Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Income Taxes (Textual) [Abstract]
Income tax (benefit) expense	$ 3	$ (1)
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	(1)	(28)
Approximate federal net operating loss carryforwards	2,051
Approximate federal alternative minimum tax credit carryforwards	45
Minimum taxable income needed to fully realize the U.S. federal net deferred tax assets	2,181
Foreign tax credit carryforwards	8
Deferred tax assets operating loss tax carryforwards	290
Approximate gross deferred tax assets operating loss and tax credit carry forwards that will expire in current year	1
Deferred tax assets, operating loss and tax credit carryforwards foreign	1
Valuation allowance			1,125
Additional valuation allowance against deferred tax assets recorded	4
Percentage of change in ownership	50.00%
Period of change in ownership	3 years
Long-term tax-exempt rate	2.77%
Time period after the change in which amount of the limitation be increased or decreased by built-in gains or losses	5 years
Approximate annual NOL utilization had an ownership change occurred	$ 79