Basis of Presentation and Summary of Significant Accounting Policies - Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Contract Liability
Beginning balance	$ 564,230	$ 388,614	$ 535,920	$ 374,102
Additions	140,548	92,511	258,441	167,782
Recognition of deferred revenue	97,515	(67,878)	(187,098)	(128,637)
Ending balance	607,263	413,247	607,263	413,247
Product Revenue and Support Subscription Revenue
Contract Liability
Ending balance	770,100		770,100
Deferred revenue recognized	$ 88,200	$ 60,900	$ 150,200	$ 106,200