Derivatives - Statements of Earnings (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Increase (decrease) in contract interest expense	$ 0	$ 4,400
Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	54,888	67,128
Derivatives not designated as hedging instruments | Equity index options | Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	(38,198)	28,024
Derivatives not designated as hedging instruments | 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	2,181	(31,266)
Derivatives not designated as hedging instruments | Embedded derivative on reinsurance contract | Net investment income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized in Income on Derivatives	$ 90,905	$ 70,370