Certain Long-Duration Contracts With Guarantees (Guarantees Associated with Variable Annuity Contracts, by guarantee, by Guarantee Type) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Unadjusted Value
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	$ 1,056,235	$ 1,244,131
Adjusted Value
Net Amount at Risk by Product and Guarantee [Line Items]
Account value	$ 1,053,952	$ 1,251,084