Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares	[1]
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares outstanding, Options Balance | shares	418,394
Number of shares outstanding, Options Granted | shares	33,333
Number of shares outstanding, Options forfeited and expired | shares	0
Exercise of stock options (in shares) | shares	(48,000)
Number of shares outstanding, Options Balance | shares	403,727
Number of shares outstanding, Exercisable | shares	290,894
Weighted-average exercise price, Options Balance | $ / shares	$ 37.29
Weighted-average exercise price, Options Granted | $ / shares	94.20
Weighted-average exercise price, Options forfeited and expired | $ / shares	0
Weighted-average exercise price, Options Exercised | $ / shares	23.63
Weighted-average exercise price, Options Balance | $ / shares	43.61
Weighted-average exercise price, Exercisable | $ / shares	$ 33.67
Weighted average remaining contractual term, Balance	6 years 7 days
Weighted average remaining contractual term, Exercisable	5 years 4 months 6 days
Aggregate intrinsic value, Balance | $	$ 29,519
Aggregate intrinsic value, Exercisable | $	$ 24,163

[1] Does not include restricted stock or employee stock purchase plans.