Segment Reporting (Details 1) (USD $)	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
Financial information by business segment
Revenues	$ 28,401,000	$ 18,574,000	$ 23,080,000	$ 34,630,000	$ 37,034,000	$ 28,020,000	$ 21,278,000	$ 26,502,000	$ 104,685,000	$ 112,834,000	$ 71,363,000
Interest income (expense), net									(378,000)	(214,000)	(127,000)
Income before taxes									13,524,000	34,330,000	6,794,000
Capital expenditures									45,659,000	63,667,000	33,119,000
Depreciation and amortization expense									34,939,000	28,774,000	22,717,000
Equipment Leasing [Member]
Financial information by business segment
Revenues									73,516,000	84,428,000	50,018,000
Interest income (expense), net									11,000	(397,000)	(470,000)
Income before taxes									2,865,000	24,081,000	1,527,000
Capital expenditures									45,181,000	63,198,000	32,876,000
Depreciation and amortization expense									34,320,000	28,215,000	22,120,000
Seamap [Member]
Financial information by business segment
Revenues									32,210,000	28,703,000	22,462,000
Interest income (expense), net										1,000	(3,000)
Income before taxes									10,835,000	10,195,000	5,402,000
Capital expenditures									478,000	469,000	243,000
Depreciation and amortization expense									$ 619,000	$ 559,000	$ 597,000