Net Income (Loss) Per Share - Schedule of Earnings Per Share, Basic and Diluted (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Earnings Per Share Basic And Diluted [Line Items]
Net income (loss)	$ 20,618	$ (220)	$ (1,529)	$ (5,371)	$ (27,376)	$ (8,082)	$ (26,884)	$ (8,907)	$ 13,498	$ (71,249)	$ (47,697)
Weighted average shares used in computing net income (loss) per share - basic									35,412	34,970	33,506
Effect of dilutive shares:
Dilutive potential common shares									273
Weighted average shares used in computing net income (loss) per share - diluted									35,685	34,970	33,506
Net income (loss) per share:
Basic	$ 0.58	$ 0.00	$ (0.05)	$ (0.15)	$ (0.78)	$ (0.23)	$ (0.77)	$ (0.26)	$ 0.38	$ (2.04)	$ (1.42)
Diluted	$ 0.58	$ 0.00	$ (0.05)	$ (0.15)	$ (0.78)	$ (0.23)	$ (0.77)	$ (0.26)	$ 0.38	$ (2.04)	$ (1.42)
Stock Options [Member]
Effect of dilutive shares:
Dilutive potential common shares									60
Restricted Stock Units [Member]
Effect of dilutive shares:
Dilutive potential common shares									63
Deferred Stock Units [Member]
Effect of dilutive shares:
Dilutive potential common shares									84
Performance Stock Units (PSUs) [Member]
Effect of dilutive shares:
Dilutive potential common shares									66