Statement Of Cash Flow Information (Non-Cash Additions and Non-Cash Revenue) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Nonmonetary Transaction [Line Items]
Non-monetary exchanges related to resale licensing revenue			$ 177	$ 585
Completion of data in progress from prior non-monetary exchanges			0	2,392
Total non-cash additions to seismic data library			177	2,977
Non-cash revenue			238	766
Underwriting [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	0	27	0	84
Specific Data Licenses and Selections [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	$ 61	$ 104	$ 238	$ 682