Investments - Fixed Maturities by Maturity Periods (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Amortized Cost:
Due in one year or less	$ 1,120
Due after one year through five years	5,697
Due after five years through ten years	6,744
Due after ten years	3,354
Mortgage and other asset-backed securities	551
Amortized Cost	17,466	$ 17,278
Fair Value:
Due in one year or less	1,127
Due after one year through five years	6,018
Due after five years through ten years	6,993
Due after ten years	4,014
Mortgage and other asset-backed securities	595
Total fair value	$ 18,747