Share-based Compensation - Summary of Company's Stock Option Plan Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares, Options outstanding, Beginning balance	958
Number of Shares, Granted	111
Number of Shares, Exercised	(60)
Number of Shares, Forfeited	0
Number of Shares, Expired	0
Number of Shares, Options outstanding, Ending balance	1,009
Number of Shares, Options exercisable	731
Number of Shares, Available for grant	1,144
Weighted Average Exercise Price Per Share, Options outstanding, Beginning balance | $ / shares	$ 17.39
Weighted Average Exercise Price Per Share, Granted | $ / shares	28.25
Weighted Average Exercise Price Per Share, Exercised | $ / shares	16.82
Weighted Average Exercise Price Per Share, Forfeited | $ / shares	0
Weighted Average Exercise Price Per Share, Expired | $ / shares	0
Weighted Average Exercise Price Per Share, Options outstanding, Ending balance | $ / shares	18.62
Weighted Average Exercise Price Per Share, Options exercisable | $ / shares	$ 17.00
Weighted Average Remaining Contractual Life (Years), Options outstanding	7 years 3 months 19 days
Weighted Average Remaining Contractual Life (Years), Options exercisable	6 years 8 months 12 days
Aggregate Intrinsic Value, Options outstanding | $	$ 13,396
Aggregate Intrinsic Value, Options exercisable | $	$ 10,901