Contracts Accounted for as Insurance - Net Expected Loss to be Expensed Insurance Contracts (Details) $ in Millions	Jun. 30, 2019 USD ($)
Insurance [Abstract]
2019 (July 1 - September 30)	$ 8
2019 (October 1 - December 31)	9
Subtotal 2019	17
2020	38
2021	35
2022	34
2023	35
2024-2028	148
2029-2033	99
2034-2038	45
After 2038	9
Net expected loss to be expensed	460
Future accretion	30
Total expected future loss and LAE	$ 490