Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		$ 1	$ 2	$ 4
Interest cost on projected benefit obligation	$ 9	9	26	27
Expected return on plan assets	(2)	(3)	(9)	(9)
Amortization of actuarial loss (gain)	2	6	5	19
Amortization of prior service cost (credit)	(35)	(35)	(106)	(105)
Net periodic costs	(26)	(22)	(82)	(64)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost				1
Interest cost on projected benefit obligation	2	2	6	6
Expected return on plan assets	(2)	(2)	(6)	(6)
Amortization of actuarial loss (gain)			(2)	(1)
Amortization of prior service cost (credit)	(4)	(4)	(10)	(11)
Net periodic costs	(4)	(4)	(12)	(11)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1		1	1
Interest cost on projected benefit obligation	4	4	11	11
Expected return on plan assets	(1)		(1)
Amortization of actuarial loss (gain)	5	7	16	21
Amortization of prior service cost (credit)	(26)	(26)	(77)	(77)
Net periodic costs	(17)	(15)	(50)	(44)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	2	6	6
Amortization of actuarial loss (gain)	3	5	9	14
Amortization of prior service cost (credit)	(16)	(17)	(50)	(50)
Net periodic costs	(11)	(10)	(35)	(30)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	3	2	6	5
Amortization of actuarial loss (gain)	2	3	7	8
Amortization of prior service cost (credit)	(8)	(9)	(26)	(25)
Net periodic costs	(3)	(4)	(13)	(12)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation			1	1
Amortization of actuarial loss (gain)	(1)		(2)
Net periodic costs	(1)		(1)	1
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	1	1	3	3
Expected return on plan assets			(1)
Amortization of actuarial loss (gain)			(1)	(1)
Amortization of prior service cost (credit)	(1)		(1)
Net periodic costs		1		2
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	36	40	109	119
Interest cost on projected benefit obligation	83	81	249	244
Expected return on plan assets	(128)	(129)	(386)	(387)
Amortization of actuarial loss (gain)	33	44	99	131
Amortization of prior service cost (credit)	(4)	(4)	(12)	(11)
Other	2	2	6	6
Net periodic costs	22	34	65	102
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	12	13	36	38
Interest cost on projected benefit obligation	21	21	64	62
Expected return on plan assets	(35)	(35)	(106)	(104)
Amortization of actuarial loss (gain)	8	10	24	30
Amortization of prior service cost (credit)	(2)	(2)	(6)	(6)
Other	1	1	2	2
Net periodic costs	5	8	14	22
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	11	11	32	33
Interest cost on projected benefit obligation	27	26	80	78
Expected return on plan assets	(42)	(43)	(126)	(127)
Amortization of actuarial loss (gain)	14	17	41	51
Amortization of prior service cost (credit)	(1)	(1)	(3)	(3)
Other	1	1	2	2
Net periodic costs	10	11	26	34
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	6	18	18
Interest cost on projected benefit obligation	12	12	37	36
Expected return on plan assets	(21)	(20)	(62)	(61)
Amortization of actuarial loss (gain)	6	8	17	25
Amortization of prior service cost (credit)			(1)	(1)
Other			1	1
Net periodic costs	3	6	10	18
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	4	5	14	15
Interest cost on projected benefit obligation	14	14	42	41
Expected return on plan assets	(21)	(22)	(63)	(66)
Amortization of actuarial loss (gain)	7	8	21	24
Amortization of prior service cost (credit)	(1)		(1)	(1)
Other	1		1	1
Net periodic costs	4	5	14	14
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	3	3
Interest cost on projected benefit obligation	5	5	15	14
Expected return on plan assets	(6)	(7)	(20)	(20)
Amortization of actuarial loss (gain)	1	3	3	8
Net periodic costs	1	2	1	5
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2	3	6	8
Interest cost on projected benefit obligation	7	7	21	21
Expected return on plan assets	(10)	(10)	(31)	(31)
Amortization of actuarial loss (gain)	3	3	9	10
Net periodic costs	2	3	5	8
Non-Qualified Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	2	2
Interest cost on projected benefit obligation	4	3	11	10
Amortization of actuarial loss (gain)	2	2	6	5
Amortization of prior service cost (credit)	(1)		(1)
Net periodic costs	6	6	18	17
Non-Qualified Pension Plan [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation			1	1
Net periodic costs			1	1
Non-Qualified Pension Plan [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost				1
Interest cost on projected benefit obligation	2	1	4	3
Amortization of actuarial loss (gain)	1	1	2	2
Net periodic costs	3	2	6	6
Non-Qualified Pension Plan [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation			1	1
Amortization of actuarial loss (gain)	1		1
Net periodic costs	1		2	1
Non-Qualified Pension Plan [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation		1	1	2
Amortization of actuarial loss (gain)	1		1	1
Net periodic costs	$ 1	$ 1	$ 2	$ 3