Reinsurance - Guaranteed Minimum Death Benefits Account Value, Net Amount at Risk and Contractholders (Details) - Variable Annuity [Member] - Guaranteed Minimum Death Benefit [Member] $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) Contractholders	Dec. 31, 2014 USD ($) Contractholders
Guaranteed Minimum Death Benefits Account Value, Net Amount at Risk And Average Age Table [Line Items]
Account value	$ 11,355	$ 13,078
Net amount at risk	$ 2,870	$ 2,763
Average attained age of contractholders (weighted by exposure)	74 years	73 years
Number of contractholders | Contractholders	324,000	354,000