Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Cash flows from operating activities:
Net income	$ 13,636	$ 14,156
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	26,270	21,038
Stock-based compensation	1,323	1,133
Provision for doubtful accounts, net of charge offs	(636)	1,281
Provision for inventory obsolescence	178	73
Gross profit from sale of lease pool equipment	(3,657)	(2,380)
Excess tax benefit from exercise of non-qualified stock options and restricted shares	(441)	(394)
Deferred tax benefit	(3,524)	(763)
Changes in non-current income taxes payable	(5,003)	822
Changes in working capital items:
Accounts receivable	17,662	(10,794)
Contracts and notes receivable	(761)	2,590
Inventories	(623)	(972)
Prepaid expenses and other current assets	(1,341)	(625)
Income taxes receivable and payable	(7,672)	1,167
Prepaid foreign income tax	3,519	(419)
Accounts payable, accrued expenses, other current liabilities and deferred revenue	(2,801)	2,447
Net cash provided by operating activities	36,129	28,360
Cash flows from investing activities:
Purchases of seismic equipment held for lease	(35,531)	(40,957)
Purchases of property and equipment	(795)	(1,084)
Sale of used lease pool equipment	7,409	3,103
Payment for earn-out provision		(148)
Net cash used in investing activities	(28,917)	(39,086)
Cash flows from financing activities:
Net proceeds from (payments on) revolving line of credit	650	(17,700)
Proceeds from equipment notes	180	37
Payments on borrowings	(1,528)	(2,647)
Net purchases of short-term investments		(101)
Proceeds from issuance of common stock upon exercise of options	331	788
Net proceeds from public offering of common stock (Note 8)		31,028
Excess tax benefit from exercise of non-qualified stock options and restricted shares	441	394
Net cash provided by financing activities	74	11,799
Effect of changes in foreign exchange rates on cash and cash equivalents	1,417	186
Net change in cash and cash equivalents	8,703	1,259
Cash and cash equivalents, beginning of period	15,287	14,647
Cash and cash equivalents, end of period	23,990	15,906
Supplemental cash flow information:
Interest paid	447	574
Income taxes paid	8,222	4,206
Purchases of seismic equipment held for lease in accounts payable at end of period	$ 835	$ 18,484