Discontinued Operations (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended		12 Months Ended			3 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Conectiv Energy [Member]	Dec. 31, 2010 Conectiv Energy [Member]	Feb. 02, 2011 Conectiv Energy [Member]	Jun. 30, 2010 Calpine Corporation [Member]	Dec. 31, 2011 Calpine Corporation [Member]	Dec. 31, 2010 Calpine Corporation [Member]	Dec. 31, 2011 Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member]		Dec. 31, 2010 Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member]		Dec. 31, 2010 Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] Conectiv Energy [Member]	Dec. 31, 2011 Significant Other Observable Inputs (Level 2) [Member]		Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member]		Dec. 31, 2010 Significant Other Observable Inputs (Level 2) [Member] Conectiv Energy [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2010 Significant Unobservable Inputs (Level 3) [Member] Conectiv Energy [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net Assets				$ 0	$ 45
Accounts receivable, less allowance for uncollectible accounts					81
Inventories					20
Adjustments to remaining miscellaneous assets and liabilities	0	4
Net derivative liabilities					(18)
Derivative instruments, assets		192	114		7					132	[1]	26	[1]		43	[1]	69	[1]	4	17	19	3
Derivative instruments, liabilities		128	216		90					50	[1]	75	[1]	10	61	[1]	118	[1]	80	17	23
After-tax income related to the sale of tolling agreement		1
Expense incurred in connection with a financial transaction		1
Net losses from dispositions of assets and businesses of discontinued operations, net of income taxes				2	113				74
Employee severance and retention benefits								9
After-tax accrued expenses								12
Losses on assets not sold									13
Unrealized loss recognized on energy contracts							(50)
Tax charges aggregated to valuation allowances							28		26
Payments against fair value of derivative						82
Administrative fee, after-tax						$ 1

[1] There were no significant transfers of instruments between level 1 and level 2 valuation categories.