Long Term Debt (Narrative) (Details)		6 Months Ended			6 Months Ended
	Mar. 31, 2013 USD ($)	Mar. 31, 2013 US Revolver [Member] USD ($)	Mar. 31, 2012 US Revolver [Member] USD ($)	Mar. 31, 2013 US Revolver [Member] Maximum [Member]	Mar. 31, 2013 Canadian Revolver [Member] USD ($)	Mar. 31, 2012 Canadian Revolver [Member] USD ($)	Mar. 31, 2012 Canadian Revolver [Member] CAD	Mar. 31, 2013 Canadian Revolver [Member] Maximum [Member]	Mar. 31, 2013 Canadian Revolver [Member] Minimum [Member]	Mar. 31, 2013 Industrial Development Revenue Bonds [Member]	Oct. 31, 2001 Industrial Development Revenue Bonds [Member] USD ($)
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		20,900,000			100,000
Amount of credit facility remaining borrowing capacity		54,100,000			9,700,000
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%
Revolving canadian credit facility						9,800,000	10,000,000
Borrowings											8,000,000
Reimbursement agreement requires annual redemptions	400,000
Balance in the restricted sinking fund	$ 234,000
Interest rate										0.26%