Earnings Per Share (Details) In Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2011		Jun. 30, 2010		Jun. 30, 2011		Jun. 30, 2010
Earnings Per Share
Basic	88.6		89.2		88.8		89.2
Dilutive share-based awards	0.5	[1]	0.8	[1]	0.5	[1]		[1]
Diluted	89.1		90.0		89.3		89.2
Anti- dilutive securities excluded from computation of earnings per share							0.9
Number of stock options and share warrants with exercise price exceeding average market price of common stock	2.2		2.4		2.2		2.4

[1] The six months ended June 30, 2010 excludes 0.9 million potentially dilutive share-based awards as their effect would be anti-dilutive.