Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
	Mar. 31, 2011	Sep. 30, 2012	Sep. 30, 2011
Effective income tax rate		33.80%	32.00%
Remeasurement gain, equity interest in Clemenger Group	$ 123.4	$ 0	$ 123.4
Tax provision related to remeasurement gain	2.8
Repositioning actions	131.3
Tax benefit related to charges incurred in connection with repositioning actions	39.5
Tax accrual for agreed upon adjustments to income tax returns under examination	9.0
Effective income tax rate, excluding repositioning actions, remeasurement gain and tax accrual for agreed upon adjustments to income tax returns under examination			34.50%
Unrecognized tax benefits		156.1
Unrecognized tax benefits that would impact effective tax rate		$ 59.4
Clemenger Group [Member]
Acquisition of controlling interests in affiliates, ownership percentage after acquisition	73.70%
Acquisition of controlling interests in affiliates, ownership percentage before acquisition	46.70%