CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (47,214,000)	$ (70,398,000)	$ (29,377,000)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization (other than multi-client library)	3,657,000	8,763,000	16,592,000
Amortization of multi-client data library	39,541,000	48,988,000	47,102,000
Impairment of long-lived assets	0	36,553,000	0
Impairment of multi-client data library	9,072,000	0	2,304,000
Stock-based compensation expense	4,701,000	3,337,000	2,552,000
Accrual of loss contingency related to legal proceedings	0	0	5,000,000
Write-down of excess and obsolete inventory	517,000	665,000	398,000
Deferred income taxes	(1,940,000)	(6,252,000)	(5,420,000)
Change in operating assets and liabilities:
Accounts receivable	(3,265,000)	(7,024,000)	1,692,000
Unbilled receivables	32,055,000	(5,245,000)	(23,947,000)
Inventories	1,067,000	(353,000)	190,000
Accounts payable, accrued expenses and accrued royalties	(2,492,000)	(7,600,000)	1,443,000
Deferred revenue	(3,207,000)	(1,112,000)	5,131,000
Other assets and liabilities	1,658,000	6,776,000	3,952,000
Net cash provided by operating activities	34,150,000	7,098,000	27,612,000
Cash flows from investing activities:
Investment in multi-client data library	(28,804,000)	(28,276,000)	(23,710,000)
Purchase of property, plant and equipment	(2,411,000)	(1,514,000)	(1,063,000)
Net cash used in investing activities	(31,215,000)	(29,790,000)	(24,773,000)
Cash flows from financing activities:
Borrowings under revolving line of credit	40,000,000	0	0
Repayments under revolving line of credit	40,000,000	10,000,000	0
Payments on notes payable and long-term debt	(2,553,000)	(30,807,000)	(4,816,000)
Cost associated with issuance of debt	0	(1,247,000)	(53,000)
Net proceeds from issuance of stocks	0	46,999,000	0
Proceeds from employee stock purchases and exercise of stock options	141,000	214,000	1,619,000
Other financing activities	(1,134,000)	(1,351,000)	(343,000)
Net cash provided by (used in) financing activities	(3,546,000)	3,808,000	(3,593,000)
Effect of change in foreign currency exchange rates on cash, cash equivalents and restricted cash	(125,000)	319,000	(260,000)
Net decrease in cash, cash equivalents and restricted cash	(736,000)	(18,565,000)	(1,014,000)
Cash, cash equivalents and restricted cash at beginning of period	33,854,000	52,419,000	53,433,000
Cash, cash equivalents and restricted cash at end of period	$ 33,118,000	$ 33,854,000	$ 52,419,000