Outstanding Exposure - Schedule of Non-Financial Guaranty Exposure (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Diversified real estate
Schedule of Insured Financial Obligations [Line Items]
Gross Exposure	$ 2,004	$ 2,004
Net Exposure	2,004	2,004
Insurance reserve financings and securitizations
Schedule of Insured Financial Obligations [Line Items]
Gross Exposure	1,495	1,449
Net Exposure	1,169	1,126
Pooled corporate obligations
Schedule of Insured Financial Obligations [Line Items]
Gross Exposure	836	868
Net Exposure	836	868
Aircraft residual value insurance
Schedule of Insured Financial Obligations [Line Items]
Gross Exposure	147	147
Net Exposure	$ 87	$ 87