Inventories (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Gross inventories at FIFO [Abstract]
Finished goods	$ 34,523,000	$ 26,751,000
Work in progress	33,615,000	31,136,000
Raw materials & component parts	197,644,000	185,739,000
Maintenance, tooling & supplies	16,028,000	14,864,000
Total gross inventories at FIFO	281,810,000	258,490,000
Less reserves [Abstract]
LIFO	35,854,000	34,954,000
Valuation	5,049,000	5,061,000
Total inventories as reported	240,907,000	218,475,000
Gross inventories on FIFO basis accounted for on a LIFO basis	$ 128,700,000	$ 120,700,000