Derivative Investments (Statements of Earnings) (Details) (Derivatives Not Designated as Hedging Instruments [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	$ (1,242)	$ (619)	$ (2,886)	$ (5,722)
Equity Index Options [Member] | Investment Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivative	35,615	32,369	126,739	42,328
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	$ (36,857)	$ (32,988)	$ (129,625)	$ (48,050)