Parent Company - Condensed Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Cash Flow Statements, Captions [Line Items]
Net income	$ 739	$ 124	$ 389
Equity in earnings (losses) of investees	(28)	39	(94)
Net realized investment gains (losses)	14	56	(15)
Net cash flows provided by (used in) operating activities	461	(2,479)	(1,937)
Sales	(4)	0	0
Maturities and paydowns	746	682	1,148
Net sales (purchases) of short-term investments with original maturities of less than three months	(872)	439	(410)
Net cash flows provided by (used in) investing activities	286	1,740	23
Dividends paid	(67)	(64)	(66)
Repurchases of common shares	(199)	(500)	(496)
Other	(19)	(6)	26
Net cash flows provided by (used in) financing activities	(670)	612	1,960
Increase (decrease) in cash and cash equivalents and restricted cash	79	(135)	44
Cash and cash equivalents and restricted cash at beginning of period	207	342	298
Cash and cash equivalents and restricted cash at end of period	286	207	342
AG Re | Assured Guaranty LTD
Condensed Cash Flow Statements, Captions [Line Items]
Dividend from a subsidiary in the form of fixed-maturity securities	0	0	46
Assured Guaranty Ltd. (Parent)
Condensed Cash Flow Statements, Captions [Line Items]
Net income	739	124	389
Equity in earnings (losses) of investees	(784)	(170)	(423)
Net realized investment gains (losses)	1	4	0
Cash dividends from subsidiaries	306	437	539
Other	36	32	22
Net cash flows provided by (used in) operating activities	298	427	527
Sales	4	52	0
Maturities and paydowns	0	5	4
Net sales (purchases) of short-term investments with original maturities of less than three months	(18)	92	41
Net cash flows provided by (used in) investing activities	(14)	149	45
Dividends paid	(67)	(64)	(66)
Repurchases of common shares	(199)	(500)	(496)
Other	(18)	(12)	(10)
Net cash flows provided by (used in) financing activities	(284)	(576)	(572)
Increase (decrease) in cash and cash equivalents and restricted cash	0	0	0
Cash and cash equivalents and restricted cash at beginning of period	0	0	0
Cash and cash equivalents and restricted cash at end of period	$ 0	$ 0	$ 0