Major Customers (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	$ 33,816,000	$ 44,243,000	$ 113,159,000	$ 145,612,000
Contracts Revenue	7,520,000	3,806,000	12,651,000	6,893,000
Revenue, Net	41,336,000	48,049,000	125,810,000	152,505,000
Navistar [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	9,575,000	12,219,000	31,304,000	38,520,000
Contracts Revenue	470,000	2,325,000	1,166,000	3,373,000
Revenue, Net	10,045,000	14,544,000	32,470,000	41,893,000
Volvo [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	6,337,000	13,080,000	23,465,000	41,720,000
Contracts Revenue	5,353,000	387,000	5,801,000	1,585,000
Revenue, Net	11,690,000	13,467,000	29,266,000	43,305,000
Paccar [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	6,887,000	8,409,000	18,434,000	27,567,000
Contracts Revenue	18,000	63,000	3,454,000	819,000
Revenue, Net	6,905,000	8,472,000	21,888,000	28,386,000
Yamaha [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	3,602,000	2,067,000	11,658,000	11,551,000
Contracts Revenue	0	0	0	0
Revenue, Net	3,602,000	2,067,000	11,658,000	11,551,000
Other Customers [Member]
Revenue, Major Customer [Line Items]
Sales Revenue, Goods, Net	7,415,000	8,468,000	28,298,000	26,254,000
Contracts Revenue	1,679,000	1,031,000	2,230,000	1,116,000
Revenue, Net	$ 9,094,000	$ 9,499,000	$ 30,528,000	$ 27,370,000