Income Taxes (Components of Net Deferred Income Tax Assets and Net Deferred Income Tax Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred income tax assets:
Intangibles	$ 17,395	$ 20,624
Stock options and restricted stock awards	2,544	6,065
Reserves and allowances	10,450	11,959
Net operating loss carryforwards	67,025	57,782
Tax credit carryforwards	18,813	12,749
Accrued liabilities	6,077	3,218
Deferred revenue	4,637	3,940
Lease Tax Asset	8,343	5,970
163(j) Limitation Carryforward	2,854	1,519
Valuation allowance	(123,113)	(109,643)
Total deferred income tax assets	15,025	14,183
Deferred income tax liabilities:
Intangibles	2,548	4,495
Property, plant and equipment	2,662	3,282
Lease Tax Liability	6,379	4,195
Liabilities related to distributions	0	0
Other	1,345	830
Total deferred income tax liabilities	12,934	12,802
Deferred income tax asset held for sale	560	0
Net deferred income tax assets	$ 1,531	$ 1,381