Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	$ 988	$ 1,103
Regulatory assets	15,622	13,879
Regulatory Liabilities	15,432	15,732
Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	99	95
Regulatory assets	3,977	3,152
Regulatory Liabilities	6,198	6,357
Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	521	545
Regulatory assets	7,701	6,751
Regulatory Liabilities	5,329	5,519
Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	237	248
Regulatory assets	4,814	3,859
Regulatory Liabilities	4,133	4,138
Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	254	264
Regulatory assets	2,888	2,892
Regulatory Liabilities	1,196	1,381
Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	79	59
Regulatory assets	564	494
Regulatory Liabilities	897	927
Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	115	76
Regulatory assets	1,157	1,143
Regulatory Liabilities	1,747	1,747
Piedmont Natural Gas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	4	5
Regulatory assets	357	378
Regulatory Liabilities	1,218	1,144
Pension Plan [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	433	680
Noncurrent pension liability	69	125
Net amount recognized	364	555
Regulatory assets	2,184	1,886
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(43)	(41)
Prior year service cost (credit) arising during the year	(4)	(5)
Net actuarial loss (gain)	126	116
Net amount recognized in accumulated other comprehensive income (loss)	79	70
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	97	132
Unrecognized prior service (credit) cost	(32)	(32)
Pension Plan [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	21	23
Noncurrent pension liability	283	308
Total accrued pension liability	304	331
Regulatory assets	62	78
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(3)	(4)
Prior year service cost (credit) arising during the year	(1)	(1)
Net actuarial loss (gain)	8	12
Net amount recognized in accumulated other comprehensive income (loss)	4	7
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	6	8
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	214	343
Net amount recognized	214	343
Regulatory assets	576	406
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	22	29
Unrecognized prior service (credit) cost	(8)	(8)
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	12	12
Total accrued pension liability	14	14
Regulatory assets	5	4
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	242	245
Noncurrent pension liability	69	68
Net amount recognized	173	177
Regulatory assets	796	756
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(2)	(3)
Net actuarial loss (gain)	5	9
Net amount recognized in accumulated other comprehensive income (loss)	3	6
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	37	44
Unrecognized prior service (credit) cost	(3)	(3)
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	8	8
Noncurrent pension liability	98	108
Total accrued pension liability	106	116
Regulatory assets	15	21
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(2)	(3)
Net actuarial loss (gain)	6	9
Net amount recognized in accumulated other comprehensive income (loss)	4	6
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	2	2
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	143	155
Net amount recognized	143	155
Regulatory assets	372	341
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	13	21
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	3
Noncurrent pension liability	28	32
Total accrued pension liability	31	35
Regulatory assets	5	8
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	1	1
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	96	87
Noncurrent pension liability	69	68
Net amount recognized	27	19
Regulatory assets	424	415
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	24	23
Unrecognized prior service (credit) cost	(1)	(1)
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	3
Noncurrent pension liability	40	44
Total accrued pension liability	43	47
Regulatory assets	10	13
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	1	1
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	24	8
Noncurrent pension liability	54	29
Net amount recognized	(30)	(21)
Regulatory assets	100	90
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	3	5
Pension Plan [Member] | Duke Energy Ohio [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	3	4
Total accrued pension liability	3	4
Regulatory assets	1	1
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	39	16
Noncurrent pension liability	46	1
Net amount recognized	(7)	15
Regulatory assets	182	152
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	5	7
Unrecognized prior service (credit) cost	(2)	(2)
Pension Plan [Member] | Duke Energy Indiana [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	3	3
Total accrued pension liability	3	3
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	41	55
Net amount recognized	41	55
Regulatory assets	81	73
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	7	11
Unrecognized prior service (credit) cost	(9)	(9)
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	3	4
Total accrued pension liability	3	4
Regulatory assets	1	1
Other Post-Retirement Benefit Plans [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	8	36
Noncurrent pension liability	525	552
Total accrued pension liability	533	588
Regulatory assets	262	125
Regulatory Liabilities	301	147
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	3	4
Prior year service cost (credit) arising during the year	(2)	(2)
Net actuarial loss (gain)	(9)	(10)
Net amount recognized in accumulated other comprehensive income (loss)	(8)	(8)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	4	5
Unrecognized prior service (credit) cost	(19)	(19)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	59	56
Total accrued pension liability	59	56
Regulatory Liabilities	38	44
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	2	3
Unrecognized prior service (credit) cost	(5)	(5)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	5	29
Noncurrent pension liability	298	313
Total accrued pension liability	303	342
Regulatory assets	262	129
Regulatory Liabilities	149
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	(7)	(7)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	15
Noncurrent pension liability	163	169
Total accrued pension liability	166	184
Regulatory assets	164	80
Regulatory Liabilities	93
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	14
Noncurrent pension liability	135	142
Total accrued pension liability	137	156
Regulatory assets	98	49
Regulatory Liabilities	56
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss		1
Unrecognized prior service (credit) cost	(6)	(6)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	19	21
Total accrued pension liability	21	23
Regulatory Liabilities	18	16
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	62	67
Total accrued pension liability	62	67
Regulatory assets	41	46
Regulatory Liabilities	67	64
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	(1)	(1)
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	1	1
Total accrued pension liability	1	1
Regulatory assets		(4)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized prior service (credit) cost	$ (2)	$ (2)