CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net loss	$ (43,839)	$ (33,049)
Adjustments to reconcile net loss to cash (used in) provided by operating activities:
Depreciation and amortization (other than multi-client data library)	4,778	9,030
Amortization of multi-client data library	19,557	21,933
Stock-based compensation expense	2,043	1,169
Accrual for loss contingency related to legal proceedings	0	5,000
Deferred income taxes	(1,866)	(932)
Change in operating assets and liabilities:
Accounts receivable	3,896	2,075
Unbilled receivables	24,013	(5,542)
Inventories	(445)	440
Accounts payable, accrued expenses and accrued royalties	(10,629)	(6,059)
Deferred revenue	(445)	5,521
Other assets and liabilities	2,733	3,905
Net cash (used in) provided by operating activities	(204)	3,491
Cash flows from investing activities:
Cash invested in multi-client data library	(13,782)	(8,482)
Purchase of property, plant, equipment and seismic rental assets	(424)	(915)
Net cash used in investing activities	(14,206)	(9,397)
Cash flows from financing activities:
Payments under revolving line of credit	(10,000)	0
Payments on notes payable and long-term debt	(29,699)	(3,157)
Net proceeds from issuance of stock	47,219	0
Dividend payment to non-controlling interest	(200)	0
Other financing activities	(881)	(296)
Net cash provided by (used in) financing activities	6,439	(3,453)
Effect of change in foreign currency exchange rates on cash, cash equivalents and restricted cash	264	(169)
Net decrease in cash, cash equivalents and restricted cash	(7,707)	(9,528)
Cash, cash equivalents and restricted cash at beginning of period	52,419	53,433
Cash, cash equivalents and restricted cash at end of period	$ 44,712	$ 43,905