Summary of Business and Significant Accounting Policies - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Jan. 31, 2017 USD ($)	Jan. 31, 2017 USD ($) Segment Customer	Jan. 31, 2016 USD ($) Customer	Jan. 31, 2015 USD ($) Customer
Summary Of Business And Accounting Policies [Line Items]
Number of operating segment | Segment		1
Highly liquid investments maturity		3 months
Impairment of goodwill	$ 0
Impairment recognized for long-lived assets		$ 0	$ 0	$ 0
Sales commission expense		22,000,000	16,400,000	13,200,000
Advertising expense		$ 200,000	$ 200,000	$ 100,000
2013 Employee Stock Purchase Plan [Member]
Summary Of Business And Accounting Policies [Line Items]
Recognition period of stock-based compensation expenses on straight-line basis		7 months
Internal-Use Software [Member]
Summary Of Business And Accounting Policies [Line Items]
Useful Lives of Intangible Assets		3 years
Customer concentration risk [Member]
Summary Of Business And Accounting Policies [Line Items]
Sales percentage from largest customers		45.00%	50.00%	54.00%
Customer concentration risk [Member] | Revenues [Member]
Summary Of Business And Accounting Policies [Line Items]
Number of customers | Customer		0	0	0
Minimum [Member]
Summary Of Business And Accounting Policies [Line Items]
Customer payment period		30 days
Minimum [Member] | 2007 Stock Plan [Member]
Summary Of Business And Accounting Policies [Line Items]
Share-based compensation cost recognition vesting service period		4 years
Maximum [Member]
Summary Of Business And Accounting Policies [Line Items]
Customer payment period		60 days
Maximum [Member] | 2007 Stock Plan [Member]
Summary Of Business And Accounting Policies [Line Items]
Share-based compensation cost recognition vesting service period		9 years