Revenue Recognition - Revenue from Non-Monetary Exchanges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Nonmonetary Transaction
Seismic data library additions			$ 1,362	$ 1,250
Non-cash revenue			1,837	1,554
Specific Data Licenses or Selections of Data [Member]
Nonmonetary Transaction
Non-cash revenue	$ 1,322	$ 0	1,385	1,250
Acquisition Contracts [Member]
Nonmonetary Transaction
Non-cash revenue	0	103	0	229
Solutions and other revenue [Member]
Nonmonetary Transaction
Non-cash revenue	418	44	452	75
Seismic Data Library [Member]
Nonmonetary Transaction
Seismic data library additions	$ 1,362	$ 0	$ 1,362	$ 1,250