Leases - Schedule of Cumulative Effect of Changes to Condensed Consolidated Balance Sheet for Adoption of ASC 842 (Detail) - USD ($) $ in Thousands	Jul. 31, 2019	Feb. 01, 2019	Jan. 31, 2019
Leases Disclosure [Line Items]
Operating lease right-of-use assets	$ 7,237		$ 0
Prepaid expenses and other current assets	4,491		6,206
Accrued and other current liabilities	24,432		24,700
Operating lease liabilities, current	2,260		0
Operating lease liabilities, non-current	$ 5,100		$ 0
Leases (ASC 842) [Member]
Leases Disclosure [Line Items]
Operating lease right-of-use assets		$ 8,581
Prepaid expenses and other current assets		6,032
Accrued and other current liabilities		24,421
Operating lease liabilities, current		2,534
Operating lease liabilities, non-current		6,152
Leases (ASC 842) [Member] | Restatement Adjustment [Member]
Leases Disclosure [Line Items]
Operating lease right-of-use assets		8,581
Prepaid expenses and other current assets		(174)
Accrued and other current liabilities		(279)
Operating lease liabilities, current		2,534
Operating lease liabilities, non-current		$ 6,152