Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Revenue from External Customer [Line Items]
Total revenue	$ 89,062	$ 100,490	$ 224,827	$ 222,789
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	45,026	53,932	139,494	142,837
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	19,000	11,286	43,050	30,449
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	20,908	32,314	29,252	40,948
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	2,582	1,261	7,566	2,626
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 1,546	$ 1,697	$ 5,465	$ 5,929