Description of Business and Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Deconsolidation, Gain (Loss), Amount			$ 1,961	$ 0
Operating income (loss)	$ (6,459)	$ (2,850)	(18,348)	$ (10,472)
Retained Earnings (Accumulated Deficit)	(568,325)		(568,325)		$ (548,862)
Cash and Cash Equivalents, at Carrying Value	$ 28,990		$ 28,990		$ 23,940