Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Net sales	$ 59,004	$ 75,498	$ 143,404	$ 190,311
Remaining performance obligation	1,800		1,800
Change In Contract With Customer Liability [Roll Forward]
Balance, beginning of period	479	693	816	1,084
Cash additions	351	304	512	993
Revenue recognition	(268)	(249)	(766)	(1,329)
Balance, end of period	562	748	562	748
United States
Disaggregation of Revenue [Line Items]
Net sales	48,897	65,498	119,085	169,079
Canada
Disaggregation of Revenue [Line Items]
Net sales	3,557	3,283	11,486	9,066
All other
Disaggregation of Revenue [Line Items]
Net sales	6,550	6,717	12,833	12,166
Product sales
Disaggregation of Revenue [Line Items]
Net sales	56,326	71,470	136,458	181,220
Extended warranties and services
Disaggregation of Revenue [Line Items]
Net sales	1,168	1,737	3,637	5,219
Other
Disaggregation of Revenue [Line Items]
Net sales	1,510	$ 2,291	3,309	$ 3,872
Retail Orders
Disaggregation of Revenue [Line Items]
Remaining performance obligation	1,400		1,400
Direct Orders
Disaggregation of Revenue [Line Items]
Remaining performance obligation	$ 400		$ 400