Stock-based Compensation - Stock Option Activities (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Oct. 31, 2016 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding | shares	1,853,390
Shares, Granted | shares	93,100
Shares, Exercised | shares	(205,018)
Shares, Forfeited | shares	(10,753)
Shares, Expired | shares	(7,721)
Shares, Outstanding | shares	1,722,998
Shares, Exercisable | shares	1,345,458
Weighted-Average Exercise Price, Outstanding	$ 19.36
Weighted-Average Exercise Price, Granted	46.10
Weighted-Average Exercise Price, Exercised	13.98
Weighted-Average Exercise Price, Forfeited	50.76
Weighted-Average Exercise Price, Expired	14.12
Weighted-Average Exercise Price, Outstanding	21.27
Weighted-Average Exercise Price, Exercisable	13.81
Weighted-Average Grant-date Fair Value, Granted	$ 17.99
Total Intrinsic Value of options Exercised | $	$ 9,469
Weighted-Average Remaining Contractual Term, Outstanding	5 years 4 months 21 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 6 months 26 days
Aggregate Intrinsic Value, Outstanding | $	$ 71,043
Aggregate Intrinsic Value, Exercisable | $	$ 64,650