Investments - Realized Gain (Loss) on Investments (Detail) - USD ($) $ in Thousands		12 Months Ended
	Jul. 15, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Realized investment gains (losses) - sales and other		$ 34,916	$ (22,999)	$ 19,354
Provision for credit losses		2,959	(3,346)	0
Fair value option—change in fair value		22,918	1,045	1,256
Other investments		7,840	21,563	11
Realized gains (losses) from investments		68,633	(3,737)	20,621
Realized loss—redemption of debt	$ (9,300)	(9,314)	(634)	0
Realized gains (losses)		59,319	(4,371)	20,621
Applicable tax		(12,457)	1,955	(4,330)
Realized gains (losses), net of tax		46,862	(2,416)	16,291
Exchanges of fixed maturities		109,200	219,800	243,200
Exchanges of fixed maturities, net realized gains		$ 25,200	$ 7,900	$ 20,500