Contingencies - Litigation and Other Matters (Details) (USD $)	3 Months Ended	6 Months Ended					12 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2013 Performance Bonds	Mar. 31, 2013 Letter of Credit	Sep. 30, 2012 Letter of Credit	Sep. 30, 2006 First Order New Jersey Department of Environmental Protection - Violation of Permit	Sep. 30, 2006 Second Order New Jersey Department of Environmental Protection - Violation of Permit	Mar. 31, 2013 Pending Litigation loan
Loss Contingencies [Line Items]
Minimum standard product warranty period		1 year
Maximum standard product warranty period		2 years
Company's liability under Deferred Prosecution Agreement (percent)	4.00%	4.00%
Maximum liability under the DPA and other settlement agreements	$ 55,000,000	$ 55,000,000
Portion of liability under DPA that has been paid as of balance sheet date	16,600,000
Amount demanded per the complaint to recover purported losses							630,000	678,000
Accrued amounts for litigation and other contingent liabilities	16,000,000	16,000,000	19,400,000
Letters of credit secured using cash collateral					23,200,000	24,700,000
Cash collateral in restricted accounts securing letters of credit				$ 148,300,000
Number of affected homes that have not accepted Company's offer to repair									2