Revenue Recognition - Revenue from Non-Monetary Exchanges (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Nonmonetary Transaction
Seismic data library additions			$ 0	$ 1,250
Non-cash revenue			97	1,407
Specific Data Licenses or Selections of Data [Member]
Nonmonetary Transaction
Non-cash revenue	$ 63	$ 1,000	63	1,250
Acquisition Contracts [Member]
Nonmonetary Transaction
Non-cash revenue	0	87	0	126
Solutions and other revenue [Member]
Nonmonetary Transaction
Non-cash revenue	29	31	34	31
Seismic Data Library [Member]
Nonmonetary Transaction
Seismic data library additions	$ 0	$ 1,000	$ 0	$ 1,250