Other Required Disclosures - Components of Accounts Payable and Other Current Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Accounts payable and other current liabilities:
Accounts payable	$ 401.7	$ 325.9
Wages and benefits	86.3	110.9
Income taxes payable	31.4	96.6
Accrued interest	76.8	50.4
Accrued expenses	22.7	25.1
Oil and natural gas revenues and royalties payable	19.1
Accrued dividends on Preferred Stock	8.4	8.3
Restructuring and related charges	7.7	6.6
Other	141.4	130.4
Total accounts payable and other current liabilities	$ 795.5	$ 754.2