Employee Benefit Plans (Components Of Net Periodic Pension Costs) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Defined contribution plan contribution by employer	$ 28		$ 31
Qualified Pension Plans [Member]
Service cost	23	[1]	24	[1]
Interest cost on benefit obligation	61	[1]	58	[1]
Expected return on plan assets	(94)	[1]	(96)	[1]
Amortization of prior service cost (credit)	1	[1]	2	[1]
Amortization of loss (gain)	24	[1]	19	[1]
Other	1	[1]	4	[1]
Net periodic costs	16	[1]	11	[1]
Regulatory asset amortization	3		4
Non-Qualified pension plans [Member]
Service cost	1
Interest cost on benefit obligation	2		2
Amortization of prior service cost (credit)			1
Net periodic costs	3		3
Other Post-Retirement Benefit plans [Member]
Service cost	2	[2]	1	[2]
Interest cost on benefit obligation	8	[2]	9	[2]
Expected return on plan assets	(4)	[2]	(4)	[2]
Amortization of prior service cost (credit)	(2)	[2]	(2)	[2]
Amortization of net transition liability	2	[2]	3	[2]
Amortization of loss (gain)	(2)	[2]	(1)	[2]
Net periodic costs	4	[2]	6	[2]
Regulatory asset amortization	$ 2		$ 2

[1] Excludes regulatory asset amortization of $3 million and $4 million for the three months ended March 31, 2012 and 2011, respectively, resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.

[2] Excludes regulatory asset amortization of $2 million for each of the three months ended March 31, 2012 and 2011, resulting from purchase accounting adjustments associated with Duke Energy's merger with Cinergy in April 2006.