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