Stock-Based Compensation - Summary of Options Including Non-Plan Stock Options (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stock Options:
Outstanding at beginning of year (in shares)	790,744
Granted (in shares)	120,019
Exercised (in shares)	(475,090)
Forfeited (in shares)	(4,937)
Outstanding at end of year (in shares)	430,736	790,744
Nonvested at end of year (in shares)	140,076	124,348
Exercisable at end of year (in shares)	290,660
Weighted- Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 22.48
Granted (in dollars per share)	43.28
Exercised (in dollars per share)	16.74
Forfeited (in dollars per share)	46.87
Outstanding at end of year (in dollars per share)	34.33	$ 22.48
Nonvested at end of year (in dollars per share)	43.91	$ 42.76
Exercisable at end of year (in dollars per share)	$ 29.70
Weighted-Average Remaining Contractual Term (Years)
Outstanding at end of year	3 years 1 month 28 days	2 years 2 months 4 days
Nonvested at end of year	5 years 7 months 9 days
Exercisable at end of year	1 year 11 months 23 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value [Roll Forward]
Outstanding at end of year	$ 4,550	$ 13,235
Nonvested at end of year	166
Exercisable at end of year	$ 4,099