Stockholders' Equity - Summary of the Company's Stock Options Activity (Detail) - Stock Options $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options, Options outstanding, beginning of year (in shares) | shares	804
Number of options, Granted (in shares) | shares	0
Number of options, Exercised (in shares) | shares	(78)
Number of options, Expired / terminated (in shares) | shares	0
Number of options, Options outstanding, end of year (in shares) | shares	726
Number of options, Options exercisable, end of period (in shares) | shares	722
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted average exercise price, Options outstanding, beginning of year (in dollars per share) | $ / shares	$ 4.99
Weighted average exercise price, Granted (in dollars per share) | $ / shares	0.00
Weighted average exercise price, Exercised (in dollars per share) | $ / shares	4.54
Weighted average exercise price, Expired / terminated (in dollars per share) | $ / shares	0.00
Weighted average exercise price, Options outstanding, end of period (in dollars per share) | $ / shares	5.04
Weighted average exercise price, Options exercisable, end of period (in dollars per share) | $ / shares	$ 5.04
Weighted average remaining contractual life, Options outstanding, end of period	11 months 27 days
Weighted average remaining contractual life, Options exercisable, end of period	1 year
Aggregate intrinsic value, Options outstanding, end of period | $	$ 24,879
Aggregate intrinsic value, Options exercisable, end of period | $	$ 24,729