Seismic Data Library (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Oct. 01, 2012
Property, Plant and Equipment [Line Items]
Internal data processing costs capitalized	$ 900,000	$ 500,000	$ 2,200,000	$ 1,400,000
Lowest amortization rate using the income forecast method			70.00%
Actual aggregate rate of amortization					70.00%
Impairment charges			$ 0	$ 0
Seismic Data Library [Member]
Property, Plant and Equipment [Line Items]
Straight-line amortization period			4 years