Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Defined Benefit Plan Disclosure [Line Items]
Maximum years of participation	35 years
Impact of plan conversion on next year's net periodic benefit cost	$ 33
Master Trust
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%
Expected long-term rate of return on plan assets	6.85%
Fair value of securities on loan	$ 351	$ 154
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 77	141	$ 19
Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	12 years
Defined Benefit Plan, Benefit Obligation	$ 8,321	7,869	$ 8,448
Accumulated Benefit Obligation at measurement date	$ 8,262	$ 7,818
Expected long-term rate of return on plan assets	6.85%	6.50%	6.75%
Employer contributions	$ 77	$ 141
Benefits paid	731	567
Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	318
Accumulated Benefit Obligation at measurement date	318
Employer contributions	25
Benefits paid	$ 25
Pension Plan | Master Trust
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage	98.00%
Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	8 years
Defined Benefit Plan, Benefit Obligation	$ 723	$ 728	$ 813
Expected long-term rate of return on plan assets	6.85%	6.50%	6.50%
Employer contributions	$ 60
Benefits paid	$ 83	$ 86
Other Post-Retirement Benefit Plans | Master Trust
Defined Benefit Plan Disclosure [Line Items]
Master trust allocation percentage	2.00%
Duke Energy Carolinas | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 7	46	$ 0
Duke Energy Carolinas | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	12 years
Defined Benefit Plan, Benefit Obligation	$ 1,923	1,954	2,029
Accumulated Benefit Obligation at measurement date	1,923	1,954
Employer contributions	7	46
Benefits paid	265	159
Duke Energy Carolinas | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	15
Accumulated Benefit Obligation at measurement date	15
Employer contributions	2
Benefits paid	$ 2
Duke Energy Carolinas | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	8 years
Defined Benefit Plan, Benefit Obligation	$ 175	174	189
Employer contributions	11
Benefits paid	19	18
Progress Energy | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 57	45	0
Progress Energy | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	12 years
Defined Benefit Plan, Benefit Obligation	$ 2,608	2,433	2,637
Accumulated Benefit Obligation at measurement date	2,578	2,404
Employer contributions	57	45
Benefits paid	191	143
Progress Energy | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	110
Accumulated Benefit Obligation at measurement date	110
Employer contributions	9
Benefits paid	$ 9
Progress Energy | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	6 years
Defined Benefit Plan, Benefit Obligation	$ 303	303	342
Employer contributions	26
Benefits paid	32	35
Duke Energy Progress | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 4	25	0
Duke Energy Progress | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	13 years
Defined Benefit Plan, Benefit Obligation	$ 1,170	1,125	1,211
Accumulated Benefit Obligation at measurement date	1,170	1,125
Employer contributions	4	25
Benefits paid	112	70
Duke Energy Progress | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	32
Accumulated Benefit Obligation at measurement date	32
Employer contributions	3
Duke Energy Progress | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	168	166	184
Employer contributions	13
Benefits paid	17	19
Duke Energy Florida | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 53	20	0
Duke Energy Florida | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	12 years
Defined Benefit Plan, Benefit Obligation	$ 1,424	1,295	1,410
Accumulated Benefit Obligation at measurement date	1,392	1,265
Employer contributions	53	20
Benefits paid	78	72
Duke Energy Florida | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	45
Accumulated Benefit Obligation at measurement date	45
Employer contributions	3
Benefits paid	$ 3
Duke Energy Florida | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Defined Benefit Plan, Benefit Obligation	$ 135	137	156
Employer contributions	13
Benefits paid	15	16
Duke Energy Ohio | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 2	0	4
Duke Energy Ohio | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	13 years
Defined Benefit Plan, Benefit Obligation	$ 481	435	479
Accumulated Benefit Obligation at measurement date	471	425
Employer contributions	2	0
Benefits paid	30	37
Duke Energy Ohio | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	4
Accumulated Benefit Obligation at measurement date	4
Benefits paid	$ 3
Duke Energy Ohio | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Defined Benefit Plan, Benefit Obligation	$ 29	29	30
Employer contributions	2
Benefits paid	3	2
Duke Energy Indiana | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 2	8	0
Duke Energy Indiana | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	13 years
Defined Benefit Plan, Benefit Obligation	$ 693	618	669
Accumulated Benefit Obligation at measurement date	686	614
Employer contributions	2	8
Benefits paid	46	55
Duke Energy Indiana | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	3
Accumulated Benefit Obligation at measurement date	$ 3
Duke Energy Indiana | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	6 years
Defined Benefit Plan, Benefit Obligation	$ 64	67	78
Employer contributions	9
Benefits paid	$ 11	12
Piedmont
Defined Benefit Plan Disclosure [Line Items]
Vesting period	3 years
Term	3 years
Piedmont | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 1	0	11
Piedmont | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	9 years
Defined Benefit Plan, Benefit Obligation	$ 292	264	313
Accumulated Benefit Obligation at measurement date	292	264
Employer contributions	1	0
Benefits paid	20	33
Piedmont | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	4
Accumulated Benefit Obligation at measurement date	$ 4
Piedmont | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	6 years
Defined Benefit Plan, Benefit Obligation	$ 30	30	$ 32
Employer contributions	0
Benefits paid	1	$ 2
Liability Hedging Assets | Pension Plan | Master Trust
Defined Benefit Plan Disclosure [Line Items]
Target allocation				58.00%
Return Seeking Assets | Pension Plan | Master Trust
Defined Benefit Plan Disclosure [Line Items]
Target allocation				42.00%
Minimum | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets			6.50%
Retirement plan settled
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	94
Retirement plan settled | Duke Energy Carolinas
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	53
Retirement plan settled | Progress Energy
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	26
Retirement plan settled | Duke Energy Progress
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	20
Retirement plan settled | Duke Energy Florida
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	6
Retirement plan settled | Duke Energy Ohio
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	2
Retirement plan settled | Duke Energy Indiana
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	4
Retirement plan settled | Piedmont
Defined Benefit Plan Disclosure [Line Items]
Settlement charges	$ 8