Income Taxes (Schedule Of Significant Components Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards - Federal		$ 12,767
Net operating loss carryforwards - State	$ 4,004	5,291
Tax credit carryforwards - Federal	47,956	30,783
Tax credit carryforwards - State	9,369	5,342
Derivative financial instruments		2,592
Deferred revenue	2,236	919
Interest expense carryforward	2,048
Investment in partnerships	50,009	55,956
Inventory valuation	3,603	1,944
Stock-based compensation	1,458	2,468
Accrued Expenses	5,439	5,541
Capital leases	2,516	2,426
Other	43	47
Total deferred tax assets	128,681	126,076
Deferred tax liabilities:
Convertible debt	(7,508)	(8,350)
Fixed assets	(118,330)	(149,746)
Derivative financial instruments	(1,573)
Organizational and start-up costs	(3,980)	(20,947)
Total deferred tax liabilities	(131,391)	(179,043)
Valuation allowance	(7,413)	(3,834)
Deferred income taxes	$ (10,123)	$ (56,801)