Debt (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Debt Instrument [Line Items]
Debt	$ 10,862,000	$ 13,581,000	$ 10,862,000	$ 13,581,000
Current portion of long-term debt	(4,691,000)	(4,104,000)	(4,691,000)	(4,104,000)
Long-term debt	6,171,000	9,477,000	6,171,000	9,477,000	9,477,000
Letter of credit - original face amount	3,332,493		3,332,493
Percent of subsidiary stock not security for financing	65.00%		65.00%
Expected investment in facility expansion	14,500,000		14,500,000
Derivatives not designated as hedging instruments, interest rate swap liabilities	252,000		252,000		331,000
Interest expense for settlements related to swaps	41,000	52,000	134,000	179,000
Capex Loan [Member]
Debt Instrument [Line Items]
Debt	6,285,000	7,571,000	6,285,000	7,571,000
Long-term Debt, Maturities, Repayment Term			7 years
Mexican Loan [Member]
Debt Instrument [Line Items]
Debt	3,200,000	4,800,000	3,200,000	4,800,000
Long-term Debt, Maturities, Repayment Term			5 years
Industrial Development Revenue Bond [Member]
Debt Instrument [Line Items]
Debt	625,000	1,210,000	625,000	1,210,000
Line of Credit [Member]
Debt Instrument [Line Items]
Debt	752,000	0	752,000	0
Mexican Expansion Revolving Loan [Member]
Debt Instrument [Line Items]
Debt	0	0	0	0
Capex Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	12,000,000		12,000,000
Debt Instrument, Interest Rate, Stated Percentage	1.98%		1.98%		2.02%
Mexican Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	8,000,000		8,000,000
Debt Instrument, Interest Rate, Stated Percentage	1.94%		1.94%		1.94%
Industrial Development Revenue Bond [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.37%		0.37%		0.37%
Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	8,000,000		8,000,000
Debt Instrument, Description of Variable Rate Basis			daily LIBOR
Debt Instrument, Interest Rate, Stated Percentage	1.94%		1.94%
Debt Instrument, Basis Spread on Variable Rate	1.75%		1.75%
Mexican Expansion Revolving Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Description of Variable Rate Basis			daily LIBOR
Debt Instrument, Basis Spread on Variable Rate	1.75%		1.75%
Mexican Expansion Revolving Loan, unused borrowing capacity, Amount	10,000,000		10,000,000
Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	2,678,563		2,678,563
Industrial Development Revenue Bond Swap Agreement [Member]
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate	4.89%		4.89%
Derivative, Description of Variable Rate Basis			76% of the 30-day commercial paper rate
Derivative, Variable Interest Rate	0.10%		0.10%
Description of Reclassification of Cash Flow Hedge Gain (Loss)			The pre-tax loss previously recognized in Accumulated Other Comprehensive Income, totaling $200,000 as of December 31, 2009, is being amortized as an increase to interest expense of $5,000 per month, or $3,000 net of tax, over the remaining term of the interest rate swap agreement.
Derivatives not designated as hedging instruments, interest rate swap liabilities	15,000		15,000		52,000
Interest income (loss) for mark-to-market adjustment of swap fair value			37,000
Notional amount of swap	625,000		625,000		1,210,000
Capex Loan Swap Agreement [Member]
Debt Instrument [Line Items]
Derivative, Fixed Interest Rate	2.295%		2.295%
Derivative, Description of Variable Rate Basis			LIBOR
Derivative, Variable Interest Rate	0.23%		0.23%
Description of Reclassification of Cash Flow Hedge Gain (Loss)			The pre-tax loss previously recognized in Accumulated Other Comprehensive Income, totaling $146,000 as of March 31, 2009, is being amortized as an increase to interest expense of $2,000 per month, or $1,000 net of tax, over the remaining term of the interest rate swap agreement.
Derivatives not designated as hedging instruments, interest rate swap liabilities	237,000		237,000		279,000
Interest income (loss) for mark-to-market adjustment of swap fair value			42,000
Notional amount of swap	$ 6,286,000		$ 6,286,000		$ 7,571,000