Net Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Net Earnings Per Share
Net earnings attributable to common stockholders	$ 368.4	$ 282.0
Basic earnings per common share:
Weighted average common shares outstanding	65.5	71.3
Net earnings attributable to common stockholders basic (in dollars per share)	$ 5.62	$ 3.95
Diluted earnings per common share:
Weighted average common shares outstanding	65.5	71.3
Dilutive common share-stock options	1.0	0.8
Diluted weighted average shares outstanding	66.5	72.1
Net earnings attributable to common stockholders diluted (in dollars per share)	$ 5.54	$ 3.91