Acquisition of Controlling Interest in OceanGeo - Narrative (Details) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended	6 Months Ended				1 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 OceanGeo [Member]	Jun. 30, 2014 OceanGeo [Member]	Jan. 31, 2014 OceanGeo [Member]	Oct. 31, 2013 OceanGeo [Member]	Feb. 28, 2013 OceanGeo [Member]	Jul. 31, 2014 Subsequent Event [Member] OceanGeo [Member]
Business Acquisition [Line Items]
Increase in ownership percentage							40.00%		30.00%	30.00%
Ownership percentage interest							70.00%			100.00%
Loan made to equity method investee								$ 25,000,000.0
Working capital loan to investee								18,900,000		40,500,000
Total consideration										6,000,000
Contingent payment to acquiree										5,000,000
Acquisition related costs						1,300,000
Income (loss) from operations	3,785,000	6,770,000	23,456,000	8,693,000	6,500,000	10,700,000
Revenues	$ 121,480,000	$ 120,915,000	$ 266,178,000	$ 250,652,000	$ 25,900,000	$ 46,500,000