Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - Qualified Pension Plans - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 42	$ 37	$ 83	$ 74
Interest cost on projected benefit obligation	68	82	135	165
Expected return on plan assets	(143)	(143)	(286)	(286)
Amortization of actuarial loss	30	25	64	49
Amortization of prior service credit	(8)	(8)	(16)	(16)
Amortization of settlement charges	3		5
Net periodic pension costs	(8)	(7)	(15)	(14)
Duke Energy Carolinas
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	14	12	26	24
Interest cost on projected benefit obligation	15	21	31	41
Expected return on plan assets	(36)	(37)	(72)	(75)
Amortization of actuarial loss	7	5	14	11
Amortization of prior service credit	(2)	(2)	(4)	(4)
Amortization of settlement charges	1		2
Net periodic pension costs	(1)	(1)	(3)	(3)
Progress Energy
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	12	10	24	21
Interest cost on projected benefit obligation	22	26	43	52
Expected return on plan assets	(47)	(45)	(95)	(89)
Amortization of actuarial loss	9	9	20	18
Amortization of prior service credit	(1)		(2)	(1)
Amortization of settlement charges			1
Net periodic pension costs	(5)		(9)	1
Duke Energy Progress
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	8	6	14	12
Interest cost on projected benefit obligation	9	12	19	24
Expected return on plan assets	(22)	(21)	(44)	(44)
Amortization of actuarial loss	4	3	9	6
Amortization of prior service credit	(1)	(1)	(1)	(1)
Amortization of settlement charges	1		1
Net periodic pension costs	(1)	(1)	(2)	(3)
Duke Energy Florida
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	6	6	11	10
Interest cost on projected benefit obligation	11	13	23	27
Expected return on plan assets	(26)	(22)	(51)	(44)
Amortization of actuarial loss	5	6	11	12
Amortization of prior service credit	(1)	(1)	(1)	(1)
Net periodic pension costs	(5)	2	(7)	4
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	8	9
Expected return on plan assets	(7)	(6)	(14)	(14)
Amortization of actuarial loss	1		3	1
Net periodic pension costs	(1)	(1)	(1)	(2)
Duke Energy Indiana
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	2	2	4	4
Interest cost on projected benefit obligation	5	7	11	13
Expected return on plan assets	(10)	(10)	(21)	(21)
Amortization of actuarial loss	3	1	6	3
Amortization of prior service credit	(1)	(1)	(1)	(1)
Net periodic pension costs	(1)	(1)	(1)	(2)
Piedmont Natural Gas
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	2	2	3	3
Interest cost on projected benefit obligation	3	3	5	6
Expected return on plan assets	(6)	(6)	(11)	(11)
Amortization of actuarial loss	3	1	5	3
Amortization of prior service credit	(3)	(2)	(5)	(5)
Net periodic pension costs	$ (1)	$ (2)	$ (3)	$ (4)