Inventories (Details) (USD $)	Sep. 27, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Aluminum and steel coil	$ 69,877,000	$ 59,651,000
Raw materials	16,947,000	14,520,000
Work in process	2,891,000	1,598,000
Finished products	17,218,000	13,525,000
Inventories, net	106,933,000	89,294,000
Inventory valuation reserves	$ (2,400,000)	$ (2,900,000)