Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Jan. 31, 2017
Accounting Policies [Abstract]
Restricted cash	$ 14,763		$ 14,763		$ 12,734
Deferred commissions, current	20,187		20,187		15,787
Deferred income taxes, non-current	18,200		18,200		$ 14,900
Sales commission expenses	$ 38,300	$ 21,600	$ 84,300	$ 58,800