Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 176	$ 159	$ 370	$ 382
Change in net unrealized gains (losses) on:
Investments with no credit impairment, net of tax provision (benefit) of $25, $(23), $16, and $(15)	152	(113)	111	(54)
Investments with credit impairment, net of tax provision (benefit) of $3, $(2), $4 and $(4)	10	(8)	18	(13)
Change in net unrealized gains (losses) on investments	162	(121)	129	(67)
Change in instrument-specific credit risk on financial guaranty variable interest entities’ liabilities with recourse, net of tax provision (benefit)	(1)	10	(1)	11
Other, net of tax provision (benefit)	0	4	0	6
Other comprehensive income (loss)	161	(107)	128	(50)
Comprehensive income (loss)	337	52	498	332
Less: Comprehensive income (loss) attributable to noncontrolling interests	5	2	12	19
Comprehensive income (loss) attributable to Assured Guaranty Ltd.	$ 332	$ 50	$ 486	$ 313