Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Accounts Receivable Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	$ 876	$ 415	$ 400
Additions, Charged to costs and expenses	79	597	59
Additions, Charged to other accounts	10	(61)
Deductions and write-offs	(949)	(75)	(44)
Balance at end of period	16	876	415
Deferred Tax Assets Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period	58,134	47,368	30,369
Additions, Charged to costs and expenses	(19,829)	10,766	16,999
Balance at end of period	$ 38,305	$ 58,134	$ 47,368