Income Taxes (Effective Tax Rates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
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 of 21%	$ 176	$ 860	$ 645
State income tax, net of federal income tax effect	(80)	(22)	30
Amortization of excess deferred income tax	(276)	(121)	(61)
AFUDC equity income	(48)	(52)	(42)
AFUDC equity depreciation	103	34	31
Noncontrolling Interests	62
Renewable energy PTCs	(110)	(120)	(129)
Other tax credits	(37)	(23)	(28)
Tax Act			20
Tax true up	(12)	(64)
Other items, net	(14)	27	(18)
Income tax (benefit) expense from continuing operations	$ (236)	$ 519	$ 448
Effective tax rate	(28.10%)	12.70%	14.60%
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 of 21%	$ 219	$ 360	$ 288
State income tax, net of federal income tax effect	(40)	(19)	14
Amortization of excess deferred income tax	(82)	(29)
AFUDC equity income	(13)	(9)	(15)
AFUDC equity depreciation	19	19	18
Other tax credits	(13)	(11)	(7)
Tax Act			1
Tax true up	(3)	(9)
Other items, net	1	9	4
Income tax (benefit) expense from continuing operations	$ 88	$ 311	$ 303
Effective tax rate	8.40%	18.10%	22.10%
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 of 21%	$ 243	$ 332	$ 263
State income tax, net of federal income tax effect	4	8	13
Amortization of excess deferred income tax	(118)	(64)	(55)
AFUDC equity income	(9)	(14)	(22)
AFUDC equity depreciation	10	10	9
Other tax credits	(16)	(9)	(13)
Tax Act			25
Tax true up	1	(8)
Other items, net	(2)	(2)	(2)
Income tax (benefit) expense from continuing operations	$ 113	$ 253	$ 218
Effective tax rate	9.70%	16.00%	17.40%
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 of 21%	$ 80	$ 202	$ 174
State income tax, net of federal income tax effect	(25)	(17)	(17)
Amortization of excess deferred income tax	(68)	(10)	(1)
AFUDC equity income	(6)	(13)	(12)
AFUDC equity depreciation	5	5	5
Other tax credits	(14)	(7)	(5)
Tax Act			19
Tax true up	(5)	(3)
Other items, net	(3)	0	(3)
Income tax (benefit) expense from continuing operations	$ (36)	$ 157	$ 160
Effective tax rate	(9.50%)	16.30%	19.30%
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 of 21%	$ 204	$ 178	$ 137
State income tax, net of federal income tax effect	39	35	28
Amortization of excess deferred income tax	(49)	(54)	(54)
AFUDC equity income	(3)	(1)	(10)
AFUDC equity depreciation	5	5	4
Other tax credits	(2)	(2)	(8)
Tax Act			0
Tax true up	5	(5)
Other items, net	(1)	(1)	4
Income tax (benefit) expense from continuing operations	$ 198	$ 155	$ 101
Effective tax rate	20.40%	18.30%	15.40%
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 of 21%	$ 62	$ 59	$ 46
State income tax, net of federal income tax effect	2	3	2
Amortization of excess deferred income tax	(20)	(12)	(3)
AFUDC equity income	(2)	(3)	(2)
AFUDC equity depreciation	1	1	1
Other tax credits	(1)	(1)	(1)
Tax Act			2
Tax true up	0	(7)
Other items, net	1	0	(2)
Income tax (benefit) expense from continuing operations	$ 43	$ 40	$ 43
Effective tax rate	14.60%	14.30%	19.60%
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 of 21%	$ 103	$ 120	$ 109
State income tax, net of federal income tax effect	19	22	20
Amortization of excess deferred income tax	(36)	(6)	(2)
AFUDC equity income	(4)	(3)	(2)
AFUDC equity depreciation	4	4	4
Noncontrolling Interests	0
Other tax credits	(3)	(1)	(1)
Tax true up	(1)	(1)
Other items, net	2	(1)
Income tax (benefit) expense from continuing operations	$ 84	$ 134	$ 128
Effective tax rate	17.10%	23.50%	24.60%
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 of 21%	$ 61	$ 51	$ 35
State income tax, net of federal income tax effect	(12)	2	4
Amortization of excess deferred income tax	(21)	(10)
AFUDC equity income	(10)
Other tax credits	(2)	(1)	(3)
Tax true up	1	0
Other items, net	1	1	1
Income tax (benefit) expense from continuing operations	$ 18	$ 43	$ 37
Effective tax rate	6.20%	17.60%	22.30%