Shared-Based Compensation - Reconciliation of Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of options, Outstanding, Beginning Balance | shares	897
Number of Options, Granted | shares	126
Number of Options, Exercised | shares	(220)
Number of Options, Forfeited or expired | shares	(6)
Number of Options, Outstanding, Ending Balance | shares	797
Number of Options, Options Exercisable | shares	555
Weighted-Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 12.22
Weighted-Average Exercise Price, Granted | $ / shares	24.20
Weighted-Average Exercise Price, Exercised | $ / shares	11.81
Weighted-Average Exercise Price, Forfeited or expired | $ / shares	7.72
Weighted-Average Exercise Price, Outstanding, Ending Balance | $ / shares	14.22
Weighted-Average Exercise Price, Options exercisable | $ / shares	$ 12.17
Weighted-Average Remaining Contractual Term, Outstanding	6 years 7 months 6 days
Weighted- Average Remaining Contractual Term, Options exercisable	5 years 6 months
Aggregate Intrinsic Value, Outstanding | $	$ 10,538
Aggregate Intrinsic Value, Options exercisable | $	$ 8,490