Derivative Investments (Statements of Earnings) (Details) (Derivatives Not Designated as Hedging Instruments [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (1,705)	$ 3,422
Equity Index Options [Member] | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	27,147	(33,335)
Fixed-Index Products [Member] | Universal Life and Annuity Contract Interest [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (28,852)	$ 36,757