Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense (benefit)	$ 2,821	$ 3,449	$ (8,105)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	32,253	(278)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized Gains and Losses on Available for Sale Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other net realized investment (gains) losses	39,610	(342)
Income tax expense (benefit)	$ (7,357)	$ 64