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