Supplemental Cash Flow Information and Non-Cash Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash paid during the period for:
Interest	$ 154	$ 497
Income taxes (refunds)	(762)	5,041
Non-cash items from investing and financing activities:
Purchases of computer equipment financed through capital leases	0	1,178
Investment in multi-client data library financed through accounts payable	3,885	7,018
Purchases of property, plant, and equipment and seismic rental equipment financed through accounts payable	179	0
Transfer of inventory to property, plant, equipment and seismic rental equipment	$ 0	$ 8,485