Stock-based Compensation - Stock Option Activities (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Oct. 31, 2015 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares, Outstanding | shares	2,281,909
Shares, Granted | shares	163,200
Shares, Exercised | shares	(509,933)
Shares, Forfeited | shares	(31,081)
Shares, Outstanding | shares	1,904,095
Shares, Exercisable | shares	1,363,586
Shares, Vested and expected to vest | shares	1,868,541
Weighted-Average Exercise Price, Outstanding	$ 13.00
Weighted-Average Exercise Price, Granted	73.06
Weighted-Average Exercise Price, Exercised	9.28
Weighted-Average Exercise Price, Forfeited	28.91
Weighted-Average Exercise Price, Outstanding	18.89
Weighted-Average Exercise Price, Exercisable	9.41
Weighted-Average Exercise Price, Vested and expected to vest	18.32
Weighted-Average Grant-date Fair Value, Granted	$ 39.79
Total Intrinsic Value of options Exercised | $	$ 35,157
Weighted-Average Remaining Contractual Term, Outstanding	6 years 29 days
Weighted-Average Remaining Contractual Term, Exercisable	5 years 15 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	6 years 11 days
Aggregate Intrinsic Value, Outstanding | $	$ 62,057
Aggregate Intrinsic Value, Exercisable | $	54,587
Aggregate Intrinsic Value, Vested and expected to vest | $	$ 61,700