Major Customers (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Revenue, Major Customer [Line Items]
Total product sales	$ 40,664,000	$ 32,858,000
Total tooling sales	411,000	1,504,000
Total sales	41,075,000	34,362,000
Navistar [Member]
Revenue, Major Customer [Line Items]
Total sales	12,713,000	12,267,000
Volvo [Member]
Revenue, Major Customer [Line Items]
Total sales	10,246,000	1,746,000
Paccar [Member]
Revenue, Major Customer [Line Items]
Total sales	8,392,000	11,471,000
Yamaha [Member]
Revenue, Major Customer [Line Items]
Total sales	5,000,000	4,007,000
Other Customers [Member]
Revenue, Major Customer [Line Items]
Total sales	4,724,000	4,871,000
Product Sales [Member] | Navistar [Member]
Revenue, Major Customer [Line Items]
Total sales	12,702,000	12,238,000
Product Sales [Member] | Volvo [Member]
Revenue, Major Customer [Line Items]
Total sales	10,075,000	1,169,000
Product Sales [Member] | Paccar [Member]
Revenue, Major Customer [Line Items]
Total sales	8,187,000	10,822,000
Product Sales [Member] | Yamaha [Member]
Revenue, Major Customer [Line Items]
Total sales	5,000,000	4,007,000
Product Sales [Member] | Other Customers [Member]
Revenue, Major Customer [Line Items]
Total sales	4,700,000	4,622,000
Tooling Sales [Member] | Navistar [Member]
Revenue, Major Customer [Line Items]
Total sales	11,000	29,000
Tooling Sales [Member] | Volvo [Member]
Revenue, Major Customer [Line Items]
Total sales	171,000	577,000
Tooling Sales [Member] | Paccar [Member]
Revenue, Major Customer [Line Items]
Total sales	205,000	649,000
Tooling Sales [Member] | Yamaha [Member]
Revenue, Major Customer [Line Items]
Total sales	0	0
Tooling Sales [Member] | Other Customers [Member]
Revenue, Major Customer [Line Items]
Total sales	$ 24,000	$ 249,000