Consolidation of Variable Interest Entities (Details) (USD $)	3 Months Ended			6 Months Ended			12 Months Ended		3 Months Ended
	Jun. 30, 2013 Entity		Jun. 30, 2012	Jun. 30, 2013 Entity		Jun. 30, 2012 Entity	Dec. 31, 2012 Entity		Jun. 30, 2013 Flagstar and UBS [Member]	Mar. 31, 2013 Flagstar	Jun. 30, 2012 AGC R&W Benefits From Deutsche Bank Settlement	Jun. 30, 2013 Total first lien Entity	Dec. 31, 2012 Total first lien Entity	Jun. 30, 2013 Second lien Entity	Dec. 31, 2012 Second lien Entity	Jun. 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	1,100			1,100
Consolidated Variable Interest Entities [Roll Forward]
Number of FG VIEs				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	2	[1]		(2)	[1]		0	[1]
Variable Interest Entity Number Matured				(1)			(2)
Variable Interest Entity Consolidation Gain or Loss				7,000,000			6,000,000
Number of FG VIEs	41			41			33
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	820,000,000			820,000,000
Difference between the aggregate unpaid principal and aggregate fair value of the VIEs' Assets	2,169,000,000			2,169,000,000
Change in the instrument specific credit risk of the VIEs' assets	97,000,000		84,000,000	168,000,000		170,000,000
Difference between the aggregate unpaid principal and aggregate fair value of the VIEs' liabilities	1,739,000,000			1,739,000,000
VIE's with recourse	41			41			33					25	14	14	16	2	3
VIE's without recourse	0			0			0
Number of FG VIEs	41			41			33
Assets	2,674,000,000			2,674,000,000			2,688,000,000					653,000,000	618,000,000	492,000,000	633,000,000	360,000,000	350,000,000
Liabilities	3,074,000,000			3,074,000,000			3,141,000,000					849,000,000	825,000,000	731,000,000	915,000,000	360,000,000	350,000,000
Total with recourse , Assets	1,505,000,000			1,505,000,000			1,601,000,000
Financial guaranty variable interest entities’ liabilities with recourse, at fair value	1,940,000,000			1,940,000,000			2,090,000,000
Without recourse, Assets	1,169,000,000			1,169,000,000			1,087,000,000
Financial guaranty variable interest entities’ liabilities without recourse, at fair value	1,134,000,000			1,134,000,000			1,051,000,000
Contractual Maturity
Unpaid principal for FG VIEs’ liabilities with recourse (1)	2,481,000,000	[2]		2,481,000,000	[2]		2,808,000,000	[2]
2014	12,000,000			12,000,000
Net change in fair value of financial guaranty variable interest entities:
Net earned premiums	(15,000,000)		(16,000,000)	(33,000,000)		(33,000,000)
Net investment income	(4,000,000)		(3,000,000)	(7,000,000)		(6,000,000)
Net realized investment gains (losses)	1,000,000		3,000,000	2,000,000		4,000,000
Fair value gains (losses) on FG VIEs	143,000,000		168,000,000	213,000,000		127,000,000			149,000,000	64,000,000	161,000,000
Loss and LAE	22,000,000		4,000,000	15,000,000		12,000,000
Total pre-tax effect on net income	147,000,000		156,000,000	190,000,000		104,000,000
Less: tax provision (benefit)	51,000,000		55,000,000	66,000,000		37,000,000
Total effect on net income (loss)	96,000,000		101,000,000	124,000,000		67,000,000
Total (decrease) increase on shareholders' equity	$ (226,000,000)			$ (226,000,000)			$ (348,000,000)

[1] Net loss on consolidation and deconsolidation was $7 million in Six 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, except for $12 million maturing in 2014.