Financial Guaranty Insurance Contracts (Details 14) (USD $)	3 Months Ended		12 Months Ended
	Jun. 30, 2012 risk		Dec. 31, 2011 risk		Mar. 31, 2012	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Financial Guaranty Insurance BIG Transaction Loss Summary
Maximum Termination Payment Possible After Swap Obligations and Taking Account of Possible Rating Downgrade of Municipal Obligors	$ 370,100,000
Present value of expected cash flows
Total BIG, Net	826,500,000
Effect of Consolidating FG VIEs	(65,700,000)
Reserves (salvage)
Total BIG, Net	351,500,000		86,100,000
Effect of consolidating FG VIEs	136,700,000		196,500,000
Total	488,200,000	[1]	282,600,000	[1]
Minimum
Reserves (salvage)
Threshold period of bonds held by bank for right of accelerated repayment (in days)	180 days
Accelerated repayment period for bank bonds (in years)	10 years
Variable rate demand obligations
Reserves (salvage)
Rate basis for bank bond rate	prime rate
Financial Guaranty Insurance Contracts, Principal Amount BBB- or below	700,000,000
Variable rate demand obligations | Minimum
Reserves (salvage)
Bank bond rate (as a percent)	2.00%
Threshold period of bonds held by bank for right of accelerated repayment (in days)	90 days
Accelerated repayment period for bank bonds (in years)	5 years
Variable rate demand obligations | Maximum
Reserves (salvage)
Bank bond rate (as a percent)	3.00%
Bank bond capped rate (as a percent)	25.00%
Financial Guaranty
Number of risks
Total BIG, Net (in contracts)	375	[2]	368	[2]
Total (in contracts)	375	[2]	368	[2]
Remaining weighted average contract period
Total BIG, Net (in years)	10.7		10.4
Total (in years)	10 years 8 months 12 days		10 years 4 months 24 days
Principal
Total BIG, Net	17,714,400,000		18,958,500,000
Total	17,714,400,000		18,958,500,000
Interest
Total BIG, Net	8,354,000,000		8,623,300,000
Total	8,354,000,000		8,623,300,000
Total net outstanding exposure
Total BIG, Net	26,068,400,000	[3]	27,581,800,000	[3]
Total	26,068,400,000	[3]	27,581,800,000	[3]
Expected cash outflows (inflows)
Total BIG, Net	5,228,600,000		5,074,400,000
Effect of Consolidating FG VIEs	(767,200,000)		(998,400,000)
Total	4,461,400,000		4,076,000,000
Potential recoveries
Total BIG, Net	(4,099,000,000)	[4]	(4,115,000,000)	[4]
Effect of Consolidating FG VIEs	805,400,000	[4]	1,059,800,000	[4]
Total	(3,293,600,000)	[4]	(3,055,200,000)	[4]
Subtotal
Total BIG, NET	1,129,600,000		959,400,000
Effect of Consolidating FG VIEs	38,200,000		61,400,000
Total	1,167,800,000		1,020,800,000
Discount
Total BIG, Net	(303,100,000)		(321,400,000)
Effect of Consolidating FG VIEs	27,500,000		45,300,000
Schedule of Insured Financial Obligations with Credit Deterioration, Reductions of Gross Claim Liability, Net Discount	(275,600,000)		(276,100,000)
Present value of expected cash flows
Total BIG, Net	826,500,000	[5]	638,000,000	[5]	752,400,000	713,000,000	32,200,000	408,800,000
Effect of Consolidating FG VIEs	65,700,000		106,700,000
Total	892,200,000		744,700,000
Deferred premium revenue
Total BIG, Net	1,145,100,000		1,325,500,000
Effect of Consolidating FG VIEs	(331,300,000)		(390,700,000)
Total	813,800,000		934,800,000
Reserves (salvage)
Total BIG, Net	355,600,000	[6]	84,200,000	[6]
Effect of consolidating FG VIEs	136,700,000	[6]	196,500,000	[6]
Total	492,300,000	[6]	280,700,000	[6]
Financial Guaranty | BIG 1
Number of risks
Gross (in contracts)	164	[2]	171	[2]
Ceded (in contracts)	(60)	[2]	(68)	[2]
Remaining weighted average contract period
Gross (in years)	10.4		10.0
Ceded (in years)	9.2		9.2
Principal
Gross	8,959,200,000		9,675,800,000
Ceded	(1,492,500,000)		(1,378,000,000)
Interest
Gross	4,207,600,000		4,307,900,000
Ceded	(563,400,000)		(485,600,000)
Total net outstanding exposure
Gross	13,166,800,000	[3]	13,983,700,000	[3]
Ceded	(2,055,900,000)	[3]	(1,863,600,000)	[3]
Expected cash outflows (inflows)
Gross	1,594,100,000		1,730,600,000
Ceded	(673,300,000)		(658,800,000)
Potential recoveries
Gross	(1,712,400,000)	[4]	(1,798,000,000)	[4]
Ceded	696,100,000	[4]	664,000,000	[4]
Subtotal
Gross	(118,300,000)		(67,400,000)
Ceded	22,800,000		5,200,000
Discount
Gross	18,600,000		15,700,000
Ceded	(6,300,000)		(4,600,000)
Present value of expected cash flows
Gross	(99,700,000)		(51,700,000)
Ceded	16,500,000		600,000
Deferred premium revenue
Gross	122,100,000		260,800,000
Ceded	(15,800,000)		(69,100,000)
Reserves (salvage)
Gross	(132,500,000)	[6]	(96,600,000)	[6]
Ceded	23,200,000	[6]	6,900,000	[6]
Financial Guaranty | BIG 2
Number of risks
Gross (in contracts)	79	[2]	71	[2]
Ceded (in contracts)	(25)	[2]	(26)	[2]
Remaining weighted average contract period
Gross (in years)	14.4		13.7
Ceded (in years)	26.1		20.5
Principal
Gross	3,622,200,000		3,731,600,000
Ceded	(268,600,000)		(274,000,000)
Interest
Gross	3,042,400,000		2,889,400,000
Ceded	(504,000,000)		(404,800,000)
Total net outstanding exposure
Gross	6,664,600,000	[3]	6,621,000,000	[3]
Ceded	(772,600,000)	[3]	(678,800,000)	[3]
Expected cash outflows (inflows)
Gross	1,738,100,000		1,833,300,000
Ceded	(225,700,000)		(120,300,000)
Potential recoveries
Gross	(653,200,000)	[4]	(1,079,300,000)	[4]
Ceded	20,300,000	[4]	38,500,000	[4]
Subtotal
Gross	1,084,900,000		754,000,000
Ceded	(205,400,000)		(81,800,000)
Discount
Gross	(247,400,000)		(240,600,000)
Ceded	29,400,000		31,600,000
Present value of expected cash flows
Gross	837,500,000		513,400,000
Ceded	(176,000,000)		(50,200,000)
Deferred premium revenue
Gross	310,400,000		280,900,000
Ceded	(32,000,000)		(12,300,000)
Reserves (salvage)
Gross	617,400,000	[6]	319,500,000	[6]
Ceded	(158,100,000)	[6]	(41,900,000)	[6]
Financial Guaranty | BIG 3
Number of risks
Gross (in contracts)	132	[2]	126	[2]
Ceded (in contracts)	(50)	[2]	(48)	[2]
Remaining weighted average contract period
Gross (in years)	9.1		9.2
Ceded (in years)	6.6		6.4
Principal
Gross	7,462,100,000		7,830,800,000
Ceded	(568,000,000)		(627,700,000)
Interest
Gross	2,328,400,000		2,486,400,000
Ceded	(157,000,000)		(170,000,000)
Total net outstanding exposure
Gross	9,790,500,000	[3]	10,317,200,000	[3]
Ceded	(725,000,000)	[3]	(797,700,000)	[3]
Expected cash outflows (inflows)
Gross	2,940,200,000		2,423,000,000
Ceded	(144,800,000)		(133,400,000)
Potential recoveries
Gross	(2,571,800,000)	[4]	(2,040,500,000)	[4]
Ceded	122,000,000	[4]	100,300,000	[4]
Subtotal
Gross	368,400,000		382,500,000
Ceded	(22,800,000)		(33,100,000)
Discount
Gross	(94,100,000)		(125,100,000)
Ceded	(3,300,000)		1,600,000
Present value of expected cash flows
Gross	274,300,000		257,400,000
Ceded	(26,100,000)		(31,500,000)
Deferred premium revenue
Gross	863,300,000		991,800,000
Ceded	(102,900,000)		(126,600,000)
Reserves (salvage)
Gross	(400,000)	[6]	(110,200,000)	[6]
Ceded	$ 6,000,000	[6]	$ 6,500,000	[6]

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

[2] A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making debt service payments. The ceded number of risks represents the number of risks for which the Company ceded a portion of its exposure.

[3] Includes BIG amounts related to FG VIEs which are not eliminated.

[4] Includes estimated future recoveries for breaches of R&W as well as excess spread, and draws on HELOCs.

[5] 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.

[6] See table “Components of net reserves (salvage).”