Employee Benefit Plans (Schedule Of Changes In Projected Benefit Obligations And Fair Value Of Plan Assets) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Obligation at prior measurement date	$ 4,661	$ 4,611
Actuarial gain			(21)	[1]
Accrued retiree drug subsidy	1	1
Employer contributions	200	400	800
Plan assets at measurement date	4,842	4,901
Qualified Pension Plans [Member]
Obligation at prior measurement date	4,861	4,695
Service cost	96	96	85
Interest cost on benefit obligation	232	248	257
Actuarial gain	(7)	190
Plan amendments	18	2
Settlement and contractual termination benefit cost		(13)
Benefits paid	(320)	(383)
Accumulated post-retirement benefit obligation at measurement date	4,880	4,861
Non-Qualified Pension Plans [Member]
Obligation at prior measurement date	167	173
Service cost	1	1	2
Interest cost on benefit obligation	8	9	10
Actuarial gain	(2)	2
Benefits paid	(14)	(18)
Accumulated post-retirement benefit obligation at measurement date	160	167
Non-Qualified Pension Plans [Member] | Duke Energy Corp [Member]
Obligation at prior measurement date	151	160
Other Post-Retirement Benefit Plans [Member]
Obligation at prior measurement date	667	723	728
Actual return on plan assets	4	19
Service cost	7	7	7
Interest cost on benefit obligation	35	38	46
Plan participants' contributions	32	35
Actuarial gain	(55)	(12)
Benefits paid	(83)	(79)
Early retiree reinsurance program subsidy	3
Accrued retiree drug subsidy	5	6
Employer contributions	42	42
Plan assets at measurement date	181	186	169
Plan Assets And Projected Benefit Obligation [Member] | Qualified Pension Plans [Member]
Plan assets at prior measurement date	4,797	4,224
Actual return on plan assets	64	556
Benefits paid	(320)	(383)
Employer contributions	200	400
Plan assets at measurement date	4,741	4,797
Plan Assets And Projected Benefit Obligation [Member] | Non-Qualified Pension Plans [Member]
Benefits paid	(14)	(18)
Employer contributions	$ 14	$ 18

[1] Net of $12 tax benefit in 2009.