Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018	Jul. 31, 2019	Feb. 01, 2019	Jan. 31, 2019	Jul. 31, 2018	Jan. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restricted cash	$ 15,287,000		$ 15,287,000				$ 15,823,000
Deferred commissions	123,131,000	$ 96,440,000	123,131,000	$ 96,440,000	$ 118,568,000		$ 114,973,000	$ 91,469,000	$ 87,313,000
Impairment	0	0	0	0
Operating lease right-of-use assets	119,403,000		119,403,000
Operating lease liabilities	$ 126,597,000		$ 126,597,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-11-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue expected to be recognized (as a percent)	41.00%		41.00%
Revenue expected to be recognized term (in months)	12 months		12 months
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets						$ 124,500,000
Operating lease liabilities						$ 130,600,000
Product Revenue and Support Subscription Revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue recognized	$ 101,400,000	$ 67,000,000.0	$ 213,200,000	$ 151,400,000