Derivative Instruments - Fair Values of Instruments (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative assets	$ 453	$ 683
Derivative liabilities	1,006	342
Foreign currency forward
Derivatives, Fair Value [Line Items]
Derivative assets	453	683
Derivative liabilities	1,006	342
Designated as hedging | Foreign currency forward | Prepaid expenses and other current assets | Cash flow hedging
Derivatives, Fair Value [Line Items]
Derivative assets	354	384
Designated as hedging | Foreign currency forward | Accrued expenses and other current liabilities | Cash flow hedging
Derivatives, Fair Value [Line Items]
Derivative liabilities	544	76
Not designated as hedging | Foreign currency forward | Prepaid expenses and other current assets
Derivatives, Fair Value [Line Items]
Derivative assets	100	299
Not designated as hedging | Foreign currency forward | Accrued expenses and other current liabilities
Derivatives, Fair Value [Line Items]
Derivative liabilities	$ 462	$ 266