Outstanding Exposure - Puerto Rico Gross Par and Gross Debt Service Outstanding (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Schedule of Insured Financial Obligations [Line Items]
Exposure to Puerto Rico	$ 236,565	$ 233,438
Gross	374,698	370,172
Puerto Rico
Schedule of Insured Financial Obligations [Line Items]
Exposure to Puerto Rico	1,367	1,378
Gross	$ 1,855	$ 1,899