Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	$ 1,088	$ 1,145
Regulatory assets	12,250	12,157
Regulatory liabilities	6,655	6,397
Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	107	111
Regulatory assets	3,071	2,864
Regulatory liabilities	2,841	2,744
Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	536	533
Regulatory assets	5,797	5,899
Regulatory liabilities	2,673	2,485
Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	262	290
Regulatory assets	2,974	2,962
Regulatory liabilities	1,963	1,903
Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	242	221
Regulatory assets	2,823	2,936
Regulatory liabilities	709	582
Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	56	48
Regulatory assets	533	561
Regulatory liabilities	257	251
Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	80	82
Regulatory assets	818	778
Regulatory liabilities	816	850
Pension Plan [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	474	441
Noncurrent pension liability	65	50
Net amount recognized	409	391
Regulatory assets	1,884	1,711
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(45)	(51)
Prior year service cost (credit) arising during the year	(4)	(5)
Net actuarial loss (gain)	130	140
Net amount recognized in accumulated other comprehensive income (loss)	81	84
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	132
Unrecognized prior service (credit) cost	(16)
Pension Plan [Member] | Brazilian Retirement Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Net amount recognized in accumulated other comprehensive income (loss)	13	22
Pension Plan [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	252	247
Noncurrent pension liability	4
Net amount recognized	248	247
Regulatory assets	472	407
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	31
Unrecognized prior service (credit) cost	(8)
Pension Plan [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	232	165
Noncurrent pension liability	43
Net amount recognized	189	165
Regulatory assets	771	753
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(6)	(11)
Net actuarial loss (gain)	17	21
Net amount recognized in accumulated other comprehensive income (loss)	11	10
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	59
Unrecognized prior service (credit) cost	(3)
Pension Plan [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	145	134
Noncurrent pension liability	4
Net amount recognized	141	134
Regulatory assets	360	346
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	25
Unrecognized prior service (credit) cost	(2)
Pension Plan [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	84	28
Noncurrent pension liability	39
Net amount recognized	45	28
Regulatory assets	410	$ 406
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	31
Unrecognized prior service (credit) cost	(1)
Pension Plan [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	1
Noncurrent pension liability	21	$ 13
Net amount recognized	(20)	(13)
Regulatory assets	79	65
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	4
Pension Plan [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Prefunded pension	6	8
Net amount recognized	6	8
Regulatory assets	162	151
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	11
Non-Qualified Pension Plans [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	27	27
Noncurrent pension liability	314	310
Total accrued pension liability	341	337
Regulatory assets	76	89
Regulatory liabilities		0
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(3)	4
Prior year service cost (credit) arising during the year		(1)
Net actuarial loss (gain)	9	(8)
Net amount recognized in accumulated other comprehensive income (loss)	6	(5)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	8
Unrecognized prior service (credit) cost	(1)
Non-Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	2	2
Noncurrent pension liability	14	14
Total accrued pension liability	16	16
Regulatory assets	7	5
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	8	8
Noncurrent pension liability	104	108
Total accrued pension liability	112	116
Regulatory assets	16	32
Regulatory liabilities		0
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax asset	(3)	2
Net actuarial loss (gain)	9	(4)
Net amount recognized in accumulated other comprehensive income (loss)	6	(2)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	1
Non-Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	3
Noncurrent pension liability	30	32
Total accrued pension liability	33	35
Regulatory assets	6	7
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	3	4
Noncurrent pension liability	43	57
Total accrued pension liability	46	61
Regulatory assets	10	25
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	0
Noncurrent pension liability	4	4
Total accrued pension liability	4	4
Regulatory assets	1	1
Regulatory liabilities		0
Non-Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	0
Noncurrent pension liability	5	5
Total accrued pension liability	5	5
Regulatory assets	1	2
Regulatory liabilities		0
Other Post-Retirement Benefit Plans [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	37	35
Noncurrent pension liability	583	654
Total accrued pension liability	620	689
Regulatory assets	1
Regulatory liabilities	288	380
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability	7	5
Prior year service cost (credit) arising during the year	(6)	(9)
Net actuarial loss (gain)	(13)	(5)
Net amount recognized in accumulated other comprehensive income (loss)	(12)	(9)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	6
Unrecognized prior service (credit) cost	(142)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	66	75
Total accrued pension liability	66	75
Regulatory liabilities	68	76
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	(3)
Unrecognized prior service (credit) cost	(14)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	31	29
Noncurrent pension liability	323	350
Total accrued pension liability	354	379
Regulatory assets	1
Regulatory liabilities	51	122
Accumulated Other Comprehensive Income (Loss) [Abstract]
Deferred income tax liability		1
Prior year service cost (credit) arising during the year	(1)
Net actuarial loss (gain)		(2)
Net amount recognized in accumulated other comprehensive income (loss)	(1)	(1)
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	22
Unrecognized prior service (credit) cost	(103)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	16	16
Noncurrent pension liability	172	192
Total accrued pension liability	188	208
Regulatory liabilities	25	61
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	13
Unrecognized prior service (credit) cost	(68)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Current pension liability	15	14
Noncurrent pension liability	149	156
Total accrued pension liability	164	170
Regulatory assets	1
Regulatory liabilities	26	61
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	9
Unrecognized prior service (credit) cost	(35)
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	25	29
Total accrued pension liability	27	31
Regulatory liabilities	21	19
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	(2)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Amounts Recognized in Consolidated Balance Sheets [Abstract]
Noncurrent pension liability	68	73
Total accrued pension liability	68	73
Regulatory assets	57	64
Regulatory liabilities	83	$ 91
Amounts to be recognized in net periodic pension expense in the next year [Abstract]
Unrecognized net actuarial loss	(2)
Unrecognized prior service (credit) cost	$ (1)