Seismic Data Library (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 01, 2015
Seismic Data Library [Abstract]
Straight-line amortization period	4 years
Net book value of seismic data library, projects in progress	18.00%	16.00%
Internal data processing costs capitalized	$ 3,600,000	$ 3,500,000	$ 3,000,000
Lowest amortization rate using the income forecast method	70.00%
Amortization of seismic data library	115,600,000	114,900,000	132,800,000
Amortization as percentage of seismic revenue, rate	60.00%	58.00%	56.00%
Actual aggregate rate of amortization				70.00%
Asset impairment charges	$ 0	$ 0	$ 0