Derivative Investments - Schedule of Effect of Derivative Instruments in Consolidated Statements of Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Change in the embedded derivative liability due to the expected collectability of asset management fees increased/(decreased) contract interest expense	$ 6,500	$ 34,400	$ (33,600)
Derivatives Not Designated as Hedging Instruments
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain or (Loss) Recognized In Income on Derivatives	72,116	(30,216)	31,783
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	120,718	14,754	123,207
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	(133,327)	(44,970)	(91,424)
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	$ 84,725	$ 0	$ 0