Reinsurance Reinsurance (Net Amount at Risk and 100 Percent Mortality) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
GMDB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.30%
Net Amount at Risk	$ 364	$ 418
GLB
Guaranteed Minimum Benefits [Line Items]
Net Amount at Risk	733	440
GLB | GLB
Guaranteed Minimum Benefits [Line Items]
Net Amount at Risk	422	235
GLB | GMDB
Guaranteed Minimum Benefits [Line Items]
Net Amount at Risk	$ 89	$ 76
Minimum | GMDB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	3.80%
Minimum | GLB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.50%
Minimum | GMDB and GLB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	4.50%
Maximum | GMDB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	5.00%
Maximum | GLB
Guaranteed Minimum Benefits [Line Items]
Long-Duration Contracts, Assumptions by Product and Guarantee, Discount Rate	5.00%