Fixed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,217,032	$ 1,156,402
Accumulated depreciation	(840,855)	(757,901)
Property, plant and equipment, net	376,177	398,501
Rental property and equipment	151,195	132,605
Accumulated depreciation	(109,970)	(86,377)
Rental property and equipment, net	41,225	46,228
Depreciation expense	123,000	110,000	$ 99,000
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	606,420	559,419
Capitalized software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	410,171	401,602
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 191,108	$ 186,048