Investments - Schedule of Net Realized (Losses) Gains on Debt Securities Available-for-sale (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Debt Securities Available-for-Sale
Total realized gains	$ 7	$ 83
Total realized losses	(23)	(3)
Net realized (losses) and gains	(16)	80
Debt Securities Available-for-sale, Fair Value at Sale
Total realized gains, Fair Value at Sale	910	10,431
Total realized losses, Fair Value at Sale	1,685	642
Net realized gains (losses), Fair Value at Sale	$ 2,595	$ 11,073