Outstanding Insurance Exposure - Puerto Rico Gross Par and Gross Debt Service Outstanding (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Schedule of Insured Financial Obligations [Line Items]
Gross Par Outstanding	$ 238,156	$ 244,191
Gross Debt Service Outstanding	375,776	375,080
Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Par Outstanding	4,458	4,971
Gross Debt Service Outstanding	$ 6,956	$ 8,035