Summary of Business and Significant Accounting Policies - Accounts Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts receivable, gross	$ 321,491
Less: Allowance for credit losses	(17,500)	$ (5,150)
Less: Allowance for returns	(8,661)
Accounts receivable, net	$ 295,330