Revenue Recognition (Revenue by customer and timing recognitions) (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) item	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Retained Earnings	$ 160,748				$ 136,765				$ 160,748	$ 136,765
Net sales	$ 160,298	$ 141,869	$ 176,356	$ 93,187	$ 151,825	$ 124,832	$ 163,446	$ 83,964	571,710	524,067	$ 474,927
Independent dealer
Disaggregation of Revenue [Line Items]
Net sales									421,114	409,384
Government
Disaggregation of Revenue [Line Items]
Net sales									72,810	52,582
Fleet
Disaggregation of Revenue [Line Items]
Net sales									66,306	58,500
Other
Disaggregation of Revenue [Line Items]
Net sales									11,480	3,601
Point in time
Disaggregation of Revenue [Line Items]
Net sales									465,899	429,117
Over time
Disaggregation of Revenue [Line Items]
Net sales									$ 105,811	94,950
Work Truck Attachments
Disaggregation of Revenue [Line Items]
Number of revenue streams | item									2
Net sales									$ 293,630	275,244
Work Truck Attachments | Independent dealer
Disaggregation of Revenue [Line Items]
Net sales									293,630	275,244
Work Truck Attachments | Point in time
Disaggregation of Revenue [Line Items]
Net sales									$ 293,630	275,244
Work Truck Solutions
Disaggregation of Revenue [Line Items]
Number of revenue streams | item									4
Net sales									$ 278,080	248,823
Work Truck Solutions | Independent dealer
Disaggregation of Revenue [Line Items]
Net sales									127,484	134,140
Work Truck Solutions | Government
Disaggregation of Revenue [Line Items]
Net sales									72,810	52,582
Work Truck Solutions | Fleet
Disaggregation of Revenue [Line Items]
Net sales									66,306	58,500
Work Truck Solutions | Other
Disaggregation of Revenue [Line Items]
Net sales									11,480	3,601
Work Truck Solutions | Point in time
Disaggregation of Revenue [Line Items]
Net sales									172,269	153,873
Work Truck Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales									105,811	94,950
Effect of Change Higher/(Lower) | ASC 2014-09
Disaggregation of Revenue [Line Items]
Retained Earnings												$ 377
Net sales									251	299
Effect of Change Higher/(Lower) | ASC 2014-09 | Work Truck Solutions | Over time
Disaggregation of Revenue [Line Items]
Net sales									$ (251)	$ 299