Stock-based Compensation - Stock Option Activities (Detail) $ / shares in Units, $ in Thousands	6 Months Ended
	Jul. 31, 2019 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding | shares	1,459,064
Shares, Granted | shares	28,300
Shares, Exercised | shares	(163,886)
Shares, Forfeited | shares	(11,508)
Shares, Expired | shares	(9,045)
Shares, Outstanding | shares	1,302,925
Shares, Exercisable | shares	1,130,044
Weighted-Average Exercise Price, Outstanding	$ 28.31
Weighted-Average Exercise Price, Granted	41.07
Weighted-Average Exercise Price, Exercised	15.30
Weighted-Average Exercise Price, Forfeited	45.29
Weighted-Average Exercise Price, Expired	56.55
Weighted-Average Exercise Price, Outstanding	29.87
Weighted-Average Exercise Price, Exercisable	27.35
Weighted-Average Grant-date Fair Value, Granted	$ 21.00
Total Intrinsic Value Of Options Exercised | $	$ 4,493
Weighted-Average Remaining Contractual Term, Outstanding	4 years 3 months 21 days
Weighted-Average Remaining Contractual Term, Exercisable	3 years 7 months 20 days
Aggregate Intrinsic Value, Outstanding | $	$ 30,053
Aggregate Intrinsic Value, Exercisable | $	$ 29,049