Subsidiary Information - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2015		Dec. 31, 2014
Assets
Total investment portfolio and cash	$ 11,706		$ 11,459
Investment in subsidiaries	0		0
Premiums receivable, net of commissions payable	703		729
Ceded unearned premium reserve	282		381
Deferred acquisition costs	119		121
Reinsurance recoverable on unpaid losses	77		78
Credit derivative assets	81		68
Deferred tax asset, net	439		260
Intercompany receivable	0		0
Financial guaranty variable interest entities’ assets, at fair value	1,601	[1]	1,402
Other	471		427
Total assets	15,479		14,925
Liabilities and shareholders’ equity
Unearned premium reserve	4,389		4,261
Loss and loss adjustment expense reserve	996		799
Long-term debt	1,305		1,303
Intercompany payable	0		0
Credit derivative liabilities	1,007		963
Deferred tax liabilities, net	0		0
Financial guaranty variable interest entities’ liabilities, at fair value	1,532	[1]	1,419
Other	444		422
Total liabilities	9,673		9,167
Effect on shareholders’ equity (decrease) increase	5,806		5,758
Noncontrolling interest	0		0
Total shareholders' equity	5,806		5,758
Total liabilities and shareholders’ equity	15,479		14,925
Reportable Legal Entities [Member] | Assured Guaranty Ltd. (Parent) [Member]
Assets
Total investment portfolio and cash	145		126
Investment in subsidiaries	5,637		5,612
Premiums receivable, net of commissions payable	0		0
Ceded unearned premium reserve	0		0
Deferred acquisition costs	0		0
Reinsurance recoverable on unpaid losses	0		0
Credit derivative assets	0		0
Deferred tax asset, net	0		0
Intercompany receivable	0		0
Financial guaranty variable interest entities’ assets, at fair value	0		0
Other	29		27
Total assets	5,811		5,765
Liabilities and shareholders’ equity
Unearned premium reserve	0		0
Loss and loss adjustment expense reserve	0		0
Long-term debt	0		0
Intercompany payable	0		0
Credit derivative liabilities	0		0
Deferred tax liabilities, net	0		0
Financial guaranty variable interest entities’ liabilities, at fair value	0		0
Other	5		7
Total liabilities	5		7
Effect on shareholders’ equity (decrease) increase	5,806		5,758
Noncontrolling interest	0		0
Total shareholders' equity	5,806		5,758
Total liabilities and shareholders’ equity	5,811		5,765
Reportable Legal Entities [Member] | AGUS (Issuer) [Member]
Assets
Total investment portfolio and cash	68		204
Investment in subsidiaries	5,271		5,072
Premiums receivable, net of commissions payable	0		0
Ceded unearned premium reserve	0		0
Deferred acquisition costs	0		0
Reinsurance recoverable on unpaid losses	0		0
Credit derivative assets	0		0
Deferred tax asset, net	48		54
Intercompany receivable	0		0
Financial guaranty variable interest entities’ assets, at fair value	0		0
Other	91		77
Total assets	5,478		5,407
Liabilities and shareholders’ equity
Unearned premium reserve	0		0
Loss and loss adjustment expense reserve	0		0
Long-term debt	847		847
Intercompany payable	90		90
Credit derivative liabilities	0		0
Deferred tax liabilities, net	0		0
Financial guaranty variable interest entities’ liabilities, at fair value	0		0
Other	11		9
Total liabilities	948		946
Effect on shareholders’ equity (decrease) increase	4,530		4,461
Noncontrolling interest	0		0
Total shareholders' equity	4,530		4,461
Total liabilities and shareholders’ equity	5,478		5,407
Reportable Legal Entities [Member] | AGMH (Issuer) [Member]
Assets
Total investment portfolio and cash	26		47
Investment in subsidiaries	3,962		3,965
Premiums receivable, net of commissions payable	0		0
Ceded unearned premium reserve	0		0
Deferred acquisition costs	0		0
Reinsurance recoverable on unpaid losses	0		0
Credit derivative assets	0		0
Deferred tax asset, net	0		0
Intercompany receivable	0		0
Financial guaranty variable interest entities’ assets, at fair value	0		0
Other	35		27
Total assets	4,023		4,039
Liabilities and shareholders’ equity
Unearned premium reserve	0		0
Loss and loss adjustment expense reserve	0		0
Long-term debt	442		437
Intercompany payable	0		0
Credit derivative liabilities	0		0
Deferred tax liabilities, net	92		94
Financial guaranty variable interest entities’ liabilities, at fair value	0		0
Other	16		16
Total liabilities	550		547
Effect on shareholders’ equity (decrease) increase	3,473		3,492
Noncontrolling interest	0		0
Total shareholders' equity	3,473		3,492
Total liabilities and shareholders’ equity	4,023		4,039
Reportable Legal Entities [Member] | Other Entities [Member]
Assets
Total investment portfolio and cash	11,767		11,382
Investment in subsidiaries	356		339
Premiums receivable, net of commissions payable	844		864
Ceded unearned premium reserve	1,373		1,469
Deferred acquisition costs	186		186
Reinsurance recoverable on unpaid losses	412		338
Credit derivative assets	274		277
Deferred tax asset, net	523		295
Intercompany receivable	90		90
Financial guaranty variable interest entities’ assets, at fair value	1,601		1,402
Other	597		538
Total assets	18,023		17,180
Liabilities and shareholders’ equity
Unearned premium reserve	5,606		5,328
Loss and loss adjustment expense reserve	1,323		1,066
Long-term debt	16		19
Intercompany payable	300		300
Credit derivative liabilities	1,200		1,172
Deferred tax liabilities, net	0		0
Financial guaranty variable interest entities’ liabilities, at fair value	1,532		1,419
Other	833		764
Total liabilities	10,810		10,068
Effect on shareholders’ equity (decrease) increase	6,857		6,773
Noncontrolling interest	356		339
Total shareholders' equity	7,213		7,112
Total liabilities and shareholders’ equity	18,023		17,180
Consolidating Adjustments [Member]
Assets
Total investment portfolio and cash	(300)		(300)
Investment in subsidiaries	(15,226)		(14,988)
Premiums receivable, net of commissions payable	(141)		(135)
Ceded unearned premium reserve	(1,091)		(1,088)
Deferred acquisition costs	(67)		(65)
Reinsurance recoverable on unpaid losses	(335)		(260)
Credit derivative assets	(193)		(209)
Deferred tax asset, net	(132)		(89)
Intercompany receivable	(90)		(90)
Financial guaranty variable interest entities’ assets, at fair value	0		0
Other	(281)		(242)
Total assets	(17,856)		(17,466)
Liabilities and shareholders’ equity
Unearned premium reserve	(1,217)		(1,067)
Loss and loss adjustment expense reserve	(327)		(267)
Long-term debt	0		0
Intercompany payable	(390)		(390)
Credit derivative liabilities	(193)		(209)
Deferred tax liabilities, net	(92)		(94)
Financial guaranty variable interest entities’ liabilities, at fair value	0		0
Other	(421)		(374)
Total liabilities	(2,640)		(2,401)
Effect on shareholders’ equity (decrease) increase	(14,860)		(14,726)
Noncontrolling interest	(356)		(339)
Total shareholders' equity	(15,216)		(15,065)
Total liabilities and shareholders’ equity	$ (17,856)		$ (17,466)

[1] nclude $119 million of FG VIE assets and $115 million of FG VIE liabilities acquired from Radian Asset.