Income Taxes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income tax (expense) benefit	$ (30,000,000)	$ 2,000,000
Effective tax rate	30.90%
Federal net operating loss carryforwards	$ 1,682,000,000
Federal alternative minimum tax credit carryforwards	40,000,000
Minimum taxable income needed to fully realize the U.S. federal net deferred tax assets	1,797,000,000
Deferred tax assets related to state net operating loss and tax credit carryforwards	228,000,000
Gross deferred tax assets related to state net operating loss and tax credit carry forwards that will expire in current year	27,000,000
Net operating loss and tax credit carryforwards in various foreign jurisdictions	1,000,000
Increase (decrease) in valuation allowance against deferred tax asset	0
Valuation allowance on deferred tax assets	$ 75,000,000
Percentage of change in ownership	50.00%
Period of change in ownership	3 years
Approximate annual NOL utilization had an ownership change occurred	$ 96,000,000