Segment Reporting (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Reconciliation of income before taxes
Income before taxes									$ 13,524	$ 34,330	$ 6,794
Consolidated income before taxes	3,365	(2,178)	1,274	11,063	14,645	9,056	2,168	8,461	13,524	34,330	6,794
Equipment Leasing [Member]
Reconciliation of income before taxes
Income before taxes									2,865	24,081	1,527
Seamap [Member]
Reconciliation of income before taxes
Income before taxes									10,835	10,195	5,402
Intersegment Sales Elimination [Member]
Reconciliation of income before taxes
Consolidated income before taxes									$ (176)	$ 54	$ (135)