Outstanding Exposure - Amortization Schedule of Puerto Rico Net Par Outstanding and Net Debt Service Outstanding (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Estimated Net Par Amortization [Abstract]
Net par amount outstanding	$ 290,620	$ 296,318
Estimated Net Debt Service Amortization [Abstract]
Total	436,045	437,535
Puerto Rico [Member]
Estimated Net Par Amortization [Abstract]
2017 (July 1 - September 30)	214
2017 (October 1 - December 31)	0
Subtotal 2017	214
2018	188
2019	210
2020	270
2021	129
2022-2026	900
2027-2031	942
2032-2036	1,249
2037-2041	417
2042-2047	418
Net par amount outstanding	4,937	$ 4,786
Estimated Net Debt Service Amortization [Abstract]
2017 (July 1 - September 30)	336
2017 (October 1 - December 31)	2
Subtotal 2017	338
2018	429
2019	440
2020	490
2021	336
2022-2026	1,819
2027-2031	1,609
2032-2036	1,669
2037-2041	588
2042-2047	492
Total	$ 8,210