Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2007	Dec. 31, 2012
Tax provision (benefit) [Abstract]
Tax provision (benefit) before valuation allowance	$ (674,000)	$ (89,106,000)	$ (17,792,000)	$ (196,535,000)
Change in valuation allowance	1,010,000	86,134,000	20,257,000	192,035,000
Provision for (benefit from) income taxes	336,000	(2,972,000)	2,465,000	(4,500,000)
Increase (decrease) in deferred tax valuation allowance, included in other comprehensive income	(2,600,000)	(13,700,000)	33,900,000	0
Valuation allowance	1,020,200,000		1,020,200,000			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					197,500,000
Estimate of federal interest that may be due	151,000,000		151,000,000
Estimate of additional state income taxes and interest that may be due	45,400,000		45,400,000
Amount of payment made related to the IRS assessment on the REMIC issue					65,200,000
Total amount of unrecognized tax benefits	105,200,000		105,200,000
Total amount of the unrecognized tax benefits that would affect our effective tax rate	92,600,000		92,600,000
Recognize accrued interest	$ 25,900,000		$ 25,900,000			$ 25,300,000