Condensed Consolidated Statement of Shareholders' Equity (unaudited) - USD ($) $ in Millions	Total	Common Shares	Retained Earnings	Accumulated Other Comprehensive Income	Deferred Equity Compensation	Total Shareholders’ Equity Attributable to Assured Guaranty Ltd.	Nonredeemable Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2019		93,274,987
Beginning balance at Dec. 31, 2019	$ 6,645	$ 1	$ 6,295	$ 342	$ 1	$ 6,639	$ 6
Increase (Decrease) in Shareholders' Equity
Net income	(56)		(55)			(55)	(1)
Dividends	(19)		(19)			(19)
Common share repurchases (in shares)		(3,629,410)
Common shares repurchases	(116)		(116)			(116)
Shared based compensation (in shares)		337,745
Share-based compensation	(5)		(5)			(5)
Other comprehensive loss	(204)			(204)		(204)
Contributions and reallocation of ownership interests	20						20
Ending balance at Mar. 31, 2020	6,265	$ 1	6,100	138	1	6,240	25
Ending balance (in shares) at Mar. 31, 2020		89,983,322
Beginning balance (in shares) at Dec. 31, 2020		77,546,896
Beginning balance at Dec. 31, 2020	6,684	$ 1	6,143	498	1	6,643	41
Increase (Decrease) in Shareholders' Equity
Net income	15		11			11	4
Dividends	(17)		(17)			(17)
Contributions	3						3
Common share repurchases (in shares)		(1,986,534)
Common shares repurchases	(77)		(77)			(77)
Shared based compensation (in shares)		375,020
Share-based compensation	(5)		(5)			(5)
Distributions	(6)						(6)
Other comprehensive loss	(125)			(125)		(125)
Ending balance at Mar. 31, 2021	$ 6,472	$ 1	$ 6,055	$ 373	$ 1	$ 6,430	$ 42
Ending balance (in shares) at Mar. 31, 2021		75,935,382