Revenue Recognition (Revenue by customer and timing recognitions) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Disaggregation of Revenue [Line Items]
Retained Earnings	$ 136,765				$ 115,737				$ 136,765	$ 115,737
Net sales	151,825	$ 124,832	$ 163,446	$ 83,964	$ 137,969	$ 125,339	$ 139,371	$ 72,248	524,067	474,927	$ 416,268
Independent dealer
Disaggregation of Revenue [Line Items]
Net sales									409,384
Government
Disaggregation of Revenue [Line Items]
Net sales									52,582
Fleet
Disaggregation of Revenue [Line Items]
Net sales									58,500
Other
Disaggregation of Revenue [Line Items]
Net sales									3,601
Point in time
Disaggregation of Revenue [Line Items]
Net sales									429,117
Over time
Disaggregation of Revenue [Line Items]
Net sales									$ 94,950
Work Truck Attachments
Disaggregation of Revenue [Line Items]
Number of revenue streams | item									3
Net sales									$ 379,636
Work Truck Attachments | Independent dealer
Disaggregation of Revenue [Line Items]
Net sales									327,054
Work Truck Attachments | Government
Disaggregation of Revenue [Line Items]
Net sales									52,582
Work Truck Attachments | Point in time
Disaggregation of Revenue [Line Items]
Net sales									$ 379,636
Work Truck Solutions
Disaggregation of Revenue [Line Items]
Number of revenue streams | item									3
Net sales									$ 154,064
Work Truck Solutions | Independent dealer
Disaggregation of Revenue [Line Items]
Net sales									82,330
Work Truck Solutions | Fleet
Disaggregation of Revenue [Line Items]
Net sales									58,500
Work Truck Solutions | Other
Disaggregation of Revenue [Line Items]
Net sales									13,234
Work Truck Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales									59,114
Work Truck Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales									94,950
Corporate & Eliminations
Disaggregation of Revenue [Line Items]
Net sales									(9,633)	$ (13,407)	$ (9,414)
Corporate & Eliminations | Other
Disaggregation of Revenue [Line Items]
Net sales									(9,633)
Corporate & Eliminations | Point in time
Disaggregation of Revenue [Line Items]
Net sales									(9,633)
Effect of Change Higher/(Lower) | ASC 2014-09
Disaggregation of Revenue [Line Items]
Retained Earnings	$ 377								377
Net sales									299
Effect of Change Higher/(Lower) | ASC 2014-09 | Work Truck Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales									$ 299