Investments - Scheduled maturities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amortized cost
Due in one year or less	$ 1,193
Due after one year through five years	8,135
Due after five years through ten years	7,220
Due after ten years	3,893
Subtotal	20,441
ABS, RMBS and CMBS	616
Amortized cost	21,057	$ 22,004
Fair value
Due in one year or less	1,205
Due after one year through five years	8,207
Due after five years through ten years	7,132
Due after ten years	4,190
Subtotal	20,734
ABS, RMBS and CMBS	666
Total	$ 21,400	$ 23,261