Employee Benefit Plans (Components of Net Periodic Pension Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Qualified Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	$ 9	$ 10	$ 12
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	159	135	167
Interest cost on projected benefit obligation	324	344	320
Expected return on plan assets	(516)	(511)	(549)
Amortization of actuarial loss (gain)	166	150	244
Amortization of prior service cost (credit)	(15)	(15)	(11)
Other	8	8	7
Net periodic costs	126	111	178
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	50	41	49
Interest cost on projected benefit obligation	83	85	80
Expected return on plan assets	(139)	(132)	(148)
Amortization of actuarial loss (gain)	39	36	60
Amortization of prior service cost (credit)	(7)	(8)	(6)
Other	2	2	2
Net periodic costs	28	24	37
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	44	40	60
Interest cost on projected benefit obligation	104	112	116
Expected return on plan assets	(171)	(173)	(199)
Amortization of actuarial loss (gain)	65	68	101
Amortization of prior service cost (credit)	(3)	(3)	(4)
Other	3	3	2
Net periodic costs	42	47	76
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	23	21	22
Interest cost on projected benefit obligation	48	54	50
Expected return on plan assets	(79)	(85)	(94)
Amortization of actuarial loss (gain)	33	32	46
Amortization of prior service cost (credit)	(2)	(2)	(1)
Other	1	1	1
Net periodic costs	24	21	24
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	20	20	30
Interest cost on projected benefit obligation	54	57	53
Expected return on plan assets	(87)	(85)	(87)
Amortization of actuarial loss (gain)	31	32	49
Amortization of prior service cost (credit)	(1)	(1)	(2)
Other	1	1	1
Net periodic costs	18	24	44
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	4	5	6
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	4	4	6
Interest cost on projected benefit obligation	18	20	21
Expected return on plan assets	(26)	(27)	(31)
Amortization of actuarial loss (gain)	7	4	13
Net periodic costs	3	1	9
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	9	11
Interest cost on projected benefit obligation	27	29	28
Expected return on plan assets	(42)	(41)	(46)
Amortization of actuarial loss (gain)	13	13	24
Amortization of prior service cost (credit)	1		1
Other	1	1	1
Net periodic costs	10	11	19
Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	3	3	3
Interest cost on projected benefit obligation	13	14	13
Amortization of actuarial loss (gain)	6	3	5
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	21	19	20
Non-Qualified Pension Plans [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 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	5	7
Amortization of actuarial loss (gain)	2	2	3
Amortization of prior service cost (credit)	(1)	(1)	(1)
Net periodic costs	6	7	10
Non-Qualified Pension Plans [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	1
Amortization of actuarial loss (gain)	1		1
Net periodic costs	2	2	3
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Interest cost on projected benefit obligation	2	2	1
Amortization of actuarial loss (gain)	2		1
Net periodic costs	4	2	2
Non-Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic costs	0	0	0
Non-Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Amortization of actuarial loss (gain)	1
Net periodic costs	1	0	0
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	10	9	8
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	6	10	24
Interest cost on projected benefit obligation	36	49	68
Expected return on plan assets	(13)	(13)	(14)
Amortization of actuarial loss (gain)	16	39	52
Amortization of prior service cost (credit)	(140)	(125)	(41)
Net periodic costs	(95)	(40)	89
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	2	2
Interest cost on projected benefit obligation	9	12	13
Expected return on plan assets	(8)	(9)	(11)
Amortization of actuarial loss (gain)	(2)	3	3
Amortization of prior service cost (credit)	(14)	(11)	(7)
Net periodic costs	(14)	(3)	0
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	4	18
Interest cost on projected benefit obligation	15	22	41
Amortization of actuarial loss (gain)	28	42	57
Amortization of prior service cost (credit)	(102)	(95)	(30)
Net periodic costs	(58)	(27)	86
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	9
Interest cost on projected benefit obligation	8	11	22
Amortization of actuarial loss (gain)	18	31	34
Amortization of prior service cost (credit)	(68)	(73)	(20)
Net periodic costs	(41)	(30)	45
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	3	7
Interest cost on projected benefit obligation	7	12	16
Amortization of actuarial loss (gain)	10	10	16
Amortization of prior service cost (credit)	(35)	(21)	(6)
Net periodic costs	(17)	4	33
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Amortization of Regulatory Asset	3	2	2
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost			1
Interest cost on projected benefit obligation	2	2	2
Expected return on plan assets	(1)		(1)
Amortization of actuarial loss (gain)	(2)	(2)	(1)
Amortization of prior service cost (credit)			(1)
Net periodic costs	(1)	0	0
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	1	1	1
Interest cost on projected benefit obligation	4	5	5
Expected return on plan assets	(1)	(1)	(1)
Amortization of actuarial loss (gain)	(2)		1
Net periodic costs	$ 2	$ 5	$ 6