Employee Benefit Plans (Projected Benefit Obligations Reconciliation of Funded Status to Net Amount Recognized) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in Projected Benefit Obligation [Rollforward]
Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation	$ 352
Settlements	(6)
Change in Fair Value of Plan Assets [Rollforward]
Assets received from acquisition	343
Impact of Settlements	(6)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Other Changes		$ (83)
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	7,727	8,107
Service cost	147	159	$ 135
Interest cost on projected benefit obligation	335	324	344
Actuarial (gains) losses	307	(241)
Plan amendments	(52)	(6)
Benefits paid	(679)	(533)
Obligation at measurement date	8,131	7,727	8,107
Accumulated benefit obligation at measurement date	8,006	7,606
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(8,136)	(8,498)
Defined Benefit Plan, Divestitures, Plan Assets		(81)
Actual return on plan assets	582	(50)
Benefits paid	(679)	(533)
Employer contributions	155	302
Plan assets at measurement date	(8,531)	(8,136)	(8,498)
Funded status of plan	400	409
Pension Plan [Member] | Duke Energy Carolinas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	1,995	2,053
Service cost	48	50	41
Interest cost on projected benefit obligation	86	83	85
Actuarial (gains) losses	46	(53)
Transfers of benefit obligation	14	8
Plan amendments	(3)
Benefits paid	(234)	(146)
Obligation at measurement date	1,952	1,995	2,053
Accumulated benefit obligation at measurement date	1,952	1,993
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(2,243)	(2,300)
Actual return on plan assets	159	(10)
Benefits paid	(234)	(146)
Employer contributions	43	91
Transfer of plan assets	14	8
Plan assets at measurement date	(2,225)	(2,243)	(2,300)
Funded status of plan	273	248
Pension Plan [Member] | Progress Energy [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	2,451	2,557
Service cost	42	44	40
Interest cost on projected benefit obligation	106	104	112
Actuarial (gains) losses	111	(111)
Transfers of benefit obligation	3	4
Benefits paid	(195)	(147)
Obligation at measurement date	2,512	2,451	2,557
Accumulated benefit obligation at measurement date	2,479	2,414
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(2,640)	(2,722)
Actual return on plan assets	190	(22)
Benefits paid	(195)	(147)
Employer contributions	43	83
Transfer of plan assets	(3)	4
Plan assets at measurement date	(2,675)	(2,640)	(2,722)
Funded status of plan	163	189
Pension Plan [Member] | Duke Energy Progress [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	1,143	1,187
Service cost	24	23	21
Interest cost on projected benefit obligation	49	48	54
Actuarial (gains) losses	52	(46)
Transfers of benefit obligation	3	7
Benefits paid	(107)	(76)
Obligation at measurement date	1,158	1,143	1,187
Accumulated benefit obligation at measurement date	1,158	1,143
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(1,284)	(1,321)
Actual return on plan assets	92	(10)
Benefits paid	(107)	(76)
Employer contributions	24	42
Transfer of plan assets	(3)	7
Plan assets at measurement date	(1,290)	(1,284)	(1,321)
Funded status of plan	132	141
Pension Plan [Member] | Duke Energy Florida [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	1,276	1,335
Service cost	19	20	20
Interest cost on projected benefit obligation	55	54	57
Actuarial (gains) losses	57	(62)
Transfers of benefit obligation		3
Benefits paid	(84)	(68)
Obligation at measurement date	1,323	1,276	1,335
Accumulated benefit obligation at measurement date	1,290	1,240
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(1,321)	(1,363)
Actual return on plan assets	95	(11)
Benefits paid	(84)	(68)
Employer contributions	20	40
Transfer of plan assets		(3)
Plan assets at measurement date	(1,352)	(1,321)	(1,363)
Funded status of plan	29	45
Pension Plan [Member] | Duke Energy Ohio [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	453	469
Service cost	4	4	4
Interest cost on projected benefit obligation	19	18	20
Actuarial (gains) losses	13	(9)
Transfers of benefit obligation	3	8
Plan amendments	(3)
Benefits paid	(36)	(37)
Obligation at measurement date	447	453	469
Accumulated benefit obligation at measurement date	436	442
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(433)	(456)
Actual return on plan assets	29	(2)
Benefits paid	(36)	(37)
Employer contributions	5	8
Transfer of plan assets	(3)	8
Plan assets at measurement date	(428)	(433)	(456)
Funded status of plan	(19)	(20)
Pension Plan [Member] | Duke Energy Indiana [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	649	673
Service cost	9	10	9
Interest cost on projected benefit obligation	28	27	29
Actuarial (gains) losses	41	(15)
Plan amendments	(15)	(4)
Benefits paid	(54)	(42)
Obligation at measurement date	658	649	673
Accumulated benefit obligation at measurement date	649	628
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(655)	(681)
Actual return on plan assets	47	(3)
Benefits paid	(54)	(42)
Employer contributions	9	19
Plan assets at measurement date	(657)	(655)	(681)
Funded status of plan	(1)	6
Non Qualified Pension Plans [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	341	337
Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation	5
Service cost	2	3	3
Interest cost on projected benefit obligation	14	13	14
Actuarial (gains) losses	4	10
Transfers of benefit obligation		4
Plan amendments	2
Benefits paid	(32)	(26)
Obligation at measurement date	332	341	337
Accumulated benefit obligation at measurement date	332	336
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(32)	(26)
Employer contributions	32	26
Non Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	16	16
Interest cost on projected benefit obligation	1	1	1
Actuarial (gains) losses	(1)	1
Benefits paid	(2)	(2)
Obligation at measurement date	14	16	16
Accumulated benefit obligation at measurement date	14	16
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(2)	(2)
Employer contributions	2	2
Non Qualified Pension Plans [Member] | Progress Energy [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	112	116
Service cost		1	1
Interest cost on projected benefit obligation	5	4	5
Actuarial (gains) losses	5	(1)
Benefits paid	(8)	(8)
Obligation at measurement date	114	112	116
Accumulated benefit obligation at measurement date	114	112
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(8)	(8)
Employer contributions	8	8
Non Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	33	35
Service cost			1
Interest cost on projected benefit obligation	1	1	1
Actuarial (gains) losses	2
Benefits paid	(3)	(3)
Obligation at measurement date	33	33	35
Accumulated benefit obligation at measurement date	33	33
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(3)	(3)
Employer contributions	3	3
Non Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	46	61
Interest cost on projected benefit obligation	2	2	2
Actuarial (gains) losses	1	(14)
Benefits paid	(3)	(3)
Obligation at measurement date	46	46	61
Accumulated benefit obligation at measurement date	46	46
Change in Fair Value of Plan Assets [Rollforward]
Benefits paid	(3)	(3)
Employer contributions	3	3
Non Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	4	4
Obligation at measurement date	4	4	4
Accumulated benefit obligation at measurement date	4	4
Non Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	5	5
Actuarial (gains) losses	(2)
Obligation at measurement date	3	5	5
Accumulated benefit obligation at measurement date	3	5
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Other Changes	39
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	828	916
Service cost	3	6	10
Interest cost on projected benefit obligation	35	36	49
Plan participants' contributions	19	20
Actuarial (gains) losses	33	(39)
Plan amendments	(1)	(9)
Benefits paid	(88)	(100)
Accrued retiree drug subsidy		1
Obligation at measurement date	868	828	916
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(208)	(227)
Defined Benefit Plan, Divestitures, Plan Assets		(3)
Assets received from acquisition	29
Actual return on plan assets	14	(1)
Benefits paid	(88)	(100)
Employer contributions	62	62
Plan participants' contributions	19	20
Plan assets at measurement date	(244)	(208)	(227)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	200	220
Service cost	1	1	2
Interest cost on projected benefit obligation	8	9	12
Plan participants' contributions	3	4
Actuarial (gains) losses	5	(18)
Transfers of benefit obligation	1	2
Benefits paid	(17)	(18)
Obligation at measurement date	201	200	220
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(134)	(145)
Actual return on plan assets	8	(1)
Benefits paid	(17)	(18)
Employer contributions	9	4
Plan participants' contributions	3	4
Plan assets at measurement date	(137)	(134)	(145)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	354	379
Service cost	1	1	4
Interest cost on projected benefit obligation	15	15	22
Plan participants' contributions	7	7
Actuarial (gains) losses	16	(1)
Benefits paid	(36)	(47)
Obligation at measurement date	357	354	379
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date
Actual return on plan assets	1	1
Benefits paid	(36)	(47)
Employer contributions	29	39
Plan participants' contributions	7	7
Plan assets at measurement date	(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	188	207
Service cost		1	1
Interest cost on projected benefit obligation	8	8	11
Plan participants' contributions	4	4
Actuarial (gains) losses	8	(13)
Benefits paid	(17)	(19)
Obligation at measurement date	191	188	207
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date		(1)
Actual return on plan assets		1
Benefits paid	(17)	(19)
Employer contributions	13	15
Plan participants' contributions	4	4
Plan assets at measurement date			(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	164	170
Service cost	1	1	3
Interest cost on projected benefit obligation	7	7	12
Plan participants' contributions	3	3
Actuarial (gains) losses	8	11
Benefits paid	(19)	(28)
Obligation at measurement date	164	164	170
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(1)
Actual return on plan assets		1
Benefits paid	(19)	(28)
Employer contributions	15	25
Plan participants' contributions	3	3
Plan assets at measurement date		(1)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	35	39
Interest cost on projected benefit obligation	1	2	2
Plan participants' contributions	1	1
Actuarial (gains) losses		(3)
Plan amendments	(1)	(1)
Benefits paid	(4)	(3)
Obligation at measurement date	32	35	39
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(8)	(8)
Actual return on plan assets	1
Benefits paid	(4)	(3)
Employer contributions	1	2
Plan participants' contributions	1	1
Plan assets at measurement date	(7)	(8)	(8)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Change in Projected Benefit Obligation [Rollforward]
Obligation at prior measurement date	87	96
Service cost		1	1
Interest cost on projected benefit obligation	4	4	5
Plan participants' contributions	2	2
Actuarial (gains) losses	3	1
Plan amendments		(4)
Benefits paid	(13)	(13)
Obligation at measurement date	83	87	96
Change in Fair Value of Plan Assets [Rollforward]
Plan assets at prior measurement date	(19)	(23)
Actual return on plan assets	2	(1)
Benefits paid	(13)	(13)
Employer contributions	12	8
Plan participants' contributions	2	2
Plan assets at measurement date	$ (22)	$ (19)	$ (23)