Condensed Consolidated Statements of Cash Flows Supplemental Information - Significant Non-cash Investing and Financing Activities - (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Net accruals related to:
Investment in joint revenue sharing arrangements	$ 2,040	$ (200)
Acquisition of other intangible assets	6	(189)
Purchases of property, plant and equipment	(432)	634
Net accruals	$ 1,614	$ 245