Revenue Recognition (Revenue from Non-Monetary Exchanges) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Nonmonetary Transaction [Line Items]
Seismic data library additions			$ 177	$ 2,977
Non-cash revenue			238	766
Specific Data Licenses or Selections of Data [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	61	104	238	682
Acquisition Contracts [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	0	27	0	84
Seismic Data Library [Member]
Nonmonetary Transaction [Line Items]
Seismic data library additions	$ 0	$ 261	$ 177	$ 2,977