Revenue Recognition (Revenue from Non-Monetary Exchanges) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Nonmonetary Transaction
Seismic data library additions	$ 222	$ 129
Non-cash revenue	1	179
Specific Data Licenses or Selections of Data [Member]
Nonmonetary Transaction
Non-cash revenue	0	17
Acquisition Contracts [Member]
Nonmonetary Transaction
Non-cash revenue	1	162
Seismic Data Library [Member]
Nonmonetary Transaction
Seismic data library additions	$ 222	$ 129