Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net loss	$ (33,049)	$ (60,299)
Adjustments to reconcile net loss to cash provided by (used in) operating activities:
Depreciation and amortization (other than multi-client data library)	9,030	11,416
Amortization of multi-client data library	21,933	14,244
Stock-based compensation expense	1,169	1,610
Accrual for loss contingency related to legal proceedings	5,000	0
Loss on extinguishment of debt	0	2,182
Deferred income taxes	(932)	381
Change in operating assets and liabilities:
Accounts receivable	2,075	23,980
Unbilled receivables	(5,542)	(2,042)
Inventories	440	1,329
Accounts payable, accrued expenses and accrued royalties	(6,059)	(5,518)
Deferred revenue	5,521	1,151
Other assets and liabilities	4,053	(773)
Net cash provided by (used in) operating activities	3,639	(12,339)
Cash flows from investing activities:
Cash invested in multi-client data library	(8,482)	(8,648)
Purchase of property, plant, equipment and seismic rental assets	(915)	(340)
Net cash used in investing activities	(9,397)	(8,988)
Cash flows from financing activities:
Borrowings under revolving line of credit	0	15,000
Payments on notes payable and long-term debt	(3,157)	(4,786)
Costs associated with issuance of debt	0	(6,174)
Payment to repurchase bonds	0	(15,000)
Repurchase of common stock	0	(964)
Costs associated with issuance of equity	(123)	0
Other financing activities	(173)	13
Net cash used in financing activities	(3,453)	(11,911)
Effect of change in foreign currency exchange rates on cash and cash equivalents	(169)	738
Net decrease in cash, and cash equivalents	(9,380)	(32,500)
Cash and cash equivalents at beginning of period	52,652	84,933
Cash and cash equivalents at end of period	$ 43,272	$ 52,433