Long-Term Debt and Commitments (Details) (USD $)	3 Months Ended
	Apr. 01, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Long-term debt, gross	$ 94,000,000	$ 94,000,000
Less: Current maturities	8,555,000	8,552,000
Long-term debt	85,455,000	85,449,000
Short-term Borrowings [Abstract]
Uncommitted short-term bank credit lines, maximum borrowing capacity	191,000,000
Uncommitted short-term bank credit lines, amount outstanding	5,494,000	5,846,000
Series 2006 Senior Notes Due 2013 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	50,000,000	50,000,000
Interest rate on debt instrument (in hundredths)	5.53%
Maturity date	Oct. 05, 2013
Floating Rate Series 2006A Senior Notes Due 2013 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	25,000,000	25,000,000
Maturity date	Oct. 05, 2013
Variable/Fixed Rate Industrial Development Revenue Bonds Due 2012 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	8,000,000	8,000,000
Maturity date	Aug. 01, 2012
Variable/Fixed Rate Industrial Development Revenue Bonds Series 1999 Due 2014 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	8,200,000	8,200,000
Maturity date	Nov. 01, 2014
Installment Obligations [Member]
Debt Instrument [Line Items]
Long-term debt, gross	1,400,000	1,400,000
Other Borrowings [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,400,000	$ 1,400,000