Basis of Presentation and Summary of Significant Accounting Policies - Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in revenue	$ 1,023,019	$ 727,977	$ 440,333
Increase in product revenue	813,985	590,001	375,733
Decrease in support revenue	(209,034)	(137,976)	(64,600)
Decrease in loss from operations	$ 185,158	244,806	$ 210,181
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contractual term	1 year
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contractual term	5 years
Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in revenue	$ 1,800	11,200
Increase in product revenue	20,500	24,500
Decrease in support revenue	(18,700)	(13,300)
Decrease in deferred revenue	31,900	30,100
Decrease in commission expense	16,000	12,300
Increase in deferred commissions	44,200	28,200
Decrease in loss from operations	$ 17,800	$ 23,500
Accounting Standards Update 2014-09 | Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contractual term	1 year
Accounting Standards Update 2014-09 | Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Contractual term	5 years