Basis of Presentation and Summary of Significant Accounting Policies - Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Contract Liability
Beginning balance	$ 607,263	$ 413,247	$ 535,920	$ 374,102
Additions	142,164	122,681	400,605	290,463
Recognition of deferred revenue	(106,229)	(74,740)	(293,327)	(203,377)
Ending balance	643,198	461,188	643,198	461,188
Product Revenue and Support Subscription Revenue
Contract Liability
Ending balance	810,800		810,800
Deferred revenue recognized	$ 101,400	$ 67,000	$ 213,200	$ 151,400