Statement Of Cash Flow Information (Non-Cash Additions and Non-Cash Revenue) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Nonmonetary Transaction [Line Items]
Non-monetary exchanges related to resale licensing revenue			$ 1,511	$ 1,293
Non-monetary exchanges from underwriting of new data acquisition			0	4,122
Completion of data in progress from prior non-monetary exchanges			2,392	142
Non-monetary exchanges for data in progress			0	(2,442)
Total non-cash additions to seismic data library			3,903	3,115
Non-cash revenue			1,710	6,175
Underwriting [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	3	1,645	87	3,273
Specific Data Licenses and Selections [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	941	1,849	1,623	2,882
Solutions [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	$ 0	$ 0	$ 0	$ 20