Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Jan. 31, 2019	Jan. 31, 2018		Jan. 31, 2017
Concentration Risk [Line Items]
Restricted cash		$ 15,823	$ 14,763	[1],[2]
Restricted cash	[1]				$ 12,734
Foreign currency transaction gains (losses)		(5,230)	5,976		(2,632)
Restricted cash		15,823	14,763
Acquisition of intangible assets		0	0	[1]	1,000	[1]
Deferred commissions, current		29,244	21,088	[2]
Deferred commissions, non-current		85,729	66,225	[2]
Sales commission expenses		118,400	102,900		71,300
Advertising expenses		10,700	10,300		10,700
Contract with Customer, Liability		535,920	374,102		$ 272,963
Product Revenue And Support Subscription Revenue
Concentration Risk [Line Items]
Contract with Customer, Liability, Revenue Recognized		191,100	$ 136,600
Contract with Customer, Liability		$ 558,200
Hardware
Concentration Risk [Line Items]
Standard product warranty period		3 years
Embedded Software
Concentration Risk [Line Items]
Standard product warranty period		90 days
Minimum | Technology patents
Concentration Risk [Line Items]
Estimated useful life of intangible assets		5 years
Maximum | Technology patents
Concentration Risk [Line Items]
Estimated useful life of intangible assets		7 years
Test equipment
Concentration Risk [Line Items]
Property and equipment, useful life		2 years
Computer equipment and software | Minimum
Concentration Risk [Line Items]
Property and equipment, useful life		2 years
Computer equipment and software | Maximum
Concentration Risk [Line Items]
Property and equipment, useful life		3 years
Furniture and fixtures
Concentration Risk [Line Items]
Property and equipment, useful life		7 years
Customer concentration risk | Sales revenue net
Concentration Risk [Line Items]
Concentration risk percentage		11.00%			11.00%

[1] * As adjusted to reflect the impact of ASU 2016-18 and the full retrospective adoption of

[2] * As adjusted to reflect the impact of the full retrospective adoption of ASC 606