Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 39	$ 34	$ 79	$ 68
Interest cost on projected benefit obligation	81	86	163	172
Expected return on plan assets	(129)	(127)	(258)	(255)
Amortization of actuarial loss (gain)	44	37	87	74
Amortization of prior service cost (credit)	(3)	(3)	(7)	(7)
Other	2	1	4	3
Net periodic costs	34	28	68	55
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	12	11	25	21
Interest cost on projected benefit obligation	20	21	41	42
Expected return on plan assets	(33)	(33)	(69)	(66)
Amortization of actuarial loss (gain)	10	9	20	18
Amortization of prior service cost (credit)	(2)	(2)	(4)	(4)
Other			1	1
Net periodic costs	7	6	14	12
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	11	10	22	20
Interest cost on projected benefit obligation	26	28	52	56
Expected return on plan assets	(41)	(43)	(84)	(86)
Amortization of actuarial loss (gain)	17	17	34	34
Amortization of prior service cost (credit)	(1)	(1)	(2)	(2)
Other			1	1
Net periodic costs	12	11	23	23
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	5	12	10
Interest cost on projected benefit obligation	12	14	24	27
Expected return on plan assets	(21)	(22)	(41)	(43)
Amortization of actuarial loss (gain)	9	8	17	16
Amortization of prior service cost (credit)	(1)	(1)	(1)	(1)
Other	1	1	1	1
Net periodic costs	6	5	12	10
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	13	15	27	29
Expected return on plan assets	(22)	(22)	(44)	(43)
Amortization of actuarial loss (gain)	8	8	16	16
Amortization of prior service cost (credit)	(1)	(1)	(1)	(1)
Other	1	1	1	1
Net periodic costs	4	6	9	12
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	4	5	9	10
Expected return on plan assets	(7)	(6)	(13)	(13)
Amortization of actuarial loss (gain)	3	1	5	2
Net periodic costs	1	1	3	1
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	2	2	5	4
Interest cost on projected benefit obligation	7	8	14	15
Expected return on plan assets	(11)	(11)	(21)	(20)
Amortization of actuarial loss (gain)	4	3	7	6
Net periodic costs	2	2	5	5
Other 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)	1	1	3	1
Net periodic costs	5	5	11	9
Other Pension Plan [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation			1
Net periodic costs			1
Other Pension Plan [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1	1	1
Interest cost on projected benefit obligation	1		2	2
Amortization of actuarial loss (gain)	1	1	1	1
Net periodic costs	2	2	4	4
Other Pension Plan [Member] | Duke Energy Progress [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] | 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	2	1
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	3	3	5
Interest cost on projected benefit obligation	9	13	18	25
Expected return on plan assets	(3)	(3)	(6)	(6)
Amortization of actuarial loss (gain)	7	10	13	20
Amortization of prior service cost (credit)	(35)	(32)	(70)	(63)
Net periodic costs	(21)	(9)	(42)	(19)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1	1
Interest cost on projected benefit obligation	2	3	4	6
Expected return on plan assets	(2)	(2)	(4)	(4)
Amortization of actuarial loss (gain)	(1)		(1)	1
Amortization of prior service cost (credit)	(3)	(2)	(7)	(5)
Net periodic costs	(3)		(7)	(1)
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1	2
Interest cost on projected benefit obligation	3	5	7	11
Amortization of actuarial loss (gain)	7	11	14	21
Amortization of prior service cost (credit)	(25)	(23)	(51)	(47)
Net periodic costs	(14)	(6)	(29)	(13)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1		1
Interest cost on projected benefit obligation	2	2	4	5
Amortization of actuarial loss (gain)	4	8	9	15
Amortization of prior service cost (credit)	(16)	(18)	(33)	(36)
Net periodic costs	(10)	(7)	(20)	(15)
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		1		2
Interest cost on projected benefit obligation	1	3	3	6
Amortization of actuarial loss (gain)	2	3	5	5
Amortization of prior service cost (credit)	(7)	(6)	(16)	(11)
Net periodic costs	(4)	1	(8)	2
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	2	2	2	3
Expected return on plan assets		(1)		(1)
Amortization of actuarial loss (gain)	(1)		(1)
Net periodic costs	$ 1	$ 1	$ 1	$ 2