Organization and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	Apr. 30, 2019	Feb. 01, 2019	Jan. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets	$ 7,911		$ 0
Lease liabilities	$ 8,025
ASU 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets		$ 8,581
Lease liabilities		$ 8,700