Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 37	$ 39	$ 73	$ 79
Interest cost on projected benefit obligation	83	81	166	163
Expected return on plan assets	(129)	(129)	(258)	(258)
Amortization of actuarial loss (gain)	33	44	66	87
Amortization of prior service cost (credit)	(4)	(3)	(8)	(7)
Other	1	2	4	4
Net periodic costs	21	34	43	68
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	12	12	24	25
Interest cost on projected benefit obligation	22	20	43	41
Expected return on plan assets	(36)	(33)	(71)	(69)
Amortization of actuarial loss (gain)	8	10	16	20
Amortization of prior service cost (credit)	(2)	(2)	(4)	(4)
Other			1	1
Net periodic costs	4	7	9	14
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	11	21	22
Interest cost on projected benefit obligation	27	26	53	52
Expected return on plan assets	(42)	(41)	(84)	(84)
Amortization of actuarial loss (gain)	13	17	27	34
Amortization of prior service cost (credit)	(1)	(1)	(2)	(2)
Other			1	1
Net periodic costs	7	12	16	23
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	6	12	12
Interest cost on projected benefit obligation	13	12	25	24
Expected return on plan assets	(20)	(21)	(41)	(41)
Amortization of actuarial loss (gain)	5	9	11	17
Amortization of prior service cost (credit)	(1)	(1)	(1)	(1)
Other	1	1	1	1
Net periodic costs	4	6	7	12
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	5	5	10	10
Interest cost on projected benefit obligation	14	13	28	27
Expected return on plan assets	(21)	(22)	(42)	(44)
Amortization of actuarial loss (gain)	7	8	14	16
Amortization of prior service cost (credit)		(1)		(1)
Other		1		1
Net periodic costs	5	4	10	9
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	2	2
Interest cost on projected benefit obligation	5	4	10	9
Expected return on plan assets	(7)	(7)	(14)	(13)
Amortization of actuarial loss (gain)	1	3	2	5
Net periodic costs		1		3
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2	2	4	5
Interest cost on projected benefit obligation	7	7	14	14
Expected return on plan assets	(11)	(11)	(21)	(21)
Amortization of actuarial loss (gain)	3	4	6	7
Net periodic costs	1	2	3	5
Non-Qualified Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1	1
Interest cost on projected benefit obligation	3	3	7	7
Amortization of actuarial loss (gain)	2	1	4	3
Net periodic costs	6	5	12	11
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	1
Net periodic costs	1		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	1	1	2	2
Amortization of actuarial loss (gain)		1	1	1
Net periodic costs	1	2	3	4
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	1	1
Net periodic costs	1	1	1	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	1	1
Amortization of actuarial loss (gain)				1
Net periodic costs	1	1	1	2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	2	3
Interest cost on projected benefit obligation	9	9	17	18
Expected return on plan assets	(4)	(3)	(7)	(6)
Amortization of actuarial loss (gain)	2	7	3	13
Amortization of prior service cost (credit)	(36)	(35)	(71)	(70)
Net periodic costs	(28)	(21)	(56)	(42)
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	2	4	4
Expected return on plan assets	(2)	(2)	(4)	(4)
Amortization of actuarial loss (gain)	(1)	(1)	(2)	(1)
Amortization of prior service cost (credit)	(3)	(3)	(6)	(7)
Net periodic costs	(4)	(3)	(8)	(7)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1		1
Interest cost on projected benefit obligation	3	3	7	7
Amortization of actuarial loss (gain)	6	7	11	14
Amortization of prior service cost (credit)	(25)	(25)	(51)	(51)
Net periodic costs	(16)	(14)	(33)	(29)
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	4	4
Amortization of actuarial loss (gain)	3	4	6	9
Amortization of prior service cost (credit)	(17)	(16)	(34)	(33)
Net periodic costs	(12)	(10)	(24)	(20)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	1	1	3	3
Amortization of actuarial loss (gain)	3	2	5	5
Amortization of prior service cost (credit)	(9)	(7)	(18)	(16)
Net periodic costs	(5)	(4)	(10)	(8)
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	1	1
Amortization of actuarial loss (gain)	(1)		(1)
Net periodic costs		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	2	2	2
Expected return on plan assets	$ (1)		(1)
Amortization of actuarial loss (gain)		(1)	$ (1)	(1)
Net periodic costs		$ 1		$ 1