Statement Of Cash Flow Information (Non-Cash Additions and Non-Cash Revenue) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Nonmonetary Transaction [Line Items]
Non-monetary exchanges related to resale licensing revenue	$ 324	$ 709
Completion of data in progress from prior non-monetary exchanges	2,392	0
Total non-cash additions to seismic data library	2,716	709
Non-cash revenue	635	2,115
Underwriting [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	57	1,268
Specific Data Licenses and Selections [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	578	827
Solutions [Member]
Nonmonetary Transaction [Line Items]
Non-cash revenue	$ 0	$ 20