Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2007	Dec. 31, 2014
Tax provision (benefit) [Abstract]
Provision for income tax	$ 39,991	$ 17,172	$ 87,874	$ 40,292
Change in valuation allowance	(38,669)	(16,054)	(83,167)	(38,448)
Provision for income taxes	1,322	1,118	4,707	1,844
Change in deferred tax valuation allowance, included in other comprehensive income	(22,000)	$ 14,600	(15,600)	$ 27,900
Valuation allowance	834,700		834,700			$ 902,300
Net operating loss carryforwards, regular tax basis	2,200,000		2,200,000
Net operating loss carryforwards for computing the alternative minimum tax	1,300,000		1,300,000
Information regarding income tax examinations [Abstract]
Amount of IRS assessment for unpaid taxes and penalties related to REMIC issue	197,500		197,500
Estimate of federal interest that may be due	175,500		175,500
Amount of payment made related to the IRS assessment on the REMIC issue					$ 65,200
Estimate of additional state income taxes and interest that may be due	48,100		48,100
Amount of IRS assessment for unpaid taxes and penalties related to disallowance of carryback of 2009 net operating loss	261,400		261,400
Total amount of unrecognized tax benefits	106,700		106,700
Total amount of the unrecognized tax benefits that would affect our effective tax rate	94,100		94,100
Unrecognized tax benefits, accrued interest	$ 27,400		$ 27,400			$ 26,900