Financial Guaranty Insurance Contracts (Details 3) (USD $)	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Gross
Total	$ 5,839,223,000	$ 5,962,799,000
Ceded
Total	631,398,000	708,872,000
Net
Total	5,207,800,000	5,253,900,000
Total net unearned premium reserve related to FG VIE	249,700,000	274,200,000
Net
Reduction in future scheduled amortization of deferred premium revenue due to consolidating FG VIEs	(396,200,000)
Reduction in net present value of expected loss due to consolidating FG VIEs	(211,000,000)
Financial Guaranty
Gross
Deferred premium revenue	5,918,800,000	6,046,300,000
Contra-paid	(87,900,000)	(92,200,000)
Total	5,830,900,000	5,954,100,000
Ceded
Deferred premium revenue	647,800,000	727,400,000
Contra-paid	(16,700,000)	(18,800,000)
Total	631,100,000	708,600,000
Net
Deferred premium revenue	5,271,000,000	5,318,900,000
Contra-paid	(71,200,000)	(73,400,000)
Total	5,199,800,000	5,245,500,000
Scheduled Net Earned Premium
2012 (April 1 - June 30)	144,300,000
2012 (July 1 - September 30)	138,200,000
2012 (October 1 - December 31)	131,600,000
Subtotal 2012	414,100,000
2013	474,100,000
2014	436,600,000
2015	387,100,000
2016	351,900,000
2017-2021	1,334,400,000
2022-2026	838,900,000
2027-2031	508,200,000
After 2031	525,700,000
Total present value basis	5,271,000,000
Discount	298,800,000
Total future value	5,569,800,000
Net Expected Loss to be Expensed
2012 (April 1 - June 30)	17,800,000
2012 (July 1 - September 30)	17,000,000
2012 (October 1 - December 31)	15,500,000
Subtotal 2012	50,300,000
2013	58,400,000
2014	46,800,000
2015	41,200,000
2016	33,200,000
2017-2021	136,900,000
2022-2026	74,000,000
2027-2031	35,800,000
After 2031	27,200,000
Total present value basis	503,800,000
Discount	292,600,000
Total future value	796,400,000
Net
2012 (April 1 - June 30)	126,500,000
2012 (July 1 - September 30)	121,200,000
2012 (October 1 - December 31)	116,100,000
Subtotal 2012	363,800,000
2013	415,700,000
2014	389,800,000
2015	345,900,000
2016	318,700,000
2017-2021	1,197,500,000
2022-2026	764,900,000
2027-2031	472,400,000
After 2031	498,500,000
Total present value basis	4,767,200,000
Discount	6,200,000
Total future value	4,773,400,000
Other
Gross
Total	8,300,000	8,700,000
Ceded
Total	300,000	300,000
Net
Total	$ 8,000,000	$ 8,400,000