Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	2 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		$ (647)	$ (247)
Current state taxes		(11)	4	$ (15)
Current foreign taxes		3	3	2
Total current income taxes		(655)	(240)	(13)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		1,064	1,344	1,064
Deferred state taxes		49	102	117
Total deferred income taxes		1,113	1,446	1,181
Investment tax credit amortization		(10)	(10)	(12)
Income tax expense (benefit) from continuing operations		448	1,196	1,156
Tax expense (benefit) from discontinued operations		(26)	(6)	(30)
Total income tax expense included in Consolidated Statements of Operations		422	1,190	1,126
Net operating loss carry forward		(18)	428	648
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Domestic		3,018	4,207	3,689
Foreign		55	59	45
Total income from continuing operations before income taxes		3,073	4,266	3,734
Equity in losses of unconsolidated affiliates		(83)	(119)	15
Tax Act [Member]
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Equity in losses of unconsolidated affiliates		16
Duke Energy Carolinas [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(8)	221	139
Current state taxes		6	20	25
Total current income taxes		(2)	241	164
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		299	381	430
Deferred state taxes		11	35	45
Total deferred income taxes		310	416	475
Investment tax credit amortization		(5)	(5)	(5)
Income tax expense (benefit) from continuing operations		303	652	634
Total income tax expense included in Consolidated Statements of Operations		303	652	634
Net operating loss carry forward		22	10	(4)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		1,374	1,866	1,800
Progress Energy [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(135)	(436)	15
Current state taxes		(5)	(5)	(19)
Total current income taxes		(140)	(441)	(4)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		341	664	486
Deferred state taxes		20	44	50
Total deferred income taxes		361	708	536
Investment tax credit amortization		(3)	(3)	(5)
Income tax expense (benefit) from continuing operations		218	264	527
Tax expense (benefit) from discontinued operations				1
Total income tax expense included in Consolidated Statements of Operations		218	264	528
Net operating loss carry forward		(293)	(74)	(190)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		1,251	1,532	1,566
Duke Energy Progress [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(71)	(95)	(59)
Current state taxes		(5)	2	(25)
Total current income taxes		(76)	(93)	(84)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		256	378	350
Deferred state taxes		(17)	10	40
Total deferred income taxes		239	388	390
Investment tax credit amortization		(3)	(3)	(5)
Income tax expense (benefit) from continuing operations		160	292	301
Total income tax expense included in Consolidated Statements of Operations		160	292	301
Net operating loss carry forward		59	1	(60)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		827	1,007	900
Duke Energy Florida [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		(49)	(188)	76
Current state taxes		(10)	(11)	22
Total current income taxes		(59)	(199)	98
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		115	194	199
Deferred state taxes		45	51	25
Total deferred income taxes		160	245	224
Income tax expense (benefit) from continuing operations		101	46	322
Total income tax expense included in Consolidated Statements of Operations		101	46	322
Net operating loss carry forward		(219)	(36)	(49)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		655	758	873
Duke Energy Ohio [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		20	(37)	(7)
Current state taxes		(1)	2	(13)
Total current income taxes		19	(35)	(20)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		21	99	88
Deferred state taxes		3	(4)	11
Total deferred income taxes		24	95	99
Investment tax credit amortization			(1)	(1)
Income tax expense (benefit) from continuing operations		43	59	78
Tax expense (benefit) from discontinued operations				(36)
Total income tax expense included in Consolidated Statements of Operations		43	59	42
Net operating loss carry forward		(17)	(17)	(26)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		219	252	270
Duke Energy Indiana [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes		29	128	7
Current state taxes		3	21	6
Total current income taxes		32	149	13
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes		74	138	202
Deferred state taxes		22	14	11
Total deferred income taxes		96	152	213
Investment tax credit amortization				(1)
Income tax expense (benefit) from continuing operations		128	301	225
Total income tax expense included in Consolidated Statements of Operations		128	301	225
Net operating loss carry forward		(21)	(42)	(58)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes		521	655	$ 606
Piedmont Natural Gas [Member]
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	$ 4	67	(90)		$ 27
Current state taxes	(2)	1	(3)		12
Total current income taxes	2	68	(93)		39
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	24	(36)	147		79
Deferred state taxes	6	5	8		6
Total deferred income taxes	30	(31)	155		85
Income tax expense (benefit) from continuing operations	32	37	62		124
Total income tax expense included in Consolidated Statements of Operations		37	62
Net operating loss carry forward	17	(39)	(79)		91
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	86	166	201		317
Equity in losses of unconsolidated affiliates	$ (2)	$ (7)	6		$ (29)
Previously Remitted Earnings [Member]
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Tax expense (benefit) from discontinued operations			$ (95)