Basis of Presentation and Significant Accounting Policies - Activity related to non-monetary exchanges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Non-monetary Transaction
Additions to seismic data library	$ 2,064	$ 2,640	$ 9,311
Non-cash revenue	1,620	3,308	6,928
Seismic Data Library [Member]
Non-monetary Transaction
Additions to seismic data library	2,064	2,640	9,311
Specific data licenses or selections of data [Member]
Non-monetary Transaction
Non-cash revenue	1,250	3,179	6,747
Acquisition contracts [Member]
Non-monetary Transaction
Non-cash revenue	279	129	168
Solutions and other revenue [Member]
Non-monetary Transaction
Non-cash revenue	$ 91	$ 0	$ 13