Property, Plant and Equipment (Summary of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 347,836	$ 353,401
Less accumulated depreciation	(248,801)	(222,940)
Total property, plant and equipment, net	99,035	130,461
Land [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	904	904
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	25,731	25,733
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	97,507	97,077
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	142,501	146,913
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	30,205	30,420
Computer Equipment And Software [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	45,217	45,473
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	5,005	4,722
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 766	$ 2,159