Fair Value Hierarchy (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2011		Sep. 30, 2010
Estimate of Fair Value, Fair Value Disclosure
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents	$ 1,226.5		$ 1,205.7
Short-term marketable securities	13.8		11.3
Long-term investments	10.5		15.0
Foreign currency derivatives			0.2	[1]
Assets, fair value disclosure, recurring	1,250.8		1,232.2
Fair value of assets measured on a recurring basis, percentage of total assets	10.60%		10.30%
Mandatorily redeemable noncontrolling interests	25.4	[2]	48.1	[2]
Fair Value, Inputs, Level 1
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents	1,226.5		1,205.7
Short-term marketable securities	13.8		11.3
Long-term investments	1.4		1.3
Foreign currency derivatives			0	[1]
Assets, fair value disclosure, recurring	1,241.7		1,218.3
Fair value of assets measured on a recurring basis, percentage of total assets	10.50%		10.20%
Mandatorily redeemable noncontrolling interests	0	[2]	0	[2]
Fair Value, Inputs, Level 2
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents	0		0
Short-term marketable securities	0		0
Long-term investments	9.1		13.7
Foreign currency derivatives			0	[1]
Assets, fair value disclosure, recurring	9.1		13.7
Fair value of assets measured on a recurring basis, percentage of total assets	0.10%		0.10%
Mandatorily redeemable noncontrolling interests	0	[2]	0	[2]
Fair Value, Inputs, Level 3
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents	0		0
Short-term marketable securities	0		0
Long-term investments	0		0
Foreign currency derivatives			0.2	[1]
Assets, fair value disclosure, recurring	0		0.2
Fair value of assets measured on a recurring basis, percentage of total assets	0.00%		0.00%
Mandatorily redeemable noncontrolling interests	$ 25.4	[2]	$ 48.1	[2]

[1] Fair value is derived from changes in market value of obligations denominated in foreign currency based on an internal valuation model.

[2] Relates to unconditional obligations to purchase additional noncontrolling equity shares of consolidated subsidiaries. Fair value measurement of the obligation was based upon the amount payable as if the forward contracts were settled. The amount redeemable within the next twelve months is classified in accrued liabilities; any interests redeemable thereafter are classified in other non-current liabilities.