Stock Based Compensation - Stock Based Compensation Stock Option Activity (Detail) - Employee Stock Option - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options, outstanding, beginning balance (in shares)	162,475
Number of options, granted (in shares)	0
Number of options, exercised (in shares)	(64,314)
Number of options, forfeited (in shares)	0
Number of options, outstanding, ending balance (in shares)	98,161	162,475
Vested and exercisable at December 31, 2019	98,161
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-average exercise price, outstanding, beginning balance (in dollars per share)	$ 20.21
Weighted-average exercise price, granted (in dollars per share)	0
Weighted-average exercise price, exercised (in dollars per share)	15.33
Weighted-average exercise price, forfeited (in dollars per share)	0
Weighted-average exercise price, outstanding, ending balance (in dollars per share)	23.39	$ 20.21
Weighted average exercise price, vested and exercisable at December 31, 2019 (in dollars per share)	$ 23.39
Aggregate intrinsic value, outstanding	$ 4,522	$ 5,267
Aggregate intrinsic value, exercised	3,187	$ 4,446	$ 23,027
Vested and exercisable at December 31, 2019	$ 4,522
Weighted-average remaining contractual life, outstanding, ending balance	1 year 10 months 9 days	2 years 2 months 26 days
Vested and exercisable at December 31, 2019	1 year 10 months 9 days