Revenue Recognition (Revenue from Non-Monetary Exchanges) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Nonmonetary Transaction
Seismic data library additions			$ 1,250	$ 1,022
Non-cash revenue			1,407	1,364
Specific Data Licenses or Selections of Data [Member]
Nonmonetary Transaction
Non-cash revenue	$ 1,000	$ 1,340	1,250	1,340
Acquisition Contracts [Member]
Nonmonetary Transaction
Non-cash revenue	87	23	126	24
Solutions and other revenue [Member]
Nonmonetary Transaction
Non-cash revenue	31	0	31	0
Seismic Data Library [Member]
Nonmonetary Transaction
Seismic data library additions	$ 1,000	$ 800	$ 1,250	$ 1,022