Segments (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information [Line Items]
Net sales	$ (119,437)	$ (109,588)	$ (233,259)	$ (208,670)
Gross profit	(30,175)	(27,585)	(55,968)	(42,975)
Operating Segments \| Units
Segment Reporting Information [Line Items]
Net sales	(110,253)	(102,691)	(217,321)	(195,666)
Gross profit	(30,742)	(29,379)	(57,285)	(45,919)
Operating Segments \| Parts
Segment Reporting Information [Line Items]
Net sales	(9,348)	(7,092)	(16,259)	(13,379)
Gross profit	(4,487)	(2,958)	(8,171)	(5,987)
Other
Segment Reporting Information [Line Items]
Net sales	164	195	321	375
Gross profit	5,054	4,752	9,488	8,931
Inter-segment
Segment Reporting Information [Line Items]
Net sales	(7,295)	(6,353)	(15,217)	(13,637)
Gross profit	$ (168)	$ 431	$ (845)	$ (364)

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
-Name Accounting Standards Codification
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