Revenue Recognition - Impacts of Adopting New Revenue Standard on Condensed Consolidated Statements of Cash Flows (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017
Cash flows from operating activities:
Net loss	$ (16,883)	$ 5,867
Prepaid expenses and other current assets	1,318	1,618
Accounts payable	3,566	3,511
Accrued liabilities	(9,054)	(9,293)
Income taxes payable	(412)	1,446
Deferred revenue	318	(1,222)
Other long-term liabilities	654	$ 39
Topic 606 [Member] | Impact of Adoption [Member]
Cash flows from operating activities:
Net loss	(5,804)
Prepaid expenses and other current assets	207
Accounts payable	(200)
Accrued liabilities	(9)
Income taxes payable	57
Deferred revenue	5,746
Other long-term liabilities	3
Topic 606 [Member] | Amounts under ASC 605 [Member]
Cash flows from operating activities:
Net loss	(22,687)
Prepaid expenses and other current assets	1,525
Accounts payable	3,366
Accrued liabilities	(9,063)
Income taxes payable	(355)
Deferred revenue	6,064
Other long-term liabilities	$ 657