Supplemental Statements of Cash Flows Information - Supplemental Disclosures of Cash Flows Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Supplemental Cash Flow Elements [Abstract]
Interest paid	$ 86	$ 673	$ 694
Income taxes paid, net	494	409	1,520
Seismic equipment purchases included in accounts payable at year-end	$ 53	$ 130	$ 325