Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - Qualified Pension Plans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 44	$ 42	$ 88	$ 83
Interest cost on projected benefit obligation	55	68	110	135
Expected return on plan assets	(140)	(143)	(279)	(286)
Amortization of actuarial loss	34	30	67	64
Amortization of prior service credit	(8)	(8)	(15)	(16)
Amortization of settlement charges	2	3	4	5
Net periodic pension costs	(13)	(8)	(25)	(15)
Duke Energy Carolinas
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	14	14	28	26
Interest cost on projected benefit obligation	12	15	25	31
Expected return on plan assets	(35)	(36)	(70)	(72)
Amortization of actuarial loss	8	7	15	14
Amortization of prior service credit	(2)	(2)	(4)	(4)
Amortization of settlement charges	2	1	3	2
Net periodic pension costs	(1)	(1)	(3)	(3)
Progress Energy
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	12	12	25	24
Interest cost on projected benefit obligation	18	22	35	43
Expected return on plan assets	(47)	(47)	(94)	(95)
Amortization of actuarial loss	9	9	19	20
Amortization of prior service credit		(1)	(1)	(2)
Amortization of settlement charges			1	1
Net periodic pension costs	(8)	(5)	(15)	(9)
Duke Energy Progress
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	8	8	15	14
Interest cost on projected benefit obligation	8	9	15	19
Expected return on plan assets	(21)	(22)	(42)	(44)
Amortization of actuarial loss	4	4	9	9
Amortization of prior service credit	(1)	(1)	(1)	(1)
Amortization of settlement charges	1	1	1	1
Net periodic pension costs	(1)	(1)	(3)	(2)
Duke Energy Florida
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	6	6	11	11
Interest cost on projected benefit obligation	9	11	19	23
Expected return on plan assets	(25)	(26)	(51)	(51)
Amortization of actuarial loss	5	5	10	11
Amortization of prior service credit		(1)		(1)
Net periodic pension costs	(5)	(5)	(11)	(7)
Duke Energy Ohio
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	2	2
Interest cost on projected benefit obligation	4	4	7	8
Expected return on plan assets	(7)	(7)	(14)	(14)
Amortization of actuarial loss	1	1	3	3
Net periodic pension costs	(1)	(1)	(2)	(1)
Duke Energy Indiana
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	3	2	5	4
Interest cost on projected benefit obligation	4	5	9	11
Expected return on plan assets	(10)	(10)	(20)	(21)
Amortization of actuarial loss	4	3	7	6
Amortization of prior service credit	(1)	(1)	(1)	(1)
Net periodic pension costs		(1)		(1)
Piedmont
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	2	2	3	3
Interest cost on projected benefit obligation	2	3	4	5
Expected return on plan assets	(5)	(6)	(10)	(11)
Amortization of actuarial loss	3	3	5	5
Amortization of prior service credit	(4)	(3)	(5)	(5)
Net periodic pension costs	$ (2)	$ (1)	$ (3)	$ (3)