Schedule II. Condensed Financial Information of Registrant (Condensed Statements of Operations) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net investment income	$ 952,447	$ 927,062	$ 910,459
Realized gains (losses)	59,319	(4,371)	20,621
Total revenue	5,112,869	4,737,921	4,527,532
Other operating expense	322,029	301,038	304,825
Interest expense	83,486	86,704	84,306
Total benefits and expenses	4,200,479	3,841,237	3,596,253
Income tax benefit (expense)	(167,431)	(164,911)	(170,397)
Net income	744,959	731,773	760,790
Other comprehensive income (loss):
Attributable to Parent Company	(351,661)	1,184,414	1,525,355
Comprehensive income (loss)	393,298	1,916,187	2,286,145
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net investment income	32,816	30,199	28,869
Realized gains (losses)	(5,682)	12,792	0
Total revenue	27,134	42,991	28,869
Other operating expense	51,378	57,679	68,419
Reimbursements from affiliates	(57,504)	(68,556)	(65,928)
Interest expense	86,751	90,197	89,317
Total benefits and expenses	80,625	79,320	91,808
Income before income taxes	(53,491)	(36,329)	(62,939)
Income tax benefit (expense)	9,682	7,773	13,133
Net operating loss before equity in earnings of affiliates	(43,809)	(28,556)	(49,806)
Equity in earnings of affiliates, net of tax	788,768	760,329	810,596
Net income	744,959	731,773	760,790
Other comprehensive income (loss):
Attributable to Parent Company	58,903	(21,477)	(11,379)
Attributable to affiliates	(410,564)	1,205,891	1,536,734
Comprehensive income (loss)	$ 393,298	$ 1,916,187	$ 2,286,145