Stockholders' Equity - Summary of the Company's Stock Options Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options expected to vest	1,100
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options, Options outstanding, beginning of year (in shares)	6,458
Number of options, Granted (in shares)	0
Number of options, Exercised (in shares)	(24)
Number of options, Expired / terminated (in shares)	0
Number of options, Options outstanding, end of year (in shares)	6,434
Number of options, Options exercisable, end of period (in shares)	68
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	$ 28.24
Weighted average exercise price, Granted (in dollars per share) | $ / shares	0
Weighted average exercise price, Exercised (in dollars per share) | $ / shares	4.20
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	28.33
Weighted average exercise price, Options exercisable, end of period (in dollars per share) | $ / shares	$ 4.54
Weighted average remaining contractual life, Options outstanding, end of period	8 years 9 months 29 days
Weighted average remaining contractual life, Options exercisable, end of period	1 year 8 months 9 days
Aggregate intrinsic value, Options outstanding, end of period | $	$ 167,827
Aggregate intrinsic value, Options exercisable, end of period | $	$ 3,397