Insurance Company Regulatory Requirements - Dividends and Surplus Notes By Insurance Company Subsidiaries (Details) - Affiliated Entity [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Assured Guaranty LTD [Member] | Assured Guaranty Re [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	$ 35	$ 20	$ 85	$ 82
AGMH [Member] | AGM [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	40	45	106	45
Repayment of surplus notes	0	0	25	25
AGUS [Member] | AGC [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	$ 15	$ 15	$ 35	$ 15