Supplemental Balance Sheet Information (Other Long-Term Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Balance Sheet Related Disclosures [Abstract]
Deferred rent	$ 206.0	$ 201.9
Unrecognized tax benefits	90.1	78.4
Asset retirement obligations	33.5	42.6
Other	26.4	22.4
Total other long-term liabilities	$ 356.0	$ 345.3

Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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-Publisher FASB

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For a classified balance sheet, the cumulative difference between the rental income or payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense, by the lessor or lessee, respectively, more than one year after the balance sheet date.

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The noncurrent portion of the amount recognized for uncertain tax positions as of the balance sheet date.

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Aggregate carrying amount, as of the balance sheet date, of noncurrent obligations not separately disclosed in the balance sheet. Noncurrent liabilities are expected to be paid after one year (or the normal operating cycle, if longer).

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Obligations not otherwise itemized or categorized in the footnotes to the financial statements that are expected to be paid after one year (or the normal operating cycle, if longer), from the balance sheet date.

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