Fair Value Measurements (Narrative) (Details) (USD $)	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Net assets measured at fair value on a recurring basis	$ 1,800,000,000		$ 1,700,000,000
Net assets measured at fair value on a recurring basis measured using unobservable inputs	11,000,000		2,000,000
Level 3 net assets as a percentage of total assets, maximum	1.00%		1.00%
Fair value option of contractual principal outstanding	550,000,000	550,000,000
Current liabilities, fair value	154,000,000	131,000,000
Nonrecurring fair value of leased assets	50,000,000	50,000,000
PSEG [Member]
Current liabilities, fair value	$ 50,000,000	$ 50,000,000