Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 117,060	$ 173,608	$ 157,779	$ 148,056
Accounts receivable, net	26,477	114,325
Unbilled receivables	13,381	22,599
Inventories	35,947	51,162
Prepaid expenses and other current assets	13,333	13,662
Total current assets	206,198	375,356
Deferred income tax asset	8,430	8,604
Property, plant, equipment and seismic rental equipment, net	83,489	69,840
Multi-client data library, net	127,758	118,669
Goodwill	27,679	27,388
Intangible assets, net	5,811	6,788
Other assets	9,845	10,612
Total assets	469,210	617,257
Current liabilities:
Current maturities of long-term debt	7,213	7,649
Accounts payable	25,338	36,863
Accrued expenses	43,059	65,264
Accrued multi-client data library royalties	18,524	35,219
Deferred revenue	10,672	8,262
Total current liabilities	104,806	153,257
Long-term debt, net of current maturities	180,955	182,945
Other long-term liabilities	42,278	143,804
Total liabilities	328,039	480,006
Redeemable noncontrolling interest	1,080	1,539
Equity:
Common stock, $0.01 par value; authorized 200,000,000 shares; outstanding 164,706,194 and 164,484,095 shares at June 30, 2015 and December 31, 2014, respectively, net of treasury stock	1,647	1,645
Additional paid-in capital	890,811	887,749
Accumulated deficit	(733,604)	(734,409)
Accumulated other comprehensive loss	(12,199)	(12,807)
Treasury stock, at cost, 849,539 shares at both June 30, 2015 and December 31, 2014	(6,565)	(6,565)
Total stockholders' equity	140,090	135,613
Noncontrolling interest	1	99
Total equity	140,091	135,712
Total liabilities and equity	$ 469,210	$ 617,257