Stock-based Compensation - Stock Option Activities (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Oct. 31, 2018 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding | shares	1,611,344
Shares, Granted | shares	97,600
Shares, Exercised | shares	(207,770)
Shares, Forfeited | shares	(16,732)
Shares, Expired | shares	(9,007)
Shares, Outstanding | shares	1,475,435
Shares, Exercisable | shares	1,254,926
Weighted-Average Exercise Price, Outstanding	$ 24.56
Weighted-Average Exercise Price, Granted	42.81
Weighted-Average Exercise Price, Exercised	5.12
Weighted-Average Exercise Price, Forfeited	54.28
Weighted-Average Exercise Price, Expired	47.55
Weighted-Average Exercise Price, Outstanding	28.03
Weighted-Average Exercise Price, Exercisable	24.13
Weighted-Average Grant-date Fair Value, Granted	$ 21.83
Total Intrinsic Value Of Options Exercised | $	$ 8,196
Weighted-Average Remaining Contractual Term, Outstanding	4 years 8 months 4 days
Weighted-Average Remaining Contractual Term, Exercisable	3 years 11 months 15 days
Aggregate Intrinsic Value, Outstanding | $	$ 20,331
Aggregate Intrinsic Value, Exercisable | $	$ 20,327