Income Taxes (Effective Tax Rates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 860	$ 645	$ 1,493
State income tax, net of federal income tax effect	(22)	30	69
Amortization of excess deferred income tax	(121)	(61)
AFUDC equity income	(52)	(42)	(81)
AFUDC equity depreciation	34	31
Renewable energy PTCs	(120)	(129)	(132)
Other tax credits	(23)	(28)
Tax Act		20	(112)
Tax true up	(64)		(52)
Other items, net	27	(18)	11
Income tax expense (benefit) from continuing operations	$ 519	$ 448	$ 1,196
Effective tax rate	12.70%	14.60%	28.00%
Duke Energy Carolinas
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 360	$ 288	$ 653
State income tax, net of federal income tax effect	(19)	14	36
Amortization of excess deferred income tax	(29)
AFUDC equity income	(9)	(15)	(37)
AFUDC equity depreciation	19	18
Other tax credits	(11)	(7)
Tax Act		1	15
Tax true up	(9)		(24)
Other items, net	9	4	9
Income tax expense (benefit) from continuing operations	$ 311	$ 303	$ 652
Effective tax rate	18.10%	22.10%	34.90%
Progress Energy
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 332	$ 263	$ 536
State income tax, net of federal income tax effect	8	13	25
Amortization of excess deferred income tax	(64)	(55)
AFUDC equity income	(14)	(22)	(32)
AFUDC equity depreciation	10	9
Other tax credits	(9)	(13)
Tax Act		25	(246)
Tax true up	(8)		(19)
Other items, net	(2)	(2)
Income tax expense (benefit) from continuing operations	$ 253	$ 218	$ 264
Effective tax rate	16.00%	17.40%	17.20%
Duke Energy Progress
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 202	$ 174	$ 353
State income tax, net of federal income tax effect	(17)	(17)	8
Amortization of excess deferred income tax	(10)	(1)
AFUDC equity income	(13)	(12)	(17)
AFUDC equity depreciation	5	5
Other tax credits	(7)	(5)
Tax Act		19	(40)
Tax true up	(3)		(13)
Other items, net		(3)	1
Income tax expense (benefit) from continuing operations	$ 157	$ 160	$ 292
Effective tax rate	16.30%	19.30%	29.00%
Duke Energy Florida
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 178	$ 137	$ 265
State income tax, net of federal income tax effect	35	28	26
Amortization of excess deferred income tax	(54)	(54)
AFUDC equity income	(1)	(10)	(16)
AFUDC equity depreciation	5	4
Other tax credits	(2)	(8)
Tax Act			(226)
Tax true up	(5)		(7)
Other items, net	(1)	4	4
Income tax expense (benefit) from continuing operations	$ 155	$ 101	$ 46
Effective tax rate	18.30%	15.40%	6.10%
Duke Energy Ohio
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 59	$ 46	$ 88
State income tax, net of federal income tax effect	3	2	(1)
Amortization of excess deferred income tax	(12)	(3)
AFUDC equity income	(3)	(2)	(4)
AFUDC equity depreciation	1	1
Other tax credits	(1)	(1)
Tax Act		2	(23)
Tax true up	(7)		(5)
Other items, net	0	(2)	4
Income tax expense (benefit) from continuing operations	$ 40	$ 43	$ 59
Effective tax rate	14.30%	19.60%	23.40%
Duke Energy Indiana
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 120	$ 109	$ 229
State income tax, net of federal income tax effect	22	20	23
Amortization of excess deferred income tax	(6)	(2)
AFUDC equity income	(3)	(2)	(8)
AFUDC equity depreciation	4	4
Other tax credits	(1)	(1)
Tax Act			55
Tax true up	(1)		(6)
Other items, net	(1)		8
Income tax expense (benefit) from continuing operations	$ 134	$ 128	$ 301
Effective tax rate	23.50%	24.60%	46.00%
Piedmont
Reconciliation of Income Tax Expense at the U.S. Federal Statutory Tax Rate to the Actual Tax Expense from Continuing Operations [Abstract]
Income tax expense, computed at the statutory rate	$ 51	$ 35	$ 70
State income tax, net of federal income tax effect	2	4	3
Amortization of excess deferred income tax	(10)
Other tax credits	(1)	(3)
Tax Act			(12)
Other items, net	1	1	1
Income tax expense (benefit) from continuing operations	$ 43	$ 37	$ 62
Effective tax rate	17.60%	22.30%	30.80%