Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018	Apr. 30, 2019	Feb. 01, 2019	Jan. 31, 2019	Apr. 30, 2018	Jan. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred commissions	$ 118,568	$ 91,469	$ 118,568	$ 91,469	$ 86,044		$ 114,973	$ 113,257	$ 87,313
Revenue recognition over next 12 months, percent	41.00%		41.00%
Operating lease right-of-use assets	$ 114,339		$ 114,339				0
Operating lease liabilities	120,946		120,946
Restricted cash	15,425	15,778	15,425	15,778			$ 15,823
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets						$ 124,500
Operating lease liabilities						$ 130,600
Product Revenue and Support Subscription Revenue
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue recognized	$ 88,200	$ 60,900	$ 150,200	$ 106,200