Basis of Presentation and Summary of Significant Accounting Policies - Deferred Commissions (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Accounting Policies [Abstract]
Remaining amortization period	6 years		6 years
Contract Assets
Beginning balance	$ 91,469,000		$ 87,313,000
Additions	31,884,000		71,887,000
Recognition of deferred commissions	(26,913,000)		(62,760,000)
Ending balance as of October 31, 2018	96,440,000		96,440,000
Impairment loss, capitalized commissions	$ 0	$ 0	$ 0	$ 0