Organization and Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Oct. 31, 2018	Jan. 31, 2018	Oct. 31, 2017	Jan. 31, 2017
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 212,338	$ 346,672	$ 320,933	$ 322,872
Restricted cash	11	9	9	8
Total as presented in the consolidated statements of cash flows	$ 212,349	$ 346,681	$ 320,942	$ 322,880