Insurance Company Regulatory Requirements - Dividends and Surplus Notes By Insurance Company Subsidiaries (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statutory Accounting Practices [Line Items]
Dividends paid			$ 55	$ 58
AGMH [Member] | Affiliated Entity [Member] | AGM [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	$ 57	$ 60	163	105
Repayment of surplus notes	0	25	25	50
AGL [Member] | Affiliated Entity [Member] | Assured Guaranty Re [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	35	0	120	82
AGUS [Member] | Affiliated Entity [Member] | AGC [Member]
Statutory Accounting Practices [Line Items]
Dividends paid	$ 15	$ 15	$ 50	$ 30