Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Net sales	$ (138,571)	$ (134,772)	$ (398,235)	$ (397,851)
Gross profit	(36,019)	(40,848)	(111,283)	(121,926)
Operating Segments | Units
Segment Reporting Information [Line Items]
Net sales	(125,862)	(123,827)	(366,597)	(372,267)
Gross profit	(35,167)	(41,675)	(111,247)	(128,523)
Operating Segments | Parts
Segment Reporting Information [Line Items]
Net sales	(12,977)	(11,222)	(32,369)	(26,162)
Gross profit	(5,072)	(4,917)	(12,385)	(11,641)
Other
Segment Reporting Information [Line Items]
Net sales	268	277	731	578
Gross profit	4,220	5,744	12,349	18,238
Inter-segment
Segment Reporting Information [Line Items]
Net sales	(6,325)	(5,659)	(19,005)	(18,074)
Gross profit	$ 366	$ 758	$ 527	$ 1,587