Rental Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Accumulated depreciation	$ 168,557		$ 168,557		$ 156,928
Depreciation - Property, plant and equipment			15,798	$ 14,237
Rental Equipment
Property, Plant and Equipment [Line Items]
Accumulated depreciation	20,800		20,800		$ 18,000
Depreciation - Property, plant and equipment	$ 2,100	$ 2,300	$ 6,600	$ 7,500