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Leases (Details Textual) (USD $)
12 Months Ended
Jan. 31, 2013
Jan. 31, 2012
Jan. 31, 2011
Foreign Country [Member]
     
Property, Plant and Equipment [Line Items]      
Office rental expense $ 1,528,000 $ 1,199,000 $ 1,007,000
Seismic equipment lease pool [Member] | Domestic Tax Authority [Member]
     
Property, Plant and Equipment [Line Items]      
Lease expense incurred by the Company $ 1,798,000 $ 1,634,000 $ 755,000