Segment Reporting - Reconciliation of Income (Loss) Before Taxes (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Segment Reporting Information [Line Items]
Income before taxes									$ 6,026	$ 13,524	$ 34,330
Reconciling items:
Consolidated income before taxes	2,179	(3,106)	(966)	7,919	3,365	(2,178)	1,274	11,063	6,026	13,524	34,330
Equipment Leasing [Member]
Segment Reporting Information [Line Items]
Income before taxes									1,087	2,865	24,081
Seamap [Member]
Segment Reporting Information [Line Items]
Income before taxes									4,720	10,835	10,195
Intersegment Sales Elimination [Member]
Reconciling items:
Consolidated income before taxes									$ 219	$ (176)	$ 54