Income Taxes (Schedule Of Significant Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets: [Abstract]
Net operating loss carryforwards - Federal	$ 11,670	$ 27,935
Net operating loss carryforwards - State	10,875	8,788
Tax credit carryforwards - Federal	64,081	49,937
Tax credit carryforwards - State	7,369	7,750
Derivative financial instruments		342
Deferred revenue	149	795
Interest expense carryforward	6,609	5,539
Investment in partnerships	45,519	46,774
Inventory valuation	290	1,560
Stock-based compensation	1,439	1,347
Accrued expenses	5,351	4,325
Leases	7,958	6,993
Organizational and start-up costs	1,047
Other	337	51
Total	162,694	162,136
Valuation allowance	(43,336)	(33,337)
Total deferred tax assets	119,358	128,799
Deferred tax liabilities:
Convertible debt	(9,154)	(12,266)
Fixed assets	(104,364)	(107,909)
Derivative financial instruments	(724)
Organizational and start-up costs		(4,484)
Right-of-use assets	(5,116)	(4,140)
Total deferred tax liabilities	(119,358)	(128,799)
Deferred income taxes