Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016	Jan. 31, 2017
Accounting Policies [Abstract]
Restricted cash	$ 12,734		$ 12,734		$ 12,734
Deferred commissions, current	19,700		19,700		15,787
Deferred income taxes, non-current	15,600		15,600		$ 14,900
Sales commission expenses	$ 25,500	$ 19,600	$ 46,000	$ 37,200