Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 34	$ 41	$ 102	$ 125
Interest cost on projected benefit obligation	86	80	258	240
Expected return on plan assets	(128)	(137)	(383)	(411)
Amortization of actuarial loss (gain)	37	61	111	183
Amortization of prior service cost (credit)	(4)	(2)	(11)	(8)
Other	3	2	6	5
Net periodic costs	28	45	83	134
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	12	31	37
Interest cost on projected benefit obligation	22	20	64	60
Expected return on plan assets	(33)	(37)	(99)	(111)
Amortization of actuarial loss (gain)	8	15	26	45
Amortization of prior service cost (credit)	(2)	(2)	(6)	(5)
Other	1	1	2	2
Net periodic costs	6	9	18	28
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	15	30	45
Interest cost on projected benefit obligation	28	29	84	87
Expected return on plan assets	(44)	(50)	(130)	(149)
Amortization of actuarial loss (gain)	17	26	51	76
Amortization of prior service cost (credit)		(1)	(2)	(3)
Other	1		2	1
Net periodic costs	12	19	35	57
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	6	16	17
Interest cost on projected benefit obligation	13	13	40	38
Expected return on plan assets	(21)	(24)	(64)	(71)
Amortization of actuarial loss (gain)	8	11	24	34
Amortization of prior service cost (credit)		(1)	(1)	(1)
Other		1	1	1
Net periodic costs	6	6	16	18
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	5	8	15	23
Interest cost on projected benefit obligation	14	13	43	40
Expected return on plan assets	(21)	(21)	(64)	(65)
Amortization of actuarial loss (gain)	8	12	24	37
Amortization of prior service cost (credit)		(1)	(1)	(2)
Other			1
Net periodic costs	6	11	18	33
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	3	4
Interest cost on projected benefit obligation	5	5	15	16
Expected return on plan assets	(7)	(7)	(20)	(22)
Amortization of actuarial loss (gain)	1	3	3	9
Amortization of prior service cost (credit)
Other
Net periodic costs	0	2	1	7
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	2	7	8
Interest cost on projected benefit obligation	7	7	22	21
Expected return on plan assets	(10)	(11)	(30)	(33)
Amortization of actuarial loss (gain)	3	6	9	17
Amortization of prior service cost (credit)
Other		1		1
Net periodic costs	3	5	8	14
Non-Qualified Pension Plans [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)	1	1	2	4
Amortization of prior service cost (credit)				(1)
Net periodic costs	5	5	14	15
Non-Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost
Interest cost on projected benefit obligation	1		1	1
Amortization of actuarial loss (gain)
Amortization of prior service cost (credit)
Net periodic costs	1	0	1	1
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1	1	1
Interest cost on projected benefit obligation	2	1	4	5
Amortization of actuarial loss (gain)		1	1	3
Amortization of prior service cost (credit)	(1)		(1)	(1)
Net periodic costs	1	3	5	8
Non-Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1	1
Interest cost on projected benefit obligation			1	1
Amortization of actuarial loss (gain)		1		1
Amortization of prior service cost (credit)
Net periodic costs	1	2	2	3
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost
Interest cost on projected benefit obligation			1	1
Amortization of actuarial loss (gain)		1		1
Amortization of prior service cost (credit)
Net periodic costs	0	1	1	2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2	7	7	21
Interest cost on projected benefit obligation	13	19	38	55
Expected return on plan assets	(3)	(4)	(9)	(11)
Amortization of actuarial loss (gain)	9	13	29	39
Amortization of prior service cost (credit)	(31)	(3)	(94)	(9)
Net periodic costs	(10)	32	(29)	95
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1	1	2
Interest cost on projected benefit obligation	3	3	9	9
Expected return on plan assets	(2)	(2)	(6)	(7)
Amortization of actuarial loss (gain)	1		2	2
Amortization of prior service cost (credit)	(3)	(2)	(8)	(6)
Net periodic costs	(1)	0	(2)	0
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	6	3	17
Interest cost on projected benefit obligation	6	12	17	35
Expected return on plan assets
Amortization of actuarial loss (gain)	10	13	31	42
Amortization of prior service cost (credit)	(24)		(71)	(1)
Net periodic costs	(7)	31	(20)	93
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		3	1	9
Interest cost on projected benefit obligation	3	7	8	19
Expected return on plan assets
Amortization of actuarial loss (gain)	8	8	23	26
Amortization of prior service cost (credit)	(19)		(55)	(1)
Net periodic costs	(8)	18	(23)	53
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		2	2	6
Interest cost on projected benefit obligation	3	5	9	13
Expected return on plan assets
Amortization of actuarial loss (gain)	3	4	8	12
Amortization of prior service cost (credit)	(5)		(16)
Net periodic costs	1	11	3	31
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost
Interest cost on projected benefit obligation			1	1
Expected return on plan assets
Amortization of actuarial loss (gain)			(1)	(1)
Amortization of prior service cost (credit)
Net periodic costs			0	0
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1		1
Interest cost on projected benefit obligation	1	1	4	4
Expected return on plan assets		(1)	(1)	(1)
Amortization of actuarial loss (gain)		1		1
Amortization of prior service cost (credit)
Net periodic costs	$ 1	$ 2	$ 3	$ 5