Financial Guaranty Insurance Contracts (Details 5) (USD $)	6 Months Ended
	Jun. 30, 2012 Payment		Dec. 31, 2011		Jun. 30, 2012 Financial Guaranty		Mar. 31, 2012 Financial Guaranty	Dec. 31, 2011 Financial Guaranty		Jun. 30, 2011 Financial Guaranty	Mar. 31, 2011 Financial Guaranty	Dec. 31, 2010 Financial Guaranty	Jun. 30, 2012 Financial Guaranty Total first lien		Mar. 31, 2012 Financial Guaranty Total first lien	Dec. 31, 2011 Financial Guaranty Total first lien		Jun. 30, 2011 Financial Guaranty Total first lien	Mar. 31, 2011 Financial Guaranty Total first lien	Dec. 31, 2010 Financial Guaranty Total first lien	Jun. 30, 2012 Financial Guaranty Second lien		Mar. 31, 2012 Financial Guaranty Second lien	Dec. 31, 2011 Financial Guaranty Second lien		Jun. 30, 2011 Financial Guaranty Second lien	Mar. 31, 2011 Financial Guaranty Second lien	Dec. 31, 2010 Financial Guaranty Second lien	Jun. 30, 2012 Financial Guaranty Subprime		Mar. 31, 2012 Financial Guaranty Subprime	Dec. 31, 2011 Financial Guaranty Subprime		Jun. 30, 2011 Financial Guaranty Subprime	Mar. 31, 2011 Financial Guaranty Subprime	Dec. 31, 2010 Financial Guaranty Subprime	Jun. 30, 2012 Other		Mar. 31, 2012 Other	Dec. 31, 2011 Other		Jun. 30, 2011 Other	Mar. 31, 2011 Other	Dec. 31, 2010 Other	Jun. 30, 2012 Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Reconciliation of Expected Loss to be Paid and Net Expected Loss to be Expensed
Net Expected Loss to be Paid	$ 826,500,000				$ 826,500,000	[1]	$ 752,400,000	$ 638,000,000	[1]	$ 713,000,000	$ 32,200,000	$ 408,800,000	$ 318,100,000	[1]	$ 344,800,000	$ 429,900,000	[1]	$ 599,200,000	$ 662,500,000	$ 909,900,000	$ (80,100,000)	[1]	$ (132,200,000)	$ (110,700,000)	[1]	$ (133,000,000)	$ (869,600,000)	$ (749,100,000)	$ 159,400,000	[1]	$ 150,400,000	$ 140,300,000	[1]	$ 161,500,000	$ 167,500,000	$ 200,400,000	$ (4,100,000)	[1]	$ 1,900,000	$ 1,900,000	[1]	$ 2,100,000	$ 2,100,000	$ 2,100,000
Less: net expected loss to be paid for FG VIEs	65,700,000				(65,700,000)			(106,700,000)
Net Expected Loss to be Paid Excluding VIEs					892,200,000			744,700,000																																					892,200,000
Contra-paid, net					103,300,000	[2]		73,400,000	[2]																																				103,300,000
Salvage and Subrogation Recoverable Payable, Net	336,500,000		327,100,000																																										370,800,000
Ceded salvage and subrogation recoverable	(40,300,000)	[3]	(40,600,000)	[3]																																									(40,300,000)	[4]
Loss and LAE reserve	(824,700,000)	[5]	(609,700,000)	[5]																																									(992,000,000)
Reinsurance recoverable on unpaid losses	(170,495,000)		(69,300,000)																																										169,200,000
Total present value basis					503,200,000	[6],[7]																																							503,200,000	[8]
Net expected loss to be expensed related to consolidated financial guaranty VIEs	$ 196,800,000
Maximum number of payments behind to be considered performing borrower	1

[1] Includes expected LAE to be paid for mitigating claim liabilities of $31.1 million as of June 30, 2012 and $35.5 million as of December 31, 2011.

[2] Total net unearned premium reserve excludes $255.5 million and $274.2 million related to FG VIEs as of June 30, 2012 and December 31, 2011, respectively.

[3] Recorded as a component of reinsurance balances payable.

[4] Recorded in reinsurance balances payable on the consolidated balance sheet.

[5] See “Components of Net Reserves (Salvage)” table for loss and LAE reserve and salvage and subrogation recoverable components.

[6] Balances represent discounted amounts.

[7] Consolidation of FG VIEs resulted in reductions of $381.4 million in future scheduled net earned premium and $196.8 million in net expected loss to be expensed.

[8] Excludes $196.8 million related to consolidated FG VIEs.