Long Term Debt (Details)	12 Months Ended				12 Months Ended
	Sep. 30, 2012 USD ($)	Sep. 30, 2012 US Revolver [Member] USD ($)	Mar. 31, 2012 US Revolver [Member] USD ($)	Sep. 30, 2012 US Revolver [Member] Maximum [Member]	Sep. 30, 2012 Canadian Revolver [Member] USD ($)	Mar. 31, 2012 Canadian Revolver [Member] USD ($)	Mar. 31, 2012 Canadian Revolver [Member] CAD	Feb. 29, 2012 Canadian Revolver [Member] USD ($)	Feb. 29, 2012 Canadian Revolver [Member] CAD	Sep. 30, 2012 Canadian Revolver [Member] Maximum [Member]	Sep. 30, 2012 Canadian Revolver [Member] Minimum [Member]	Sep. 30, 2012 Industrial Development Revenue Bonds [Member] USD ($)	Oct. 31, 2001 Industrial Development Revenue Bonds [Member] USD ($)
Line of Credit Facility [Line Items]
Revolving credit facility			$ 75,000,000
Revolving credit interest rate		The interest rate for amounts outstanding under the Amended Credit Agreement for the US Revolver is a floating rate based upon the higher of the Federal Funds Rate plus 0.5%, or the bank's prime rate.
Basis spread on variable rate		0.50%
Margin				1.75%						1.125%	0.375%
Outstanding letters of credit		36,500,000			100,000
Amount of credit facility remaining borrowing capacity		38,500,000			10,000,000
Maximum Fixed Charge Coverage Ratio	125.00%
Maximum Leverage Ratio	275.00%
Revolving canadian credit facility						10,200,000	10,000,000	20,300,000	20,000,000
Credit facility expiration date		Dec. 31, 2016			Feb. 28, 2015
Percentage of voting capital stock pledged as collateral		100.00%
Non-domestic subsidiaries of voting capital stock		66.00%
Borrowings													8,000,000
Reimbursement agreement requires annual redemptions												400,000
Balance in the restricted sinking fund	$ 434,000
Interest rate												0.45%