Consolidation of Variable Interest Entities (Details) (USD $)	3 Months Ended			6 Months Ended		9 Months Ended			12 Months Ended		6 Months Ended	3 Months Ended
	Sep. 30, 2013 Entity		Sep. 30, 2012	Jun. 30, 2013 Entity		Sep. 30, 2013 Entity		Sep. 30, 2012 Entity	Dec. 31, 2012 Entity		Jun. 30, 2013 Flagstar	Jun. 30, 2012 AGC R&W Benefits From Deutsche Bank Settlement	Sep. 30, 2013 Total first lien Entity	Dec. 31, 2012 Total first lien Entity	Sep. 30, 2013 Second lien Entity	Dec. 31, 2012 Second lien Entity	Sep. 30, 2013 Other VIE with recourse Entity	Dec. 31, 2012 Other VIE with recourse Entity
Consolidated VIEs
Net fair value gains and losses on FG VIEs are expected to reverse to zero at maturity of the VIE debt	$ 0					$ 0
Number of VIE that did not require consolidation	1,000					1,000
Consolidated Variable Interest Entities [Roll Forward]
Number of FG VIEs, beginning of period				33		33		33	33
Variable Interest Entity, Number of Entities to be Consolidated						11	[1]		2	[1]
Variable Interest Entity, Number of Entities to be Deconsolidated	1	[1]		2	[1]	(3)	[1]		0	[1]
Variable Interest Entity Number Matured						(1)			(2)
Number of FG VIEs, end of period	40					40			33
Variable Interest Entity Consolidation Gain or Loss						7,000,000			6,000,000
Credit Risk Derivatives at Fair Value before Effect of Credit Spread Net 1 [Abstract]
Number of days VIEs' assets were past due (in days)	90 days
Total unpaid principal balance for the VIEs' assets that were over 90 days or more past due	791,000,000					791,000,000
Difference between the aggregate unpaid principal and aggregate fair value of the VIEs' Assets	2,117,000,000					2,117,000,000
Change in the instrument specific credit risk of the VIEs' assets	83,000,000		65,000,000			252,000,000		235,000,000
Difference between the aggregate unpaid principal and aggregate fair value of the VIEs' liabilities	1,725,000,000					1,725,000,000
VIE's with recourse	40					40			33				25	14	14	16	1	3
VIE's without recourse	0					0			0
Number of FG VIEs	40					40			33
Assets	2,515,000,000					2,515,000,000			2,688,000,000				620,000,000	618,000,000	456,000,000	633,000,000	358,000,000	350,000,000
Total with recourse , Assets	1,434,000,000					1,434,000,000			1,601,000,000
Without recourse, Assets	1,081,000,000					1,081,000,000			1,087,000,000
Liabilities	2,875,000,000					2,875,000,000			3,141,000,000				799,000,000	825,000,000	671,000,000	915,000,000	358,000,000	350,000,000
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	1,828,000,000					1,828,000,000			2,090,000,000
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	1,047,000,000					1,047,000,000			1,051,000,000
Contractual Maturity
Unpaid principal for FG VIEs’ liabilities with recourse (1)	2,385,000,000	[2]				2,385,000,000	[2]		2,808,000,000	[2]
Net change in fair value of financial guaranty variable interest entities:
Net earned premiums	(14,000,000)		(17,000,000)			(47,000,000)		(50,000,000)
Net investment income	(3,000,000)		(3,000,000)			(10,000,000)		(9,000,000)
Net realized investment gains (losses)	0		0			2,000,000		4,000,000
Fair value gains (losses) on FG VIEs	40,000,000		34,000,000			253,000,000		161,000,000			213,000,000	163,000,000
Loss and LAE	11,000,000		2,000,000			26,000,000		14,000,000
Total pre-tax effect on net income	34,000,000		16,000,000			224,000,000		120,000,000
Less: tax provision (benefit)	12,000,000		5,000,000			78,000,000		42,000,000
Total effect on net income (loss)	22,000,000		11,000,000			146,000,000		78,000,000
Total (decrease) increase on shareholders' equity	$ (209,000,000)					$ (209,000,000)			$ (348,000,000)

[1] Net loss on consolidation and deconsolidation was $7 million in Nine Months 2013 and $6 million in 2012, respectively, and recorded in “fair value gains (losses) on FG VIEs” in the consolidated statement of operations.

[2] FG VIE liabilities with recourse will mature at various dates ranging from 2025 to 2047.