Comprehensive Income and Accumulated Other Comprehensive Loss - Reclassification Out of Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments	$ 2	$ (222)
Income before income taxes	11,221	20,745
Income tax expense	(2,272)	(3,820)
Net income	8,949	16,925
Unrealized Losses On Debt Securities, Net Of Tax [Member] | Reclassification Out of Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Net realized gains (losses) on investments	(6)	(115)
Income before income taxes	(6)	(115)
Income tax expense	2	24
Net income	$ (4)	$ (91)