Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 3.5	$ 3.2	$ 6.7	$ 6.7
Gain on termination of lease			4.0
Gain on reversal of deferred rent			34.5
Impairment of property and equipment			20.7
Cash payments associated with termination and other fees			9.8
Assets under Capital Leases
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 1.0	$ 0.1	$ 1.6	$ 0.1