Supplemental Cash Flow Information and Non-cash Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Cash paid during the period for:
Interest	$ 6,628	$ 6,085
Income taxes	6,759	7,607
Non-cash items from investing and financing activities:
Investment in multi-client data library in accounts payable and accrued expenses	0	4,741
Cash and Cash Equivalents
Cash and cash equivalents	51,056	27,894	$ 33,065
Restricted cash included in prepaid expenses and other assets	2,326	303
Total cash, cash equivalents, and restricted cash shown in statements of cash flows	$ 53,382	$ 28,197	$ 33,118	$ 33,854