Condensed Consolidated Statements of Cash Flows Supplemental Information - Significant Non-cash Investing Activities - (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Net (decrease) increase in accruals related to:
Investment in joint revenue sharing arrangements	$ (1,897)	$ 2,040
Acquisition of other intangible assets	69	6
Purchases of property, plant and equipment	158	(432)
Net accruals	$ (1,670)	$ 1,614