Derivative Investments (Statements of Earnings) (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	$ 6,829	$ 6,081	$ 26,190	$ 5,507
Equity index options | Investment Income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	3,296	69,683	63,127	35,581
Fixed-index products | Universal Life and Annuity Contract Interest
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	$ 3,533	$ (63,602)	$ (36,937)	$ (30,074)