Parent Company - Condensed Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Condensed Balance Sheet Statements, Captions [Line Items]
Other assets	$ 700	$ 597
Total assets	12,539	16,843
Other liabilities	435	457
Total liabilities	6,774	11,551
Total shareholders’ equity attributable to AGL	5,713	5,064
Total liabilities and shareholders’ equity	12,539	16,843
Assured Guaranty Ltd. (Parent)
Condensed Balance Sheet Statements, Captions [Line Items]
Investments	40	26
Investments in subsidiaries	5,553	4,984
Dividends receivable from subsidiaries	80	18
Other assets	64	58
Total assets	5,737	5,086
Other liabilities	24	22
Total liabilities	24	22
Total shareholders’ equity attributable to AGL	5,713	5,064
Total liabilities and shareholders’ equity	$ 5,737	$ 5,086