Net Income Per Common Share - Summary of Net Income Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Line Items]
Net income	$ 9,745	$ 13,595	$ 17,956	$ 17,733
Basic weighted-average common shares outstanding (in shares)	38,233	37,235	38,060	37,063
Effect of dilutive stock options (in shares)	37	324	90	347
Effect of dilutive restricted stock (in shares)	1,128	1,341	1,318	1,316
Diluted weighted-average common shares outstanding (in shares)	39,398	38,900	39,468	38,726
Basic income per common share (in dollars per share)	$ 0.25	$ 0.37	$ 0.47	$ 0.48
Diluted income per common share (in dollars per share)	$ 0.25	$ 0.35	$ 0.45	$ 0.46
Stock options | Nonvested restricted stock
Earnings Per Share [Line Items]
Antidilutive securities excluded from diluted income per common share (in shares)	327	339	300	379