Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 5	$ 20	$ 55	$ 137
Change in net unrealized gains (losses) on:
Investments with no credit impairment, net of tax provision (benefit) of $(39), $(8), $(139) and $(18)	(277)	(66)	(857)	(134)
Investments with credit impairment, net of tax provision (benefit) of $1, $(2), $(18) and $3	2	(6)	(81)	12
Change in net unrealized gains (losses) on investments	(275)	(72)	(938)	(122)
Change in instrument-specific credit risk on financial guaranty variable interest entities’ liabilities with recourse, net of tax	(3)	2	(1)	(1)
Other, net of tax	(4)	(1)	(13)	(1)
Other comprehensive income (loss)	(282)	(71)	(952)	(124)
Comprehensive income (loss)	(277)	(51)	(897)	13
Less: Comprehensive income (loss) attributable to noncontrolling interests	(6)	3	25	11
Comprehensive income (loss) attributable to Assured Guaranty Ltd.	$ (271)	$ (54)	$ (922)	$ 2