Other Required Disclosures - Schedule of Other Assets (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
Other Assets:
Prepaid expenses and other current assets	$ 90.5	$ 53.1
Debt issuance costs	104.7	50.9
Deferred charges and other assets	76.7	68.6
Total other assets	$ 271.9	$ 172.6