Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	$ 934	$ 988
Regulatory assets	15,018	15,622
Regulatory liabilities	16,048	15,432
Duke Energy Carolinas
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	84	99
Regulatory assets	3,910	3,977
Regulatory liabilities	6,678	6,198
Progress Energy
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	488	521
Regulatory assets	7,292	7,701
Regulatory liabilities	5,555	5,329
Duke Energy Progress
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	238	237
Regulatory assets	4,678	4,814
Regulatory liabilities	4,468	4,133
Duke Energy Florida
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	218	254
Regulatory assets	2,613	2,888
Regulatory liabilities	1,087	1,196
Duke Energy Ohio
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	100	79
Regulatory assets	598	564
Regulatory liabilities	827	897
Duke Energy Indiana
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	148	115
Regulatory assets	1,172	1,157
Regulatory liabilities	1,740	1,747
Piedmont
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	3	4
Regulatory assets	363	357
Regulatory liabilities	1,212	1,218
Pension Plan | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	621	433
Noncurrent pension liability	32	69
Net amount recognized	589	364
Regulatory assets	1,972	2,184
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(23)	(43)
Prior year service cost (credit) arising during the year	(3)	(4)
Net actuarial loss (gain)	111	126
Net amount recognized in accumulated other comprehensive income (loss)	85	79
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	135	97
Unrecognized prior service (credit) cost	(32)	(32)
Pension Plan | Duke Energy Carolinas | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	340	214
Noncurrent pension liability	0	0
Net amount recognized	340	214
Regulatory assets	420	576
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	22
Unrecognized prior service (credit) cost	(8)	(8)
Pension Plan | Progress Energy | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	322	242
Noncurrent pension liability	32	69
Net amount recognized	290	173
Regulatory assets	717	796
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(1)	(2)
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	3	5
Net amount recognized in accumulated other comprehensive income (loss)	2	3
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	43	37
Unrecognized prior service (credit) cost	(3)	(3)
Pension Plan | Duke Energy Progress | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	194	143
Noncurrent pension liability	0	0
Net amount recognized	194	143
Regulatory assets	313	372
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	13
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan | Duke Energy Florida | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	123	96
Noncurrent pension liability	32	69
Net amount recognized	91	27
Regulatory assets	404	424
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(1)	0
Prior year service cost (credit) arising during the year	0	0
Net actuarial loss (gain)	3	0
Net amount recognized in accumulated other comprehensive income (loss)	2	0
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	24	24
Unrecognized prior service (credit) cost	(1)	(1)
Pension Plan | Duke Energy Ohio | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	38	24
Noncurrent pension liability	76	54
Net amount recognized	(38)	(30)
Regulatory assets	112	100
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	3
Unrecognized prior service (credit) cost	(1)	0
Pension Plan | Duke Energy Indiana | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	57	39
Noncurrent pension liability	83	46
Net amount recognized	(26)	(7)
Regulatory assets	204	182
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	5
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan | Piedmont | Qualified Plan
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	43	41
Noncurrent pension liability	0	0
Net amount recognized	43	41
Regulatory assets	81	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	7
Unrecognized prior service (credit) cost	(9)	(9)
Other Post-Retirement Benefit Plans
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	9	8
Noncurrent pension liability	494	525
Total accrued pension liability	503	533
Regulatory assets	135	262
Regulatory liabilities	149	301
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	3	3
Prior year service cost (credit) arising during the year	(2)	(2)
Net actuarial loss (gain)	(13)	(9)
Net amount recognized in accumulated other comprehensive income (loss)	(12)	(8)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	5	4
Unrecognized prior service (credit) cost	(14)	(19)
Other Post-Retirement Benefit Plans | Duke Energy Carolinas
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	0	0
Noncurrent pension liability	45	59
Total accrued pension liability	45	59
Regulatory assets	0	0
Regulatory liabilities	39	38
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	2
Unrecognized prior service (credit) cost	(4)	(5)
Other Post-Retirement Benefit Plans | Progress Energy
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	5	5
Noncurrent pension liability	299	298
Total accrued pension liability	304	303
Regulatory assets	135	262
Regulatory liabilities	0	149
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	1
Unrecognized prior service (credit) cost	(3)	(7)
Other Post-Retirement Benefit Plans | Duke Energy Progress
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	3
Noncurrent pension liability	166	163
Total accrued pension liability	169	166
Regulatory assets	82	164
Regulatory liabilities	0	93
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	0
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans | Duke Energy Florida
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	133	135
Total accrued pension liability	135	137
Regulatory assets	53	98
Regulatory liabilities	0	56
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	0
Unrecognized prior service (credit) cost	(2)	(6)
Other Post-Retirement Benefit Plans | Duke Energy Ohio
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	1	2
Noncurrent pension liability	19	19
Total accrued pension liability	20	21
Regulatory assets	0	0
Regulatory liabilities	17	18
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	0
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans | Duke Energy Indiana
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	0	0
Noncurrent pension liability	59	62
Total accrued pension liability	59	62
Regulatory assets	36	41
Regulatory liabilities	63	67
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	0
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans | Piedmont
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	0	0
Noncurrent pension liability	(4)	1
Total accrued pension liability	(4)	1
Regulatory assets	0	0
Regulatory liabilities	3	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	0
Unrecognized prior service (credit) cost	$ (2)	$ (2)