Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current income taxes
Federal	$ (281)	$ (299)	$ (647)
State	(9)	10	(11)
Foreign	1	2	3
Total current income taxes	(289)	(287)	(655)
Deferred income taxes
Federal	155	855	1,064
State	(92)	(38)	49
Total deferred income taxes	63	817	1,113
ITC amortization	(10)	(11)	(10)
Income tax (benefit) expense from continuing operations	(236)	519	448
Tax expense from discontinued operations	2	(2)	(26)
Total income tax (benefit) expense included in Consolidated Statements of Operations	(234)	517	422
Net operating loss carry forward	79	775	(18)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Domestic	826	4,053	3,018
Foreign	13	44	55
Total income from continuing operations before income taxes	839	4,097	3,073
Duke Energy Carolinas
Current income taxes
Federal	314	164	(8)
State	35	13	6
Foreign		0	0
Total current income taxes	349	177	(2)
Deferred income taxes
Federal	(171)	175	299
State	(86)	(37)	11
Total deferred income taxes	(257)	138	310
ITC amortization	(4)	(4)	(5)
Income tax (benefit) expense from continuing operations	88	311	303
Total income tax (benefit) expense included in Consolidated Statements of Operations	88	311	303
Net operating loss carry forward	20	8	(22)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	1,044	1,714	1,374
Progress Energy
Current income taxes
Federal	280	(173)	(135)
State	29	(7)	(5)
Foreign		0	0
Total current income taxes	309	(180)	(140)
Deferred income taxes
Federal	(167)	422	341
State	(24)	17	20
Total deferred income taxes	(191)	439	361
ITC amortization	(5)	(6)	(3)
Income tax (benefit) expense from continuing operations	113	253	218
Total income tax (benefit) expense included in Consolidated Statements of Operations	113	253	218
Net operating loss carry forward	39	243	(293)
Duke Energy Progress
Current income taxes
Federal	181	(36)	(71)
State	17	(3)	(5)
Foreign		0	0
Total current income taxes	198	(39)	(76)
Deferred income taxes
Federal	(180)	220	256
State	(49)	(18)	(17)
Total deferred income taxes	(229)	202	239
ITC amortization	(5)	(6)	(3)
Income tax (benefit) expense from continuing operations	(36)	157	160
Total income tax (benefit) expense included in Consolidated Statements of Operations	(36)	157	160
Net operating loss carry forward	3	35	(59)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	379	962	827
Duke Energy Florida
Current income taxes
Federal	148	(43)	(49)
State	24	18	(10)
Foreign		0	0
Total current income taxes	172	(25)	(59)
Deferred income taxes
Federal	1	153	115
State	25	27	45
Total deferred income taxes	26	180	160
ITC amortization		0	0
Income tax (benefit) expense from continuing operations	198	155	101
Total income tax (benefit) expense included in Consolidated Statements of Operations	198	155	101
Net operating loss carry forward	30	152	(219)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	969	847	655
Duke Energy Ohio
Current income taxes
Federal	10	(41)	20
State	1	(1)	(1)
Foreign		0	0
Total current income taxes	11	(42)	19
Deferred income taxes
Federal	30	77	21
State	2	5	3
Total deferred income taxes	32	82	24
ITC amortization		0	0
Income tax (benefit) expense from continuing operations	43	40	43
Total income tax (benefit) expense included in Consolidated Statements of Operations	43	40	43
Net operating loss carry forward		25	(17)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	295	279	219
Duke Energy Indiana
Current income taxes
Federal	48	(23)	29
State	7	1	3
Foreign		0	0
Total current income taxes	55	(22)	32
Deferred income taxes
Federal	12	128	74
State	17	28	22
Total deferred income taxes	29	156	96
ITC amortization		0	0
Income tax (benefit) expense from continuing operations	84	134	128
Total income tax (benefit) expense included in Consolidated Statements of Operations	84	134	128
Net operating loss carry forward	8	60	(21)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	492	570	521
Piedmont
Current income taxes
Federal	(27)	(92)	67
State	(8)	(1)	1
Foreign		0	0
Total current income taxes	(35)	(93)	68
Deferred income taxes
Federal	60	133	(36)
State	(7)	3	5
Total deferred income taxes	53	136	(31)
ITC amortization		0	0
Income tax (benefit) expense from continuing operations	18	43	37
Total income tax (benefit) expense included in Consolidated Statements of Operations	18	43	37
Net operating loss carry forward	11	90	(39)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	$ 291	$ 245	$ 166