Income Taxes (Components of Income Tax Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		$ (141)	$ (108)
Current state taxes	56	(40)	29
Current foreign taxes	144	151	133
Total current income taxes	200	(30)	54
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	1,517	1,092	491
Deferred state taxes	35	144	71
Deferred foreign taxes	(67)	14	20
Total deferred income taxes	1,485	1,250	582
Investment tax credit amortization	(16)	(15)	(13)
Income tax expense (benefit) from continuing operations	1,669	1,205	623
Tax expense (benefit) from discontinued operations	(295)	29	107
Total income tax expense included in Consolidated Statements of Operations	1,374	1,234	730
Net operating loss utilization	1,544
Net operating loss carry forward		808	1,062
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Domestic	3,600	3,183	1,600
Foreign	534	612	634
Total income (loss) from continuing operations before income taxes	4,134	3,795	2,234
Duke Energy Carolinas [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	161	49	(1)
Current state taxes	51	11	(25)
Total current income taxes	212	60	(26)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	407	464	408
Deferred state taxes	(25)	75	77
Total deferred income taxes	382	539	485
Investment tax credit amortization	(6)	(5)	(6)
Income tax expense (benefit) from continuing operations	588	594	453
Total income tax expense included in Consolidated Statements of Operations	588	594	453
Net operating loss utilization	345
Net operating loss carry forward	0		245
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	1,660	1,570	1,318
Progress Energy [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(466)	(221)	(88)
Current state taxes	(8)	(37)	2
Total current income taxes	(474)	(258)	(86)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	938	555	226
Deferred state taxes	84	84	40
Total deferred income taxes	1,022	639	266
Investment tax credit amortization	(8)	(8)	(8)
Income tax expense (benefit) from continuing operations	540	373	172
Tax expense (benefit) from discontinued operations	(4)	(26)	29
Total income tax expense included in Consolidated Statements of Operations	536	347	201
Net operating loss utilization	530
Net operating loss carry forward		458	357
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	1,420	1,032	527
Duke Energy Progress [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(184)	(70)	(48)
Current state taxes	14	(10)	(6)
Total current income taxes	(170)	(80)	(54)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	436	316	162
Deferred state taxes	25	59	9
Total deferred income taxes	461	375	171
Investment tax credit amortization	(6)	(7)	(7)
Income tax expense (benefit) from continuing operations	285	288	110
Total income tax expense included in Consolidated Statements of Operations	285	288	110
Net operating loss utilization	291
Net operating loss carry forward		64	257
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	752	788	382
Duke Energy Florida [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(53)	(143)	6
Current state taxes	1	(13)
Total current income taxes	(52)	(156)	6
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	350	326	121
Deferred state taxes	52	44	21
Total deferred income taxes	402	370	142
Investment tax credit amortization	(1)	(1)	(1)
Income tax expense (benefit) from continuing operations	349	213	147
Total income tax expense included in Consolidated Statements of Operations	349	213	147
Net operating loss utilization	64
Net operating loss carry forward		301	25
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	897	538	413
Duke Energy Ohio [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(73)	(24)	(8)
Current state taxes	3	(4)	5
Total current income taxes	(70)	(28)	(3)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	113	65	40
Deferred state taxes	1	6	(2)
Total deferred income taxes	114	71	38
Investment tax credit amortization	(1)		(2)
Income tax expense (benefit) from continuing operations	43	43	33
Tax expense (benefit) from discontinued operations	(300)	32	65
Total income tax expense included in Consolidated Statements of Operations	(257)	75	98
Net operating loss utilization	56
Net operating loss carry forward			34
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	111	110	78
Duke Energy Indiana [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(112)	(88)	(27)
Current state taxes	1	7	27
Total current income taxes	(111)	(81)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	294	276	(47)
Deferred state taxes	15	29	(25)
Total deferred income taxes	309	305	(72)
Investment tax credit amortization	(1)	(1)	(1)
Income tax expense (benefit) from continuing operations	197	223	(73)
Total income tax expense included in Consolidated Statements of Operations	197	223	(73)
Net operating loss utilization	141
Net operating loss carry forward		179	205
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income (loss) from continuing operations before income taxes	$ 556	$ 581	$ (123)