Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	$ (299)	$ (647)	$ (247)
Current state taxes	10	(11)	4
Current foreign taxes	2	3	3
Total current income taxes	(287)	(655)	(240)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	855	1,064	1,344
Deferred state taxes	(38)	49	102
Total deferred income taxes	817	1,113	1,446
ITC amortization	(11)	(10)	(10)
Income tax expense (benefit) from continuing operations	519	448	1,196
Tax expense (benefit) from discontinued operations	(2)	(26)	(6)
Total income tax expense included in Consolidated Statements of Operations	517	422	1,190
Net operating loss carry forward	(775)	(18)	428
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Domestic	4,053	3,018	4,207
Foreign	44	55	59
Total income from continuing operations before income taxes	4,097	3,073	4,266
Equity in losses of unconsolidated affiliates	(162)	(83)	(119)
Duke Energy Carolinas
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	164	(8)	221
Current state taxes	13	6	20
Current foreign taxes		0	0
Total current income taxes	177	(2)	241
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	175	299	381
Deferred state taxes	(37)	11	35
Total deferred income taxes	138	310	416
ITC amortization	(4)	(5)	(5)
Income tax expense (benefit) from continuing operations	311	303	652
Tax expense (benefit) from discontinued operations		0	0
Total income tax expense included in Consolidated Statements of Operations	311	303	652
Net operating loss carry forward	8	22	10
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	1,714	1,374	1,866
Progress Energy
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(173)	(135)	(436)
Current state taxes	(7)	(5)	(5)
Current foreign taxes		0	0
Total current income taxes	(180)	(140)	(441)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	422	341	664
Deferred state taxes	17	20	44
Total deferred income taxes	439	361	708
ITC amortization	(6)	(3)	(3)
Income tax expense (benefit) from continuing operations	253	218	264
Tax expense (benefit) from discontinued operations		0	0
Total income tax expense included in Consolidated Statements of Operations	253	218	264
Net operating loss carry forward	(243)	(293)	(74)
Duke Energy Progress
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(36)	(71)	(95)
Current state taxes	(3)	(5)	2
Current foreign taxes		0	0
Total current income taxes	(39)	(76)	(93)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	220	256	378
Deferred state taxes	(18)	(17)	10
Total deferred income taxes	202	239	388
ITC amortization	(6)	(3)	(3)
Income tax expense (benefit) from continuing operations	157	160	292
Tax expense (benefit) from discontinued operations		0	0
Total income tax expense included in Consolidated Statements of Operations	157	160	292
Net operating loss carry forward	35	59	1
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	962	827	1,007
Duke Energy Florida
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(43)	(49)	(188)
Current state taxes	18	(10)	(11)
Current foreign taxes		0	0
Total current income taxes	(25)	(59)	(199)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	153	115	194
Deferred state taxes	27	45	51
Total deferred income taxes	180	160	245
ITC amortization		0	0
Income tax expense (benefit) from continuing operations	155	101	46
Tax expense (benefit) from discontinued operations		0	0
Total income tax expense included in Consolidated Statements of Operations	155	101	46
Net operating loss carry forward	(152)	(219)	(36)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	847	655	758
Duke Energy Ohio
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(41)	20	(37)
Current state taxes	(1)	(1)	2
Current foreign taxes		0	0
Total current income taxes	(42)	19	(35)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	77	21	99
Deferred state taxes	5	3	(4)
Total deferred income taxes	82	24	95
ITC amortization		0	(1)
Income tax expense (benefit) from continuing operations	40	43	59
Tax expense (benefit) from discontinued operations		0	0
Total income tax expense included in Consolidated Statements of Operations	40	43	59
Net operating loss carry forward	(25)	(17)	(17)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	279	219	252
Duke Energy Indiana
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(23)	29	128
Current state taxes	1	3	21
Current foreign taxes		0	0
Total current income taxes	(22)	32	149
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	128	74	138
Deferred state taxes	28	22	14
Total deferred income taxes	156	96	152
ITC amortization		0	0
Income tax expense (benefit) from continuing operations	134	128	301
Tax expense (benefit) from discontinued operations		0	0
Total income tax expense included in Consolidated Statements of Operations	134	128	301
Net operating loss carry forward	(60)	(21)	(42)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	570	521	655
Piedmont
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current federal taxes	(92)	67	(90)
Current state taxes	(1)	1	(3)
Current foreign taxes		0	0
Total current income taxes	(93)	68	(93)
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred federal taxes	133	(36)	147
Deferred state taxes	3	5	8
Total deferred income taxes	136	(31)	155
ITC amortization		0	0
Income tax expense (benefit) from continuing operations	43	37	62
Tax expense (benefit) from discontinued operations		0	0
Total income tax expense included in Consolidated Statements of Operations	43	37	62
Net operating loss carry forward	(90)	(39)	(79)
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Total income from continuing operations before income taxes	245	166	201
Equity in losses of unconsolidated affiliates	$ (8)	$ (7)	6
Tax Act
Duke Energy Income from Continuing Operations Before Income Taxes [Abstract]
Equity in losses of unconsolidated affiliates			$ 16