Long-Term Debt - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended		3 Months Ended	12 Months Ended					12 Months Ended	0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Nov. 01, 2012 Senior Secured Term Loan B	Apr. 18, 2007 Senior Secured Term Loan B	Dec. 31, 2012 Senior Secured Term Loan B	Sep. 30, 2013 Senior Secured Term Loan B	Sep. 30, 2012 Senior Secured Term Loan B	Sep. 30, 2011 Senior Secured Term Loan B	Sep. 30, 2010 Senior Secured Term Loan B	Apr. 18, 2012 Senior Secured Term Loan B	Sep. 30, 2013 Term Loan And Amendments Of Prior Credit Facility	Apr. 03, 2013 Industrial revenue bond	Sep. 30, 2012 Industrial revenue bond
Debt Instrument [Line Items]
Senior secured Term Loan proceeds					$ 90,000,000
Remaining Term Loan B balance prepaid				13,427,000
Condition for interest rate on term loan							The interest rate on the Term Loan was equal to, at the Company’s election, either (1) the prime rate plus 1.00%, or (2) a LIBOR rate plus the applicable margin
Excess interest rate over prime rate					1.00%
Fixed margin minimum on term loan B LIBOR						2.25%		2.25%	2.25%
Minimum quarterly repayment amount						225,000	225,000		0
Percentage of Excess Cash Flow due as principal repayment							25.00%
Minimum excess cash flow to generate additional annual principal repayment							5,000,000
Prepayment of outstanding Term Loan							13,427,000	15,000,000	12,623,000
Prepayment under the annual excess cash flow provision of term Loan										2,623,000
Senior Secured Term Loan B					90,000,000
Interest Rate on Term Loan								7.25%	7.25%
Notional Amount of Interest Rate Swap					75,000,000						5,000,000
Pretax losses with the exchange of interest rate payments under the swap agreement								(144,000)	(808,000)
Payments of Financing Costs	927,000	61,000	26,000									1,112,000
Outstanding borrowings under an Industrial Revenue Bond ("IRB")		15,257,000												1,830,000
Repayment of long-term debt	$ 15,257,000	$ 16,085,000	$ 13,819,000										$ 1,830,000