Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of Regulatory Asset	$ 4	$ 5	$ 7
Pension Plan | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	158	182
Service cost	150	174	159
Interest cost	317	299	328
Expected return on plan assets	(567)	(559)	(545)
Amortization of actuarial loss (gain)	108	132	146
Amortization of prior service cost (credit)	(32)	(32)	(24)
Settlement charge			12
Other	6		8
Net periodic costs	(10)	22	84
Pension Plan | Duke Energy Carolinas | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	49	58
Service cost	47	56	48
Interest cost	75	72	79
Expected return on plan assets	(147)	(147)	(142)
Amortization of actuarial loss (gain)	24	29	31
Amortization of prior service cost (credit)	(8)	(8)	(8)
Settlement charge			0
Other	2		2
Net periodic costs	(5)	4	10
Pension Plan | Progress Energy | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	46	51
Service cost	43	49	45
Interest cost	100	94	100
Expected return on plan assets	(178)	(178)	(167)
Amortization of actuarial loss (gain)	39	44	52
Amortization of prior service cost (credit)	(3)	(3)	(3)
Settlement charge			0
Other	1		2
Net periodic costs	5	8	29
Pension Plan | Duke Energy Progress | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	26	29
Service cost	25	28	26
Interest cost	45	43	47
Expected return on plan assets	(88)	(85)	(82)
Amortization of actuarial loss (gain)	15	21	23
Amortization of prior service cost (credit)	(2)	(2)	(2)
Settlement charge			0
Other	1		1
Net periodic costs	(3)	6	13
Pension Plan | Duke Energy Florida | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	20	22
Service cost	18	21	19
Interest cost	54	50	53
Expected return on plan assets	(89)	(91)	(85)
Amortization of actuarial loss (gain)	24	23	29
Amortization of prior service cost (credit)	(1)	(1)	(1)
Settlement charge			0
Other	0		1
Net periodic costs	8	3	16
Pension Plan | Duke Energy Ohio
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Amortization of Regulatory Asset	2	2	3
Pension Plan | Duke Energy Ohio | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	4	5
Service cost	4	5	4
Interest cost	18	17	18
Expected return on plan assets	(28)	(28)	(27)
Amortization of actuarial loss (gain)	4	5	5
Amortization of prior service cost (credit)	0	0	(1)
Settlement charge			0
Other	2		0
Net periodic costs	0	(1)	(1)
Pension Plan | Duke Energy Indiana | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	9	11
Service cost	8	10	9
Interest cost	26	23	26
Expected return on plan assets	(43)	(42)	(42)
Amortization of actuarial loss (gain)	8	10	12
Amortization of prior service cost (credit)	(2)	(2)	(2)
Settlement charge			0
Other	0		1
Net periodic costs	(2)	0	4
Pension Plan | Piedmont | Qualified Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	5	7
Service cost	5	7	10
Interest cost	10	11	14
Expected return on plan assets	(22)	(22)	(24)
Amortization of actuarial loss (gain)	8	11	11
Amortization of prior service cost (credit)	(9)	(10)	(2)
Settlement charge			12
Other	0		1
Net periodic costs	(8)	(3)	22
Other Post-Retirement Benefit Plans
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	4	6	4
Interest cost	30	28	34
Expected return on plan assets	(12)	(13)	(14)
Amortization of actuarial loss (gain)	4	6	10
Amortization of prior service cost (credit)	(19)	(19)	(115)
Curtailment credit			(30)
Net periodic costs	7	8	(111)
Amortization of Regulatory Asset	6	7	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	7	7	8
Expected return on plan assets	(7)	(8)	(8)
Amortization of actuarial loss (gain)	2	3	(2)
Amortization of prior service cost (credit)	(5)	(5)	(10)
Curtailment credit			(4)
Net periodic costs	(2)	(2)	(15)
Other Post-Retirement Benefit Plans | Progress Energy
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	0
Interest cost	12	12	13
Expected return on plan assets	0	0	0
Amortization of actuarial loss (gain)	1	1	21
Amortization of prior service cost (credit)	(8)	(8)	(84)
Curtailment credit			(16)
Net periodic costs	6	6	(66)
Other Post-Retirement Benefit Plans | Duke Energy Progress
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	0	0
Interest cost	7	6	7
Expected return on plan assets	0	0	0
Amortization of actuarial loss (gain)	0	1	12
Amortization of prior service cost (credit)	(1)	(1)	(54)
Net periodic costs	6	6	(35)
Other Post-Retirement Benefit Plans | Duke Energy Florida
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	0
Interest cost	5	6	6
Expected return on plan assets	0	0	0
Amortization of actuarial loss (gain)	1	0	9
Amortization of prior service cost (credit)	(7)	(7)	(30)
Curtailment credit			(16)
Net periodic costs	0	0	(31)
Other Post-Retirement Benefit Plans | Duke Energy Ohio
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	1	0
Interest cost	1	1	1
Expected return on plan assets	0	0	0
Amortization of actuarial loss (gain)	0	0	(2)
Amortization of prior service cost (credit)	(1)	(1)	0
Curtailment credit			(2)
Net periodic costs	0	1	(3)
Amortization of Regulatory Asset	2	2	2
Other Post-Retirement Benefit Plans | Duke Energy Indiana
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1	0
Interest cost	3	3	3
Expected return on plan assets	0	0	(1)
Amortization of actuarial loss (gain)	4	4	(1)
Amortization of prior service cost (credit)	(1)	(1)	(1)
Curtailment credit			(2)
Net periodic costs	7	7	(2)
Other Post-Retirement Benefit Plans | Piedmont
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	1	1
Interest cost	1	1	1
Expected return on plan assets	(1)	(2)	(2)
Amortization of actuarial loss (gain)	0	0	1
Amortization of prior service cost (credit)	(2)	(2)	0
Curtailment credit			0
Net periodic costs	$ (2)	$ (2)	$ 1