Basis of Presentation and Summary of Significant Accounting Policies - Deferred Commissions (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Accounting Policies [Abstract]
Remaining amortization period			6 years
Contract Assets
Beginning balance	$ 86,044,000		$ 87,313,000
Additions	24,582,000		40,003,000
Recognition of deferred commissions	(19,157,000)		(35,847,000)
Ending balance as of July 31, 2018	91,469,000		91,469,000
Impairment loss, capitalized commissions	$ 0	$ 0	$ 0	$ 0