Investments - Fixed Maturities by Maturity Periods (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Amortized Cost:
Due in one year or less	$ 1,550
Due after one year through five years	6,581
Due after five years through ten years	7,353
Due after ten years	3,447
Mortgage and other asset-backed securities	461
Amortized Cost	19,392	$ 18,456
Fair Value:
Due in one year or less	1,557
Due after one year through five years	6,928
Due after five years through ten years	7,881
Due after ten years	4,379
Mortgage and other asset-backed securities	499
Total fair value	$ 21,244