Income Taxes (Income Tax Expense (Benefit)) (Details) (USD $)	3 Months Ended		6 Months Ended			12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011		Dec. 31, 2011
Income Tax Disclosure [Abstract]
Operating Loss Carryforwards Available To Offset Future Income						$ 6,300,000,000
One time tax benefit from consolidation				76,000,000
Income tax expense (benefit)	(52,000,000)	18,000,000	(58,000,000)	(65,000,000)	[1]
Effective Income Tax Rate, Continuing Operations	14.00%	(35.00%)	15.00%	15.00%
Income Tax Expense (Benefit), Intraperiod Tax Allocation	(2,000,000)	(18,000,000)	(4,000,000)	16,000,000
NOLs expected to expire unutilized						640,000,000
NOLs expired unutilized			50,000,000
Percent Decline In Market Cap Required To Trigger Transfer Restrictions	35.00%		35.00%
Emergence Date Capitalization	8,600,000,000		8,600,000,000
Percent Change in Ownership Required To Trigger Transfer Restrictions	25.00%		25.00%
Holders with ownership that could be affected by transfer restrictions	5.00%		5.00%
Unrecognized Tax Benefits	84,000,000		84,000,000
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	38,000,000		38,000,000
Unrecognized Tax Benefits Resulting in Net Operating Loss Carryforward	46,000,000		46,000,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	22,000,000		22,000,000
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions			9,000,000
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Lower Bound	0		0
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Estimated Range of Change, Upper Bound	$ 23,000,000		$ 23,000,000

[1] approximately $76 million related to the election to consolidate our CCFC and Calpine groups for federal income tax reporting purposes for the six months ended June 30, 2011.