Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Cash flows from operating activities:
Net income	$ 5,614,000	$ 14,858,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	15,624,000	17,567,000
Stock-based compensation	553,000	1,064,000
Provision for doubtful accounts, net of charge offs		(17,000)
Provision for inventory obsolescence	58,000	118,000
Gross profit from sale of lease pool equipment	(2,058,000)	(3,125,000)
Excess tax benefit from exercise of non-qualified stock options and restricted shares	(44,000)	(350,000)
Deferred tax provision	(695,000)	(1,815,000)
Changes in non-current income taxes payable		(5,003,000)
Changes in working capital items:
Accounts receivable	(2,568,000)	11,722,000
Contracts and notes receivable	1,329,000	(850,000)
Inventories	(1,028,000)	(370,000)
Prepaid expenses and other current assets	(1,382,000)	1,109,000
Income taxes payable	(1,666,000)	(7,105,000)
Prepaid foreign income tax		3,519,000
Accounts payable, accrued expenses, other current liabilities and deferred revenue	2,224,000	(2,042,000)
Net cash provided by operating activities	15,961,000	29,280,000
Cash flows from investing activities:
Purchases of seismic equipment held for lease	(7,829,000)	(27,316,000)
Purchases of property and equipment	(405,000)	(485,000)
Sale of used lease pool equipment	3,019,000	5,536,000
Net cash used in investing activities	(5,215,000)	(22,265,000)
Cash flows from financing activities:
Net payments on revolving line of credit	(4,000,000)	(150,000)
Payments on borrowings	(72,000)	(1,494,000)
Net purchases of short-term investments	7,000
Proceeds from issuance of common stock upon exercise of options	252,000	96,000
Purchase of treasury stock	(1,527,000)
Excess tax benefit from exercise of non-qualified stock options and restricted shares	44,000	350,000
Net cash used in financing activities	(5,296,000)	(1,198,000)
Effect of changes in foreign exchange rates on cash and cash equivalents	(302,000)	441,000
Net change in cash and cash equivalents	5,148,000	6,258,000
Cash and cash equivalents, beginning of period	15,150,000	15,287,000
Cash and cash equivalents, end of period	20,298,000	21,545,000
Supplemental cash flow information:
Interest paid	82,000	325,000
Income taxes paid	3,625,000	7,035,000
Purchases of seismic equipment held for lease in accounts payable at end of period	$ 1,190,000	$ 385,000