975,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member]
Valuation and Qualifying Accounts [Abstract]
Asbestos-related injuries and damages reserves				536,000,000	575,000,000
Reinsurance retention policy, excess retention, amount reinsured				847,000,000
Probable insurance recoveries				$ 599,000,000	616,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Non Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims				156
Asbestos-related injuries and damages reserves				$ 37,000,000
Duke Energy Carolinas [Member] | Asbestos Issue [Member] | Malignant Asbestos Claim [Member]
Valuation and Qualifying Accounts [Abstract]
Loss contingency, pending claims, number | Claims				70
Asbestos-related injuries and damages reserves				$ 11,000,000
Duke Energy Progress [Member]
Insurance [Abstract]
Primary nuclear liability program coverage				375,000,000
Max Retroactive Premium Assessments				108,000,000
Duke Energy Progress [Member] | Robinson Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses				1,500,000,000
Additional nuclear accident limit				1,250,000,000
Accidental outage insurance coverage policy limit				457,000,000
Duke Energy Progress [Member] | Brunswick Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses				1,500,000,000
Additional nuclear accident limit				1,250,000,000
Accidental outage insurance coverage policy limit				490,000,000
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Insurance [Abstract]
Sublimit property damage losses				1,500,000,000
Additional nuclear accident limit				1,250,000,000
Accidental outage insurance coverage policy limit				490,000,000
Duke Energy Progress [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Valuation and Qualifying Accounts [Abstract]
Minimum Master Credit Facility Balance required				250,000,000
Duke Energy Progress [Member] | North Carolina Ash Basins [Member] | L V Sutton Plant [Member]
Valuation and Qualifying Accounts [Abstract]
Civil Penalty Assessed				25,000,000
Duke Energy Progress [Member] | North Carolina Ash Basins [Member] | Operating Expense [Member] | USDOJ [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement, Expense					30,000,000
Duke Energy Progress [Member] | Groundwater Violation [Member]
Valuation and Qualifying Accounts [Abstract]
Charge for settlement agreement				6,000,000
Duke Energy Progress [Member] | Groundwater Violation [Member] | L V Sutton Plant [Member]
Valuation and Qualifying Accounts [Abstract]
Civil Penalty Assessed				25,000,000
Duke Energy Progress [Member] | Spent Nuclear Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Gain related to litigation settlement					83,000,000
Gain contingency, unrecorded amount				48,000,000
Duke Energy Florida [Member]
Insurance [Abstract]
Primary nuclear liability program coverage				375,000,000
Max Retroactive Premium Assessments				7,000,000
Duke Energy Florida [Member] | Crystal River Unit 3 [Member]
Insurance [Abstract]
Sublimit property damage losses				$ 1,000,000,000
Potential Obligation percentage				100.00%
Duke Energy Florida [Member] | Spent Nuclear Fuels [Member]
Valuation and Qualifying Accounts [Abstract]
Gain related to litigation settlement					$ 21,000,000
Gain contingency, unrecorded amount				$ 25,000,000
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, value				510,000,000
Duke Energy Ohio [Member] | W.C. Beckjord Station [Member]
Valuation and Qualifying Accounts [Abstract]
Gallons of Fuel Released | gal							9,000
Duke Energy Ohio [Member] | Antitrust Lawsuit [Member]
Valuation and Qualifying Accounts [Abstract]
Litigation Settlement, Expense				81,000,000
Charge for settlement agreement				$ 81,000,000
Subsequent Event [Member] | Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | Dan River [Member]
Valuation and Qualifying Accounts [Abstract]
Civil Penalty Assessed	$ 6,800,000

Commitments and Contingencies81

Commitments and Contingencies (Schedule of Environmental Loss Contingencies)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	$ 97	$ 79	$ 75
Provision/adjustments	9	32	26
Cash reductions	(9)	(14)	(22)
Ending balance	97	97	79
Duke Energy Carolinas [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	10	11	12
Provision/adjustments	1	(1)
Cash reductions	(1)		(1)
Ending balance	10	10	11
Progress Energy [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	17	27	33
Provision/adjustments	4	1	4
Cash reductions	(4)	(11)	(10)
Ending balance	17	17	27
Duke Energy Progress [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	5	8	14
Provision/adjustments		4	(1)
Cash reductions	(2)	(7)	(5)
Ending balance	3	5	8
Duke Energy Florida [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	12	19	19
Provision/adjustments	4	(3)	5
Cash reductions	(2)	(4)	(5)
Ending balance	14	12	19
Duke Energy Ohio [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	54	27	15
Provision/adjustments	1	28	20
Cash reductions	(1)	(1)	(8)
Ending balance	54	54	27
Duke Energy Indiana [Member]
Accrual for Environmental Loss Contingencies [Roll Forward]
Beginning balance	10	7	8
Provision/adjustments	5	4	1
Cash reductions	(3)	(1)	(2)
Ending balance	12	$ 10	$ 7
Environmental Reserves [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	74
Environmental Reserves [Member] | Duke Energy Carolinas [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	22
Environmental Reserves [Member] | Duke Energy Ohio [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	42
Environmental Reserves [Member] | Duke Energy Indiana [Member]
Disclosure Environmental Matters Details [Line Items]
Environmental Exit Costs, Reasonably Possible Additional Loss	$ 7

Commitments and Contingencies82

Commitments and Contingencies (Schedule of Legal Reserves) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Legal Reserves Details [Line Items]
Reserves for legal matters	$ 166	$ 323
Duke Energy Carolinas [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	11	72
Progress Energy [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	54	93
Duke Energy Progress [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	6	37
Duke Energy Florida [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	31	$ 36
Duke Energy Ohio [Member]
Legal Reserves Details [Line Items]
Reserves for legal matters	$ 80

Commitments and Contingencies83

Commitments and Contingencies (PurchPower)(Details) - Public Utilities Purchased Power [Member] $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Duke Energy Progress [Member]
Unconditional Purchase Obligations [Abstract]
2,016	$ 54
2,017	60
2,018	61
2,019	62
2,020	49
Thereafter	363
Total	$ 649
Duke Energy Progress [Member] | Minimum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term contract for purchase of electric power, date of contract expiration	2,019
Long-term contract for purchase of electric power, share of plant output being purchased	15.00%
Duke Energy Progress [Member] | Maximum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term contract for purchase of electric power, date of contract expiration	2,031
Long-term contract for purchase of electric power, share of plant output being purchased	100.00%
Duke Energy Florida [Member]
Unconditional Purchase Obligations [Abstract]
2,016	$ 305
2,017	345
2,018	360
2,019	377
2,020	394
Thereafter	1,591
Total	$ 3,372
Duke Energy Florida [Member] | Minimum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term contract for purchase of electric power, date of contract expiration	2,021
Long-term contract for purchase of electric power, share of plant output being purchased	80.00%
Duke Energy Florida [Member] | Maximum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term contract for purchase of electric power, date of contract expiration	2,043
Long-term contract for purchase of electric power, share of plant output being purchased	100.00%
Duke Energy Ohio [Member]
Unconditional Purchase Obligations [Abstract]
2,016	$ 236
2,017	195
2,018	59
Total	$ 490
Duke Energy Ohio [Member] | Minimum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term contract for purchase of electric power, date of contract expiration	2,017
Long-term contract for purchase of electric power, share of plant output being purchased	1.00%
Duke Energy Ohio [Member] | Maximum [Member]
Unconditional Purchase Obligations [Abstract]
Long-term contract for purchase of electric power, date of contract expiration	2,018
Long-term contract for purchase of electric power, share of plant output being purchased	11.00%

Commitments and Contingencies84

Commitments and Contingencies (Future Minimum Payments for Operating and Capital Leases) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Leased Assets
Rental expense on operating leases	$ 318	$ 355	$ 321
Operating Leases, Future Minimum Payments Due [Abstract]
2,016	219
2,017	182
2,018	161
2,019	146
2,020	127
Thereafter	864
Total future minimum lease payments	1,699
Capital Leases, Future Minimum Payments Due [Abstract]
2,016	173
2,017	171
2,018	180
2,019	178
2,020	182
Thereafter	1,176
Minimum annual payments	2,060
Less amount representing interest	(724)
Total	1,336
Duke Energy Carolinas [Member]
Operating Leased Assets
Rental expense on operating leases	41	41	39
Operating Leases, Future Minimum Payments Due [Abstract]
2,016	41
2,017	33
2,018	24
2,019	21
2,020	16
Thereafter	51
Total future minimum lease payments	186
Capital Leases, Future Minimum Payments Due [Abstract]
2,016	6
2,017	6
2,018	6
2,019	6
2,020	5
Thereafter	30
Minimum annual payments	59
Less amount representing interest	(35)
Total	24
Progress Energy [Member]
Operating Leased Assets
Rental expense on operating leases	230	257	225
Operating Leases, Future Minimum Payments Due [Abstract]
2,016	132
2,017	111
2,018	108
2,019	102
2,020	93
Thereafter	622
Total future minimum lease payments	1,168
Capital Leases, Future Minimum Payments Due [Abstract]
2,016	46
2,017	46
2,018	46
2,019	45
2,020	46
Thereafter	367
Minimum annual payments	596
Less amount representing interest	(295)
Total	301
Duke Energy Progress [Member]
Operating Leased Assets
Rental expense on operating leases	149	161	153
Operating Leases, Future Minimum Payments Due [Abstract]
2,016	66
2,017	63
2,018	61
2,019	56
2,020	48
Thereafter	365
Total future minimum lease payments	659
Capital Leases, Future Minimum Payments Due [Abstract]
2,016	20
2,017	21
2,018	21
2,019	22
2,020	21
Thereafter	272
Minimum annual payments	377
Less amount representing interest	(230)
Total	147
Duke Energy Florida [Member]
Operating Leased Assets
Rental expense on operating leases	81	96	72
Operating Leases, Future Minimum Payments Due [Abstract]
2,016	66
2,017	48
2,018	47
2,019	46
2,020	45
Thereafter	257
Total future minimum lease payments	509
Capital Leases, Future Minimum Payments Due [Abstract]
2,016	26
2,017	25
2,018	25
2,019	25
2,020	25
Thereafter	95
Minimum annual payments	221
Less amount representing interest	(65)
Total	156
Duke Energy Ohio [Member]
Operating Leased Assets
Rental expense on operating leases	13	17	14
Operating Leases, Future Minimum Payments Due [Abstract]
2,016	13
2,017	9
2,018	6
2,019	4
2,020	3
Thereafter	5
Total future minimum lease payments	40
Capital Leases, Future Minimum Payments Due [Abstract]
2,016	7
2,017	1
2,018	5
2,019	1
Thereafter	1
Minimum annual payments	15
Less amount representing interest	(2)
Total	13
Duke Energy Indiana [Member]
Operating Leased Assets
Rental expense on operating leases	20	$ 21	$ 22
Operating Leases, Future Minimum Payments Due [Abstract]
2,016	20
2,017	15
2,018	12
2,019	8
2,020	5
Thereafter	8
Total future minimum lease payments	68
Capital Leases, Future Minimum Payments Due [Abstract]
2,016	3
2,017	1
2,018	2
2,019	1
2,020	1
Thereafter	43
Minimum annual payments	51
Less amount representing interest	(38)
Total	$ 13

Debt and Credit Facilities (Nar

Debt and Credit Facilities (Narrative) (Details)	Feb. 22, 2016USD ($)	Jun. 30, 2016USD ($)	Feb. 24, 2016USD ($)	Jan. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Debt Instrument [Line Items]
Debt issuances					$ 2,700,000,000	$ 2,922,000,000
Other Debt Matters [Abstract]
Demand notes, maximum amount available for sale					3,000,000,000
Demand notes, maximum amount outstanding					1,500,000,000
Principal amount of demand notes					1,121,000,000	968,000,000
Subsidiary debt guaranteed by parent					767,000,000	767,000,000
Other Loans [Abstract]
Other loans outstanding against cash surrender value of life insurance policies					$ 629,000,000	603,000,000
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower					0.65
Subsequent Event [Member] | Line of Credit [Member] | Term Loan Facility [Member]
Debt Instrument [Line Items]
Debt instrument term (in years)	6 months
Facility size	$ 1,000,000,000
Expiration period (in days following February 22, 2016)	45 days
Amount outstanding at period end			$ 0
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Debt issuances					$ 500,000,000
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower					0.65
Progress Energy [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower					0.65
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Debt issuances					$ 1,200,000,000	1,350,000,000
Other Loans [Abstract]
Other loans outstanding against cash surrender value of life insurance policies					$ 41,000,000	44,000,000
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower					0.65
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Debt issuances						$ 225,000,000
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower					0.65
Duke Energy Ohio [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower					0.65
Duke Energy Indiana [Member]
Restrictive Debt Covenants [Abstract]
Debt to total capitalization percentage, for each borrower					0.65
Duke Energy Kentucky [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Debt issuances				$ 95,000,000
Duke Energy Kentucky [Member] | Subsequent Event [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances				$ 95,000,000
Duke Energy Kentucky [Member] | Subsequent Event [Member] | 3.42% Unsecured Debenture Maturing January 2026 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Interest rate				3.42%
Debt issuances				$ 45,000,000
Duke Energy Kentucky [Member] | Subsequent Event [Member] | 4.45% Unsecured Debenture Maturing January 2046 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Interest rate				4.45%
Debt issuances				$ 50,000,000
Florida Public Service Commission [Member] | Nuclear Asset Securitizable Balance, Net [Member] | Crystal River Unit 3 [Member] | Florida Public Service Commission Settlement Agreement 2013 [Member] | Duke Energy Florida [Member] | Corporate Debt Securities [Member] | Scenario, Forecast [Member]
Debt Instrument [Line Items]
Debt issuances		$ 1,300,000,000
Piedmont Natural Gas [Member]
Debt Instrument [Line Items]
Facility size					$ 4,900,000,000

Debt and Credit Facilities (Sum

Debt and Credit Facilities (Summary of Debt and Related Terms) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured Debt	$ 13,392	$ 12,937
Secured Debt	2,635	2,806
First mortgage bonds	18,980	19,180
Capital leases	1,336	1,428
Tax exempt bonds	1,053	1,296
Notes payable and commercial paper	4,258	2,989
Fair value hedge carrying value adjustment	6	8
Unamortized debt discount and premium, net	1,712	1,890
Unamortized debt issuance costs	(43)	(19)
Total debt	43,202	42,382
Short-term notes payable and commercial paper	(3,633)	(2,514)
Current maturities of long-term debt	(2,074)	(2,807)
Total long-term debt	37,495	37,061
Short term obligations classified as long-term debt	$ 972	$ 1,022
Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2073	Dec. 31, 2073
Weighted-average rate	4.99%	4.92%
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2016
Debt Instrument, Maturity Date Range, End	Dec. 31, 2037	Dec. 31, 2037
Weighted-average rate	2.57%	2.50%
Short term obligations classified as long-term debt		$ 200
First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2045	Dec. 31, 2044
Weighted-average rate	4.74%	4.76%
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2051	Dec. 31, 2051
Weighted-average rate	5.38%	5.30%
Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date Range, Start	Dec. 31, 2017	Dec. 31, 2015
Debt Instrument, Maturity Date Range, End	Dec. 31, 2041	Dec. 31, 2041
Weighted-average rate	2.59%	2.13%
Short term obligations classified as long-term debt	$ 347	$ 347
Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	625	475
Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Unamortized debt discount and premium, net	$ 1,798	$ 1,975
Notes Payable And Commercial Paper [Member]
Debt Instrument [Line Items]
Weighted-average rate	0.88%	0.70%
Short term obligations classified as long-term debt	$ 625	$ 475
TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (170)	$ (152)
Weighted-average rate	4.25%	4.29%
Parent Company [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 59
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Unsecured Debt	1,152	$ 1,155
Secured Debt	425	400
First mortgage bonds	6,161	6,161
Capital leases	24	27
Tax exempt bonds	355	355
Money pool borrowings	300	300
Fair value hedge carrying value adjustment	6	8
Unamortized debt discount and premium, net	(17)	(15)
Unamortized debt issuance costs	(4)	(4)
Total debt	8,367	8,353
Current maturities of long-term debt	(356)	(507)
Total long-term debt	8,011	7,846
Short term obligations classified as long-term debt	335	335
Duke Energy Carolinas [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	35	35
Duke Energy Carolinas [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	300	300
Duke Energy Carolinas [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(39)	(38)
Progress Energy [Member]
Debt Instrument [Line Items]
Unsecured Debt	3,850	3,850
Secured Debt	479	525
First mortgage bonds	9,750	9,800
Capital leases	300	314
Tax exempt bonds	48	291
Money pool borrowings	1,458	835
Unamortized debt discount and premium, net	(28)	(26)
Unamortized debt issuance costs	(5)	(5)
Total debt	15,772	15,503
Short-term money pool borrowings	(1,308)	(835)
Current maturities of long-term debt	(315)	(1,507)
Total long-term debt	14,149	13,161
Progress Energy [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(85)	(86)
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Secured Debt	254	300
First mortgage bonds	5,975	5,475
Capital leases	144	146
Tax exempt bonds	48	291
Money pool borrowings	359
Unamortized debt discount and premium, net	(16)	(11)
Unamortized debt issuance costs	(3)	(3)
Total debt	6,727	6,170
Short-term money pool borrowings	(209)
Current maturities of long-term debt	(2)	(945)
Total long-term debt	6,516	5,225
Short term obligations classified as long-term debt	150
Duke Energy Progress [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150
Duke Energy Progress [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Capital leases	114	129
Duke Energy Progress [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(37)	(31)
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Unsecured Debt	150	150
Secured Debt	225	225
First mortgage bonds	3,775	4,325
Capital leases	156	168
Money pool borrowings	813	84
Unamortized debt discount and premium, net	(8)	(8)
Unamortized debt issuance costs	(2)	(2)
Total debt	5,079	4,907
Short-term money pool borrowings	(813)	(84)
Current maturities of long-term debt	(13)	(562)
Total long-term debt	4,253	4,261
Duke Energy Florida [Member] | Purchase Accounting Adjustments [Member]
Debt Instrument [Line Items]
Capital leases	731	787
Duke Energy Florida [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(32)	(37)
Duke Energy Ohio [Member]
Debt Instrument [Line Items]
Unsecured Debt	765	773
First mortgage bonds	750	900
Capital leases	13	20
Tax exempt bonds	77	77
Money pool borrowings	128	516
Unamortized debt discount and premium, net	(28)	(29)
Unamortized debt issuance costs	(2)	(2)
Total debt	1,701	2,251
Short-term money pool borrowings	(103)	(491)
Current maturities of long-term debt	(106)	(157)
Total long-term debt	1,492	1,603
Short term obligations classified as long-term debt	52	52
Duke Energy Ohio [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	27	27
Duke Energy Ohio [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	25	25
Duke Energy Ohio [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	(4)	(6)
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Unsecured Debt	740	742
First mortgage bonds	2,319	2,319
Capital leases	14	16
Tax exempt bonds	572	573
Money pool borrowings	150	221
Unamortized debt discount and premium, net	(8)	(9)
Unamortized debt issuance costs	(2)	(2)
Total debt	3,768	3,840
Short-term money pool borrowings		(71)
Current maturities of long-term debt	(547)	(5)
Total long-term debt	3,221	3,764
Short term obligations classified as long-term debt	435	435
Duke Energy Indiana [Member] | Tax Exempt Bonds [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	285	285
Duke Energy Indiana [Member] | Commercial Paper [Member]
Debt Instrument [Line Items]
Short term obligations classified as long-term debt	150	150
Duke Energy Indiana [Member] | TotalDebtAndCapitalLeaseObligations [Member]
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (19)	$ (22)

Debt and Credit Facilities (S87

Debt and Credit Facilities (Summary of Debt Issuances) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Debt issuances	$ 2,700	$ 2,922
November 2015 3.750% Senior Unsecured Notes Maturing April 2024 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	$ 400
Interest rate	3.75%
Repayments of Debt	$ 300
November 2015 4.800% Senior Unsecured Notes Maturing December 2045 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	$ 600
Interest rate	4.80%
Repayments of Debt	$ 300
March 2015 3.750% First Mortgage Bonds Maturing June 2045 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500
Interest rate	3.75%
Repayments of Debt	$ 500
August 2015 3.250% First Mortgage bonds Maturing August 2025 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 500
Interest rate	3.25%
Repayments of Debt	$ 400
August 2015 4.200% First Mortgage Bonds Maturing August 2045 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	$ 700
Interest rate	4.20%
Repayments of Debt	$ 400
April 2014 3.75% Senior Unsecured Notes Maturing April 2024 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 600
Interest rate		3.75%
Repayments of Debt		$ 402
April 2014 0.613% Senior Unsecured Floating Notes Maturing April 2017 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 400
Interest rate		0.613%
Fixed credit spread		0.38%
Repayments of Debt		$ 402
June 2014 11.970% Senior Unsecured Floating Notes Maturing May 2019 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 108
Interest rate		11.97%
Repayments of Debt		$ 196
June 2014 13.680% Senior Unsecured Floating Notes Maturing May 2021 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 110
Interest rate		13.68%
Repayments of Debt		$ 196
March 2014 0.863% Secured Credit Facility Maturing March 2017 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 225
Interest rate		0.863%
July 2014 5.340% Secured Debt Maturing July 2036 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 129
Interest rate		5.34%
March 2014 4.375% First Mortgage Bonds Maturing March 2044 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 400
Interest rate		4.375%
March 2014 0.435% First Mortgage Bonds Maturing March 2017[Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 250
Interest rate		0.435%
Fixed credit spread		0.20%
November 2014 4.150% Fixed First Mortgage Bonds Maturing December 2044 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500
Interest rate		4.15%
Repayments of Debt		$ 450
November 2014 0.432% Floating First Mortgage Bonds Maturing November 2017 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 200
Interest rate		0.432%
Fixed credit spread		0.20%
Repayments of Debt		$ 450
Parent Company [Member]
Debt Instrument [Line Items]
Debt issuances	1,000	1,000
Parent Company [Member] | November 2015 3.750% Senior Unsecured Notes Maturing April 2024 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	400
Repayments of Debt	300
Parent Company [Member] | November 2015 4.800% Senior Unsecured Notes Maturing December 2045 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances	600
Repayments of Debt	300
Parent Company [Member] | April 2014 3.75% Senior Unsecured Notes Maturing April 2024 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		600
Repayments of Debt		402
Parent Company [Member] | April 2014 0.613% Senior Unsecured Floating Notes Maturing April 2017 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 400
Fixed credit spread		0.38%
Repayments of Debt		$ 402
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Debt issuances	500
Duke Energy Carolinas [Member] | March 2015 3.750% First Mortgage Bonds Maturing June 2045 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	500
Repayments of Debt	500
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Debt issuances	1,200	1,350
Duke Energy Progress [Member] | August 2015 3.250% First Mortgage bonds Maturing August 2025 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	500
Repayments of Debt	400
Duke Energy Progress [Member] | August 2015 4.200% First Mortgage Bonds Maturing August 2045 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances	700
Repayments of Debt	$ 400
Duke Energy Progress [Member] | March 2014 4.375% First Mortgage Bonds Maturing March 2044 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		400
Duke Energy Progress [Member] | March 2014 0.435% First Mortgage Bonds Maturing March 2017[Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 250
Fixed credit spread		0.20%
Duke Energy Progress [Member] | November 2014 4.150% Fixed First Mortgage Bonds Maturing December 2044 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 500
Repayments of Debt		450
Duke Energy Progress [Member] | November 2014 0.432% Floating First Mortgage Bonds Maturing November 2017 [Member] | First Mortgage Bonds [Member]
Debt Instrument [Line Items]
Debt issuances		$ 200
Fixed credit spread		0.20%
Repayments of Debt		$ 450
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Debt issuances		225
Duke Energy Florida [Member] | March 2014 0.863% Secured Credit Facility Maturing March 2017 [Member] | Secured Debt [Member]
Debt Instrument [Line Items]
Debt issuances		$ 225

Debt and Credit Facilities (Ann

Debt and Credit Facilities (Annual Maturities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	$ 2,074	$ 2,807
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	2,074
2,017	2,468
2,018	3,441
2,019	3,022
2,020	2,091
Thereafter	24,616
Total long-term debt, including current maturities	37,712
Other Debt Obligations [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	449
Purchase Accounting Adjustments [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Purchase accounting adjustments	$ (1,857)
Parent Company [Member] | 2.150% November 2016 Debt Maturity [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	2.15%
Current maturities of long-term debt	$ 500
Duke Energy Carolinas [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	356	507
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	356
2,017	115
2,018	1,629
2,019	5
2,020	755
Thereafter	5,507
Total long-term debt, including current maturities	$ 8,367
Duke Energy Carolinas [Member] | 1.750% December 2016 Debt Maturity 1 [Member] | First Mortgage Bonds [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	1.75%
Current maturities of long-term debt	$ 350
Progress Energy [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	315	1,507
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	315
2,017	923
2,018	510
2,019	1,667
2,020	415
Thereafter	10,634
Total long-term debt, including current maturities	14,464
Duke Energy Progress [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	2	945
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	2
2,017	446
2,019	855
2,020	152
Thereafter	5,063
Total long-term debt, including current maturities	6,518
Duke Energy Florida [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	13	562
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	13
2,017	482
2,018	512
2,019	14
2,020	265
Thereafter	2,980
Total long-term debt, including current maturities	4,266
Duke Energy Ohio [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	106	157
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	106
2,017	1
2,018	5
2,019	552
2,020	25
Thereafter	909
Total long-term debt, including current maturities	1,598
Duke Energy Indiana [Member]
Current Maturities Of Long Term Debt [Abstract]
Current maturities of long-term debt	547	$ 5
Long-term Debt, Fiscal Year Maturity [Abstract]
2,016	547
2,017	2
2,018	3
2,019	63
2,020	653
Thereafter	2,500
Total long-term debt, including current maturities	$ 3,768
Duke Energy Indiana [Member] | 6.05% June 2016 Debt Maturity [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	6.05%
Current maturities of long-term debt	$ 325
Duke Energy Indiana [Member] | 0.670% July 2016 Debt Maturity [Member] | First Mortgage Bonds [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	0.67%
Current maturities of long-term debt	$ 150
Progress Energy Parent [Member] | 5.625% January 2016 Debt Maturity [Member] | Unsecured Debt [Member]
Current Maturities Of Long Term Debt [Abstract]
Interest rate	5.625%
Current maturities of long-term debt	$ 300

Debt and Credit Facilities (Sch

Debt and Credit Facilities (Schedule of Line of Credit Facilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Tax exempt bonds	$ (1,053)	$ (1,296)
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	7,500
Commercial Paper	(3,138)
Outstanding letters of credit	(72)
Tax exempt bonds	(116)
Coal ash set-aside	(500)
Available capacity	3,674
Parent Company [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	3,475
Commercial Paper	(1,531)
Outstanding letters of credit	(65)
Available capacity	1,879
Parent Company [Member] | Proceeds Loaned To Subsidiary Registrants [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Commercial Paper	625
Duke Energy Carolinas [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(355)	(355)
Duke Energy Carolinas [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance required	250
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	800
Commercial Paper	(300)
Outstanding letters of credit	(4)
Tax exempt bonds	(35)
Coal ash set-aside	(250)
Available capacity	211
Duke Energy Carolinas [Member] | Revolving Credit Facility [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance required	250
Duke Energy Progress [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(48)	(291)
Duke Energy Progress [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance required	250
Duke Energy Progress [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	1,000
Commercial Paper	(333)
Outstanding letters of credit	(2)
Coal ash set-aside	(250)
Available capacity	415
Duke Energy Progress [Member] | Revolving Credit Facility [Member] | North Carolina Ash Basins [Member] | USDOJ [Member]
Line of Credit Facility [Line Items]
Minimum Master Credit Facility Balance required	250
Duke Energy Florida [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	1,200
Commercial Paper	(709)
Outstanding letters of credit	(1)
Available capacity	490
Duke Energy Ohio [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(77)	(77)
Duke Energy Ohio [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	425
Commercial Paper	(115)
Available capacity	310
Duke Energy Indiana [Member]
Line of Credit Facility [Line Items]
Tax exempt bonds	(572)	$ (573)
Duke Energy Indiana [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Facility size	600
Commercial Paper	(150)
Tax exempt bonds	(81)
Available capacity	$ 369

Guarantees and Indemnificatio90

Guarantees and Indemnifications(Narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Liabilities Recorded for Third Party Guarantees [Abstract]
Face value of guarantees	$ 21	$ 28
Surety Bond [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	47
Standby Letters Of Credit [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	427
Unused letters of credit	58
Performance Guarantee [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	253
Maximum potential of future amounts associated with guarantees with expiration dates	112
Performance Guarantee [Member] | Less Than Wholly Owned Entity [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	15
Spectra Capital [Member] | Performance Guarantee [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	205
Progress Energy [Member]
Liabilities Recorded for Third Party Guarantees [Abstract]
Face value of guarantees	7	13
Progress Energy [Member] | Indemnification Agreement [Member]
Guarantor Obligations [Line Items]
Maximum potential amount of future payments associated with guarantees	97
Maximum potential amount of future payments associated with guarantees with no expiration date	7
Duke Energy Florida [Member]
Liabilities Recorded for Third Party Guarantees [Abstract]
Face value of guarantees	$ 7	$ 7

Joint Ownership of Generating91

Joint Ownership of Generating and Transmission Facilities Joint Ownership of Generating and Transmission Facilities (Table) (Details) $ in Millions	Dec. 31, 2015USD ($)
International Energy Brazil-Canoas I and II [Member]
Jointly Owned Utility Plant Interests [Line Items]
Joint owner ownership percentage	47.20%
Property, plant, and equipment	$ 160
Accumulated depreciation	$ 57
Duke Energy Carolinas [Member] | Duke Energy Carolinas Catawba Nuclear Station (Units 1 and 2) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Joint owner ownership percentage	19.25%
Property, plant, and equipment	$ 926
Accumulated depreciation	567
Construction work in progress	$ 9
Duke Energy Florida [Member] | Duke Energy Florida Intercession City Station (Unit P11) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Joint owner ownership percentage	66.67%
Property, plant, and equipment	$ 24
Accumulated depreciation	15
Duke Energy Ohio [Member] | Duke Energy Ohio Transmission [Member]
Jointly Owned Utility Plant Interests [Line Items]
Property, plant, and equipment	85
Accumulated depreciation	50
Construction work in progress	$ 1
Duke Energy Indiana [Member] | Duke Energy Indiana Gibson Station (Unit 5) [Member]
Jointly Owned Utility Plant Interests [Line Items]
Joint owner ownership percentage	50.05%
Property, plant, and equipment	$ 329
Accumulated depreciation	151
Construction work in progress	$ 5
Duke Energy Indiana [Member] | Vermillion Generation Station [Member]
Jointly Owned Utility Plant Interests [Line Items]
Joint owner ownership percentage	62.50%
Property, plant, and equipment	$ 153
Accumulated depreciation	108
Construction work in progress	0
Duke Energy Indiana [Member] | Duke Energy Indiana Transmission and local facilities [Member]
Jointly Owned Utility Plant Interests [Line Items]
Property, plant, and equipment	4,094
Accumulated depreciation	$ 1,688

Joint Ownership of Generating92

Joint Ownership of Generating and Transmission Facilities Joint Ownership of Generating and Transmission Facilities (Narrative) (Details) - Crystal River Nuclear Station (Unit 3) [Member] $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Seminole Electric Cooperative [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	1.70%
Florida Municipal Joint Owners [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	6.52%
Joint Owner Settlement	$ 55
Duke Energy Florida [Member]
Jointly Owned Utility Plant Interests [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share	98.30%

Asset Retirement Obligations As

Asset Retirement Obligations Asset Retirement Obligations (Recorded on the Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	$ 10,264	$ 8,466	$ 4,958
Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	5,072
Closure of Ash Basins [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	4,958
Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	234
Duke Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	3,918	3,428	1,594
Duke Energy Carolinas [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	1,730
Duke Energy Carolinas [Member] | Closure of Ash Basins [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,161
Duke Energy Carolinas [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	27
Progress Energy [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	5,369	4,711	2,570
Progress Energy [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	3,093
Progress Energy [Member] | Closure of Ash Basins [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,196
Progress Energy [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	80
Duke Energy Progress [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	4,567	3,905	1,737
Duke Energy Progress [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,349
Duke Energy Progress [Member] | Closure of Ash Basins [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	2,188
Duke Energy Progress [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	30
Duke Energy Florida [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	802	806	833
Duke Energy Florida [Member] | Decommissioning of Nuclear Power Facilities [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	744
Duke Energy Florida [Member] | Closure of Ash Basins [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	7
Duke Energy Florida [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	51
Duke Energy Ohio [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	125	27	28
Duke Energy Ohio [Member] | Closure of Ash Basins [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	94
Duke Energy Ohio [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	31
Duke Energy Indiana [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	525	$ 32	$ 30
Duke Energy Indiana [Member] | Closure of Ash Basins [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	507
Duke Energy Indiana [Member] | Other [Member]
Asset Retirement Obligation [Line Items]
Asset Retirement Obligation	$ 18

Asset Retirement Obligations (N

Asset Retirement Obligations (NDTF Information)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
NDTF Information [Abstract]
Decommissioning contribution requirement	$ 14
Decommissioning cost study estimate	8,130
Legally restricted NDTF investments, fair value	4,670	$ 5,182
Duke Energy Carolinas [Member]
NDTF Information [Abstract]
Legally restricted NDTF investments, fair value	2,686	2,678
Duke Energy Carolinas [Member] | 2013 Cost Study [Member]
NDTF Information [Abstract]
Decommissioning cost study estimate	3,420
Duke Energy Progress [Member]
NDTF Information [Abstract]
Legally restricted NDTF investments, fair value	1,984	1,701
Duke Energy Progress [Member] | 2014 Cost Study [Member]
NDTF Information [Abstract]
Decommissioning contribution requirement	14
Decommissioning cost study estimate	3,550
Duke Energy Florida [Member]
NDTF Information [Abstract]
Legally restricted NDTF investments, fair value		$ 803
Duke Energy Florida [Member] | 2013 Cost Study [Member]
NDTF Information [Abstract]
Decommissioning cost study estimate	$ 1,160

Asset Retirement Obligations 95

Asset Retirement Obligations (Nuclear Operating Licenses)(Details)	12 Months Ended
	Dec. 31, 2015
Duke Energy Carolinas [Member] | Catawba Units 1 and 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,043
Duke Energy Carolinas [Member] | McGuire Unit 1 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,041
Duke Energy Carolinas [Member] | McGuire Unit 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,043
Duke Energy Carolinas [Member] | Oconee Units 1 and 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,033
Duke Energy Carolinas [Member] | Oconee Unit 3 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,034
Duke Energy Progress [Member] | Brunswick Unit 1 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,036
Duke Energy Progress [Member] | Brunswick Unit 2 [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,034
Duke Energy Progress [Member] | Shearon Harris Nuclear Station [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,046
Duke Energy Progress [Member] | Robinson Nuclear Station [Member]
Asset Retirement Obligation [Line Items]
Year of expiration	2,030

Asset Retirement Obligations (R

Asset Retirement Obligations (Rollforward)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Asset Retirement Obligation [Line Items]
Balance as of January 1	$ 8,466	$ 4,958
Acquisitions	226	4
Accretion expense	384	246
Liabilities settled	(422)	(68)
Liabilities incurred in the current year	1,016	3,500
Revisions in estimates of cash flows	594	(174)
Balance as of December 31	10,264	8,466
Duke Energy Carolinas [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	3,428	1,594
Accretion expense	165	113
Liabilities settled	(200)
Liabilities incurred in the current year	178	1,717
Revisions in estimates of cash flows	347	4
Balance as of December 31	3,918	3,428
Progress Energy [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	4,711	2,570
Acquisitions	226
Accretion expense	203	135
Liabilities settled	(195)	(68)
Liabilities incurred in the current year	282	1,783
Revisions in estimates of cash flows	142	291
Balance as of December 31	5,369	4,711
Duke Energy Progress [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	3,905	1,737
Acquisitions	204
Accretion expense	169	97
Liabilities settled	(125)
Liabilities incurred in the current year	282	1,783
Revisions in estimates of cash flows	132	288
Balance as of December 31	4,567	3,905
Duke Energy Florida [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	806	833
Acquisitions	23
Accretion expense	34	38
Liabilities settled	(70)	(68)
Revisions in estimates of cash flows	9	3
Balance as of December 31	802	806
Duke Energy Ohio [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	27	28
Accretion expense	4	2
Liabilities settled	(4)
Liabilities incurred in the current year	116
Revisions in estimates of cash flows	(18)	(3)
Balance as of December 31	125	27
Duke Energy Indiana [Member]
Asset Retirement Obligation [Line Items]
Balance as of January 1	32	30
Accretion expense	15	2
Liabilities settled	(23)
Liabilities incurred in the current year	418
Revisions in estimates of cash flows	83
Balance as of December 31	$ 525	$ 32

Property, Plant and Equipment97

Property, Plant and Equipment (Schedule Of Property, Plant and Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land	$ 1,466	$ 1,459
Nuclear fuel	3,194	2,865
Equipment	1,791	1,762
Construction in process	4,525	4,519
Other	4,744	3,497
Total property, plant and equipment	112,826	104,861
Total accumulated depreciation	(37,665)	(34,824)
Generation Facilities To Be Retired Net	548	9
Total net property, plant and equipment	75,709	70,046
Capitalized leases	1,470	1,548
Accumulated amortization on capitalized leases	58	52
Capitalized Interest Costs [Abstract]
Capitalized interest	98	75	$ 89
Operating Leases [Abstract]
Accumulated depreciation and amortization	$ (37,665)	$ (34,824)
Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Equipment, estimated useful life, years	3 years	3 years
Other, estimated useful life, in years	2 years	5 years
Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Equipment, estimated useful life, years	38 years	34 years
Other, estimated useful life, in years	60 years	80 years
Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	$ (1,621)	$ (1,408)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(1,621)	(1,408)
Variable Interest Entity, Primary Beneficiary [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	2,033	1,873
Total accumulated depreciation	(327)	(257)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(327)	(257)
Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(35,367)	(32,628)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(35,367)	(32,628)
Regulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	$ 87,593	$ 82,206
Regulated Operation [Member] | Electric [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	8 years	2 years
Regulated Operation [Member] | Electric [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	100 years	138 years
Regulated Operation [Member] | Natural Gas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	$ 2,322	$ 2,230
Regulated Operation [Member] | Natural Gas [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	12 years	12 years
Regulated Operation [Member] | Natural Gas [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	67 years	67 years
Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	$ 1,480	$ 1,445
Regulated Operation [Member] | Other Buildings And Improvements [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	15 years	9 years
Regulated Operation [Member] | Other Buildings And Improvements [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	100 years	100 years
Nonregulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	$ (2,298)	$ (2,196)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(2,298)	(2,196)
Nonregulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	$ 3,348	$ 2,380
Nonregulated Operation [Member] | Electric [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	1 year	1 year
Nonregulated Operation [Member] | Electric [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	30 years	30 years
Nonregulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	$ 2,363	$ 2,498
Nonregulated Operation [Member] | Other Buildings And Improvements [Member] | Minimum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	5 years	5 years
Nonregulated Operation [Member] | Other Buildings And Improvements [Member] | Maximum [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution, estimated useful life, in years	50 years	50 years
Duke Energy Carolinas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land	$ 407	$ 403
Nuclear fuel	1,827	1,676
Equipment	368	341
Construction in process	1,860	2,081
Other	836	655
Total property, plant and equipment	39,398	37,372
Total accumulated depreciation	(13,521)	(12,700)
Total net property, plant and equipment	25,877	24,672
Capitalized leases	40	40
Accumulated amortization on capitalized leases	11	8
Capitalized Interest Costs [Abstract]
Capitalized interest	38	38	41
Operating Leases [Abstract]
Accumulated depreciation and amortization	(13,521)	(12,700)
Duke Energy Carolinas [Member] | Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(976)	(847)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(976)	(847)
Duke Energy Carolinas [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(13,521)	(12,700)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(13,521)	(12,700)
Duke Energy Carolinas [Member] | Regulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	33,623	31,751
Duke Energy Carolinas [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	477	465
Progress Energy [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land	719	704
Nuclear fuel	1,367	1,190
Equipment	530	506
Construction in process	1,827	1,215
Other	1,180	756
Total property, plant and equipment	42,666	38,650
Total accumulated depreciation	(14,867)	(13,506)
Generation Facilities To Be Retired Net	548
Total net property, plant and equipment	28,347	25,144
Capitalized leases	302	315
Accumulated amortization on capitalized leases	85	72
Capitalized Interest Costs [Abstract]
Capitalized interest	24	11	19
Operating Leases [Abstract]
Accumulated depreciation and amortization	(14,867)	(13,506)
Progress Energy [Member] | Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(645)	(561)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(645)	(561)
Progress Energy [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(14,867)	(13,506)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(14,867)	(13,506)
Progress Energy [Member] | Regulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	36,422	33,672
Progress Energy [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	621	607
Duke Energy Progress [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land	392	380
Nuclear fuel	1,367	1,190
Equipment	398	388
Construction in process	1,118	908
Other	856	439
Total property, plant and equipment	27,313	24,207
Total accumulated depreciation	(10,141)	(9,021)
Generation Facilities To Be Retired Net	548
Total net property, plant and equipment	17,720	15,186
Capitalized leases	144	146
Accumulated amortization on capitalized leases	7	5
Capitalized Interest Costs [Abstract]
Capitalized interest	20	10	16
Operating Leases [Abstract]
Accumulated depreciation and amortization	(10,141)	(9,021)
Duke Energy Progress [Member] | Nuclear Fuel [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(645)	(561)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(645)	(561)
Duke Energy Progress [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(10,141)	(9,021)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(10,141)	(9,021)
Duke Energy Progress [Member] | Regulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	22,888	20,616
Duke Energy Progress [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	294	286
Duke Energy Florida [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land	327	324
Equipment	132	118
Construction in process	709	307
Other	319	310
Total property, plant and equipment	15,343	14,433
Total accumulated depreciation	(4,720)	(4,478)
Total net property, plant and equipment	10,623	9,955
Capitalized leases	158	169
Accumulated amortization on capitalized leases	78	67
Capitalized Interest Costs [Abstract]
Capitalized interest	4	1	3
Operating Leases [Abstract]
Accumulated depreciation and amortization	(4,720)	(4,478)
Duke Energy Florida [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(4,720)	(4,478)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(4,720)	(4,478)
Duke Energy Florida [Member] | Regulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	13,534	13,056
Duke Energy Florida [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	322	318
Duke Energy Ohio [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land	118	114
Equipment	344	330
Construction in process	180	97
Other	153	214
Total property, plant and equipment	7,750	7,141
Total accumulated depreciation	(2,507)	(2,213)
Generation Facilities To Be Retired Net		9
Total net property, plant and equipment	5,243	4,937
Capitalized leases	96	98
Accumulated amortization on capitalized leases	27	25
Capitalized Interest Costs [Abstract]
Capitalized interest	10	10	11
Operating Leases [Abstract]
Accumulated depreciation and amortization	(2,507)	(2,213)
Duke Energy Ohio [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(2,507)	(2,213)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(2,507)	(2,213)
Duke Energy Ohio [Member] | Regulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	4,429	3,956
Duke Energy Ohio [Member] | Regulated Operation [Member] | Natural Gas [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	2,322	2,230
Duke Energy Ohio [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	204	200
Duke Energy Indiana [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Land	108	108
Equipment	173	166
Construction in process	214	481
Other	215	195
Total property, plant and equipment	14,007	13,034
Total accumulated depreciation	(4,484)	(4,219)
Total net property, plant and equipment	9,523	8,815
Capitalized leases	39	30
Accumulated amortization on capitalized leases	7	6
Capitalized Interest Costs [Abstract]
Capitalized interest	6	6	9
Operating Leases [Abstract]
Accumulated depreciation and amortization	(4,484)	(4,219)
Duke Energy Indiana [Member] | Regulated Operation [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(4,484)	(4,219)
Operating Leases [Abstract]
Accumulated depreciation and amortization	(4,484)	(4,219)
Duke Energy Indiana [Member] | Regulated Operation [Member] | Electric [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	13,118	11,911
Duke Energy Indiana [Member] | Regulated Operation [Member] | Other Buildings And Improvements [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Plant - transmission and distribution	179	173
Commercial Portfolio [Member] | Assets Leased to Others [Member]
Public Utilities, Property, Plant and Equipment, Net [Abstract]
Total accumulated depreciation	(258)
Operating Leases [Abstract]
Contingent lease payments	172	$ 164	$ 154
Renewable energy projects	2,455
Accumulated depreciation and amortization	$ (258)

Goodwill and Intangible Asset98

Goodwill and Intangible Assets (Goodwill By Reportable Operating Segment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 16,343	$ 16,321
Foreign exchange and other changes	(36)
Goodwill, Acquired During Period	58
Regulated Utilities [Member]
Goodwill [Line Items]
Goodwill	15,950	15,950
International [Member]
Goodwill [Line Items]
Goodwill	271	307
Foreign exchange and other changes	(36)
Commercial Portfolio [Member]
Goodwill [Line Items]
Goodwill	122	64
Goodwill, Acquired During Period	58
Progress Energy [Member]
Goodwill [Line Items]
Goodwill	3,655	3,655
Duke Energy Ohio [Member]
Goodwill [Line Items]
Accumulated impairment charges	216
Goodwill	$ 920	$ 920

Goodwill and Intangible Asset99

Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	$ 343	$ 317
Accumulated amortization	(58)	(54)
Total intangible assets, net	285	263
Amortization expense	4	6	$ 13
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2,016	8
2,017	8
2,018	8
2,019	7
2,020	7
Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	20	23
Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	116	97
Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	(16)	(15)
Wind Development Rights [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	115	97
Accumulated amortization	(18)	(14)
Other Intangible Assets [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	68	76
Accumulated amortization	(24)	(25)
Duke Energy Carolinas [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	31	26
Total intangible assets, net	31	26
Duke Energy Carolinas [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	1	1
Duke Energy Carolinas [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	30	25
Progress Energy [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	86	76
Total intangible assets, net	86	76
Progress Energy [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	6	7
Progress Energy [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	80	69
Duke Energy Progress [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	82	72
Total intangible assets, net	82	72
Duke Energy Progress [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	2	3
Duke Energy Progress [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	80	69
Duke Energy Florida [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	4	4
Total intangible assets, net	4	4
Duke Energy Florida [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	4	4
Duke Energy Ohio [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	5	3
Total intangible assets, net	5	3
Amortization expense		2	8
Duke Energy Ohio [Member] | Renewable Energy Certificates [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	5	3
Duke Energy Indiana [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	38	40
Accumulated amortization	(16)	(15)
Total intangible assets, net	22	25
Amortization expense	1	1	$ 1
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
2,016	2
2,017	2
2,018	2
2,019	2
2,020	2
Duke Energy Indiana [Member] | Emission Allowances [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	14	16
Duke Energy Indiana [Member] | Gas Coal And Power Contracts [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross carrying amount	24	24
Accumulated amortization	$ (16)	$ (15)

Investments in Unconsolidate100

Investments in Unconsolidated Affiliates (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 31, 2017
Investments In Unconsolidated Affiliates [Line Items]
Gain on sale of equity investment	$ 7	$ 17	$ 100
Distributions from equity investments	$ 104	$ 154	$ 144
National Methanol Company [Member] | International Energy [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage	25.00%
Sweetwater I-V [Member] | Commercial Power [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage	50.00%
DS Cornerstone [Member] | Commercial Power [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage	50.00%
Duke American Transmission Co. [Member] | Commercial Power [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage	50.00%
Atlantic Coast Pipeline (ACP) [Member] | Commercial Power [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage	40.00%
Sabal Trail Transmission Pipeline [Member] | Commercial Power [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage	7.50%
DukeNet [Member] | Other [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage			50.00%
Net sales proceeds			$ 215
Gain on sale of equity investment			$ 105
Scenario, Forecast [Member] | National Methanol Company [Member] | International Energy [Member]
Investments In Unconsolidated Affiliates [Line Items]
Equity method investment, ownership percentage				17.50%

Investments in Unconsolidate101

Investments in Unconsolidated Affiliates (Investments in Equity Method Unconsolidated Affiliates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Investments In Unconsolidated Affiliates [Line Items]
Investments in unconsolidated affiliates	$ 499	$ 358
Equity in earnings (losses) of unconsolidated affiliates	69	130	$ 122
Regulated Utilities [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in unconsolidated affiliates	2	3
Equity in earnings (losses) of unconsolidated affiliates	(4)	(3)	(1)
International Energy [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in unconsolidated affiliates	39	69
Equity in earnings (losses) of unconsolidated affiliates	74	120	110
Commercial Power [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in unconsolidated affiliates	433	258
Equity in earnings (losses) of unconsolidated affiliates	(3)	10	7
Other [Member]
Investments In Unconsolidated Affiliates [Line Items]
Investments in unconsolidated affiliates	25	28
Equity in earnings (losses) of unconsolidated affiliates	$ 2	$ 3	$ 6

Related Party Transactions (Oth

Related Party Transactions (Other Revenue and Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Duke Energy Carolinas [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 914	$ 851	$ 927
Duke Energy Carolinas [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	24	21	22
Duke Energy Carolinas [Member] | Joint Dispatch Agreement (JDA) [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	51	133	121
Related party transaction, expenses from transactions with related party	183	198	116
Progress Energy [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party			96
Related party transaction, expenses from transactions with related party	712	732	290
Progress Energy [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	38	33	34
Progress Energy [Member] | Joint Dispatch Agreement (JDA) [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	183	198	116
Related party transaction, expenses from transactions with related party	51	133	121
Duke Energy Progress [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	403	386	266
Duke Energy Progress [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	16	17	20
Duke Energy Progress [Member] | Joint Dispatch Agreement (JDA) [Member]
Related Party Transaction [Line Items]
Related party transaction, other revenues from transactions with related party	183	198	116
Related party transaction, expenses from transactions with related party	51	133	121
Duke Energy Florida [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	309	346	182
Duke Energy Florida [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	22	16	14
Duke Energy Ohio [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	342	316	347
Duke Energy Ohio [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	6	13	15
Duke Energy Indiana [Member] | Corporate Governance And Shared Service Expenses [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	349	384	422
Duke Energy Indiana [Member] | Indemnification Coverages [Member]
Related Party Transaction [Line Items]
Related party transaction, expenses from transactions with related party	$ 9	$ 11	$ 14

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - Duke Energy Ohio [Member] - USD ($) $ in Millions	Dec. 31, 2015	Apr. 01, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Intercompany loan payable	$ 103		$ 491
DECAM [Member]
Related Party Transaction [Line Items]
Intercompany loan payable		$ 294	$ 459

Related Party Transactions Inte

Related Party Transactions Intercompany Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Duke Energy Carolinas [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	$ 107	$ 75
Due to Related Parties, Current	229	154
Duke Energy Carolinas [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	122	43
Progress Energy [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	375	59
Due to Related Parties, Current	311	203
Progress Energy [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	120	713
Duke Energy Progress [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	16	10
Due to Related Parties, Current	190	120
Duke Energy Progress [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	104	267
Duke Energy Florida [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	84	40
Due to Related Parties, Current	116	70
Duke Energy Florida [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current		174
Due to Related Parties, Current	96
Duke Energy Ohio [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	84	107
Due to Related Parties, Current	53	74
Duke Energy Ohio [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	54	39
Duke Energy Indiana [Member]
Income Tax Disclosure [Line Items]
Due from Related Parties, Current	71	115
Due to Related Parties, Current	83	58
Duke Energy Indiana [Member] | Income Taxes
Income Tax Disclosure [Line Items]
Due from Related Parties, Current		$ 95
Due to Related Parties, Current	$ 47

Derivatives and Hedging (Notion

Derivatives and Hedging (Notional Amounts of Derivative Instruments) (Details) Bcf in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)GWhBcf	Dec. 31, 2014USD ($)GWhBcf	Jan. 31, 2016USD ($)	Oct. 31, 2015USD ($)	Jan. 31, 2015USD ($)
Derivative [Line Items]
Undesignated Commodity Contracts Latest Expiration Year	2,048
Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 2,527	$ 1,027
Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	70	25,370
Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	398	676
Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 700	$ 750
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	1,827	277
Variable Interest Entity, Primary Beneficiary [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	497	$ 541
Subsequent Event [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount			$ 500
Piedmont Natural Gas [Member]
Derivative [Line Items]
Notional amount	900
Piedmont Natural Gas [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	900
Duke Energy Carolinas [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 400			$ 400
Duke Energy Carolinas [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	66	35
Duke Energy Carolinas [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 400
Progress Energy [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 500	$ 250
Progress Energy [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	332	328
Progress Energy [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 500	$ 250
Duke Energy Progress [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 250
Duke Energy Progress [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	117	116
Duke Energy Progress [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Floating interest rate					1.75%
Notional amount	$ 250				$ 250
Duke Energy Florida [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 250	$ 250
Duke Energy Florida [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf	215	212
Duke Energy Florida [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 250	$ 250
Duke Energy Ohio [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	34	19,141
Duke Energy Ohio [Member] | Commodity Contracts [Member] | Natural Gas [Member]
Derivative [Line Items]
Notional amount, volume, in millions of dekatherms | Bcf		313
Duke Energy Ohio [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	$ 27	$ 27
Duke Energy Indiana [Member] | Commodity Contracts [Member] | Electricity [Member]
Derivative [Line Items]
Notional amount, energy measure, in gigawatt-hours | GWh	36

Derivatives and Hedging (Locati

Derivatives and Hedging (Location and Fair Value Amounts of Derivatives Reflected in the Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	$ 26	$ 351
Location and fair value amounts of derivatives (Liability)	419	909
Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	45	19
Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	11	2
Location and fair value amounts of derivatives (Liability)	322	371
Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2
Location and fair value amounts of derivatives (Liability)	98	132
Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	7	2
Location and fair value amounts of derivatives (Liability)	216	239
Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	341
Location and fair value amounts of derivatives (Liability)	7	473
Duke Energy Indiana [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	7	14
Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	18	210
Current Assets, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	7	2
Current Assets, Other [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2
Current Assets, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	2
Current Assets, Other [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	204
Current Assets, Other [Member] | Duke Energy Indiana [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	7	14
Investments And Other Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	8	136
Investments And Other Assets, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4
Investments And Other Assets, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4
Investments And Other Assets, Other [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		137
Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	271	573
Current Liabilities, Other [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	32	14
Current Liabilities, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	225	289
Current Liabilities, Other [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	77	109
Current Liabilities, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	145	180
Current Liabilities, Other [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1	257
Deferred Credits And Other Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	148	319
Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	13	5
Deferred Credits And Other Liabilities, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	97	82
Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	21	23
Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	71	59
Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	6	216
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	16	339
Location and fair value amounts of derivatives (Liability)	356	859
Commodity Contract [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	40	19
Commodity Contract [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	5
Location and fair value amounts of derivatives (Liability)	314	369
Commodity Contract [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	93	132
Commodity Contract [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	5
Location and fair value amounts of derivatives (Liability)	216	237
Commodity Contract [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3	341
Location and fair value amounts of derivatives (Liability)		467
Commodity Contract [Member] | Duke Energy Indiana [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	7	14
Commodity Contract [Member] | Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		1
Commodity Contract [Member] | Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		1
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	12
Location and fair value amounts of derivatives (Liability)	256
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	32
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1
Location and fair value amounts of derivatives (Liability)	222
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	77
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	1
Location and fair value amounts of derivatives (Liability)	145
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	3
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Indiana [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	7
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4
Location and fair value amounts of derivatives (Liability)	100
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	8
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4
Location and fair value amounts of derivatives (Liability)	92
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	16
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4
Location and fair value amounts of derivatives (Liability)	71
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		18
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Other [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Other [Member] | Duke Energy Indiana [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		14
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Assets Held For Sale [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		15
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Assets Held For Sale [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		28
Location and fair value amounts of derivatives (Liability)		4
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Investments And Other Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		3
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Investments And Other Assets, Assets Held For Sale [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		15
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Investments And Other Assets, Assets Held For Sale [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		26
Location and fair value amounts of derivatives (Liability)		4
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		1
Location and fair value amounts of derivatives (Liability)		307
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		14
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		288
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		108
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		180
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Assets Held For Sale [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		174
Location and fair value amounts of derivatives (Liability)		253
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Assets Held For Sale [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		175
Location and fair value amounts of derivatives (Liability)		252
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		2
Location and fair value amounts of derivatives (Liability)		91
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		5
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		80
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		23
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		57
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits and Other Liabilities, Assets Held For Sale [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		111
Location and fair value amounts of derivatives (Liability)		208
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits and Other Liabilities, Assets Held For Sale [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		111
Location and fair value amounts of derivatives (Liability)		207
Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	10	12
Location and fair value amounts of derivatives (Liability)	63	50
Interest Rate Contract [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5
Interest Rate Contract [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6	2
Location and fair value amounts of derivatives (Liability)	8	2
Interest Rate Contract [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2
Location and fair value amounts of derivatives (Liability)	5
Interest Rate Contract [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2	2
Location and fair value amounts of derivatives (Liability)		2
Interest Rate Contract [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	7	6
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Current [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	11
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Noncurrent [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	4
Location and fair value amounts of derivatives (Liability)	33
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Investments And Other Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		10
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		13
Interest Rate Contract [Member] | Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		29
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6
Location and fair value amounts of derivatives (Liability)	4
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	6
Location and fair value amounts of derivatives (Liability)	3
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)	2
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	1
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	15
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Duke Energy Carolinas [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Duke Energy Progress [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	5
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Noncurrent [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)	$ 6
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		2
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		2
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Asset)		2
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		1
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities, Other [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		1
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		7
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member] | Progress Energy [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		2
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Florida [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		2
Interest Rate Contract [Member] | Not Designated as Hedging Instrument [Member] | Deferred Credits And Other Liabilities, Other [Member] | Duke Energy Ohio [Member]
Derivatives, Fair Value [Line Items]
Location and fair value amounts of derivatives (Liability)		$ 5

Derivatives and Hedging (Schedu

Derivatives and Hedging (Schedule of Offsetting Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 26	$ 351
Net amounts presented on Balance Sheets	26	110
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	419	909
Net amounts presented on Balance Sheets	419	668
Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	18	210
Gross amounts offset	(3)	(153)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		57
Net amounts presented on Balance Sheets	15	57
Investments And Other Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	8	136
Gross amounts offset	(4)	(88)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		48
Derivative Asset, Not Subject to Master Netting Arrangement		5
Net amounts presented on Balance Sheets	4	53
Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	271	573
Gross amounts offset	(22)	(213)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		360
Derivative Liability, Not Subject to Master Netting Arrangement		1
Net amounts presented on Balance Sheets	249	361
Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	148	319
Gross amounts offset	(16)	(173)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		146
Derivative Liability, Not Subject to Master Netting Arrangement		16
Net amounts presented on Balance Sheets	132	162
Duke Energy Carolinas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	45	19
Net amounts presented on Balance Sheets	45	19
Duke Energy Carolinas [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	32	14
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		14
Net amounts presented on Balance Sheets	32	14
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	13	5
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		5
Net amounts presented on Balance Sheets	13	5
Progress Energy [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	11	2
Net amounts presented on Balance Sheets	11	4
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	322	371
Net amounts presented on Balance Sheets	322	373
Progress Energy [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	7	2
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	5
Progress Energy [Member] | Investments And Other Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	4
Gross amounts offset	(4)
Progress Energy [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	225	289
Gross amounts offset	(21)	(17)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		272
Net amounts presented on Balance Sheets	204	272
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	97	82
Gross amounts offset	(15)	(8)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		74
Net amounts presented on Balance Sheets	82	74
Duke Energy Progress [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2
Net amounts presented on Balance Sheets	2
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	98	132
Net amounts presented on Balance Sheets	98	132
Duke Energy Progress [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2
Net amounts presented on Balance Sheets	2
Duke Energy Progress [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	77	109
Gross amounts offset	(1)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		109
Net amounts presented on Balance Sheets	76	109
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	21	23
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		23
Net amounts presented on Balance Sheets	21	23
Duke Energy Florida [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	7	2
Net amounts presented on Balance Sheets	7	4
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	216	239
Net amounts presented on Balance Sheets	216	241
Duke Energy Florida [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	2
Gross amounts offset	(2)	(2)
Net amounts presented on Balance Sheets	1
Duke Energy Florida [Member] | Investments And Other Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	4
Gross amounts offset	(4)
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	145	180
Gross amounts offset	(20)	(17)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		163
Net amounts presented on Balance Sheets	125	163
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	71	59
Gross amounts offset	(15)	(8)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		51
Net amounts presented on Balance Sheets	56	51
Duke Energy Ohio [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	341
Net amounts presented on Balance Sheets	3	49
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	7	473
Net amounts presented on Balance Sheets	7	181
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	204
Gross amounts offset		(179)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		25
Net amounts presented on Balance Sheets	3	25
Duke Energy Ohio [Member] | Investments And Other Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		137
Gross amounts offset		(114)
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		23
Net amounts presented on Balance Sheets		23
Duke Energy Ohio [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1	257
Gross amounts offset		(222)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		35
Net amounts presented on Balance Sheets	1	35
Duke Energy Ohio [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	6	216
Gross amounts offset		(193)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		23
Net amounts presented on Balance Sheets	6	23
Duke Energy Indiana [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	7	14
Net amounts presented on Balance Sheets	7	14
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	7	14
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		14
Net amounts presented on Balance Sheets	$ 7	$ 14

Derivatives and Hedging (Deriva

Derivatives and Hedging (Derivative Instruments That Contain Credit-Risk Related Contingent Features and Cash Collateral) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	$ 334	$ 845
Collateral Already Posted, Aggregate Fair Value	30	209
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	304	407
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts not offset against net derivative positions		64
Derivative Liability, Fair Value, Amount Offset Against Collateral	30	145
Duke Energy Carolinas [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	45	19
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	45	19
Progress Energy [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	290	370
Collateral Already Posted, Aggregate Fair Value	30	23
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	260	347
Information Regarding Cash Collateral Under Master Netting Arrangements
Derivative Liability, Fair Value, Amount Offset Against Collateral	30	23
Duke Energy Progress [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	93	131
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	93	131
Duke Energy Florida [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position	194	239
Collateral Already Posted, Aggregate Fair Value	30	23
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered	164	216
Information Regarding Cash Collateral Under Master Netting Arrangements
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 30	23
Duke Energy Ohio [Member]
Schedule Of Information Regarding Derivative Instruments That Contain Credit-Risk Related Contingent Features
Aggregate fair value of derivatives in a net liability position		456
Collateral Already Posted, Aggregate Fair Value		186
Additional cash collateral or letters of credit in the event credit-risk-related contingent features were triggered		41
Information Regarding Cash Collateral Under Master Netting Arrangements
Amounts not offset against net derivative positions		64
Derivative Liability, Fair Value, Amount Offset Against Collateral		$ 122

Investments in Debt and Equi109

Investments in Debt and Equity Securities (Available-For-Sale Investments) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	$ 1,882	$ 2,004
Gross Unrealized Holding Losses	83	38
Estimated Fair Value	6,214	5,901
NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,846	1,965
Gross Unrealized Holding Losses	76	35
Estimated Fair Value	5,817	5,549
NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	179	136
NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,823	1,926
Gross Unrealized Holding Losses	58	29
Estimated Fair Value	3,590	3,650
NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	7	14
Gross Unrealized Holding Losses	8	2
Estimated Fair Value	432	454
NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	5	5
Gross Unrealized Holding Losses	1
Estimated Fair Value	185	184
NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	11	19
Gross Unrealized Holding Losses	5	2
Estimated Fair Value	1,254	978
NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains		1
Gross Unrealized Holding Losses	4	2
Estimated Fair Value	177	147
Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	36	39
Gross Unrealized Holding Losses	7	3
Estimated Fair Value	397	352
Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	29	15
Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	32	34
Gross Unrealized Holding Losses	1
Estimated Fair Value	95	96
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	3	1
Estimated Fair Value	92	58
Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	3
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	74	76
Other Classification [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	45	27
Other Classification [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains		1
Gross Unrealized Holding Losses	2	1
Estimated Fair Value	62	80
Duke Energy Carolinas [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,028	1,119
Gross Unrealized Holding Losses	40	23
Estimated Fair Value	3,041	3,035
Duke Energy Carolinas [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,028	1,119
Gross Unrealized Holding Losses	39	22
Estimated Fair Value	3,038	3,032
Duke Energy Carolinas [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	34	51
Duke Energy Carolinas [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1,021	1,102
Gross Unrealized Holding Losses	27	17
Estimated Fair Value	2,094	2,162
Duke Energy Carolinas [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	8
Gross Unrealized Holding Losses	5	2
Estimated Fair Value	292	316
Duke Energy Carolinas [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	1	1
Estimated Fair Value	33	62
Duke Energy Carolinas [Member] | NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	7
Gross Unrealized Holding Losses	3	1
Estimated Fair Value	438	308
Duke Energy Carolinas [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains		1
Gross Unrealized Holding Losses	4	2
Estimated Fair Value	147	133
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	821	849
Gross Unrealized Holding Losses	37	13
Estimated Fair Value	2,842	2,575
Progress Energy [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	818	846
Gross Unrealized Holding Losses	37	13
Estimated Fair Value	2,779	2,517
Progress Energy [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	145	85
Progress Energy [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	802	824
Gross Unrealized Holding Losses	31	12
Estimated Fair Value	1,496	1,488
Progress Energy [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	6
Gross Unrealized Holding Losses	3
Estimated Fair Value	140	138
Progress Energy [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	4
Gross Unrealized Holding Losses	1
Estimated Fair Value	152	122
Progress Energy [Member] | NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	8	12
Gross Unrealized Holding Losses	2	1
Estimated Fair Value	816	670
Progress Energy [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	30	14
Progress Energy [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	3
Estimated Fair Value	63	58
Progress Energy [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	18	15
Progress Energy [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	3
Estimated Fair Value	45	43
Duke Energy Progress [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	609	630
Gross Unrealized Holding Losses	30	11
Estimated Fair Value	2,039	1,711
Duke Energy Progress [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	609	630
Gross Unrealized Holding Losses	30	11
Estimated Fair Value	2,038	1,711
Duke Energy Progress [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	110	50
Duke Energy Progress [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	596	612
Gross Unrealized Holding Losses	25	10
Estimated Fair Value	1,178	1,171
Duke Energy Progress [Member] | NDTF [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	5
Gross Unrealized Holding Losses	2
Estimated Fair Value	96	97
Duke Energy Progress [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	4	4
Gross Unrealized Holding Losses	1
Estimated Fair Value	150	120
Duke Energy Progress [Member] | NDTF [Member] | US Treasury and Government [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	6	9
Gross Unrealized Holding Losses	2	1
Estimated Fair Value	486	265
Duke Energy Progress [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	18	8
Duke Energy Progress [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	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
Duke Energy Florida [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	212	219
Gross Unrealized Holding Losses	7	2
Estimated Fair Value	792	850
Duke Energy Florida [Member] | NDTF [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	209	216
Gross Unrealized Holding Losses	7	2
Estimated Fair Value	741	806
Duke Energy Florida [Member] | NDTF [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	35	35
Duke Energy Florida [Member] | NDTF [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	206	212
Gross Unrealized Holding Losses	6	2
Estimated Fair Value	318	317
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	44	41
Duke Energy Florida [Member] | NDTF [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	2	2
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
Estimated Fair Value	330	405
Duke Energy Florida [Member] | NDTF [Member] | Other Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	12	6
Duke Energy Florida [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	3
Estimated Fair Value	51	44
Duke Energy Florida [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	6	1
Duke Energy Florida [Member] | Other Classification [Member] | Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	3	3
Estimated Fair Value	45	43
Duke Energy Indiana [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	27	28
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	101	101
Duke Energy Indiana [Member] | Other Classification [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	27	28
Gross Unrealized Holding Losses	1	1
Estimated Fair Value	101	101
Duke Energy Indiana [Member] | Other Classification [Member] | Cash and Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	2
Duke Energy Indiana [Member] | Other Classification [Member] | Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Holding Gains	27	28
Estimated Fair Value	71	71
Duke Energy Indiana [Member] | Other Classification [Member] | Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Estimated Fair Value	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	$ 26	$ 30

Investments in Debt and Equi110

Investments in Debt and Equity Securities (Maturities) (Details) $ in Millions	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Due in one year or less	$ 120
Due after one through five years	775
Due after five through ten years	598
Due after ten years	828
Total	2,321
Duke Energy Carolinas [Member]
Debt Instrument [Line Items]
Due in one year or less	13
Due after one through five years	187
Due after five through ten years	275
Due after ten years	438
Total	913
Progress Energy [Member]
Debt Instrument [Line Items]
Due in one year or less	94
Due after one through five years	496
Due after five through ten years	254
Due after ten years	339
Total	1,183
Duke Energy Progress [Member]
Debt Instrument [Line Items]
Due in one year or less	15
Due after one through five years	285
Due after five through ten years	206
Due after ten years	244
Total	750
Duke Energy Florida [Member]
Debt Instrument [Line Items]
Due in one year or less	79
Due after one through five years	211
Due after five through ten years	48
Due after ten years	95
Total	433
Duke Energy Indiana [Member]
Debt Instrument [Line Items]
Due in one year or less	2
Due after one through five years	14
Due after five through ten years	9
Due after ten years	3
Total	$ 28

Investments in Debt and Equi111

Investments in Debt and Equity Securities Investments in Debt and Equity Securities (Realized Gains and Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	$ 193	$ 271	$ 209
Realized losses	98	105	65
Duke Energy Carolinas [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	158	109	115
Realized losses	83	93	12
Progress Energy [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	33	157	90
Realized losses	13	11	46
Duke Energy Progress [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	26	19	58
Realized losses	11	5	26
Duke Energy Florida [Member]
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Realized gains	7	138	32
Realized losses	$ 2	$ 5	$ 20

Fair Value Measurements (Fair V

Fair Value Measurements (Fair Value Measurement Amounts for Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	$ 26	$ 110
Assets, fair value disclosure	6,240	6,018
Derivative liabilities	(419)	(668)
Net assets, fair value	5,821	5,350
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0	49
Assets, fair value disclosure	4,260	4,327
Derivative liabilities	0	(162)
Net assets, fair value	4,260	4,165
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	16	24
Assets, fair value disclosure	1,793	1,498
Derivative liabilities	(419)	(468)
Net assets, fair value	1,374	1,030
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	10	37
Assets, fair value disclosure	15	42
Derivative liabilities	0	(38)
Net assets, fair value	15	4
Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	172	151
Net assets, fair value	172	151
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	3,041	3,035
Derivative liabilities	(45)	(19)
Net assets, fair value	2,996	3,016
Duke Energy Carolinas [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	2,168	2,143
Net assets, fair value	2,168	2,143
Duke Energy Carolinas [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	698	738
Derivative liabilities	(45)	(19)
Net assets, fair value	653	719
Duke Energy Carolinas [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	3	3
Net assets, fair value	3	3
Duke Energy Carolinas [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	172	151
Net assets, fair value	172	151
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	11	4
Assets, fair value disclosure	2,853	2,579
Derivative liabilities	(322)	(373)
Net assets, fair value	2,531	2,206
Progress Energy [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	1,940	2,013
Net assets, fair value	1,940	2,013
Progress Energy [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	11	4
Assets, fair value disclosure	913	566
Derivative liabilities	(322)	(373)
Net assets, fair value	591	193
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2
Assets, fair value disclosure	2,041	1,711
Derivative liabilities	(98)	(132)
Net assets, fair value	1,943	1,579
Duke Energy Progress [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	1,320	1,322
Net assets, fair value	1,320	1,322
Duke Energy Progress [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	2
Assets, fair value disclosure	721	389
Derivative liabilities	(98)	(132)
Net assets, fair value	623	257
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	4
Assets, fair value disclosure	799	854
Derivative liabilities	(216)	(241)
Net assets, fair value	583	613
Duke Energy Florida [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Assets, fair value disclosure	609	676
Net assets, fair value	609	676
Duke Energy Florida [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	4
Assets, fair value disclosure	190	178
Derivative liabilities	(216)	(241)
Net assets, fair value	(26)	(63)
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	49
Derivative liabilities	(7)	(181)
Net assets, fair value	(4)	(132)
Duke Energy Ohio [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets		20
Derivative liabilities	0	(117)
Net assets, fair value		(97)
Duke Energy Ohio [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets		9
Derivative liabilities	(7)	(26)
Net assets, fair value	(7)	(17)
Duke Energy Ohio [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	3	20
Derivative liabilities		(38)
Net assets, fair value	3	(18)
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	14
Net assets, fair value	108	115
Duke Energy Indiana [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	0
Net assets, fair value	73	71
Duke Energy Indiana [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Net assets, fair value	28	30
Duke Energy Indiana [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative assets	7	14
Net assets, fair value	7	14
NDTF [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,590	3,650
NDTF [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3,418	3,493
NDTF [Member] | Equity Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		6
NDTF [Member] | Equity Securities [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	172	151
NDTF [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,227	1,899
NDTF [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	672	648
NDTF [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,555	1,251
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	2,094	2,162
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,922	2,005
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		6
NDTF [Member] | Duke Energy Carolinas [Member] | Equity Securities [Member] | Fair Value, Inputs, Not Categorized [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	172	151
NDTF [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	944	870
NDTF [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	246	138
NDTF [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	698	732
NDTF [Member] | Progress Energy [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,496	1,488
NDTF [Member] | Progress Energy [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,496	1,488
NDTF [Member] | Progress Energy [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,283	1,029
NDTF [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	426	510
NDTF [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	857	519
NDTF [Member] | Duke Energy Progress [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,178	1,171
NDTF [Member] | Duke Energy Progress [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,178	1,171
NDTF [Member] | Duke Energy Progress [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	860	540
NDTF [Member] | Duke Energy Progress [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	141	151
NDTF [Member] | Duke Energy Progress [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	719	389
NDTF [Member] | Duke Energy Florida [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	318	317
NDTF [Member] | Duke Energy Florida [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	318	317
NDTF [Member] | Duke Energy Florida [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	423	489
NDTF [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	285	359
NDTF [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	138	130
Other Classification [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	95	96
Other Classification [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	95	96
Other Classification [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	302	263
Other Classification [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	75	41
Other Classification [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	222	217
Other Classification [Member] | Debt Securities [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	5	5
Other Classification [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Other Classification [Member] | Duke Energy Carolinas [Member] | Debt Securities [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	3	3
Other Classification [Member] | Progress Energy [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	63	58
Other Classification [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	18	15
Other Classification [Member] | Progress Energy [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	45	43
Other Classification [Member] | Duke Energy Progress [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1
Other Classification [Member] | Duke Energy Progress [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1
Other Classification [Member] | Duke Energy Florida [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	51	44
Other Classification [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	6
Other Classification [Member] | Duke Energy Florida [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	45	44
Other Classification [Member] | Duke Energy Indiana [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, equity securities	71	71
Other Classification [Member] | Duke Energy Indiana [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, equity securities	71	71
Other Classification [Member] | Duke Energy Indiana [Member] | Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, debt securities	30	30
Other Classification [Member] | Duke Energy Indiana [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, debt securities	2
Other Classification [Member] | Duke Energy Indiana [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, debt securities	$ 28	$ 30

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	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 4	$ 33
Total pretax gains (losses) included in earnings	21	(7)
Purchases	24	50
Sales	(1)	(15)
Settlements	(37)	(54)
Transfers in and/or out of level 3		6
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3		6
Total gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability	4	(9)
Ending balance	15	4
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(1)	13
Total pretax gains (losses) included in earnings	21	(7)
Purchases	24	50
Sales	1
Settlements	37	54
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability	4	(9)
Ending balance	10	(1)
Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at end of period		(14)
Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	5	20
Sales		(15)
Ending balance	5	5
Derivative [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at end of period		(14)
Duke Energy Carolinas [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3	1
Settlements		(2)
Ending balance		3
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance		(2)
Settlements		(2)
Duke Energy Carolinas [Member] | Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3	3
Ending balance		3
Duke Energy Ohio [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3		6
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	(18)	(4)
Total pretax gains (losses) included in earnings	21	(9)
Purchases	5	1
Settlements	5	13
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability	0	1
Ending balance	3	(18)
Duke Energy Indiana [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	14	12
Total pretax gains (losses) included in earnings		3
Purchases	19	49
Settlements	(30)	(41)
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability	4	(9)
Ending balance	$ 7	$ 14

Fair Value Measurements (Quanti

Fair Value Measurements (Quantitative Level 3 Fair Value Disclosure) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)$ / MWh	Dec. 31, 2014USD ($)$ / MWh	Dec. 31, 2013USD ($)
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 10	$ (1)	$ 13
Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (5)
Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu		2.12
Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu		4.35
Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 10	$ 14
Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	(0.74)	(1.92)
Financial Transmission Rights [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh	7.29	9.86
Commodity Power Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (1)
Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		25.16
Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		51.75
Commodity Capacity Option Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ 2
Commodity Capacity Option Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per Mwd		21
Commodity Capacity Option Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per Mwd		109
Derivative Financial Instruments Liabilities Reserves [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (11)
Duke Energy Carolinas [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $			(2)
Duke Energy Ohio [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 3	(18)	(4)
Duke Energy Ohio [Member] | Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (5)
Duke Energy Ohio [Member] | Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu		2.12
Duke Energy Ohio [Member] | Commodity Natural Gas Hedges [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair Value Inputs Price Per MMBtu		4.35
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 3
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price FTR	0.67
Duke Energy Ohio [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price FTR	2.53
Duke Energy Ohio [Member] | Commodity Power Contracts [Member] | Discounted Cash Flow [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (6)
Duke Energy Ohio [Member] | Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		25.25
Duke Energy Ohio [Member] | Commodity Power Contracts [Member] | Discounted Cash Flow [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price per MWh		51.75
Duke Energy Ohio [Member] | Derivative Financial Instruments Liabilities Reserves [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $		$ (7)
Duke Energy Indiana [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 7	14	$ 12
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Net derivative asset (liability) | $	$ 7	$ 14
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member] | Minimum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price FTR	(0.74)	(1.92)
Duke Energy Indiana [Member] | Financial Transmission Rights [Member] | RTO Market Pricing [Member] | Maximum [Member]
Net Derivative Asset (Liability) Fair Value Inputs [Line Items]
Fair value inputs, price FTR	7.29	9.86

Fair Value Measurements (Additi

Fair Value Measurements (Additional Fair Value Disclosure) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 39,569	$ 39,868
Long-term debt, fair value	42,537	44,566
Duke Energy Carolinas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	8,367	8,353
Long-term debt, fair value	9,156	9,626
Progress Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	14,464	14,668
Long-term debt, fair value	15,856	16,951
Duke Energy Progress [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	6,518	6,170
Long-term debt, fair value	6,757	6,696
Duke Energy Florida [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	4,266	4,823
Long-term debt, fair value	4,908	5,767
Duke Energy Ohio [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	1,598	1,760
Long-term debt, fair value	1,724	1,970
Duke Energy Indiana [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	3,768	3,769
Long-term debt, fair value	$ 4,219	$ 4,456

Variable Interest Entities (Nar

Variable Interest Entities (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 2,700,000,000	$ 2,922,000,000
Impairment charges	120,000,000	81,000,000	$ 399,000,000
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 325,000,000
Line of credit facility, expiration date	Dec. 1, 2018
Percent of proceeds received as cash	75.00%
Percent of proceeds received as subordinated note	25.00%
Minimum Equity Balance required by Cinergy Receivables	$ 3,000,000
Duke American Transmission Company [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Ownership Interest	50.00%
Atlantic Coast Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Ownership Interest	40.00%
Sabal Trail Transmission Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Ownership Interest	7.50%
Duke Energy Carolinas [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 500,000,000
Impairment charges	1,000,000	3,000,000
Duke Energy Progress [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	1,200,000,000	1,350,000,000
Impairment charges	5,000,000	(18,000,000)	22,000,000
Duke Energy Progress [Member] | DEPR [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 300,000,000
Line of credit facility, expiration date	Feb. 1, 2019
Duke Energy Florida [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount		225,000,000
Impairment charges	$ 7,000,000	2,000,000	358,000,000
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Impairment charges		94,000,000	$ 5,000,000
Duke Energy Ohio [Member] | Cinergy Receivables [Member]
Variable Interest Entity [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%
Duke Energy Ohio [Member] | Other VIEs [Member]
Variable Interest Entity [Line Items]
Impairment charges		$ 94,000,000
Duke Energy Ohio [Member] | OVEC [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Ownership Interest	9.00%
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Impairment charges	$ 88,000,000
Duke Energy Indiana [Member] | Cinergy Receivables [Member]
Variable Interest Entity [Line Items]
Fixed interest rate added to LIBOR to compute variable rate	1.00%

Variable Interest Entities (Con

Variable Interest Entities (Consolidated VIEs) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	$ 857	$ 2,036	$ 1,501	$ 1,424
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	1,748	1,973
Other current assets	327	1,837
Investments and other assets	3,042	3,008
Total property, plant and equipment	112,826	104,861
Accumulated depreciation and amortization	(37,665)	(34,824)
Other deferred debits	43	19
Accounts payable	2,400	2,271
Current maturities of long-term debt	2,074	2,807
Other current liabilities	2,115	2,188
Long-Term debt	37,495	37,061
Deferred income taxes	12,705	13,423
Asset retirement obligations	10,264	8,466
Other Liabilities	1,706	1,675
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	2
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	1,748	1,973
Other current assets	142	74
Investments and other assets	70	50
Total property, plant and equipment	2,035	1,873
Accumulated depreciation and amortization	(327)	(255)
Other deferred debits		36
Total assets	3,670	3,751
Accounts payable	35	3
Taxes accrued	14	6
Current maturities of long-term debt	125	84
Other current liabilities	17	21
Long-Term debt	2,197	2,234
Deferred income taxes	289	283
Asset retirement obligations	35	29
Other Liabilities	33	38
Total liabilities	2,745	2,698
Net assets of consolidated VIEs	925	1,053
Duke Energy Carolinas [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	13	13	23	19
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	596	647
Other current assets	128	77
Investments and other assets	999	959
Total property, plant and equipment	39,398	37,372
Accumulated depreciation and amortization	(13,521)	(12,700)
Other deferred debits	4	4
Accounts payable	753	709
Current maturities of long-term debt	356	507
Other current liabilities	519	434
Long-Term debt	7,711	7,546
Deferred income taxes	6,146	5,812
Asset retirement obligations	3,918	3,428
Other Liabilities	621	642
Duke Energy Progress [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	15	9	21	18
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	349	436
Other current assets	121	384
Investments and other assets	486	412
Total property, plant and equipment	27,313	24,207
Accumulated depreciation and amortization	(10,141)	(9,021)
Other deferred debits	3	3
Accounts payable	399	481
Current maturities of long-term debt	2	945
Other current liabilities	412	409
Long-Term debt	6,366	5,225
Deferred income taxes	3,027	2,908
Asset retirement obligations	4,567	3,905
Other Liabilities	45	89
Duke Energy Florida [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	8	8	$ 16	$ 131
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	308	305
Other current assets	21	521
Investments and other assets	292	204
Total property, plant and equipment	15,343	14,433
Accumulated depreciation and amortization	(4,720)	(4,478)
Other deferred debits	2	2
Accounts payable	322	365
Current maturities of long-term debt	13	562
Other current liabilities	452	586
Long-Term debt	4,253	4,261
Deferred income taxes	2,460	2,452
Asset retirement obligations	802	806
Other Liabilities	146	158
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	596	647
Total assets	596	647
Taxes accrued	5
Long-Term debt	425	400
Total liabilities	430	400
Net assets of consolidated VIEs	166	247
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	349	436
Total assets	349	436
Taxes accrued	3
Long-Term debt	254	300
Total liabilities	257	300
Net assets of consolidated VIEs	92	136
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	309	305
Total assets	309	305
Long-Term debt	225	$ 225
Deferred income taxes
Asset retirement obligations
Other Liabilities
Total liabilities	225	$ 225
Net assets of consolidated VIEs	84	80
Cinergy Receivables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	454	547
Total assets	454	547
Long-Term debt	325	325
Total liabilities	325	325
Net assets of consolidated VIEs	129	222
Renewables [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	19	20
Other current assets	138	68
Investments and other assets	70	25
Total property, plant and equipment	2,015	1,855
Accumulated depreciation and amortization	(321)	(250)
Other deferred debits		34
Total assets	1,921	1,752
Accounts payable	35	3
Taxes accrued	5	6
Current maturities of long-term debt	108	68
Other current liabilities	15	16
Long-Term debt	968	967
Deferred income taxes	289	283
Asset retirement obligations	35	29
Other Liabilities	33	34
Total liabilities	1,488	1,406
Net assets of consolidated VIEs	433	346
Other VIEs [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity Consolidated Carrying Amount, Assets and Liabilities, Net [Abstract]
Cash and Cash Equivalents, at Carrying Value	2
Restricted receivables of variable interest entities (net of allowance for doubtful accounts)	21	18
Other current assets	4	6
Investments and other assets		25
Total property, plant and equipment	20	18
Accumulated depreciation and amortization	(6)	(5)
Other deferred debits		2
Total assets	41	64
Taxes accrued	1
Current maturities of long-term debt	17	16
Other current liabilities	2	5
Long-Term debt		17
Deferred income taxes	0
Other Liabilities		4
Total liabilities	20	42
Net assets of consolidated VIEs	$ 21	$ 22

Variable Interest Entities (Sch

Variable Interest Entities (Schedule of Accounts Receivable Securitizations)(Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 2,700,000,000	$ 2,922,000,000
Duke Energy Carolinas [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	500,000,000
Duke Energy Progress [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	1,200,000,000	1,350,000,000
Duke Energy Florida [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount		$ 225,000,000
DERF [Member] | Duke Energy Carolinas [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 425,000,000
Line of credit facility, expiration date	Dec. 1, 2018
DEPR [Member] | Duke Energy Progress [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 300,000,000
Line of credit facility, expiration date	Feb. 1, 2019
DEFR [Member] | Duke Energy Florida [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Debt Instrument, Face Amount	$ 225,000,000
Line of credit facility, expiration date	Mar. 1, 2017

Variable Interest Entities (119

Variable Interest Entities (Schedule of Non-Consolidated VIEs) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	$ 499	$ 358
Investments and other assets	3,042	3,008
Other current liabilities	2,115	2,188
Other liabilities	32,490	31,364
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	387	188
Investments and other assets		4
Total assets	387	192
Other current liabilities	3	3
Other liabilities	14	14
Total liabilities	17	17
Net assets of non-consolidated VIEs	370	175
Renewables [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	235	150
Total assets	235	150
Net assets of non-consolidated VIEs	235	150
Other VIEs [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Investments in equity method unconsolidated affiliates	152	38
Investments and other assets		4
Total assets	152	42
Other current liabilities	3	3
Other liabilities	14	14
Total liabilities	17	17
Net assets of non-consolidated VIEs	135	25
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Investments and other assets	20	23
Other current liabilities	153	66
Other liabilities	1,998	2,281
Duke Energy Ohio [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables	47	91
Total assets	47	91
Net assets of non-consolidated VIEs	47	91
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Other current liabilities	97	98
Other liabilities	3,219	2,730
Duke Energy Indiana [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Receivables	60	113
Total assets	60	113
Net assets of non-consolidated VIEs	$ 60	$ 113

Variable Interest Entities (Fai

Variable Interest Entities (Fair Value Assumptions)(Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Cinergy Receivables [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Anticipated credit loss ratio	0.60%	0.60%
Discount rate	1.20%	1.20%
Receivable turnover rate	12.90%	12.80%
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Anticipated credit loss ratio	0.30%	0.30%
Discount rate	1.20%	1.20%
Receivable turnover rate	10.60%	10.50%

Variable Interest Entities (Rec

Variable Interest Entities (Receivables Sold)(Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Cinergy Receivables [Member] - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Receivables sold	$ 233	$ 273
Less: retained interests	47	91
Net receivables sold	186	182
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Receivables sold	260	310
Less: retained interests	60	113
Net receivables sold	$ 200	$ 197

Variable Interest Entities (Sal

Variable Interest Entities (Sales and Cash Flows)(Details) - Variable Interest Entity, Not Primary Beneficiary [Member] - Cinergy Receivables [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Duke Energy Ohio [Member]
Variable Interest Entity [Line Items]
Receivables sold	$ 1,963	$ 2,246	$ 2,251
Loss recognized on sale	9	11	12
Cash proceeds from receivables sold	1,995	2,261	2,220
Collection fees received	1	1	1
Return received on retained interests	3	4	5
Duke Energy Indiana [Member]
Variable Interest Entity [Line Items]
Receivables sold	2,627	2,913	2,985
Loss recognized on sale	11	11	11
Cash proceeds from receivables sold	2,670	2,932	2,944
Collection fees received	1	1	1
Return received on retained interests	$ 5	$ 6	$ 6

Common Stock (Earnings Per Shar

Common Stock (Earnings Per Share Data)(Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent									$ 2,796	$ 2,451	$ 2,574
Weighted Average Number of Shares Outstanding, Basic									694	707	706
Weighted Average Number of Shares Outstanding, Diluted									694	707	706
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.70	$ 1.36	$ 0.87	$ 1.09	$ 0.14	$ 1.25	$ 1.02	$ 1.05	$ 4.02	$ 3.46	$ 3.64
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.70	$ 1.36	$ 0.87	$ 1.09	$ 0.14	$ 1.25	$ 1.02	$ 1.05	$ 4.02	$ 3.46	$ 3.63
Common Class A [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Income (Loss) from Continuing Operations Attributable to Parent									$ 2,791	$ 2,446	$ 2,565
Weighted Average Number of Shares Outstanding, Basic									694	707	706
Weighted Average Number of Shares Outstanding, Diluted									694	707	706
Income (Loss) from Continuing Operations, Per Basic Share									$ 4.02	$ 3.46	$ 3.64
Income (Loss) from Continuing Operations, Per Diluted Share									$ 4.02	$ 3.46	$ 3.63
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									2	2	2
Common Stock, Dividends, Per Share, Declared									$ 3.24	$ 3.15	$ 3.09

Common Stock Common Stock (Acce

Common Stock Common Stock (Accelerated Share Repurchase) (Details) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended		12 Months Ended
	Jun. 30, 2015	Apr. 30, 2015	Dec. 31, 2015	Apr. 06, 2015
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount		$ 1,500
Payments for Repurchase of Common Stock		$ 1,500	$ 1,500
Stock Repurchased and Retired During Period, Shares	3.2	16.6	19.8
Stock Repurchased and Retired During Period, Value	$ 225	$ 1,275	$ 1,500
Percentage of ASR common stock received				85.00%
Forward Contracts Indexed to Issuer's Equity, Value	$ 225
Accelerated Share Repurchases, Final Price Paid Per Share			$ 75.75
Goldman Sachs [Member]
Accelerated Share Repurchases [Line Items]
Payments for Repurchase of Common Stock		750
JPMorgan Chase [Member]
Accelerated Share Repurchases [Line Items]
Payments for Repurchase of Common Stock		$ 750

Severance (Narrative) (Details)

Severance (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015Employees	Dec. 31, 2013USD ($)
2015 Severance Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of eligible employees | Employees	900
Duke Energy Florida [Member] | Crystal River Unit 3 2013 Severance Plan [Member]
Restructuring Cost and Reserve [Line Items]
Deferred severance costs | $		$ 26

Severance (Expenses) (Details)

Severance (Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013
2015 Severance Plan [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 142
2015 Severance Plan [Member] | Duke Energy Carolinas [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	93
2015 Severance Plan [Member] | Progress Energy [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	36
2015 Severance Plan [Member] | Duke Energy Progress [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	28
2015 Severance Plan [Member] | Duke Energy Florida [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	8
2015 Severance Plan [Member] | Duke Energy Ohio [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	2
2015 Severance Plan [Member] | Duke Energy Indiana [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 6
Severance Plan 2011 [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		$ 34
Accelerated stock compensation expense		5
COBRA and healthcare expense reimbursement		2
Severance Plan 2011 [Member] | Duke Energy Carolinas [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		8
Severance Plan 2011 [Member] | Progress Energy [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		19
Severance Plan 2011 [Member] | Duke Energy Progress [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		14
Severance Plan 2011 [Member] | Duke Energy Florida [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		5
Severance Plan 2011 [Member] | Duke Energy Ohio [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		2
Severance Plan 2011 [Member] | Duke Energy Indiana [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		$ 2

Severance (Rollforward) (Detail

Severance (Rollforward) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Restructuring Reserve [Roll Forward]
Balance, beginning of period	$ 28
Provision/adjustments	144
Cash reductions	(36)
Balance, end of period	136
Duke Energy Carolinas [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	2
Provision/adjustments	80
Cash reductions	(4)
Balance, end of period	78
Progress Energy [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	18
Provision/adjustments	20
Cash reductions	(15)
Balance, end of period	23
Duke Energy Progress [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	1
Provision/adjustments	20
Cash reductions	(2)
Balance, end of period	19
Duke Energy Florida [Member]
Restructuring Reserve [Roll Forward]
Balance, beginning of period	17
Cash reductions	(13)
Balance, end of period	$ 4

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares reserved for awards to employees and outside directors	10
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum option term, years	10 years
Restricted Stock Units Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant date fair value of shares vested	$ 41	$ 52	$ 50
Unrecognized compensation cost	$ 19
Unrecognized compensation cost, period of recognition, years	1 year 11 months
Restricted Stock Units Awards [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total grant date fair value of shares vested	$ 26	$ 27	$ 42
Unrecognized compensation cost	$ 22
Unrecognized compensation cost, period of recognition, years	1 year 2 months
Risk Free Interest Rate	1.00%
Expected Volatility Rate	13.60%

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule of Stock-Based Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	$ 38	$ 38	$ 52
Pretax stock-based compensation expense	61	61	85
Tax benefit associated with stock-based compensation expense	23	23	33
Stock-based compensation costs capitalized	3	4	3
Restricted Stock Units Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation expense	38	39	49
Performance Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation expense	23	22	34
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax stock-based compensation expense			2
Duke Energy Carolinas [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	14	12	13
Progress Energy [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	14	14	23
Duke Energy Progress [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	9	9	14
Duke Energy Florida [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	5	5	9
Duke Energy Ohio [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	2	5	4
Duke Energy Indiana [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense, Net of Tax	$ 4	$ 3	$ 4

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock Options) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Option Activity, Options [Roll Forward]
Outstanding at beginning of period	373
Granted			310
Exercised	(270)
Outstanding at end of period	103	373
Options expected to vest	103
Stock Option Activity, Weighted Average Exercise Price [Roll Forward]
Weighted average exercise price of options outstanding at beginning of period	$ 64
Exercised	62
Weighted average exercise price of options outstanding end of period	69	$ 64
Weighted average exercise price of options expected to vest	$ 69
Weighted-Average Remaining Life [Abstract]
Weighted average remaining life of options outstanding at end of period, years	7 years 2 months
Weighted average remaining life of options expected to vest, years	7 years 2 months
Schedule Of Information Related To Stock Options [Abstract]
Intrinsic value of options exercised	$ 5	$ 6	$ 26
Tax benefit related to options exercised	2	2	10
Cash received from options exercised	$ 17	$ 25	$ 9
Stock options granted			310

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary of Stock Awards Outstanding) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock Units Awards [Member]
Schedule Of Shares Awarded [Abstract]
Shares awarded (in thousands)	524	557	612
Fair value	$ 41	$ 40	$ 42
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period	1,080
Granted	524	557	612
Vested	(602)
Forfeited	(49)
Outstanding at end of period	953	1,080
Stock awards expected to vest	924
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average fair value at beginning of period	$ 69
Granted	79
Vested	68
Forfeited	73
Weighted average fair value at end of period	75	$ 69
Weighted average fair value of awards expected to vest	$ 75
Performance Awards [Member]
Schedule Of Shares Awarded [Abstract]
Shares awarded (in thousands)	642	542	633
Fair value	$ 26	$ 19	$ 28
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period	1,627
Granted	642	542	633
Vested	(271)
Forfeited	(301)
Outstanding at end of period	1,697	1,627
Stock awards expected to vest	1,301
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Weighted average fair value at beginning of period	$ 42
Granted	41
Vested	51
Forfeited	38
Weighted average fair value at end of period	40	$ 42
Weighted average fair value of awards expected to vest	$ 40

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Maximum years of participation	35 years
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of securities on loan	$ 305	$ 383
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Qualified Pension Plans [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage	98.00%
Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	10 years
Other Post-Retirement Benefit Plans [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage	2.00%
Duke Energy Carolinas [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Carolinas [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Progress Energy [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Progress Energy [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	10 years
Duke Energy Progress [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Progress [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	12 years
Duke Energy Florida [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Florida [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	17 years
Duke Energy Ohio [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Ohio [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Indiana [Member] | Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Duke Energy Indiana [Member] | Non-Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years

Employee Benefit Plans (Contrib

Employee Benefit Plans (Contributions to Defined Benefit Pension Plans) (Details) - Qualified Pension Plans [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 302	$ 250
Anticipated contribution	145
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	91
Anticipated contribution	43
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	83	250
Anticipated contribution	43
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	42	63
Anticipated contribution	24
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	40	$ 133
Anticipated contribution	20
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	8
Anticipated contribution	4
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	19
Anticipated contribution	$ 9

Employee Benefit Plans (Compone

Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	$ 9	$ 10	$ 12
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	159	135	167
Interest cost on projected benefit obligation	324	344	320
Expected return on plan assets	(516)	(511)	(549)
Amortization of actuarial loss (gain)	166	150	244
Amortization of prior service cost (credit)	(15)	(15)	(11)
Other	8	8	7
Net periodic costs	126	111	178
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	50	41	49
Interest cost on projected benefit obligation	83	85	80
Expected return on plan assets	(139)	(132)	(148)
Amortization of actuarial loss (gain)	39	36	60
Amortization of prior service cost (credit)	(7)	(8)	(6)
Other	2	2	2
Net periodic costs	28	24	37
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	44	40	60
Interest cost on projected benefit obligation	104	112	116
Expected return on plan assets	(171)	(173)	(199)
Amortization of actuarial loss (gain)	65	68	101
Amortization of prior service cost (credit)	(3)	(3)	(4)
Other	3	3	2
Net periodic costs	42	47	76
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	23	21	22
Interest cost on projected benefit obligation	48	54	50
Expected return on plan assets	(79)	(85)	(94)
Amortization of actuarial loss (gain)	33	32	46
Amortization of prior service cost (credit)	(2)	(2)	(1)
Other	1	1	1
Net periodic costs	24	21	24
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	20	20	30
Interest cost on projected benefit obligation	54	57	53
Expected return on plan assets	(87)	(85)	(87)
Amortization of actuarial loss (gain)	31	32	49
Amortization of prior service cost (credit)	(1)	(1)	(2)
Other	1	1	1
Net periodic costs	18	24	44
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	4	5	6
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	4	4	6
Interest cost on projected benefit obligation	18	20	21
Expected return on plan assets	(26)	(27)	(31)
Amortization of actuarial loss (gain)	7	4	13
Net periodic costs	3	1	9
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	9	11
Interest cost on projected benefit obligation	27	29	28
Expected return on plan assets	(42)	(41)	(46)
Amortization of actuarial loss (gain)	13	13	24
Amortization of prior service cost (credit)	1		1
Other	1	1	1
Net periodic costs	10	11	19
Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	3	3
Interest cost on projected benefit obligation	13	14	13
Amortization of actuarial loss (gain)	6	3	5
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	21	19	20
Non-Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	1	1	1
Net periodic costs	1	1	1
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1
Interest cost on projected benefit obligation	4	5	7
Amortization of actuarial loss (gain)	2	2	3
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	6	7	10
Non-Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1	1
Interest cost on projected benefit obligation	1	1	1
Amortization of actuarial loss (gain)	1		1
Net periodic costs	2	2	3
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	2	1
Amortization of actuarial loss (gain)	2		1
Net periodic costs	4	2	2
Non-Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic costs	0	0	0
Non-Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Amortization of actuarial loss (gain)	1
Net periodic costs	1	0	0
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	10	9	8
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	10	24
Interest cost on projected benefit obligation	36	49	68
Expected return on plan assets	(13)	(13)	(14)
Amortization of actuarial loss (gain)	16	39	52
Amortization of prior service cost (credit)	(140)	(125)	(41)
Net periodic costs	(95)	(40)	89
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	2	2
Interest cost on projected benefit obligation	9	12	13
Expected return on plan assets	(8)	(9)	(11)
Amortization of actuarial loss (gain)	(2)	3	3
Amortization of prior service cost (credit)	(14)	(11)	(7)
Net periodic costs	(14)	(3)	0
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	4	18
Interest cost on projected benefit obligation	15	22	41
Amortization of actuarial loss (gain)	28	42	57
Amortization of prior service cost (credit)	(102)	(95)	(30)
Net periodic costs	(58)	(27)	86
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	9
Interest cost on projected benefit obligation	8	11	22
Amortization of actuarial loss (gain)	18	31	34
Amortization of prior service cost (credit)	(68)	(73)	(20)
Net periodic costs	(41)	(30)	45
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	3	7
Interest cost on projected benefit obligation	7	12	16
Amortization of actuarial loss (gain)	10	10	16
Amortization of prior service cost (credit)	(35)	(21)	(6)
Net periodic costs	(17)	4	33
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	3	2	2
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost			1
Interest cost on projected benefit obligation	2	2	2
Expected return on plan assets	(1)		(1)
Amortization of actuarial loss (gain)	(2)	(2)	(1)
Amortization of prior service cost (credit)			(1)
Net periodic costs	(1)	0	0
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1
Interest cost on projected benefit obligation	4	5	5
Expected return on plan assets	(1)	(1)	(1)
Amortization of actuarial loss (gain)	(2)		1
Net periodic costs	$ 2	$ 5	$ 6

Employee Benefit Plans (Amounts

Employee Benefit Plans (Amounts Recognized in Accumulated Other Comprehensive Income and Regulatory Assets and Liabilities) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax benefit (expense)				$ 17
Net amount recognized in accumulated other comprehensive (income) loss	[1]	$ 13	$ (4)	(38)
Progress Energy [Member]
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		10	(9)	(9)
Duke Energy Ohio [Member]
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss				$ (1)
Other Post-Retirement Benefit Plans [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		1	162
Regulatory liabilities, net increase (decrease)		(92)	249
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax benefit (expense)		2	1
Actuarial (gains) losses arising during the year		(5)	1
Prior year service cost (credit) arising during the year			(6)
Defined Benefit Plan Amounts Transferred with Disposal Group		(3)
Amortization of Prior Year Prior Service Credit		3	2
Net amount recognized in accumulated other comprehensive (income) loss		(3)	(2)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)			34
Regulatory liabilities, net increase (decrease)		(8)	76
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		1	129
Regulatory liabilities, net increase (decrease)		(71)	122
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax benefit (expense)		(1)	1
Actuarial (gains) losses arising during the year		2	(2)
Amortization of Prior Year Prior Service Credit		(1)
Net amount recognized in accumulated other comprehensive (income) loss			(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)			97
Regulatory liabilities, net increase (decrease)		(36)	61
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		1	(4)
Regulatory liabilities, net increase (decrease)		(35)	61
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory liabilities, net increase (decrease)		2	(2)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(7)	(7)
Regulatory liabilities, net increase (decrease)		(8)	14
Qualified Pension Plans [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		173	112
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax benefit (expense)		6	(10)
Actuarial (gains) losses arising during the year		4	29
Amortization of prior year actuarial gains (losses)		(11)	(9)
Defined Benefit Plan Amounts Transferred with Disposal Group		3
Amortization of Prior Year Prior Service Credit		1
Reclassification of actuarial gains (losses) to regulatory assets		(6)	(1)
Net amount recognized in accumulated other comprehensive (income) loss		(3)	9
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		65	30
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		0	0
Qualified Pension Plans [Member] | Progress Energy [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		18	(73)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax benefit (expense)		5	(2)
Amortization of prior year actuarial gains (losses)		(4)
Net amount recognized in accumulated other comprehensive (income) loss		1	(2)
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		14	(17)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		0	0
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		4	11
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		0	0
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		14	17
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		0	0
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		11	4
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Net amount recognized in accumulated other comprehensive (income) loss		0	0
Non Qualified Pension Plans [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(13)	44
Regulatory liabilities, net increase (decrease)			(7)
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax benefit (expense)		(7)	4
Actuarial (gains) losses arising during the year		17	(9)
Prior year service cost (credit) arising during the year		1
Net amount recognized in accumulated other comprehensive (income) loss		11	(5)
Non Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		2	1
Non Qualified Pension Plans [Member] | Progress Energy [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(16)	14
Amounts Recognized in Accumulated Other Comprehensive Loss (Income) [Abstract]
Deferred income tax benefit (expense)		(5)	5
Actuarial (gains) losses arising during the year		13	(11)
Net amount recognized in accumulated other comprehensive (income) loss		8	(6)
Non Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(1)	4
Non Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		(15)	19
Non Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)			1
Non Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Regulatory Assets and Liabilities [Abstract]
Regulatory assets, net increase (decrease)		$ (1)	$ 2
[1]	Net of insignificant tax expense in 2015, 2014 and $17 million tax expense in 2013. See Note 21 for additional information.

Employee Benefit Plans (Project

Employee Benefit Plans (Projected Benefit Obligations Reconciliation of Funded Status to Net Amount Recognized) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plan [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	$ 8,107	$ 7,510
Defined Benefit Plan, Other Changes	(83)
Service cost	159	135	$ 167
Interest cost on projected benefit obligation	324	344	320
Actuarial (gains) losses	(241)	618
Plan amendments	(6)	(4)
Benefits paid	(533)	(496)
Obligation at measurement date	7,727	8,107	7,510
Accumulated benefit obligation at measurement date	7,606	7,966
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	8,498	8,142
Defined Benefit Plan, Divestitures, Plan Assets	(81)
Actual return on plan assets	(50)	852
Benefits paid	(533)	(496)
Employer contributions	302		250
Plan assets at measurement date	8,136	8,498	8,142
Funded status of plan	409	391
Pension Plan [Member] | Change in Assumptions for Pension Plans [Member]
Change in Projected Benefit Obligation [Rollforward]
Actuarial (gains) losses		180
Pension Plan [Member] | Duke Energy Carolinas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	2,053	1,875
Service cost	50	41	49
Interest cost on projected benefit obligation	83	85	80
Actuarial (gains) losses	(53)	132
Transfers of benefit obligation	8	37
Plan amendments		(1)
Benefits paid	(146)	(116)
Obligation at measurement date	1,995	2,053	1,875
Accumulated benefit obligation at measurement date	1,993	2,052
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	2,300	2,162
Actual return on plan assets	(10)	217
Benefits paid	(146)	(116)
Transfer of plan assets	8	37
Employer contributions	91
Plan assets at measurement date	2,243	2,300	2,162
Funded status of plan	248	247
Pension Plan [Member] | Progress Energy [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	2,557	2,739
Service cost	44	40	60
Interest cost on projected benefit obligation	104	112	116
Actuarial (gains) losses	(111)	211
Transfers of benefit obligation	4	(375)
Benefits paid	(147)	(170)
Obligation at measurement date	2,451	2,557	2,739
Accumulated benefit obligation at measurement date	2,414	2,519
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	2,722	2,944
Actual return on plan assets	(22)	300
Benefits paid	(147)	(170)
Transfer of plan assets	4	(352)
Employer contributions	83		250
Plan assets at measurement date	2,640	2,722	2,944
Funded status of plan	189	165
Pension Plan [Member] | Duke Energy Progress [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	1,187	1,172
Service cost	23	21	22
Interest cost on projected benefit obligation	48	54	50
Actuarial (gains) losses	(46)	98
Transfers of benefit obligation	7	(61)
Benefits paid	(76)	(97)
Obligation at measurement date	1,143	1,187	1,172
Accumulated benefit obligation at measurement date	1,143	1,187
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	1,321	1,330
Actual return on plan assets	(10)	149
Benefits paid	(76)	(97)
Transfer of plan assets	7	(61)
Employer contributions	42		63
Plan assets at measurement date	1,284	1,321	1,330
Funded status of plan	141	134
Pension Plan [Member] | Duke Energy Florida [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	1,335	1,233
Service cost	20	20	30
Interest cost on projected benefit obligation	54	57	53
Actuarial (gains) losses	(62)	105
Transfers of benefit obligation	(3)	(9)
Benefits paid	(68)	(71)
Obligation at measurement date	1,276	1,335	1,233
Accumulated benefit obligation at measurement date	1,240	1,297
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	1,363	1,299
Actual return on plan assets	(11)	144
Benefits paid	(68)	(71)
Transfer of plan assets	(3)	(9)
Employer contributions	40		133
Plan assets at measurement date	1,321	1,363	1,299
Funded status of plan	45	28
Pension Plan [Member] | Duke Energy Ohio [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	469	442
Service cost	4	4	6
Interest cost on projected benefit obligation	18	20	21
Actuarial (gains) losses	(9)	41
Transfers of benefit obligation	8	(6)
Plan amendments		(1)
Benefits paid	(37)	(31)
Obligation at measurement date	453	469	442
Accumulated benefit obligation at measurement date	442	459
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	456	448
Actual return on plan assets	(2)	45
Benefits paid	(37)	(31)
Transfer of plan assets	8	(6)
Employer contributions	8
Plan assets at measurement date	433	456	448
Funded status of plan	(20)	(13)
Pension Plan [Member] | Duke Energy Indiana [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	673	632
Service cost	10	9	11
Interest cost on projected benefit obligation	27	29	28
Actuarial (gains) losses	(15)	41
Plan amendments	(4)
Benefits paid	(42)	(38)
Obligation at measurement date	649	673	632
Accumulated benefit obligation at measurement date	628	645
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	681	654
Actual return on plan assets	(3)	65
Benefits paid	(42)	(38)
Employer contributions	19
Plan assets at measurement date	655	681	654
Funded status of plan	6	8
Non Qualified Pension Plans [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	337	304
Service cost	3	3	3
Interest cost on projected benefit obligation	13	14	13
Actuarial (gains) losses	10	43
Transfers of benefit obligation	4
Benefits paid	(26)	(27)
Obligation at measurement date	341	337	304
Accumulated benefit obligation at measurement date	336	333
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(26)	(27)
Employer contributions	26	27
Non Qualified Pension Plans [Member] | Change in Assumptions for Pension Plans [Member]
Change in Projected Benefit Obligation [Rollforward]
Actuarial (gains) losses		21
Non Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	16	15
Interest cost on projected benefit obligation	1	1	1
Actuarial (gains) losses	1	2
Benefits paid	(2)	(2)
Obligation at measurement date	16	16	15
Accumulated benefit obligation at measurement date	16	15
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(2)	(2)
Employer contributions	2	2
Non Qualified Pension Plans [Member] | Progress Energy [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	116	140
Service cost	1	1	1
Interest cost on projected benefit obligation	4	5	7
Actuarial (gains) losses	(1)	11
Transfers of benefit obligation		(32)
Benefits paid	(8)	(9)
Obligation at measurement date	112	116	140
Accumulated benefit obligation at measurement date	112	116
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(8)	(9)
Employer contributions	8	9
Non Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	35	34
Service cost		1	1
Interest cost on projected benefit obligation	1	1	1
Actuarial (gains) losses		2
Benefits paid	(3)	(3)
Obligation at measurement date	33	35	34
Accumulated benefit obligation at measurement date	33	35
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(3)	(3)
Employer contributions	3	3
Non Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	61	39
Interest cost on projected benefit obligation	2	2	1
Actuarial (gains) losses	(14)	20
Transfers of benefit obligation		4
Benefits paid	(3)	(4)
Obligation at measurement date	46	61	39
Accumulated benefit obligation at measurement date	46	61
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(3)	(4)
Employer contributions	3	4
Non Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	4	3
Actuarial (gains) losses		1
Obligation at measurement date	4	4	3
Accumulated benefit obligation at measurement date	4	4
Non Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	5	5
Actuarial (gains) losses		1
Settlements		0
Benefits paid		(1)
Obligation at measurement date	5	5	5
Accumulated benefit obligation at measurement date	5	5
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid		(1)
Employer contributions		1
Other Post-Retirement Benefit Plans [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	916	1,106
Defined Benefit Plan, Other Changes	(3)
Service cost	6	10	24
Interest cost on projected benefit obligation	36	49	68
Plan participants' contributions	20	25
Actuarial (gains) losses	(39)	(87)
Plan amendments	(9)	(85)
Benefits paid	(100)	(103)
Accrued retiree drug subsidy	1	1
Obligation at measurement date	828	916	1,106
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	227	214
Actual return on plan assets	(1)	18
Benefits paid	(100)	(103)
Employer contributions	62	73
Plan participants' contributions	20	25
Plan assets at measurement date	208	227	214
Other Post-Retirement Benefit Plans [Member] | Change in Assumptions for Pension Plans [Member]
Change in Projected Benefit Obligation [Rollforward]
Actuarial (gains) losses		7
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	220	265
Service cost	1	2	2
Interest cost on projected benefit obligation	9	12	13
Plan participants' contributions	4	10
Actuarial (gains) losses	(18)	(35)
Transfers of benefit obligation	2	1
Plan amendments		(4)
Benefits paid	(18)	(31)
Obligation at measurement date	200	220	265
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	145	143
Actual return on plan assets	(1)	12
Benefits paid	(18)	(31)
Transfer of plan assets		(1)
Employer contributions	4	12
Plan participants' contributions	4	10
Plan assets at measurement date	134	145	143
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	379	533
Service cost	1	4	18
Interest cost on projected benefit obligation	15	22	41
Plan participants' contributions	7	8
Actuarial (gains) losses	$ (1)	(19)
Transfers of benefit obligation		(48)
Plan amendments		(77)
Benefits paid	$ (47)	(44)
Obligation at measurement date	354	379	533
Change in Fair Value of Plan Assets [Rollforward]
Actual return on plan assets	1
Benefits paid	(47)	(44)
Employer contributions	39	36
Plan participants' contributions	7	8
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	207	233
Service cost	1	1	9
Interest cost on projected benefit obligation	8	11	22
Plan participants' contributions	4	4
Actuarial (gains) losses	$ (13)	(21)
Transfers of benefit obligation		$ (2)
Plan amendments
Benefits paid	$ (19)	$ (19)
Obligation at measurement date	188	207	233
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(1)
Actual return on plan assets	1
Benefits paid	(19)	(19)
Employer contributions	15	14
Plan participants' contributions	4	4
Plan assets at measurement date		(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	170	253
Service cost	1	3	7
Interest cost on projected benefit obligation	7	12	16
Plan participants' contributions	3	4
Actuarial (gains) losses	11
Plan amendments		(78)
Benefits paid	(28)	(24)
Obligation at measurement date	164	170	253
Change in Fair Value of Plan Assets [Rollforward]
Actual return on plan assets	1
Benefits paid	(28)	(24)
Employer contributions	25	20
Plan participants' contributions	3	4
Plan assets at measurement date	1
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	39	42
Service cost			1
Interest cost on projected benefit obligation	2	2	2
Plan participants' contributions	1
Actuarial (gains) losses	(3)
Transfers of benefit obligation		(1)
Plan amendments	(1)	(1)
Benefits paid	(3)	(3)
Obligation at measurement date	35	39	42
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	8	8
Benefits paid	(3)	(3)
Employer contributions	2	3
Plan participants' contributions	1
Plan assets at measurement date	8	8	8
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	96	118
Service cost	1	1	1
Interest cost on projected benefit obligation	4	5	5
Plan participants' contributions	2	2
Actuarial (gains) losses	1	(20)
Plan amendments	(4)
Benefits paid	(13)	(10)
Obligation at measurement date	87	96	118
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	23	18
Actual return on plan assets	(1)	2
Benefits paid	(13)	(10)
Employer contributions	8	11
Plan participants' contributions	2	2
Plan assets at measurement date	$ 19	$ 23	$ 18

Employee Benefit Plans (Amou137

Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	$ 1,088	$ 1,145
Regulatory assets	12,250	12,157
Regulatory liabilities	6,655	6,397
Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	107	111
Regulatory assets	3,071	2,864
Regulatory liabilities	2,841	2,744
Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	536	533
Regulatory assets	5,797	5,899
Regulatory liabilities	2,673	2,485
Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	262	290
Regulatory assets	2,974	2,962
Regulatory liabilities	1,963	1,903
Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	242	221
Regulatory assets	2,823	2,936
Regulatory liabilities	709	582
Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	56	48
Regulatory assets	533	561
Regulatory liabilities	257	251
Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	80	82
Regulatory assets	818	778
Regulatory liabilities	816	850
Pension Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	474	441
Noncurrent pension liability	65	50
Net amount recognized	409	391
Regulatory assets	1,884	1,711
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(45)	(51)
Prior year service cost (credit) arising during the year	(4)	(5)
Net actuarial loss (gain)	130	140
Net amount recognized in accumulated other comprehensive income (loss)	81	84
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	132
Unrecognized prior service (credit) cost	(16)
Pension Plan [Member] | Brazilian Retirement Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Net amount recognized in accumulated other comprehensive income (loss)	13	22
Pension Plan [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	252	247
Noncurrent pension liability	4
Net amount recognized	248	247
Regulatory assets	472	407
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	31
Unrecognized prior service (credit) cost	(8)
Pension Plan [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	232	165
Noncurrent pension liability	43
Net amount recognized	189	165
Regulatory assets	771	753
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(6)	(11)
Net actuarial loss (gain)	17	21
Net amount recognized in accumulated other comprehensive income (loss)	11	10
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	59
Unrecognized prior service (credit) cost	(3)
Pension Plan [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	145	134
Noncurrent pension liability	4
Net amount recognized	141	134
Regulatory assets	360	346
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	25
Unrecognized prior service (credit) cost	(2)
Pension Plan [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	84	28
Noncurrent pension liability	39
Net amount recognized	45	28
Regulatory assets	410	$ 406
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	31
Unrecognized prior service (credit) cost	(1)
Pension Plan [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	1
Noncurrent pension liability	21	$ 13
Net amount recognized	(20)	(13)
Regulatory assets	79	65
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	4
Pension Plan [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	6	8
Net amount recognized	6	8
Regulatory assets	162	151
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	11
Non-Qualified Pension Plans [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	27	27
Noncurrent pension liability	314	310
Total accrued pension liability	341	337
Regulatory assets	76	89
Regulatory liabilities		0
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(3)	4
Prior year service cost (credit) arising during the year		(1)
Net actuarial loss (gain)	9	(8)
Net amount recognized in accumulated other comprehensive income (loss)	6	(5)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	8
Unrecognized prior service (credit) cost	(1)
Non-Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	14	14
Total accrued pension liability	16	16
Regulatory assets	7	5
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	8	8
Noncurrent pension liability	104	108
Total accrued pension liability	112	116
Regulatory assets	16	32
Regulatory liabilities		0
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(3)	2
Net actuarial loss (gain)	9	(4)
Net amount recognized in accumulated other comprehensive income (loss)	6	(2)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	1
Non-Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	3
Noncurrent pension liability	30	32
Total accrued pension liability	33	35
Regulatory assets	6	7
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	4
Noncurrent pension liability	43	57
Total accrued pension liability	46	61
Regulatory assets	10	25
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	0
Noncurrent pension liability	4	4
Total accrued pension liability	4	4
Regulatory assets	1	1
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	0
Noncurrent pension liability	5	5
Total accrued pension liability	5	5
Regulatory assets	1	2
Regulatory liabilities		0
Other Post-Retirement Benefit Plans [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	37	35
Noncurrent pension liability	583	654
Total accrued pension liability	620	689
Regulatory assets	1
Regulatory liabilities	288	380
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	7	5
Prior year service cost (credit) arising during the year	(6)	(9)
Net actuarial loss (gain)	(13)	(5)
Net amount recognized in accumulated other comprehensive income (loss)	(12)	(9)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	6
Unrecognized prior service (credit) cost	(142)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	66	75
Total accrued pension liability	66	75
Regulatory liabilities	68	76
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	(3)
Unrecognized prior service (credit) cost	(14)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	31	29
Noncurrent pension liability	323	350
Total accrued pension liability	354	379
Regulatory assets	1
Regulatory liabilities	51	122
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability		1
Prior year service cost (credit) arising during the year	(1)
Net actuarial loss (gain)		(2)
Net amount recognized in accumulated other comprehensive income (loss)	(1)	(1)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	22
Unrecognized prior service (credit) cost	(103)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	16	16
Noncurrent pension liability	172	192
Total accrued pension liability	188	208
Regulatory liabilities	25	61
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	13
Unrecognized prior service (credit) cost	(68)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	15	14
Noncurrent pension liability	149	156
Total accrued pension liability	164	170
Regulatory assets	1
Regulatory liabilities	26	61
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	9
Unrecognized prior service (credit) cost	(35)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	25	29
Total accrued pension liability	27	31
Regulatory liabilities	21	19
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	(2)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	68	73
Total accrued pension liability	68	73
Regulatory assets	57	64
Regulatory liabilities	83	$ 91
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	(2)
Unrecognized prior service (credit) cost	$ (1)

Employee Benefit Plans (Informa

Employee Benefit Plans (Information For Plans with Accumulated Benefit Obligation in Excess of Plan Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Qualified Pension Plans [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	$ 1,216	$ 702
Accumulated benefit obligation	1,158	672
Fair value of plan assets	1,151	652
Qualified Pension Plans [Member] | Progress Energy [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	611
Accumulated benefit obligation	575
Fair value of plan assets	574
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	611
Accumulated benefit obligation	575
Fair value of plan assets	574
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	307	315
Accumulated benefit obligation	298	306
Fair value of plan assets	289	302
Non-Qualified Pension Plans [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	341	337
Accumulated benefit obligation	336	333
Non-Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	16	16
Accumulated benefit obligation	16	15
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	112	116
Accumulated benefit obligation	112	116
Non-Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	33	35
Accumulated benefit obligation	33	35
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	46	61
Accumulated benefit obligation	46	61
Non-Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	4	4
Accumulated benefit obligation	4	4
Non-Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Information For Plans With Accumulated Benefit Obligation In Excess Of Plan Assets [Abstract]
Projected benefit obligation	5	5
Accumulated benefit obligation	$ 5	$ 5

Employee Benefit Plans (Assumpt

Employee Benefit Plans (Assumptions Used For Pension Benefits Accounting) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Qualified Pension Plans [Member]
Benefit Obligations [Abstract]
Discount rate	4.40%	4.10%	4.70%
Net Periodic Benefit Cost [Abstract]
Discount rate	4.10%	4.70%	4.10%
Expected long-term rate of return on plan assets	6.50%	6.75%	7.75%
Qualified Pension Plans [Member] | Minimum [Member]
Benefit Obligations [Abstract]
Salary increase	4.00%	4.00%	4.00%
Net Periodic Benefit Cost [Abstract]
Discount rate
Salary increase	4.00%	4.00%	4.00%
Expected long-term rate of return on plan assets
Qualified Pension Plans [Member] | Maximum [Member]
Benefit Obligations [Abstract]
Salary increase	4.40%	4.40%	4.40%
Net Periodic Benefit Cost [Abstract]
Salary increase	4.40%	4.40%	4.30%
Non-Qualified Pension Plans [Member]
Benefit Obligations [Abstract]
Discount rate	4.40%	4.10%	4.70%
Salary increase	4.40%	4.40%	4.40%
Net Periodic Benefit Cost [Abstract]
Discount rate	4.10%	4.70%	4.10%
Salary increase	4.40%	4.40%	4.30%
Other Post-Retirement Benefit Plans [Member]
Benefit Obligations [Abstract]
Discount rate	4.40%	4.10%	4.70%
Net Periodic Benefit Cost [Abstract]
Discount rate	4.10%	4.70%	4.10%
Expected long-term rate of return on plan assets	6.50%	6.75%	7.75%
Assumed tax rate	35.00%	35.00%	35.00%

Employee Benefit Plans (Assumed

Employee Benefit Plans (Assumed Health Care Cost Trend Rates) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for next year	7.50%	6.75%
Rate to which the cost trend is assumed to decline (the ultimate trend rate)	4.75%	4.75%
Year that the rate reaches the ultimate trend rate	2,023	2,023

Employee Benefit Plans (Sensiti

Employee Benefit Plans (Sensitivity to Changes in Assumed Health Care Cost Trend Rates) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest costs - 1 Percentage Point Increase	$ 2
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	29
Effect on total service and interest costs - 1 Percentage Point Decrease	(1)
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(26)
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	7
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(6)
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest costs - 1 Percentage Point Increase	1
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	12
Effect on total service and interest costs - 1 Percentage Point Decrease	(1)
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(11)
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on total service and interest costs - 1 Percentage Point Increase	1
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	6
Effect on total service and interest costs - 1 Percentage Point Decrease	(1)
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(6)
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	6
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(5)
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	1
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	(1)
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Effect on post-retirement benefit obligation - 1 Percentage Point Increase	3
Effect on post-retirement benefit obligation - 1 Percentage Point Decrease	$ (3)

Employee Benefit Plans (Expecte

Employee Benefit Plans (Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2015USD ($)
Qualified Pension Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	$ 628
2,017	639
2,018	640
2,019	643
2,020	641
2021-2025	3,053
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	189
2,017	199
2,018	203
2,019	202
2,020	201
2021-2025	906
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	164
2,017	167
2,018	169
2,019	171
2,020	174
2021-2025	869
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	91
2,017	92
2,018	92
2,019	91
2,020	92
2021-2025	438
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	71
2,017	73
2,018	75
2,019	77
2,020	80
2021-2025	420
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	35
2,017	35
2,018	34
2,019	34
2,020	35
2021-2025	171
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	48
2,017	47
2,018	47
2,019	47
2,020	47
2021-2025	230
Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	28
2,017	29
2,018	25
2,019	26
2,020	25
2021-2025	126
Non-Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	2
2,017	2
2,018	2
2,019	2
2,020	2
2021-2025	9
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	8
2,017	8
2,018	8
2,019	8
2,020	8
2021-2025	38
Non-Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	3
2,017	3
2,018	3
2,019	3
2,020	3
2021-2025	12
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	3
2,017	3
2,018	3
2,019	3
2,020	3
2021-2025	16
Non-Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2021-2025	1
Non-Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,020	1
2021-2025	2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	76
2,017	76
2,018	74
2,019	73
2,020	71
2021-2025	312
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	16
2,017	17
2,018	18
2,019	18
2,020	18
2021-2025	80
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	31
2,017	31
2,018	30
2,019	29
2,020	29
2021-2025	129
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	16
2,017	16
2,018	16
2,019	15
2,020	15
2021-2025	68
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	15
2,017	15
2,018	14
2,019	14
2,020	13
2021-2025	60
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	4
2,017	3
2,018	3
2,019	3
2,020	3
2021-2025	14
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	10
2,017	10
2,018	9
2,019	9
2,020	8
2021-2025	$ 33

Employee Benefit Plans (Target

Employee Benefit Plans (Target and Actual Asset Allocations) (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
Master Trust [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	11.00%	10.00%
Target allocation	10.00%
Master Trust [Member] | Non US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	8.00%	8.00%
Target allocation	8.00%
Master Trust [Member] | Global Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	10.00%	10.00%
Target allocation	10.00%
Master Trust [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	63.00%	63.00%
Target allocation	63.00%
Master Trust [Member] | Global Private Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	3.00%
Target allocation	3.00%
Master Trust [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	3.00%
Target allocation	2.00%
Master Trust [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	1.00%
Target allocation	2.00%
Master Trust [Member] | Other Global Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	2.00%	2.00%
Target allocation	2.00%
VEBA I [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	100.00%	100.00%
Target allocation	100.00%
VEBA I [Member] | US Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	29.00%	29.00%
Target allocation	30.00%
VEBA I [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	43.00%	43.00%
Target allocation	25.00%
VEBA I [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocation	28.00%	28.00%
Target allocation	45.00%

Employee Benefit Plans (Fair Va

Employee Benefit Plans (Fair Value Measurements of Plan Assets - Master Retirement Trust) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	$ 8,243	$ 8,618
Master Trust [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	1,636	1,816
Master Trust [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	5,375	5,502
Master Trust [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	31	34
Master Trust [Member] | Fair Value, Inputs, Not Categorized [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	1,201	1,266
Master Trust [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	2,160	2,346
Master Trust [Member] | Equity Securities [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	1,470	1,625
Master Trust [Member] | Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	2	3
Master Trust [Member] | Equity Securities [Member] | Fair Value, Inputs, Not Categorized [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	688	718
Master Trust [Member] | Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	4,362	4,349
Master Trust [Member] | Corporate Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	4,362	4,348
Master Trust [Member] | Corporate Debt Securities [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets		1
Master Trust [Member] | Short Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	404	333
Master Trust [Member] | Short Term Investments [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	192	171
Master Trust [Member] | Short Term Investments [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	212	162
Master Trust [Member] | Partnership Interest [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	185	298
Master Trust [Member] | Partnership Interest [Member] | Fair Value, Inputs, Not Categorized [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	185	298
Master Trust [Member] | Hedge Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	210	146
Master Trust [Member] | Hedge Funds [Member] | Fair Value, Inputs, Not Categorized [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	210	146
Master Trust [Member] | Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	118	104
Master Trust [Member] | Real Estate [Member] | Fair Value, Inputs, Not Categorized [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	118	104
Master Trust [Member] | US Treasury and Government [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	748	917
Master Trust [Member] | US Treasury and Government [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	748	916
Master Trust [Member] | US Treasury and Government [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets		1
Master Trust [Member] | Guaranteed Investment Contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	31	32
Master Trust [Member] | Guaranteed Investment Contracts [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	31	32
Master Trust [Member] | Government Bonds - Foreign [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	34	44
Master Trust [Member] | Government Bonds - Foreign [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	34	44
Master Trust [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	10	30
Master Trust [Member] | Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	10	30
Master Trust [Member] | Asset Backed Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	9	9
Master Trust [Member] | Asset Backed Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	9	9
Master Trust [Member] | Miscellaneous Investments And Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	(28)	10
Master Trust [Member] | Miscellaneous Investments And Other [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	(36)	(10)
Master Trust [Member] | Miscellaneous Investments And Other [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	8	20
VEBA I [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	42	48
VEBA I [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	42	48
VEBA I [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	12	14
VEBA I [Member] | Equity Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	12	14
VEBA I [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	18	21
VEBA I [Member] | Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	18	21
VEBA I [Member] | Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	12	13
VEBA I [Member] | Debt Securities [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Total assets	$ 12	$ 13
Duke Energy Carolinas [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	28.00%	28.00%
Progress Energy [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	32.00%	31.00%
Duke Energy Progress [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	15.00%	15.00%
Duke Energy Florida [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	16.00%	16.00%
Duke Energy Ohio [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	5.00%	5.00%
Duke Energy Indiana [Member] | Master Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Allocated assets	8.00%	8.00%

Employee Benefit Plans (Reconci

Employee Benefit Plans (Reconciliation of Assets Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 4	$ 33
Purchases	24	50
Sales	(1)	(15)
Total gains (losses) and other, net	21	(7)
Ending balance	15	4
Master Trust [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	34	37
Sales	(2)	(4)
Total gains (losses) and other, net	(1)	1
Ending balance	$ 31	$ 34

Employee Benefit Plans (Employe

Employee Benefit Plans (Employee Savings Plans)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Savings Plans [Abstract]
Matching contribution percentage	100.00%
Eligible pay percentage	6.00%
Additional contribution percentage for employees not participating in defined pension plans	4.00%
Pretax employer matching contributions	$ 159	$ 143	$ 134
Duke Energy Carolinas [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	54	47	45
Progress Energy [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	48	43	45
Duke Energy Progress [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	34	30	25
Duke Energy Florida [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	13	14	14
Duke Energy Ohio [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	3	3	3
Duke Energy Indiana [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	$ 7	$ 7	$ 7

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes			$ (141)
Current state taxes	$ (12)	$ 56	(40)
Current foreign taxes	99	144	151
Total current income taxes	87	200	(30)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	1,089	1,517	1,092
Deferred state taxes	181	35	144
Deferred foreign taxes	(17)	(67)	14
Total deferred income taxes	1,253	1,485	1,250
Investment tax credit amortization	(14)	(16)	(15)
Income tax expense (benefit) from continuing operations	1,326	1,669	1,205
Tax expense (benefit) from discontinued operations	19	(295)	29
Total income tax expense included in Consolidated Statements of Operations	1,345	1,374	1,234
Net operating loss utilization		1,544
Net operating loss carry forward	264		808
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Domestic	3,828	3,600	3,183
Foreign	309	534	612
Total income (loss) from continuing operations before income taxes	4,137	4,134	3,795
Duke Energy Carolinas [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	216	161	49
Current state taxes	14	51	11
Total current income taxes	230	212	60
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	345	407	464
Deferred state taxes	57	(25)	75
Total deferred income taxes	402	382	539
Investment tax credit amortization	(5)	(6)	(5)
Income tax expense (benefit) from continuing operations	627	588	594
Total income tax expense included in Consolidated Statements of Operations	627	588	594
Net operating loss utilization		345
Net operating loss carry forward	15
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	1,708	1,660	1,570
Progress Energy [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(193)	(466)	(221)
Current state taxes	1	(8)	(37)
Total current income taxes	(192)	(474)	(258)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	694	938	555
Deferred state taxes	27	84	84
Total deferred income taxes	721	1,022	639
Investment tax credit amortization	(7)	(8)	(8)
Income tax expense (benefit) from continuing operations	522	540	373
Tax expense (benefit) from discontinued operations	(1)	(4)	(26)
Total income tax expense included in Consolidated Statements of Operations	521	536	347
Net operating loss utilization		530
Net operating loss carry forward	119		458
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	1,587	1,420	1,032
Duke Energy Progress [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(56)	(184)	(70)
Current state taxes	(4)	14	(10)
Total current income taxes	(60)	(170)	(80)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	334	436	316
Deferred state taxes	27	25	59
Total deferred income taxes	361	461	375
Investment tax credit amortization	(7)	(6)	(7)
Income tax expense (benefit) from continuing operations	294	285	288
Total income tax expense included in Consolidated Statements of Operations	294	285	288
Net operating loss utilization		291
Net operating loss carry forward	21		64
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	860	752	788
Duke Energy Florida [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	1	(53)	(143)
Current state taxes	(7)	1	(13)
Total current income taxes	(6)	(52)	(156)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	290	350	326
Deferred state taxes	58	52	44
Total deferred income taxes	348	402	370
Investment tax credit amortization		(1)	(1)
Income tax expense (benefit) from continuing operations	342	349	213
Total income tax expense included in Consolidated Statements of Operations	342	349	213
Net operating loss utilization		64
Net operating loss carry forward	84		301
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	941	897	538
Duke Energy Ohio [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(18)	(73)	(24)
Current state taxes	(1)	3	(4)
Total current income taxes	(19)	(70)	(28)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	96	113	65
Deferred state taxes	5	1	6
Total deferred income taxes	101	114	71
Investment tax credit amortization	(1)	(1)
Income tax expense (benefit) from continuing operations	81	43	43
Tax expense (benefit) from discontinued operations	22	(300)	32
Total income tax expense included in Consolidated Statements of Operations	103	(257)	75
Net operating loss utilization		56
Net operating loss carry forward	3
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	230	111	110
Duke Energy Indiana [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(86)	(112)	(88)
Current state taxes	(12)	1	7
Total current income taxes	(98)	(111)	(81)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	245	294	276
Deferred state taxes	17	15	29
Total deferred income taxes	262	309	305
Investment tax credit amortization	(1)	(1)	(1)
Income tax expense (benefit) from continuing operations	163	197	223
Total income tax expense included in Consolidated Statements of Operations	163	197	223
Net operating loss utilization		141
Net operating loss carry forward	45		179
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	$ 479	$ 556	$ 581

Income Taxes (Effective Tax Rat

Income Taxes (Effective Tax Rates) (Details) - USD ($) $ in Millions	12 Months Ended			96 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2022
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate of 35%	$ 1,448	$ 1,447	$ 1,328
State income tax, net of federal income tax effect	109	59	66
Tax differential on foreign earnings	(27)	(110)	(49)
AFUDC equity income	(58)	(47)	(55)
Renewable energy production tax credits	(72)	(67)	(62)
International Tax Dividend		373
Audit Adjustment	(22)
Tax true-up	2
Other items, net	(54)	14	(23)
Income tax expense (benefit) from continuing operations	$ 1,326	$ 1,669	$ 1,205
Effective tax rate	32.10%	40.40%	31.80%
Foreign Earnings of Subsidiaries
Undistributed Earnings of Foreign Subsidiaries	$ 250
Deferred Tax Liability Not Recognized, Amount of Unrecognized Deferred Tax Liability, Undistributed Earnings of Foreign Subsidiaries	12
Foreign Jurisdictions [Member] | Merger of Subsidiaries [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense (benefit) from continuing operations		$ (57)
Duke Energy Carolinas [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate of 35%	598	581	$ 549
State income tax, net of federal income tax effect	46	17	56
AFUDC equity income	(34)	(32)	(32)
Tax true-up	2
Other items, net	15	22	21
Income tax expense (benefit) from continuing operations	$ 627	$ 588	$ 594
Effective tax rate	36.70%	35.40%	37.80%
Progress Energy [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate of 35%	$ 555	$ 497	$ 361
State income tax, net of federal income tax effect	18	49	31
AFUDC equity income	(19)	(9)	(18)
Renewable energy production tax credits	(1)
Audit Adjustment	(23)
Tax true-up	(3)
Other items, net	(5)	3	(1)
Income tax expense (benefit) from continuing operations	$ 522	$ 540	$ 373
Effective tax rate	32.90%	38.00%	36.20%
Duke Energy Progress [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate of 35%	$ 302	$ 263	$ 276
State income tax, net of federal income tax effect	15	25	31
AFUDC equity income	(17)	(9)	(15)
Audit Adjustment	1
Tax true-up	(4)
Other items, net	(3)	6	(4)
Income tax expense (benefit) from continuing operations	$ 294	$ 285	$ 288
Effective tax rate	34.20%	37.90%	36.50%
Duke Energy Florida [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate of 35%	$ 330	$ 314	$ 188
State income tax, net of federal income tax effect	33	34	20
AFUDC equity income	(3)		(3)
Audit Adjustment	(24)
Tax true-up	2
Other items, net	4	1	8
Income tax expense (benefit) from continuing operations	$ 342	$ 349	$ 213
Effective tax rate	36.30%	38.90%	39.60%
Duke Energy Ohio [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate of 35%	$ 81	$ 39	$ 39
State income tax, net of federal income tax effect	2	3	2
AFUDC equity income	(1)	(1)
Tax true-up	(5)
Other items, net	4	2	2
Income tax expense (benefit) from continuing operations	$ 81	$ 43	$ 43
Effective tax rate	35.20%	38.90%	39.10%
Duke Energy Indiana [Member]
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate of 35%	$ 168	$ 195	$ 203
State income tax, net of federal income tax effect	2	10	23
AFUDC equity income	(4)	(5)	(5)
Tax true-up	(9)
Other items, net	6	(3)	2
Income tax expense (benefit) from continuing operations	$ 163	$ 197	$ 223
Effective tax rate	34.00%	35.50%	38.40%
International Energy [Member]
Foreign Earnings of Subsidiaries
Foreign Earnings Repatriated	$ 1,500
Scenario, Forecast [Member] | International Energy [Member]
Foreign Earnings of Subsidiaries
Foreign Earnings Repatriated				$ 2,700

Income Taxes (Deferred Income T

Income Taxes (Deferred Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		$ 245	$ 188
Capital lease obligations		63	63
Pension, postretirement and other employee benefits		580	546
Progress Energy merger purchase accounting adjustments		1,009	1,124
Tax credits and NOL carryforwards		3,719	3,540
Other		206
Valuation allowance		(160)	(184)
Total deferred income tax assets		5,662	5,277
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(1,584)	(1,625)
Accelerated depreciation rates		(13,070)	(11,715)
Regulatory assets and deferred debits, net		(3,633)	(3,694)
Other			(44)
Total deferred income tax liabilities		(18,287)	(17,078)
Net deferred income tax liabilities		(12,625)	(11,801)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		3,719	3,540
Valuation allowance		(160)	(184)
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Current Assets: Other			1,593
Investments and Other Assets: Other		80	29
Deferred Credits and Other Liabilities: Other		(12,705)	(13,423)
Net deferred income tax liabilities		(12,625)	(11,801)
State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Net reduction in deferred tax liability		95		$ 145
Investment Tax Credits [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		864
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		$ 864
Investment Tax Credits [Member] | Minimum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2029
Investment Tax Credits [Member] | Maximum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2035
Alternative Minimum Tax Credit [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		$ 1,121
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		1,121
NOL Carryforwards [Member] | Federal [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		484
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		$ 484
NOL Carryforwards [Member] | Federal [Member] | Minimum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2030
NOL Carryforwards [Member] | Federal [Member] | Maximum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2033
NOL Carryforwards [Member] | State [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		$ 299
Valuation allowance		(81)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		299
Valuation allowance		$ (81)
NOL Carryforwards [Member] | State [Member] | Minimum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2016
NOL Carryforwards [Member] | State [Member] | Maximum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2035
NOL Carryforwards [Member] | Foreign Jurisdictions [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		$ 100
Valuation allowance		(79)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		100
Valuation allowance		$ (79)
NOL Carryforwards [Member] | Foreign Jurisdictions [Member] | Minimum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2026
NOL Carryforwards [Member] | Foreign Jurisdictions [Member] | Maximum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2034
Foreign Tax Credit [Member]
Deferred Tax Assets, Gross [Abstract]
Tax credits and NOL carryforwards		$ 851
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		$ 851
Foreign Tax Credit [Member] | Foreign Jurisdictions [Member] | Minimum [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Expiration year		Dec. 31, 2024
Duke Energy Carolinas [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		$ 38	53
Capital lease obligations		9	10
Pension, postretirement and other employee benefits		46	4
Tax credits and NOL carryforwards		170	157
Other		20	12
Total deferred income tax assets		283	236
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(1,057)	(1,051)
Accelerated depreciation rates		(4,429)	(4,046)
Regulatory assets and deferred debits, net		(943)	(953)
Total deferred income tax liabilities		(6,429)	(6,050)
Net deferred income tax liabilities		(6,146)	(5,814)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		170	157
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Current Assets: Other			3
Current Liabilities: Other			(5)
Deferred Credits and Other Liabilities: Other		(6,146)	(5,812)
Net deferred income tax liabilities		(6,146)	(5,814)
Progress Energy [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		115	108
Pension, postretirement and other employee benefits		186	188
Tax credits and NOL carryforwards		997	980
Other		48
Valuation allowance		(38)	(13)
Total deferred income tax assets		1,308	1,263
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(412)	(427)
Accelerated depreciation rates		(4,169)	(3,284)
Regulatory assets and deferred debits, net		(1,517)	(1,602)
Other			(151)
Total deferred income tax liabilities		(6,098)	(5,464)
Net deferred income tax liabilities		(4,790)	(4,201)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		997	980
Valuation allowance		(38)	(13)
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Current Assets: Other			558
Deferred Credits and Other Liabilities: Other		(4,790)	(4,759)
Net deferred income tax liabilities		(4,790)	(4,201)
Duke Energy Progress [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		25	28
Pension, postretirement and other employee benefits		92	96
Tax credits and NOL carryforwards		163	91
Other		2	55
Valuation allowance			(1)
Total deferred income tax assets		282	269
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(228)	(232)
Accelerated depreciation rates		(2,325)	(2,030)
Regulatory assets and deferred debits, net		(756)	(809)
Total deferred income tax liabilities		(3,309)	(3,071)
Net deferred income tax liabilities		(3,027)	(2,802)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		163	91
Valuation allowance			(1)
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Current Assets: Other			106
Deferred Credits and Other Liabilities: Other		(3,027)	(2,908)
Net deferred income tax liabilities		(3,027)	(2,802)
Duke Energy Florida [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		66	78
Pension, postretirement and other employee benefits		82	93
Tax credits and NOL carryforwards		177	252
Other		46
Total deferred income tax assets		371	423
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(201)	(245)
Accelerated depreciation rates		(1,868)	(1,252)
Regulatory assets and deferred debits, net		(762)	(792)
Other			(246)
Total deferred income tax liabilities		(2,831)	(2,535)
Net deferred income tax liabilities		(2,460)	(2,112)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		177	252
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Current Assets: Other			340
Deferred Credits and Other Liabilities: Other		(2,460)	(2,452)
Net deferred income tax liabilities		(2,460)	(2,112)
Duke Energy Ohio [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		29	(8)
Pension, postretirement and other employee benefits		24	17
Tax credits and NOL carryforwards		25	38
Investments and other assets		3	14
Other		37	35
Total deferred income tax assets		118	96
Deferred Tax Liabilities, Gross [Abstract]
Accelerated depreciation rates		(1,356)	(1,660)
Regulatory assets and deferred debits, net		(169)	(141)
Total deferred income tax liabilities		(1,525)	(1,801)
Net deferred income tax liabilities		(1,407)	(1,705)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		25	38
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Current Assets: Other			60
Deferred Credits and Other Liabilities: Other		(1,407)	(1,765)
Net deferred income tax liabilities		(1,407)	(1,705)
Duke Energy Indiana [Member]
Deferred Tax Assets, Gross [Abstract]
Deferred credits and other liabilities		5	12
Capital lease obligations		2	2
Pension, postretirement and other employee benefits		40	43
Tax credits and NOL carryforwards		215	260
Other		20	11
Total deferred income tax assets		282	328
Deferred Tax Liabilities, Gross [Abstract]
Investments and other assets		(7)	(4)
Accelerated depreciation rates		(1,797)	(1,603)
Regulatory assets and deferred debits, net		(135)	(106)
Total deferred income tax liabilities		(1,939)	(1,713)
Net deferred income tax liabilities		(1,657)	(1,385)
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Tax credits and NOL carryforwards		215	260
Classification of Deferred Tax Assets (Liabiliities) in the Consolidated Balance Sheets [Abstract]
Current Assets: Other			206
Deferred Credits and Other Liabilities: Other		(1,657)	(1,591)
Net deferred income tax liabilities		$ (1,657)	$ (1,385)
2013 [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate				6.90%
2013 [Member] | Duke Energy Carolinas [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate				6.90%
2013 [Member] | Duke Energy Progress [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate				6.90%
January 2014 [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate			6.00%
January 2014 [Member] | Duke Energy Carolinas [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate			6.00%
January 2014 [Member] | Duke Energy Progress [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate			6.00%
January 2015 [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate		5.00%
January 2015 [Member] | Duke Energy Carolinas [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate		5.00%
January 2015 [Member] | Duke Energy Progress [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate		5.00%
Scenario, Forecast [Member] | January 2016 [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate	4.00%
Scenario, Forecast [Member] | January 2016 [Member] | Duke Energy Carolinas [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate	4.00%
Scenario, Forecast [Member] | January 2016 [Member] | Duke Energy Progress [Member] | State [Member]
Components and Expiration Dates of Tax Credits and NOL Carryforwards [Abstract]
Statutory Tax Rate	4.00%

Income Taxes (Other Disclosures

Income Taxes (Other Disclosures) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	$ 213	$ 230	$ 540
Gross decreases-tax positions in prior periods	(48)	(2)	(231)
Decreases due to settlements	(45)	(15)	(66)
Reduction due to lapse of statute of limitations	(32)		(13)
Total changes	(125)	(17)	(310)
Unrecognized Tax Benefits - December 31	88	213	230
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit	65
Amount that if recognized, would affect the effective tax rate or regulatory liability	62
Amount that if recognized, would be recorded as a component of discontinued operations	4
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	12	6	2
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest receivable related to income taxes	3
Interest payable related to income taxes		13	27
Duke Energy Carolinas [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	160	171	271
Gross decreases-tax positions in prior periods	(45)		(100)
Decreases due to settlements	(43)	(11)
Total changes	(88)	(11)	(100)
Unrecognized Tax Benefits - December 31	72	160	171
Significant change in unrecognized tax benefits is reasonably possible, amount of unrecorded benefit	63
Amount that if recognized, would affect the effective tax rate or regulatory liability	54
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes			2
Net interest expense recognized related to income taxes	1	1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	14	13	8
Progress Energy [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	32	32	131
Gross increases-tax positions in prior periods	1	1
Gross decreases-tax positions in prior periods			(86)
Decreases due to settlements		(1)
Reduction due to lapse of statute of limitations	(32)		(13)
Total changes	(31)		(99)
Unrecognized Tax Benefits - December 31	1	32	32
Amount that if recognized, would affect the effective tax rate or regulatory liability	2
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	2	3	6
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes		5	10
Duke Energy Progress [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	23	22	67
Gross increases-tax positions in prior periods	1	1
Gross decreases-tax positions in prior periods			(45)
Reduction due to lapse of statute of limitations	(21)
Total changes	(20)	1	(45)
Unrecognized Tax Benefits - December 31	3	23	22
Amount that if recognized, would affect the effective tax rate or regulatory liability	3
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	2		7
Net interest expense recognized related to income taxes		1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes	1	3	2
Duke Energy Florida [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	8	8	44
Gross decreases-tax positions in prior periods			(37)
Reduction due to lapse of statute of limitations	(8)		1
Total changes	(8)		(36)
Unrecognized Tax Benefits - December 31		8	8
Amount that if recognized, would affect the effective tax rate or regulatory liability	1
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	1	1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest payable related to income taxes		5	7
Duke Energy Ohio [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1			36
Gross decreases-tax positions in prior periods			(36)
Total changes			(36)
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes		4	4
Duke Energy Indiana [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits - January 1	1	1	32
Gross decreases-tax positions in prior periods			(31)
Total changes			(31)
Unrecognized Tax Benefits - December 31	1	1	1
Amount that if recognized, would affect the effective tax rate or regulatory liability	2
Income Tax Examination, Penalties and Interest Expense [Abstract]
Net interest income recognized related to income taxes	1	4	$ 1
Income Tax Examination, Penalties and Interest Accrued [Abstract]
Interest receivable related to income taxes	$ 3	$ 2

Other Income and Expenses, N151

Other Income and Expenses, Net Other Income and Expenses, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	$ 38	$ 57	$ 26
Foreign exchange gains (losses)	(4)	3	(18)
AFUDC equity	164	135	157
Post in-service equity returns	73	89	39
Nonoperating income (expense), other	36	67	58
Other income and expenses, net	307	351	262
Duke Energy Carolinas [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2	4	1
AFUDC equity	96	91	91
Post in-service equity returns	60	71	32
Nonoperating income (expense), other	2	6	(4)
Other income and expenses, net	160	172	120
Progress Energy [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	4	3	7
AFUDC equity	54	26	50
Post in-service equity returns	13	17	7
Nonoperating income (expense), other	26	31	30
Other income and expenses, net	97	77	94
Duke Energy Progress [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2		1
AFUDC equity	47	25	42
Post in-service equity returns	13	17	7
Nonoperating income (expense), other	9	9	7
Other income and expenses, net	71	51	57
Duke Energy Florida [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	2	2	3
AFUDC equity	7		8
Nonoperating income (expense), other	15	18	19
Other income and expenses, net	24	20	30
Duke Energy Ohio [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	4	8	5
AFUDC equity	3	4	1
Nonoperating income (expense), other	(1)	(2)	(4)
Other income and expenses, net	6	10	2
Duke Energy Indiana [Member]
Component Of Other Income Expense Nonoperating [Line Items]
Interest income	6	6	6
AFUDC equity	11	14	15
Nonoperating income (expense), other	(6)	2	(3)
Other income and expenses, net	$ 11	$ 22	$ 18

Quarterly Financial Data (Un152

Quarterly Financial Data (Unaudited) (Schedule of Quarterly Financial Information) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	$ 5,322	$ 6,483	$ 5,589	$ 6,065	$ 5,559	$ 6,395	$ 5,708	$ 6,263	$ 23,459	$ 23,925	$ 22,756
Operating income (loss)	977	1,688	1,246	1,456	988	1,619	1,289	1,362	5,367	5,258	4,854
Income (loss) from continuing operations	491	940	604	776	98	891	726	750	2,811	2,465	2,590
Income (Loss) From Discontinued Operations, net of tax	(9)	(5)	(57)	91	2	378	(113)	(843)	20	(576)	86
Net income (loss)	482	935	547	867	100	1,269	613	(93)	2,831	1,889	2,676
Net income (loss) attributable to Parent	$ 477	$ 932	$ 543	$ 864	$ 97	$ 1,274	$ 609	$ (97)	$ 2,816	$ 1,883	$ 2,665
Income (loss) from continuing operations attributable to Duke Energy Corporation common shareholders [Abstract]
Basic	$ 0.70	$ 1.36	$ 0.87	$ 1.09	$ 0.14	$ 1.25	$ 1.02	$ 1.05	$ 4.02	$ 3.46	$ 3.64
Diluted	0.70	1.36	0.87	1.09	0.14	1.25	1.02	1.05	4.02	3.46	3.63
Income (loss) from discontinued operations attributable To Duke Energy Corporation common shareholders [Abstract]
Basic	(0.01)	(0.01)	(0.09)	0.13		0.55	(0.16)	(1.19)	0.03	(0.80)	0.13
Diluted	(0.01)	(0.01)	(0.09)	0.13		0.55	(0.16)	(1.19)	0.03	(0.80)	0.13
Net income attributable to Duke Energy Corporation common shareholders [Abstract]
Basic	0.69	1.35	0.78	1.22	0.14	1.80	0.86	(0.14)	4.05	2.66	3.77
Diluted	$ 0.69	$ 1.35	$ 0.78	$ 1.22	$ 0.14	$ 1.80	$ 0.86	$ (0.14)	$ 4.05	$ 2.66	$ 3.76
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	$ 1,560	$ 2,061	$ 1,707	$ 1,901	$ 1,658	$ 1,938	$ 1,755	$ 2,000	$ 7,229	$ 7,351	$ 6,954
Operating income (loss)	296	666	483	515	318	630	438	509	1,960	1,895	1,809
Net income (loss)	141	383	265	292	139	377	270	286	1,081	1,072
Net income (loss) attributable to Parent									1,081	1,072	976
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	2,336	2,929	2,476	2,536	2,341	2,863	2,421	2,541	10,277	10,166	9,533
Operating income (loss)	351	756	504	549	388	665	488	477	2,160	2,018	1,618
Income (loss) from continuing operations	132	452	217	264	139	330	207	204	1,065	880	659
Income (Loss) From Discontinued Operations, net of tax									(3)	(6)	16
Net income (loss)	131	451	217	263	139	330	202	203	1,062	874	675
Net income (loss) attributable to Parent	128	448	215	260	136	329	202	202	1,051	869	672
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	1,160	1,488	1,193	1,449	1,196	1,367	1,191	1,422	5,290	5,176	4,992
Operating income (loss)	130	394	184	316	180	285	212	258	1,024	935	932
Net income (loss)	69	229	85	183	76	157	101	133	566	467	500
Net income (loss) attributable to Parent									566	467	500
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	1,174	1,436	1,281	1,086	1,143	1,491	1,225	1,116	4,977	4,975	4,527
Operating income (loss)	216	357	315	227	205	378	276	219	1,115	1,078	688
Net income (loss)	105	216	165	113	93	205	142	108	599	548	325
Net income (loss) attributable to Parent									599	548	325
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	452	462	405	586	480	446	412	575	1,905	1,913	1,805
Operating income (loss)	73	76	43	111	76	58	60	(7)	303	187	182
Income (loss) from continuing operations									149	68	67
Income (Loss) From Discontinued Operations, net of tax		(2)	(65)	90	34	413	(135)	(875)	23	(563)	35
Net income (loss)	43	32	(52)	149	63	439	(107)	(890)	172	(495)	102
Net income (loss) attributable to Parent									172	(495)	102
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Operating revenues	667	749	686	788	792	790	748	845	2,890	3,175	2,926
Operating income (loss)	171	117	146	210	130	182	178	215	644	705	733
Net income (loss)	$ 94	$ 46	$ 68	$ 108	$ 58	$ 101	$ 87	$ 113	316	359
Net income (loss) attributable to Parent									$ 316	$ 359	$ 358

Quarterly Financial Data (Un153

Quarterly Financial Data (Unaudited) (Unusual or Infrequently Occurring Items) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers	$ (30)	$ (24)	$ (22)	$ (21)	$ (33)	$ (56)	$ (61)	$ (55)	$ (97)	$ (205)
Cost Savings Initiative	(142)	0	0	0					(142)
Pretax impairment charge									(120)	(81)	$ (399)
Deferred foreign taxes									17	67	(14)
Total	(182)	(121)	(63)	(21)	(547)	421	(61)	(1,436)	(387)	(1,623)
Edwardsport Settlement [Member]
Quarterly Financial Information Disclosure [Line Items]
Settlements and penalties	(3)	(90)							(93)
Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Settlements and penalties	(7)	(7)			(102)	0	0	0	(14)	(102)
Midwest Generation Business [Member]
Quarterly Financial Information Disclosure [Line Items]
State Tax Adjustment related to Midwest Generation Sale			(41)						(41)
Midwest Generation Impairment [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge					(39)	477	0	(1,287)		(849)
International Tax Adjustment [Member]
Quarterly Financial Information Disclosure [Line Items]
Deferred foreign taxes					(373)					(373)
Ohio Valley Electric Corporation [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge								(94)		(94)
Duke Energy Carolinas [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers	(16)	(11)	(11)	(9)	(17)	(25)	(38)	(29)	(47)	(109)
Cost Savings Initiative	(93)	0	0	0					(93)
Pretax impairment charge									(1)	(3)
Total	(116)	(12)	(11)	(9)	(89)	(25)	(38)	(29)	(148)	(181)
Duke Energy Carolinas [Member] | Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Settlements and penalties	(7)	(1)			(72)				(8)	(72)
Progress Energy [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers	(10)	(8)	(8)	(8)	(13)	(21)	(12)	(19)	(34)	(65)
Cost Savings Initiative	(36)	0	0	0					(36)
Pretax impairment charge									(12)	16	(380)
Total	(46)	(14)	(8)	(8)	(43)	(21)	(12)	(19)	(76)	(95)
Progress Energy [Member] | Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Settlements and penalties		(6)			(30)				(6)	(30)
Duke Energy Progress [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers	(6)	(6)	(5)	(5)	(10)	(15)	(3)	(14)	(22)	(42)
Cost Savings Initiative	(28)	0	0	0					(28)
Pretax impairment charge									(5)	18	(22)
Total	(34)	(12)	(5)	(5)	(40)	(15)	(3)	(14)	(56)	(72)
Duke Energy Progress [Member] | Ash Basin [Member]
Quarterly Financial Information Disclosure [Line Items]
Settlements and penalties		(6)			(30)				(6)	(30)
Duke Energy Florida [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers	(4)	(3)	(3)	(3)	(3)	(6)	(9)	(5)	(13)	(23)
Cost Savings Initiative	(8)	0	0	0					(8)
Pretax impairment charge									(7)	(2)	(358)
Total	(12)	(3)	(3)	(3)					(21)
Duke Energy Ohio [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers	(1)	(1)	(1)	(1)	(2)	(3)	(4)	(2)	(4)	(11)
Cost Savings Initiative	(2)	0	0	0					(2)
Pretax impairment charge										(94)	$ (5)
Total	(3)	(1)	(1)	(1)	(41)	474	(4)	(1,414)	(6)	(985)
Duke Energy Ohio [Member] | Midwest Generation Impairment [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge					(39)	477	0	(1,318)		(880)
Duke Energy Ohio [Member] | Ohio Valley Electric Corporation [Member]
Quarterly Financial Information Disclosure [Line Items]
Pretax impairment charge								(94)		(94)
Duke Energy Indiana [Member]
Quarterly Financial Information Disclosure [Line Items]
Costs to achieve mergers	(2)	(2)	(1)	(2)	$ (2)	$ (3)	$ (5)	$ (2)	(7)	$ (12)
Cost Savings Initiative	(6)	0	0	0					(6)
Pretax impairment charge									(88)
Total	(11)	(92)	$ (1)	$ (2)					(106)
Duke Energy Indiana [Member] | Edwardsport Settlement [Member]
Quarterly Financial Information Disclosure [Line Items]
Settlements and penalties	$ (3)	$ (90)							$ (93)