Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Oct. 31, 2018	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Operating Loss Carryforwards [Line Items]
Deferred tax assets, increase (decrease) in valuation allowance		$ (85,500,000)	$ 28,400,000
Gross unrecognized tax benefit		18,891,000	12,401,000	$ 6,375,000	$ 15,470,000
Current or cumulative interest and penalties related to uncertain tax positions		0
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		772,100,000
Research and development tax credit carryforwards		40,500,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards		451,500,000
Research and development tax credit carryforwards		34,400,000
Rest of the world
Operating Loss Carryforwards [Line Items]
Undistributed earnings of foreign subsidiaries		$ 31.2
StorReduce, Inc.
Operating Loss Carryforwards [Line Items]
Deferred tax assets, increase (decrease) in valuation allowance	$ (3,700,000)
Accounting Standards Update 2014-09 | Adjustment
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Net, Current			7,800,000
Deferred Tax Liabilities, Net, Noncurrent			10,800,000
Tax Credit Carryforward, Valuation Allowance			$ 18,600,000