Stock Based Compensation - Changes in Common and Preferred Stock Options Issued (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Jan. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Outstanding-beginning of period	2,307,280
Number of Options, Granted	184,728
Number of Options, Exercised	(73,167)
Number of Options, Cancelled	(43,954)
Number of Options, Outstanding-end of period	2,374,887
Number of Options, Exercisable-end of period	1,855,542
Number of Options, Vested or Expected to Vest-end of period	2,317,942
Weighted Average Exercise Price, Outstanding-beginning of period	$ 4.58
Weighted Average Exercise Price, Granted	$ 13.36
Weighted Average Exercise Price, Exercised	$ 3.46
Weighted Average Exercise Price, Cancelled	$ 10.49
Weighted Average Exercise Price, Outstanding-end of period	$ 5.19
Weighted Average Exercise Price, Exercisable-end of period	$ 3.30
Weighted Average Exercise Price, Vested or Expected to Vest-end of period	$ 5.02
Weighted Average Remaining Contractual Term (in years), Outstanding-end of period	4 years 2 months 12 days
Weighted Average Remaining Contractual Term (in years), Exercisable-end of period	3 years
Weighted Average Remaining Contractual Term (in Years), Vested or Expected to Vest-end of period	4 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding-end of period	$ 21,137
Aggregate Intrinsic Value, Exercisable-end of period	19,999
Aggregate Intrinsic Value, Vested or Expected to Vest-end of period	$ 21,009