Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of regulatory asset	$ 4	$ 4	$ 5
Pension Plan | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	165	158
Service cost	157	150	182
Interest cost	269	317	299
Expected return on plan assets	(572)	(567)	(559)
Amortization of prior service credit	128	108	132
Amortization of prior service cost (credit)	(32)	(32)	(32)
Amortization of settlement charges	18	6
Net periodic costs	(24)	(10)	22
Pension Plan | Duke Energy Carolinas | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	51	49
Service cost	49	47	58
Interest cost	62	75	72
Expected return on plan assets	(145)	(147)	(147)
Amortization of prior service credit	28	24	29
Amortization of prior service cost (credit)	(8)	(8)	(8)
Amortization of settlement charges	9	2
Net periodic costs	(3)	(5)	4
Pension Plan | Progress Energy | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	48	46
Service cost	46	43	51
Interest cost	85	100	94
Expected return on plan assets	(190)	(178)	(178)
Amortization of prior service credit	41	39	44
Amortization of prior service cost (credit)	(3)	(3)	(3)
Amortization of settlement charges	7	1
Net periodic costs	(12)	5	8
Pension Plan | Duke Energy Progress | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	27	26
Service cost	26	25	29
Interest cost	38	45	43
Expected return on plan assets	(87)	(88)	(85)
Amortization of prior service credit	18	15	21
Amortization of prior service cost (credit)	(2)	(2)	(2)
Amortization of settlement charges	6	1
Net periodic costs	0	(3)	6
Pension Plan | Duke Energy Florida | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	21	20
Service cost	20	18	22
Interest cost	46	54	50
Expected return on plan assets	(101)	(89)	(91)
Amortization of prior service credit	23	24	23
Amortization of prior service cost (credit)	(1)	(1)	(1)
Amortization of settlement charges	1	0
Net periodic costs	(11)	8	3
Pension Plan | Duke Energy Ohio
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of regulatory asset	2	2	2
Pension Plan | Duke Energy Ohio | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	5	4
Service cost	4	4	5
Interest cost	15	18	17
Expected return on plan assets	(28)	(28)	(28)
Amortization of prior service credit	6	4	5
Amortization of prior service cost (credit)	0	0	0
Amortization of settlement charges	0	2
Net periodic costs	(2)	0	(1)
Pension Plan | Duke Energy Indiana | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	9	9
Service cost	8	8	11
Interest cost	22	26	23
Expected return on plan assets	(42)	(43)	(42)
Amortization of prior service credit	12	8	10
Amortization of prior service cost (credit)	(2)	(2)	(2)
Amortization of settlement charges	1	0
Net periodic costs	0	(2)	0
Pension Plan | Piedmont | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	6	5
Service cost	5	5	7
Interest cost	9	10	11
Expected return on plan assets	(21)	(22)	(22)
Amortization of prior service credit	9	8	11
Amortization of prior service cost (credit)	(9)	(9)	(10)
Amortization of settlement charges	1	0
Net periodic costs	(5)	(8)	(3)
Other Post-Retirement Benefit Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	4	4	6
Interest cost	23	30	28
Expected return on plan assets	(13)	(12)	(13)
Amortization of prior service credit	2	4	6
Amortization of prior service cost (credit)	(14)	(19)	(19)
Net periodic costs	2	7	8
Amortization of regulatory asset	6	6	7
Other Post-Retirement Benefit Plans | Duke Energy Carolinas
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	1
Interest cost	5	7	7
Expected return on plan assets	(8)	(7)	(8)
Amortization of prior service credit	0	2	3
Amortization of prior service cost (credit)	(4)	(5)	(5)
Net periodic costs	(6)	(2)	(2)
Other Post-Retirement Benefit Plans | Progress Energy
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	1
Interest cost	10	12	12
Expected return on plan assets	0	0	0
Amortization of prior service credit	1	1	1
Amortization of prior service cost (credit)	(3)	(8)	(8)
Net periodic costs	9	6	6
Other Post-Retirement Benefit Plans | Duke Energy Progress
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	0	0
Interest cost	5	7	6
Expected return on plan assets	0	0	0
Amortization of prior service credit	0	0	1
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	4	6	6
Other Post-Retirement Benefit Plans | Duke Energy Florida
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	1	1
Interest cost	4	5	6
Expected return on plan assets	0	0	0
Amortization of prior service credit	1	1	0
Amortization of prior service cost (credit)	(2)	(7)	(7)
Net periodic costs	3	0	0
Other Post-Retirement Benefit Plans | Duke Energy Ohio
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	0	1
Interest cost	1	1	1
Expected return on plan assets	0	0	0
Amortization of prior service credit	0	0	0
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	0	0	1
Amortization of regulatory asset	1	2	2
Other Post-Retirement Benefit Plans | Duke Energy Indiana
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	1
Interest cost	2	3	3
Expected return on plan assets	0	0	0
Amortization of prior service credit	4	4	4
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	6	7	7
Other Post-Retirement Benefit Plans | Piedmont
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	0	1
Interest cost	1	1	1
Expected return on plan assets	(2)	(1)	(2)
Amortization of prior service credit	0	0	0
Amortization of prior service cost (credit)	(2)	(2)	(2)
Net periodic costs	$ (3)	$ (2)	$ (2)