Derivative Investments (Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Asset Derivatives	$ 95,987		$ 114,287
Liability Derivatives	111,627	[1]	133,236	[1]
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	95,987		114,287
Liability Derivatives	111,627		133,236
Derivatives Not Designated as Hedging Instruments [Member] | Equity Index Options [Member] | Derivatives, Index Options [Member]
Derivatives, Fair Value [Line Items]
Asset Derivatives	95,987		114,287
Derivatives Not Designated as Hedging Instruments [Member] | Fixed-Index Products [Member] | Universal Life and Annuity Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 111,627		$ 133,236

[1] Represents the fair value of certain product-related embedded derivatives that were recorded at fair value.