Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Differences in the expected income tax provision based on statutory rates applied to earnings before income taxes and the income tax provision reflected in the consolidated statements of operations
Income tax provision	$ 206.0	$ 184.9	$ 722.0	$ 624.7
Pre-tax income	640.2	550.6	2,241.3	1,848.5
Differences in the expected income tax provision based on statutory rates applied to earnings before income taxes and the income tax provision reflected in the consolidated statements of operations (as a percent)
Effective income tax rate (as a percent)	32.20%	33.60%
Effective tax rate based on pre-tax income exclusive of earnings attributable to noncontrolling interests (as a percent)	35.20%	37.10%
Decrease in unrecognized tax benefits	23.5
Unrecognized Tax Benefits	114.4		114.4
Portion of unrecognized tax benefits, if recognized, would affect the effective tax rate	$ 48.2		$ 48.2