Segments (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Net sales	$ (113,500)	$ (112,937)	$ (346,759)	$ (321,607)
Gross profit	(27,385)	(32,763)	(83,353)	(75,738)
Operating Segments \| Units
Segment Reporting Information [Line Items]
Net sales	(102,499)	(104,957)	(319,820)	(300,623)
Gross profit	(27,713)	(33,488)	(84,998)	(79,407)
Operating Segments \| Parts
Segment Reporting Information [Line Items]
Net sales	(11,028)	(8,321)	(27,287)	(21,700)
Gross profit	(5,074)	(3,893)	(13,245)	(9,880)
Other
Segment Reporting Information [Line Items]
Net sales	27	341	348	716
Gross profit	5,402	4,618	14,890	13,549
Inter-segment
Segment Reporting Information [Line Items]
Net sales	(6,448)	(7,669)	(21,665)	(21,306)
Gross profit	$ (44)	$ 39	$ (889)	$ (325)

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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