Earnings Per Share - Basic and Diluted Earnings Per 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
Basic net income per share:
Net income available to common shareholders	$ 3,768	$ 2,759	$ 173	$ 7,546
Weighted average common shares outstanding (in shares)	44,691	46,429	44,860	46,490
Basic net income per share (in usd per share)	$ 0.08	$ 0.06	$ 0.00	$ 0.16
Diluted net income per share:
Net income available to common shareholders	$ 3,768	$ 2,759	$ 173	$ 7,546
Weighted average common shares outstanding (in shares)	44,691	46,429	44,860	46,490
Dilutive stock options and non-vested RSUs and PSUs (in shares)	748	721	601	709
Weighted average common shares outstanding for purposes of computing diluted net income per share (in shares)	45,439	47,150	45,461	47,199
Diluted net income per share (in usd per share)	$ 0.08	$ 0.06	$ 0.00	$ 0.16