Derivative Investments (Balance Sheet) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 42,179	$ 38,409
Liability Derivatives	63,308	58,359
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	42,179	38,409
Liability Derivatives	63,308	58,359
Derivatives Not Designated as Hedging Instruments [Member] | Equity Index Options [Member] | Derivatives, Index Options [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	42,179	38,409
Derivatives Not Designated as Hedging Instruments [Member] | Fixed-Index Products [Member] | Universal Life and Annuity Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 63,308	$ 58,359