Revenue Recognition - Impacts of Adopting New Revenue Standard on Condensed Consolidated Statements of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ 57,286	$ 89,062	$ 176,698	$ 224,827
Cost of revenue	22,701	32,448	69,208	82,445
Gross profit	34,585	56,614	107,490	142,382
Loss from operations	(9,422)	15,118	(26,054)	23,040
Loss before income taxes	(8,429)	15,437	(23,537)	23,736
Provision for income taxes	592	3,713	2,367	6,145
Net loss	$ (9,021)	$ 11,724	$ (25,904)	$ 17,591
Net loss per share:
Basic	$ (0.28)	$ 0.35	$ (0.79)	$ 0.53
Diluted	$ (0.28)	$ 0.34	$ (0.79)	$ 0.51
Topic 606 [Member] | Impact of Adoption [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ 727		$ (7,583)
Cost of revenue	234		(2,537)
Gross profit	493		(5,046)
Loss from operations	493		(5,046)
Loss before income taxes	493		(5,046)
Provision for income taxes	(71)		194
Net loss	$ 564		$ (5,240)
Net loss per share:
Basic	$ 0.02		$ (0.16)
Diluted	$ 0.02		$ (0.16)
Topic 606 [Member] | Amounts under ASC 605 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ 58,013		$ 169,115
Cost of revenue	22,935		66,671
Gross profit	35,078		102,444
Loss from operations	(8,929)		(31,100)
Loss before income taxes	(7,936)		(28,583)
Provision for income taxes	521		2,561
Net loss	$ (8,457)		$ (31,144)
Net loss per share:
Basic	$ (0.26)		$ (0.95)
Diluted	$ (0.26)		$ (0.95)