Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 159	$ 5	$ 382	$ 55
Change in net unrealized gains (losses) on:
Investments with no credit impairment, net of tax provision (benefit) of $(23), $(39), $(15) and $(139)	(113)	(277)	(54)	(857)
Investments with credit impairment, net of tax provision (benefit) of $(2), $1, $(4) and $(18)	(8)	2	(13)	(81)
Change in net unrealized gains (losses) on investments	(121)	(275)	(67)	(938)
Change in instrument-specific credit risk on financial guaranty variable interest entities’ liabilities with recourse, net of tax	10	(3)	11	(1)
Other, net of tax	4	(4)	6	(13)
Other comprehensive income (loss)	(107)	(282)	(50)	(952)
Comprehensive income (loss)	52	(277)	332	(897)
Less: Comprehensive income (loss) attributable to noncontrolling interests	2	(6)	19	25
Comprehensive income (loss) attributable to Assured Guaranty Ltd.	$ 50	$ (271)	$ 313	$ (922)