Derivative Investments (Statements of Earnings) (Details) (Derivatives Not Designated as Hedging Instruments [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ 75	$ (1,484)	$ (5,103)	$ (1,030)
Equity Index Options [Member] | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	(32,478)	(9,098)	9,959	22,751
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	$ 32,553	$ 7,614	$ (15,062)	$ (23,781)