Income Taxes (Details) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2007	Dec. 31, 2012
Tax provision (benefit) [Abstract]
Tax provision (benefit) before valuation allowance	$ 4,472,000	$ (101,367,000)	$ (17,118,000)	$ (107,429,000)
Change in valuation allowance	(3,482,000)	98,476,000	19,247,000	105,901,000
Provision for (benefit from) income taxes	990,000	(2,891,000)	2,129,000	(1,528,000)
Increase (decrease) in deferred tax valuation allowance, included in other comprehensive income	33,500,000	(1,600,000)	36,600,000	13,700,000
Valuation allowance	1,021,800,000		1,021,800,000			966,000,000
Net operating loss carryforwards, regular tax basis	2,600,000,000		2,600,000,000
Net operating loss carryforwards for computing the alternative minimum tax	1,700,000,000		1,700,000,000
Information regarding income tax examinations [Abstract]
Amount of IRS assessment for unpaid taxes and penalties related to REMIC issue					190,700,000
Amount of payment made related to the IRS assessment on the REMIC issue					65,200,000
Total amount of unrecognized tax benefits	104,900,000		104,900,000
Total amount of the unrecognized tax benefits that would affect our effective tax rate	92,300,000		92,300,000
Recognize accrued interest	$ 25,600,000		$ 25,600,000			$ 25,300,000