Investments - Scheduled Maturities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Amortized cost
Due in one year or less	$ 1,251
Due after one year through five years	7,969
Due after five years through ten years	7,113
Due after ten years	3,670
Subtotal	20,003
ABS, RMBS and CMBS	509
Amortized cost	20,512	$ 21,057
Fair value
Due in one year or less	1,267
Due after one year through five years	8,265
Due after five years through ten years	7,499
Due after ten years	4,248
Subtotal	21,279
ABS, RMBS and CMBS	564
Fair value	$ 21,843	$ 21,400