Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2007
Net deferred tax assets and liabilities [Abstract]
Total deferred tax assets	$ 1,043,477,000	$ 997,784,000	$ 683,645,000
Total deferred tax liabilities	(42,158,000)	(44,350,000)
Net deferred tax asset before valuation allowance	1,001,319,000	953,434,000
Valuation allowance	(1,004,256,000)	(965,987,000)	(608,800,000)
Net deferred tax liability	(2,937,000)	(12,553,000)
Components of net deferred tax liability [Abstract]
Benefit plans	(26,111,000)	77,000
Net operating loss	915,378,000	866,700,000
Loss reserves	36,236,000	55,615,000
Unrealized (appreciation) depreciation in investments	29,230,000	(14,448,000)
Mortgage investments	13,450,000	14,602,000
Deferred compensation	15,994,000	13,288,000
Premium deficiency reserves	16,961,000	25,823,000
Other, net	181,000	(8,223,000)
Net deferred tax asset before valuation allowance	1,001,319,000	953,434,000
Valuation allowance	(1,004,256,000)	(965,987,000)	(608,800,000)
Net deferred tax liability	(2,937,000)	(12,553,000)
Tax provision (benefit) [Abstract]
Benefit from income taxes	(17,239,000)	(330,740,000)	(196,835,000)
Change in valuation allowance	20,935,000	329,175,000	198,428,000
Provision for (benefit from) income taxes (note 14)	3,696,000	(1,565,000)	1,593,000
Increase (decrease) in deferred tax valuation allowance, included in other comprehensive income	17,300,000	28,100,000	0
Net operating loss carryforwards, regular tax basis	2,616,000,000
Net operating loss carryforwards for computing the alternative minimum tax	1,731,000,000
Components of provisions for (benefit from) income taxes [Abstract]
Current	916,000	(4,251,000)	598,000
Deferred	7,000	90,000	(945,000)
Other	2,773,000	2,596,000	1,940,000
Provision for (benefit from) income taxes	3,696,000	(1,565,000)	1,593,000
Federal income tax received	0	7,000,000	0
Federal income tax paid	100,000
Reconciliation of effective income tax rate [Abstract]
Federal statutory income tax benefit rate (in hundredths)	(35.00%)	(35.00%)	(35.00%)
Valuation allowance (in hundredths)	45.40%	35.40%	41.00%
Tax exempt municipal bond interest (in hundredths)	(3.70%)	(0.80%)	(5.40%)
Other, net (in hundredths)	1.30%	0.20%	(0.30%)
Effective income tax (benefit) rate (in hundredths)	8.00%	(0.20%)	0.30%
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	154,500,000
Estimate of additional state income taxes and interest that may be due	46,000,000
Amount of payment made related to the IRS assessment on the REMIC issue				65,200,000
Unrecognized tax benefits [Roll Forward]
Balance at beginning of year	104,550,000	110,080,000	109,282,000
Additions based on tax positions related to the current year	0	0	0
Additions for tax positions of prior years	816,000	511,000	798,000
Reductions for tax positions of prior years	0	(4,041,000)	0
Settlements	0	(2,000,000)	0
Balance at end of year	105,366,000	104,550,000	110,080,000
Unrecognized tax benefits [Abstract]
Total amount of unrecognized tax benefits that would affect effective tax rate	92,800,000
Unrecognized tax benefits, interest expense	800,000
Unrecognized tax benefits, accrued interest	$ 26,100,000	$ 25,300,000