Major Customers (Details)	3 Months Ended
Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Revenue, Major Customer [Line Items]
Number of Major Customers	5
Revenues	$ 64,023,000	$ 72,266,000
Product [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	61,930,000	71,451,000
Service [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	2,093,000	815,000
Navistar [Member]
Revenue, Major Customer [Line Items]
Revenues	10,765,000	14,292,000
Navistar [Member] \| Product [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	10,667,000	14,253,000
Navistar [Member] \| Service [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	98,000	39,000
Volvo [Member]
Revenue, Major Customer [Line Items]
Revenues	9,098,000	14,622,000
Volvo [Member] \| Product [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7,573,000	14,515,000
Volvo [Member] \| Service [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	1,525,000	107,000
Universal Forest Products [Member]
Revenue, Major Customer [Line Items]
Revenues	8,987,000	6,121,000
Universal Forest Products [Member] \| Product [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	8,987,000	6,121,000
Universal Forest Products [Member] \| Service [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	0	0
Paccar [Member]
Revenue, Major Customer [Line Items]
Revenues	8,156,000	11,985,000
Paccar [Member] \| Product [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7,949,000	11,812,000
Paccar [Member] \| Service [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	207,000	173,000
BRP [Member]
Revenue, Major Customer [Line Items]
Revenues	7,467,000	5,638,000
BRP [Member] \| Product [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	7,247,000	5,547,000
BRP [Member] \| Service [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	220,000	91,000
Other Customers [Member]
Revenue, Major Customer [Line Items]
Revenues	19,550,000	19,608,000
Other Customers [Member] \| Product [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	19,507,000	19,203,000
Other Customers [Member] \| Service [Member]
Revenue, Major Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 43,000	$ 405,000