Contracts Accounted for as Insurance - Net Expected Loss to be Expensed Insurance Contracts (Details) $ in Millions	Jun. 30, 2017 USD ($)
Insurance [Abstract]
2017 (July 1 – September 30)	$ 8
2017 (October 1 – December 31)	9
Subtotal 2017	17
2018	38
2019	33
2020	35
2021	33
2022-2026	142
2027-2031	84
2032-2036	45
After 2036	15
Net expected loss to be expensed	442
Future accretion	285
Total expected future loss and LAE	$ 727