Outstanding Insurance Exposure - Amortization Schedule of Puerto Rico Net Par Outstanding and Net Debt Service Outstanding (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Estimated Net Par Amortization [Abstract]
Total	$ 231,959	$ 236,807
Estimated Net Debt Service Amortization [Abstract]
Total	362,529	374,130
Puerto Rico [Member]
Estimated Net Par Amortization [Abstract]
2020 (July 1 - September 30)	291
2020 (October 1 - December 31)	0
Subtotal 2020	291
2021	153
2022	176
2023	206
2024	222
2025-2029	1,173
2030-2034	1,053
2035-2039	764
2040-2044	104
2045-2047	246
Total	4,388	$ 4,270
Estimated Net Debt Service Amortization [Abstract]
2020 (July 1 - September 30)	399
2020 (October 1 - December 31)	3
Subtotal 2020	402
2021	360
2022	375
2023	397
2024	403
2025-2029	1,895
2030-2034	1,527
2035-2039	942
2040-2044	179
2045-2047	272
Total	$ 6,752