Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	$ 969	$ 934
Regulatory assets	14,062	15,018
Regulatory liabilities	16,406	16,048
Duke Energy Carolinas
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	73	84
Regulatory assets	3,469	3,910
Regulatory liabilities	7,008	6,678
Progress Energy
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	505	488
Regulatory assets	6,533	7,292
Regulatory liabilities	5,691	5,555
Duke Energy Progress
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	242	238
Regulatory assets	4,468	4,678
Regulatory liabilities	4,924	4,468
Duke Energy Florida
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	231	218
Regulatory assets	2,064	2,613
Regulatory liabilities	768	1,087
Duke Energy Ohio
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	113	100
Regulatory assets	649	598
Regulatory liabilities	813	827
Duke Energy Indiana
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	171	148
Regulatory assets	1,328	1,172
Regulatory liabilities	1,738	1,740
Piedmont
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	8	3
Regulatory assets	455	363
Regulatory liabilities	1,132	1,212
Pension Plan | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	780	621
Noncurrent pension liability	77	32
Net amount recognized	703	589
Regulatory assets	1,910	1,972
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(21)	(23)
Prior year service cost (credit) arising during the year	(2)	(3)
Net actuarial loss (gain)	100	111
Net amount recognized in accumulated other comprehensive income (loss)	77	85
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		135
Unrecognized prior service (credit) cost		(32)
Pension Plan | Duke Energy Carolinas | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	393	340
Noncurrent pension liability	0	0
Net amount recognized	393	340
Regulatory assets	381	420
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		29
Unrecognized prior service (credit) cost		(8)
Pension Plan | Progress Energy | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	379	322
Noncurrent pension liability	45	32
Net amount recognized	334	290
Regulatory assets	691	717
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	0	(1)
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	2	3
Net amount recognized in accumulated other comprehensive income (loss)	2	2
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		43
Unrecognized prior service (credit) cost		(3)
Pension Plan | Duke Energy Progress | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	229	194
Noncurrent pension liability	0	0
Net amount recognized	229	194
Regulatory assets	283	313
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		19
Unrecognized prior service (credit) cost		(2)
Pension Plan | Duke Energy Florida | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	143	123
Noncurrent pension liability	45	32
Net amount recognized	98	91
Regulatory assets	408	404
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	0	(1)
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	3
Net amount recognized in accumulated other comprehensive income (loss)	0	2
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		24
Unrecognized prior service (credit) cost		(1)
Pension Plan | Duke Energy Ohio | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	58	38
Noncurrent pension liability	88	76
Net amount recognized	(30)	(38)
Regulatory assets	110	112
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		7
Unrecognized prior service (credit) cost		(1)
Pension Plan | Duke Energy Indiana | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	79	57
Noncurrent pension liability	110	83
Net amount recognized	(31)	(26)
Regulatory assets	209	204
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		10
Unrecognized prior service (credit) cost		(2)
Pension Plan | Piedmont | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	50	43
Noncurrent pension liability	0	0
Net amount recognized	50	43
Regulatory assets	80	81
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		9
Unrecognized prior service (credit) cost		(9)
Other Post-Retirement Benefit Plans
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	8
Current pension liability	9	9
Noncurrent pension liability	471	494
Net amount recognized	(472)
Total accrued pension liability		503
Regulatory assets	144	135
Regulatory liabilities	139	149
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	3	3
Prior year service cost (credit) arising during the year	(1)	(2)
Net actuarial loss (gain)	(13)	(13)
Net amount recognized in accumulated other comprehensive income (loss)	(11)	(12)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		5
Unrecognized prior service (credit) cost		(14)
Other Post-Retirement Benefit Plans | Duke Energy Carolinas
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	0
Current pension liability	0	0
Noncurrent pension liability	35	45
Net amount recognized	(35)
Total accrued pension liability		45
Regulatory assets	0	0
Regulatory liabilities	32	39
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		3
Unrecognized prior service (credit) cost		(4)
Other Post-Retirement Benefit Plans | Progress Energy
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	0
Current pension liability	6	5
Noncurrent pension liability	294	299
Net amount recognized	(300)
Total accrued pension liability		304
Regulatory assets	144	135
Regulatory liabilities	0	0
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		1
Unrecognized prior service (credit) cost		(3)
Other Post-Retirement Benefit Plans | Duke Energy Progress
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	0
Current pension liability	4	3
Noncurrent pension liability	164	163
Net amount recognized	(168)
Total accrued pension liability		166
Regulatory assets	88	82
Regulatory liabilities	0	0
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		0
Unrecognized prior service (credit) cost		(1)
Other Post-Retirement Benefit Plans | Duke Energy Florida
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	0
Current pension liability	2	2
Noncurrent pension liability	129	133
Net amount recognized	(131)
Total accrued pension liability		135
Regulatory assets	56	53
Regulatory liabilities	0	0
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		1
Unrecognized prior service (credit) cost		(2)
Other Post-Retirement Benefit Plans | Duke Energy Ohio
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	1
Current pension liability	2	1
Noncurrent pension liability	17	19
Net amount recognized	(18)
Total accrued pension liability		20
Regulatory assets	0	0
Regulatory liabilities	17	17
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		0
Unrecognized prior service (credit) cost		(1)
Other Post-Retirement Benefit Plans | Duke Energy Indiana
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	0
Current pension liability	0	0
Noncurrent pension liability	54	59
Net amount recognized	(54)
Total accrued pension liability		59
Regulatory assets	32	36
Regulatory liabilities	62	63
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		0
Unrecognized prior service (credit) cost		(1)
Other Post-Retirement Benefit Plans | Piedmont
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	7
Current pension liability	0	0
Noncurrent pension liability	0	(4)
Net amount recognized	7
Total accrued pension liability		(4)
Regulatory assets	0	0
Regulatory liabilities	3	3
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	0	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	0	0
Net amount recognized in accumulated other comprehensive income (loss)	$ 0	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		0
Unrecognized prior service (credit) cost		$ (2)