Basis of Presentation and Summary of Significant Accounting Policies - Deferred Commissions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Accounting Policies [Abstract]
Remaining amortization period	6 years		6 years
Contract Assets
Beginning balance	$ 118,568	$ 91,469	$ 114,973	$ 87,313
Additions	34,071	31,884	82,381	71,887
Recognition of deferred commissions	(29,508)	(26,913)	(74,223)	(62,760)
Ending balance	$ 123,131	$ 96,440	$ 123,131	$ 96,440