Reinsurance and Other Monoline Exposures - Exposure by Reinsurer (Details) $ in Millions		Jun. 30, 2015 USD ($)
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	$ 17,455
Second-to- Pay Insured Par Outstanding	[1]	17,592
Assumed Par Outstanding	[1]	24,015
American Overseas Reinsurance Company Limited (f/k/a Ram Re) [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1],[2]	6,006
Second-to- Pay Insured Par Outstanding	[1],[2]	0
Assumed Par Outstanding	[1],[2]	30
Tokio Marine & Nichido Fire Insurance Co., Ltd. (“Tokio”) [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1],[3]	4,768
Second-to- Pay Insured Par Outstanding	[1],[3]	0
Assumed Par Outstanding	[1],[3]	0
Syncora Guarantee Inc. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	3,671
Second-to- Pay Insured Par Outstanding	[1]	1,612
Assumed Par Outstanding	[1]	160
Mitsui Sumitomo Insurance Co. Ltd. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1],[3]	1,927
Second-to- Pay Insured Par Outstanding	[1],[3]	0
Assumed Par Outstanding	[1],[3]	0
Aca Financial Guaranty Corp [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1],[4]	745
Second-to- Pay Insured Par Outstanding	[1],[4]	19
Assumed Par Outstanding	[1],[4]	0
Swiss Reinsurance Co. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	25
Second-to- Pay Insured Par Outstanding	[1]	0
Assumed Par Outstanding	[1]	0
Ambac [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	117
Second-to- Pay Insured Par Outstanding	[1]	4,725
Assumed Par Outstanding	[1]	12,320
National Public Finance Guarantee Corporation [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1],[5]	0
Second-to- Pay Insured Par Outstanding	[1],[5]	5,680
Assumed Par Outstanding	[1],[5]	5,391
MBIA Inc. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1],[6]	0
Second-to- Pay Insured Par Outstanding	[1],[6]	2,704
Assumed Par Outstanding	[1],[6]	469
Financial Guaranty Insurance Co [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	0
Second-to- Pay Insured Par Outstanding	[1]	1,797
Assumed Par Outstanding	[1]	690
Ambac Assurance Corp. Segregated account [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	0
Second-to- Pay Insured Par Outstanding	[1]	100
Assumed Par Outstanding	[1]	903
CIFG Assurance North America Inc. [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	0
Second-to- Pay Insured Par Outstanding	[1]	102
Assumed Par Outstanding	[1]	3,914
Other [Member]
Ceded Credit Risk [Line Items]
Ceded Par Outstanding	[1]	196
Second-to- Pay Insured Par Outstanding	[1]	853
Assumed Par Outstanding	[1]	$ 138

[1] Includes par related to insured credit derivatives.

[2] Represents “Withdrawn Rating.”

[3] The Company benefits from trust arrangements that satisfy the triple-A credit requirement of S&P and/or Moody’s.

[4] Represents “Not Rated.”

[5] NPFGC is also rated AA+ by KBRA.

[6] MBIA includes subsidiaries MBIA Insurance Corp. rated B by S&P and B2 by Moody's and MBIA U.K. Insurance Ltd. rated B by S&P and Ba2 by Moody’s.