Financial Instruments And Fair Value - Schedule of Cash Equivalents and Marketable Debt Securities (Detail) - USD ($) $ in Thousands	Apr. 30, 2021	Jan. 31, 2021
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	$ 214,861	$ 214,802
Included in cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	6,841	15,368
Included in marketable debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Total cash equivalents and marketable debt securities	$ 208,020	$ 199,434