Parent Company - Condensed Statements of Operations and Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Condensed Income Statements, Captions [Line Items]
Net investment income	$ 340	$ 365	$ 269
Net realized investment gains (losses)	9	(14)	(56)
Total revenues	872	1,373	723
Other expenses	159	217	167
Total expenses	446	733	536
Income (loss) before income taxes and equity in earnings (losses) of investees	426	640	187
Equity in earnings (losses) of investees	62	28	(39)
Net income (loss) attributable to Assured Guaranty Ltd.	376	739	124
Other comprehensive income (loss)	(26)	156	(815)
Comprehensive income (loss) attributable to Assured Guaranty Ltd.	350	895	(691)
Assured Guaranty Ltd. (Parent)
Condensed Income Statements, Captions [Line Items]
Net investment income	2	1	3
Net realized investment gains (losses)	0	(1)	(4)
Total revenues	2	0	(1)
Other expenses	42	45	45
Total expenses	42	45	45
Income (loss) before income taxes and equity in earnings (losses) of investees	(40)	(45)	(46)
Equity in earnings (losses) of investees	416	784	170
Net income (loss) attributable to Assured Guaranty Ltd.	376	739	124
Other comprehensive income (loss)	(26)	156	(815)
Comprehensive income (loss) attributable to Assured Guaranty Ltd.	$ 350	$ 895	$ (691)