Fixed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,274,269	$ 1,217,032
Accumulated depreciation	(882,989)	(840,855)
Property, plant and equipment, net	391,280	376,177
Rental property and equipment	145,954	151,195
Accumulated depreciation	(107,519)	(109,970)
Rental property and equipment, net	38,435	41,225
Depreciation expense	127,000	123,000	$ 110,000
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,333	9,333
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	617,748	606,420
Capitalized software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	443,400	410,171
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 203,788	$ 191,108