Derivative Investments (Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Derivatives, index options	$ 87,833		$ 30,844
Liability Derivatives	98,396	[1]	47,129	[1]
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivatives, index options	87,833		30,844
Liability Derivatives	98,396		47,129
Derivatives Not Designated as Hedging Instruments [Member] | Equity Index Options [Member] | Derivatives, Index Options [Member]
Derivatives, Fair Value [Line Items]
Derivatives, index options	87,833		30,844
Derivatives Not Designated as Hedging Instruments [Member] | Fixed-Index Products [Member] | Universal Life and Annuity Contracts [Member]
Derivatives, Fair Value [Line Items]
Liability Derivatives	$ 98,396		$ 47,129

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