Segment Reporting - Company's Revenue by Geographic Region Based on Bill-to Location (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Revenue from External Customer [Line Items]
Total revenue	$ 227,768	$ 295,402	$ 310,297
Taiwan [Member]
Revenue from External Customer [Line Items]
Total revenue	132,199	174,486	185,225
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	66,981	57,862	42,461
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	18,244	45,185	71,556
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	7,028	11,110	3,686
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 3,316	$ 6,759	$ 7,369