Investments - Scheduled Maturities (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Amortized cost
Due in one year or less	$ 1,410
Due after one year through five years	7,675
Due after five years through ten years	7,354
Due after ten years	3,520
Subtotal	19,959
ABS, RMBS and CMBS	460
Amortized cost	20,419	$ 21,057
Fair value
Due in one year or less	1,426
Due after one year through five years	7,982
Due after five years through ten years	7,845
Due after ten years	4,231
Subtotal	21,484
ABS, RMBS and CMBS	516
Fair value	$ 22,000	$ 21,400