Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Defined Benefit Plan Disclosure [Line Items]
Maximum years of participation	35 years
Vesting period	3 years
Master Trust
Defined Benefit Plan Disclosure [Line Items]
Target allocation	100.00%
Expected long-term rate of return on plan assets	6.50%
Fair value of securities on loan	$ 482	$ 351
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	77	$ 141
Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	13 years
Defined Benefit Plan, Benefit Obligation	$ 8,634	8,321	$ 7,869
Accumulated Benefit Obligation at measurement date	$ 8,577	$ 8,262
Expected long-term rate of return on plan assets	6.85%	6.85%	6.50%
Employer contributions		$ 77
Benefits paid	$ 541	731
Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	320
Accumulated Benefit Obligation at measurement date	320
Employer contributions	23
Benefits paid	$ 23
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	$ 709	$ 723	$ 728
Expected long-term rate of return on plan assets	6.85%	6.85%	6.50%
Employer contributions	$ 53
Benefits paid	$ 75	$ 83
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	$ 0	7	$ 46
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	$ 1,988	1,923	1,954
Accumulated Benefit Obligation at measurement date	1,989	1,923
Employer contributions		7
Benefits paid	137	265
Duke Energy Carolinas | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	13
Accumulated Benefit Obligation at measurement date	13
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	$ 174	175	174
Employer contributions	10
Benefits paid	18	19
Progress Energy | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	57	45
Progress Energy | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	14 years
Defined Benefit Plan, Benefit Obligation	$ 2,715	2,608	2,433
Accumulated Benefit Obligation at measurement date	2,684	2,578
Employer contributions		57
Benefits paid	160	191
Progress Energy | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	111
Accumulated Benefit Obligation at measurement date	111
Employer contributions	8
Benefits paid	$ 8
Progress Energy | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	7 years
Defined Benefit Plan, Benefit Obligation	$ 299	303	303
Employer contributions	23
Benefits paid	28	32
Duke Energy Progress | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	4	25
Duke Energy Progress | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	14 years
Defined Benefit Plan, Benefit Obligation	$ 1,193	1,170	1,125
Accumulated Benefit Obligation at measurement date	1,194	1,170
Employer contributions		4
Benefits paid	83	112
Duke Energy Progress | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	33
Accumulated Benefit Obligation at measurement date	33
Employer contributions	3
Benefits paid	$ 3
Duke Energy Progress | Other Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	6 years
Defined Benefit Plan, Benefit Obligation	$ 166	168	166
Employer contributions	11
Benefits paid	15	17
Duke Energy Florida | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	53	20
Duke Energy Florida | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	14 years
Defined Benefit Plan, Benefit Obligation	$ 1,507	1,424	1,295
Accumulated Benefit Obligation at measurement date	1,476	1,392
Employer contributions		53
Benefits paid	76	78
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	$ 130	135	137
Employer contributions	10
Benefits paid	13	15
Duke Energy Ohio | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	2	0
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	$ 502	481	435
Accumulated Benefit Obligation at measurement date	493	471
Employer contributions		2
Benefits paid	34	30
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
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	$ 27	29	29
Employer contributions	3
Benefits paid	4	3
Duke Energy Indiana | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	2	8
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	$ 715	693	618
Accumulated Benefit Obligation at measurement date	709	686
Employer contributions		2
Benefits paid	49	46
Duke Energy Indiana | Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation	2
Accumulated Benefit Obligation at measurement date	$ 2
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	$ 61	64	67
Employer contributions	8
Benefits paid	$ 9	11
Piedmont
Defined Benefit Plan Disclosure [Line Items]
Term	3 years
Piedmont | Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0	1	0
Piedmont | Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Average remaining service period, in years	9 years
Defined Benefit Plan, Benefit Obligation	$ 293	292	264
Accumulated Benefit Obligation at measurement date	294	292
Employer contributions		1
Benefits paid	27	20
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	$ 30
Employer contributions	1
Benefits paid	$ 2	1
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
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