Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	$ 290,436		$ 290,436		$ 280,391
Less: accumulated depreciation and amortization	(200,241)		(200,241)		(196,334)
Total property, plant, and equipment, net	90,195		90,195		84,057
Depreciation expense	7,100	$ 7,600	14,400	$ 15,100
Amortization of finance right-of-use assets	200	$ 100	300	$ 200
Land
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	554		554		634
Buildings
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	3,747		3,747		4,110
Furniture and fixtures
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	14,705		14,705		13,835
Machinery and equipment
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	26,315		26,315		25,438
Equipment leased to third parties under operating leases
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	29,110		29,110		29,217
Leasehold improvements
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	137,273		137,273		131,617
Computers and software
Property, Plant and Equipment, Net
Total property, plant, and equipment, gross	$ 78,732		$ 78,732		$ 75,540