Statement of Cash Flow Information (Non-Cash Additions and Non-Cash Revenue) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Nonmonetary Transaction [Line Items]
Non-monetary exchanges related to resale licensing revenue	$ 741	$ 1,656	$ 1,554
Non-monetary exchanges from underwriting of new data acquisition	209	0	4,122
Completion of data in progress from prior non-monetary exchanges	0	2,429	142
Less: Non-monetary exchanges for data in progress	0	0	(2,442)
Total non-cash additions to seismic data library	950	4,085	3,376
Non-cash revenue	1,071	2,486	8,518
Underwriting [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	38	87	5,451
Specific Data Licenses and Selections [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	1,033	2,399	3,047
Solutions [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	$ 0	$ 0	$ 20