Seismic Data Library (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Seismic Data Library [Abstract]
Straight-line amortization period	4 years
Net book value of seismic data library, projects in progress	26.00%	34.00%
Internal data processing costs capitalized	$ 3,000,000	$ 1,900,000	$ 1,600,000
Lowest amortization rate using the income forecast method	70.00%
Amortization of seismic data library	132,800,000	135,000,000	167,800,000
Amortization as percentage of seismic revenue, rate	57.00%	63.00%	98.00%
Actual aggregate rate of amortization	70.00%
Asset impairment charges	$ 0	$ 0	$ 0