Comprehensive Income and Accumulated Other Comprehensive Income - Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Unrealized gain (loss) on available-for-sale securities, Pre-Tax Amount	$ (6,695)	$ 12,074	$ 15,670
Reclassification adjustment for gains (losses) realized in net income, Pre-Tax Amount	(2,776)	(925)	841
Net unrealized gain loss, Pre-Tax Amount	(9,471)	11,149	16,511
Other comprehensive income (loss), Pre-Tax Amount	(9,471)	11,149	16,511
Unrealized gain loss on available-for-sale securities, Tax Expense (Benefit)	(1,406)	2,536	3,291
Reclassification adjustment for gains (losses) realized in net income, Tax Expense (Benefit)	(583)	(195)	177
Net unrealized gain loss, Tax Expense (Benefit)	(1,989)	2,341	3,468
Other comprehensive income (loss), Tax Expense (Benefit)	(1,989)	2,341	3,468
Unrealized gain (loss) on available-for-sale securities, Net-of-Tax Amount	(5,289)	9,538	12,379
Reclassification adjustment for gains (losses) realized in net income, Net-of-Tax Amount	(2,193)	(730)	664
Net unrealized gain loss, Net-of-Tax Amount	(7,482)	8,808	13,043
Other comprehensive income (loss), Net-of-Tax Amount	$ (7,482)	$ 8,808	$ 13,043