Schedule II. Condensed Financial Information of Registrant - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating activities
Net cash provided by operating activities	$ 29,842	$ 28,194	$ 37,979
Investing activities
Purchases of property and equipment	(553)	(2,089)	(1,296)
Net cash provided by investing activities	43,884	75,426	70,959
Financing activities
Finance lease purchases	(91)	(58)	(44)
Share-based compensation related tax withholding	(944)
Purchase of treasury stock	(2,171)	(12,388)
Dividends to shareholders	(93,307)	(100,427)	(99,929)
Net cash used in financing activities	(96,513)	(112,873)	(99,973)
Change in cash and cash equivalents	(22,787)	(9,253)	8,965
Cash and cash equivalents at beginning of year	61,469	70,722	61,757
Cash and cash equivalents at end of year	38,682	61,469	70,722
Parent Company [Member]
Operating activities
Net cash provided by operating activities	5,591	6,121	6,622
Investing activities
Purchases of investments	(24,885)	(31,909)	(87,289)
Proceeds from sales of investments	35,013	75,950	28,780
Purchases of property and equipment	(482)	(1,903)	(1,277)
Dividends from subsidiary	56,000	77,700	148,400
Net cash provided by investing activities	65,646	119,838	88,614
Financing activities
Finance lease purchases	(91)	(58)	(44)
Share-based compensation related tax withholding	(944)
Purchase of treasury stock	(2,171)	(12,388)
Dividends to shareholders	(93,307)	(100,427)	(99,929)
Net cash used in financing activities	(96,513)	(112,873)	(99,973)
Change in cash and cash equivalents	(25,276)	13,086	(4,737)
Cash and cash equivalents at beginning of year	31,911	18,825	23,562
Cash and cash equivalents at end of year	$ 6,635	$ 31,911	$ 18,825