Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017	Jan. 31, 2018	Nov. 27, 2017
Commitments And Contingencies [Line Items]
Non-cancellable sublease expiration year			2023
Rent expense	$ 8.8	$ 8.1	$ 25.4	$ 20.3
Sublease income	1.8	$ 1.9	5.7	$ 5.6
Subleases Expire in Fiscal 2018 and 2023
Commitments And Contingencies [Line Items]
Non-cancellable sublease proceeds for the year ending January 31, 2019	1.9		1.9
Non-cancellable sublease proceeds for the year ending January 31, 2020	8.2		8.2
Non-cancellable sublease proceeds for the year ending January 31, 2021	7.5		7.5
Non-cancellable sublease proceeds for the year ending January 31, 2022	5.1		5.1
Non-cancellable sublease proceeds for the year ending January 31, 2023	4.2		$ 4.2
Minimum
Commitments And Contingencies [Line Items]
Operating lease expiration year			2020
Capital lease initial term			3 years
Term of sublease arrangement			25 months
Maximum
Commitments And Contingencies [Line Items]
Operating lease expiration year			2029
Capital lease initial term			4 years
Term of sublease arrangement			55 months
November 2017 Facility | Letters of Credit | Secured Debt | Wells Fargo Bank
Commitments And Contingencies [Line Items]
Agreement entered date			Nov. 27, 2017
Letters of credit facility	$ 26.8		$ 26.8		$ 26.4
Line of credit facility, maximum borrowing capacity sublimit						$ 30.0