Statement Of Cash Flow Information (Non-Cash Additions and Non-Cash Revenue) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Nonmonetary Transaction [Line Items]
Non-monetary exchanges related to resale licensing revenue	$ 177	$ 324
Completion of data in progress from prior non-monetary exchanges	0	2,392
Total non-cash additions to seismic data library	177	2,716
Non-cash revenue	177	635
Underwriting [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	0	57
Specific Data Licenses and Selections [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	$ 177	$ 578