Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 40	$ 34	$ 119	$ 102
Interest cost on projected benefit obligation	81	86	244	258
Expected return on plan assets	(129)	(128)	(387)	(383)
Amortization of actuarial loss (gain)	44	37	131	111
Amortization of prior service cost (credit)	(4)	(4)	(11)	(11)
Other	2	3	6	6
Net periodic costs	34	28	102	83
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	13	10	38	31
Interest cost on projected benefit obligation	21	22	62	64
Expected return on plan assets	(35)	(33)	(104)	(99)
Amortization of actuarial loss (gain)	10	8	30	26
Amortization of prior service cost (credit)	(2)	(2)	(6)	(6)
Other	1	1	2	2
Net periodic costs	8	6	22	18
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	11	10	33	30
Interest cost on projected benefit obligation	26	28	78	84
Expected return on plan assets	(43)	(44)	(127)	(130)
Amortization of actuarial loss (gain)	17	17	51	51
Amortization of prior service cost (credit)	(1)		(3)	(2)
Other	1	1	2	2
Net periodic costs	11	12	34	35
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	6	18	16
Interest cost on projected benefit obligation	12	13	36	40
Expected return on plan assets	(20)	(21)	(61)	(64)
Amortization of actuarial loss (gain)	8	8	25	24
Amortization of prior service cost (credit)			(1)	(1)
Other			1	1
Net periodic costs	6	6	18	16
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	5	5	15	15
Interest cost on projected benefit obligation	14	14	41	43
Expected return on plan assets	(22)	(21)	(66)	(64)
Amortization of actuarial loss (gain)	8	8	24	24
Amortization of prior service cost (credit)			(1)	(1)
Other			1	1
Net periodic costs	5	6	14	18
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	14	15
Expected return on plan assets	(7)	(7)	(20)	(20)
Amortization of actuarial loss (gain)	3	1	8	3
Net periodic costs	2		5	1
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	3	8	7
Interest cost on projected benefit obligation	7	7	21	22
Expected return on plan assets	(10)	(10)	(31)	(30)
Amortization of actuarial loss (gain)	3	3	10	9
Net periodic costs	3	3	8	8
Other Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	2	2
Interest cost on projected benefit obligation	3	3	10	10
Amortization of actuarial loss (gain)	2	1	5	2
Net periodic costs	6	5	17	14
Other Pension Plan [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation		1	1	1
Net periodic costs		1	1	1
Other Pension Plan [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost			1	1
Interest cost on projected benefit obligation	1	2	3	4
Amortization of actuarial loss (gain)	1		2	1
Amortization of prior service cost (credit)		(1)		(1)
Net periodic costs	2	1	6	5
Other Pension Plan [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1		1
Interest cost on projected benefit obligation			1	1
Net periodic costs		1	1	2
Other Pension Plan [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	1		2	1
Amortization of actuarial loss (gain)			1
Net periodic costs	1		3	1
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	2	4	7
Interest cost on projected benefit obligation	9	13	27	38
Expected return on plan assets	(3)	(3)	(9)	(9)
Amortization of actuarial loss (gain)	6	9	19	29
Amortization of prior service cost (credit)	(35)	(31)	(105)	(94)
Net periodic costs	(22)	(10)	(64)	(29)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost			1	1
Interest cost on projected benefit obligation	2	3	6	9
Expected return on plan assets	(2)	(2)	(6)	(6)
Amortization of actuarial loss (gain)		1	(1)	2
Amortization of prior service cost (credit)	(4)	(3)	(11)	(8)
Net periodic costs	(4)	(1)	(11)	(2)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1	1	3
Interest cost on projected benefit obligation	4	6	11	17
Amortization of actuarial loss (gain)	7	10	21	31
Amortization of prior service cost (credit)	(26)	(24)	(77)	(71)
Net periodic costs	(15)	(7)	(44)	(20)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost				1
Interest cost on projected benefit obligation	2	3	6	8
Amortization of actuarial loss (gain)	5	8	14	23
Amortization of prior service cost (credit)	(17)	(19)	(50)	(55)
Net periodic costs	(10)	(8)	(30)	(23)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost				2
Interest cost on projected benefit obligation	2	3	5	9
Amortization of actuarial loss (gain)	3	3	8	8
Amortization of prior service cost (credit)	(9)	(5)	(25)	(16)
Net periodic costs	(4)	1	(12)	3
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)
Net periodic costs			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	4
Expected return on plan assets				(1)
Amortization of actuarial loss (gain)			(1)
Net periodic costs	$ 1	$ 1	$ 2	$ 3