Outstanding Exposure - BIG Net Par Outstanding (Details) $ in Millions		Jun. 30, 2015 USD ($) risk		Dec. 31, 2014 USD ($) risk
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Credit Derivative		$ 32,309	[1]	$ 34,996
Net Par Outstanding (excluding loss mitigation bonds)		390,384	[2],[3]	403,729	[4]
BIG [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	[5]	16,904		15,222
Net Par Outstanding, Credit Derivative	[6]	3,500		3,025
Net Par Outstanding (excluding loss mitigation bonds)		$ 20,404	[3]	$ 18,247
Number of Risks, Financial Guaranty Insurance | risk	[5],[7]	468		358
Number of Risks, Credit Derivative | risk	[7]	57		56
Number of Risks | risk	[7]	525		414
BIG [Member] | BIG 1 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	[5]	$ 10,504		$ 10,195
Net Par Outstanding, Credit Derivative		2,218		1,670
Net Par Outstanding (excluding loss mitigation bonds)		$ 12,722		$ 11,865
Number of Risks, Financial Guaranty Insurance | risk	[5],[7]	266		164
Number of Risks, Credit Derivative | risk	[7]	22		18
Number of Risks | risk	[7]	288		182
BIG [Member] | BIG 2 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	[5]	$ 3,389		$ 2,135
Net Par Outstanding, Credit Derivative		723		554
Net Par Outstanding (excluding loss mitigation bonds)		$ 4,112		$ 2,689
Number of Risks, Financial Guaranty Insurance | risk	[5],[7]	76		75
Number of Risks, Credit Derivative | risk	[7]	11		14
Number of Risks | risk	[7]	87		89
BIG [Member] | BIG 3 [Member]
Schedule of Insured Financial Obligations [Line Items]
Net Par Outstanding, Financial Guaranty Insurance	[5]	$ 3,011		$ 2,892
Net Par Outstanding, Credit Derivative		559		801
Net Par Outstanding (excluding loss mitigation bonds)		$ 3,570		$ 3,693
Number of Risks, Financial Guaranty Insurance | risk	[5],[7]	126		119
Number of Risks, Credit Derivative | risk	[7]	24		24
Number of Risks | risk	[7]	150		143

[1] The June 30, 2015 total amount includes $4.3 billion net par outstanding of credit derivatives acquired from Radian Asset.

[2] Excludes $1.2 billion of loss mitigation securities insured and held by the Company as of June 30, 2015, which are primarily in the BIG category.

[3] amounts include $13.1 billion of net par acquired from Radian Asset.

[4] Excludes $1.3 billion of loss mitigation securities insured and held by the Company as of December 31, 2014, which are primarily in the BIG category.

[5] Includes net par outstanding for VIEs.

[6] The June 30, 2015 BIG amount includes $933 million net par outstanding of credit derivatives acquired from Radian Asset.

[7] A risk represents the aggregate of the financial guaranty policies that share the same revenue source for purposes of making Debt Service payments.