Reinsurance - Guaranteed Minimum Death Benefits Account Value, Net Amount at Risk and Contractholders (Details) - Variable Annuity [Member] - Guaranteed Minimum Death Benefit [Member] Contractholders in Thousands, $ in Billions	9 Months Ended	12 Months Ended
	Sep. 30, 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	$ 11.3	$ 13.1
Net amount at risk	$ 3.1	$ 2.8
Number of contractholders | Contractholders	330	354