Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - Qualified Pension Plans - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 41	$ 42	$ 124	$ 116
Interest cost on projected benefit obligation	67	77	202	242
Expected return on plan assets	(143)	(140)	(429)	(426)
Amortization of actuarial loss	32	28	96	77
Amortization of prior service credit	(8)	(8)	(24)	(24)
Amortization of settlement charges	11		16
Net periodic pension costs		(1)	(15)	(15)
Duke Energy Carolinas
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	12	13	38	37
Interest cost on projected benefit obligation	16	17	47	58
Expected return on plan assets	(36)	(36)	(108)	(111)
Amortization of actuarial loss	7	6	21	17
Amortization of prior service credit	(2)	(2)	(6)	(6)
Amortization of settlement charges	6		8
Net periodic pension costs	3	(2)		(5)
Progress Energy
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	12	13	36	34
Interest cost on projected benefit obligation	21	24	64	76
Expected return on plan assets	(48)	(45)	(143)	(134)
Amortization of actuarial loss	10	10	30	28
Amortization of prior service credit		(1)	(2)	(2)
Amortization of settlement charges	5		6
Net periodic pension costs		1	(9)	2
Duke Energy Progress
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	6	7	20	19
Interest cost on projected benefit obligation	10	10	29	34
Expected return on plan assets	(22)	(22)	(66)	(66)
Amortization of actuarial loss	4	4	13	10
Amortization of prior service credit			(1)	(1)
Amortization of settlement charges	5		6
Net periodic pension costs	3	(1)	1	(4)
Duke Energy Florida
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	5	5	16	15
Interest cost on projected benefit obligation	12	14	35	41
Expected return on plan assets	(25)	(22)	(76)	(66)
Amortization of actuarial loss	6	6	17	18
Amortization of prior service credit			(1)	(1)
Amortization of settlement charges	1		1
Net periodic pension costs	(1)	3	(8)	7
Duke Energy Ohio
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	3	3
Interest cost on projected benefit obligation	4	5	12	14
Expected return on plan assets	(7)	(7)	(21)	(21)
Amortization of actuarial loss	2	2	5	3
Net periodic pension costs		1	(1)	(1)
Duke Energy Indiana
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	2	2	6	6
Interest cost on projected benefit obligation	6	6	17	19
Expected return on plan assets	(11)	(11)	(32)	(32)
Amortization of actuarial loss	3	3	9	6
Amortization of prior service credit			(1)	(1)
Amortization of settlement charges	1		1
Net periodic pension costs	1			(2)
Piedmont Natural Gas
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	4	4
Interest cost on projected benefit obligation	2	2	7	8
Expected return on plan assets	(5)	(5)	(16)	(16)
Amortization of actuarial loss	2	2	7	5
Amortization of prior service credit	(2)	(2)	(7)	(7)
Amortization of settlement charges	1		1
Net periodic pension costs	$ (1)	$ (2)	$ (4)	$ (6)