Fair Value on a Recurring Basis (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Level 1
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents	$ 511.0		$ 1,806.6
Short-term marketable securities	5.2		16.0
Long-term investments	1.5		1.5
Fair Value of Total Assets, Recurring	517.7		1,824.1
Fair value of assets measured on a recurring basis, percentage of total assets	4.50%		13.50%
Mandatorily redeemable noncontrolling interests	0	[1]	0	[1]
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	0		0
Fair Value of Total Assets, Recurring	0		0
Fair value of assets measured on a recurring basis, percentage of total assets	0.00%		0.00%
Mandatorily redeemable noncontrolling interests	0	[1]	0	[1]
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
Fair Value of Total Assets, Recurring	0		0
Fair value of assets measured on a recurring basis, percentage of total assets	0.00%		0.00%
Mandatorily redeemable noncontrolling interests	26.0	[1]	25.3	[1]
Fair Value, Total
Fair value assets and liabilities measured on recurring and nonrecurring basis
Cash equivalents	511.0		1,806.6
Short-term marketable securities	5.2		16.0
Long-term investments	1.5		1.5
Fair Value of Total Assets, Recurring	517.7		1,824.1
Fair value of assets measured on a recurring basis, percentage of total assets	4.50%		13.50%
Mandatorily redeemable noncontrolling interests	$ 26.0	[1]	$ 25.3	[1]

[1] 1 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.