Industry Segments - Revenue by type of service (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013 category	Dec. 31, 2012	Dec. 31, 2011
Revenue from External Customer [Line Items]
Number of Revenue Categories by Type of Service									2
Revenue	$ 59,569	$ 44,410	$ 47,544	$ 51,351	$ 70,327	$ 51,556	$ 46,028	$ 72,547	$ 202,874	$ 240,458	$ 218,008
Acquisition and Licensing of Seismic Data [Member]
Revenue from External Customer [Line Items]
Revenue									198,109	234,785	213,656
Reproduction and Delivery of Seismic Data and Other Services [Member]
Revenue from External Customer [Line Items]
Revenue									$ 4,765	$ 5,673	$ 4,352