Condensed Consolidated Statements of Cash Flows Supplemental Information - Significant Non-cash Investing Activities - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net (decrease) increase in accruals related to:
Investment in joint revenue sharing arrangements	$ 117	$ (1,226)
Acquisition of other intangible assets	(858)	20
Purchases of property, plant and equipment		(22)
Net accruals	$ (741)	$ (1,228)