Restatement of Previously Issued Financial Statements (Details 4) (USD $)	9 Months Ended				9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2010 As Previously Filed	Dec. 31, 2010 As Previously Filed	Sep. 30, 2010 FG VIE Eliminations	Dec. 31, 2010 FG VIE Eliminations
Net cash flows provided by (used in) operating activities	$ 600,998,000	$ (104,267,000)	$ (140,000,000)		$ 35,700,000
Fixed maturity securities:
Purchases	(1,787,990,000)	(1,928,744,000)	(1,928,700,000)
Sales	848,416,000	835,716,000	835,700,000
Maturities	502,929,000	729,559,000	729,600,000
Net sales (purchases) of short-term investments	182,407,000	731,216,000	759,900,000		(28,700,000)
Net proceeds from paydowns on financial guaranty variable interest entities' assets	598,160,000	323,626,000	323,600,000
Other	13,988,000	15,718,000	15,700,000
Net cash flows provided by (used in) investing activities	357,910,000	707,091,000	735,800,000		(28,700,000)
Financing activities
Dividends paid	(24,830,000)	(24,889,000)	(24,900,000)
Repurchases of common stock	(23,311,000)	(10,457,000)	(10,500,000)
Share activity under option and incentive plans	(2,609,000)	(2,323,000)	(2,200,000)
Net paydowns of financial guaranty variable interest entities' liabilities	(830,063,000)	(497,296,000)	(497,300,000)
Repayment of long-term debt	(16,902,000)	(16,090,000)	(16,100,000)
Net cash flows provided by (used in) financing activities	(897,715,000)	(551,055,000)	(551,000,000)
Effect of foreign exchange rate changes	3,678,000	(1,496,000)	(1,500,000)
Increase in cash	64,871,000	50,273,000	43,300,000		7,000,000
Cash at beginning of period	108,389,000	44,133,000	44,100,000	107,200,000		1,200,000
Cash at end of period	$ 173,260,000	$ 94,406,000	$ 87,400,000	$ 107,200,000	$ 7,000,000	$ 1,200,000