Outstanding Exposure - Puerto Rico Gross Par and Gross Debt Service Outstanding (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Schedule of Insured Financial Obligations [Line Items]
Exposure to Puerto Rico	$ 244,193	$ 233,438
Gross	387,145	370,172
Puerto Rico
Schedule of Insured Financial Obligations [Line Items]
Exposure to Puerto Rico	1,365	1,378
Gross	$ 1,849	$ 1,899