Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
	Jul. 31, 2012	Jul. 31, 2011
Cash flows from operating activities:
Net income	$ 14,858,000	$ 7,393,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	17,567,000	13,479,000
Stock-based compensation	1,064,000	937,000
Provision for doubtful accounts, net of charge offs	(17,000)
Provision for inventory obsolescence	118,000	63,000
Gross profit from sale of lease pool equipment	(3,125,000)	(457,000)
Excess tax benefit from exercise of non-qualified stock options and restricted shares	(350,000)	(394,000)
Deferred tax benefit	(1,815,000)	(109,000)
Changes in non-current income taxes payable	(5,003,000)	694,000
Changes in working capital items:
Accounts receivable	11,722,000	(2,753,000)
Contracts receivable	(850,000)	1,718,000
Inventories	(370,000)	(565,000)
Prepaid expenses and other current assets	1,109,000	(1,119,000)
Income taxes receivable and payable	(7,105,000)	(1,272,000)
Prepaid foreign income tax	3,519,000
Accounts payable, accrued expenses, other current liabilities and deferred revenue	(2,042,000)	2,023,000
Net cash provided by operating activities	29,280,000	19,638,000
Cash flows from investing activities:
Purchases of seismic equipment held for lease	(27,316,000)	(30,461,000)
Purchases of property and equipment	(485,000)	(253,000)
Sale of used lease pool equipment	5,536,000	661,000
Payment for earn-out provision		(155,000)
Net cash used in investing activities	(22,265,000)	(30,208,000)
Cash flows from financing activities:
Net payments on line of credit	(150,000)	(20,900,000)
Proceeds from equipment notes		37,000
Payments on borrowings	(1,494,000)	(2,000,000)
Net purchases of short-term investments		(101,000)
Proceeds from issuance of common stock upon exercise of options	96,000	739,000
Net proceeds from public offering of common stock (Note 8)		30,994,000
Excess tax benefit from exercise of non-qualified stock options and restricted shares	350,000	394,000
Net cash provided by (used in) financing activities	(1,198,000)	9,163,000
Effect of changes in foreign exchange rates on cash and cash equivalents	441,000	657,000
Net change in cash and cash equivalents	6,258,000	(750,000)
Cash and cash equivalents, beginning of period	15,287,000	14,647,000
Cash and cash equivalents, end of period	21,545,000	15,287,000
Supplemental cash flow information:
Interest paid	325,000	497,000
Income taxes paid	7,035,000	3,529,000
Purchases of seismic equipment held for lease in accounts payable at end of period	$ 385,000	$ 7,524,000