Repositioning Actions (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Repositioning Actions [Abstract]
Severance				$ 92.8
Real estate lease terminations				15.3
Asset and goodwill write-offs related to disposals and other costs				23.2
Repositioning actions, total				131.3
Severance payments related to repositioning actions									92.8
Operating Expenses [Abstract]
Salary and service costs									10,250.6	9,214.2	8,450.6
Office and general expenses									1,950.8	1,868.1	1,895.2
Operating Expenses	3,365.5	3,007.5	2,999.3	2,829.2	3,147.0	2,680.5	2,625.8	2,629.0	12,201.4	11,082.3	10,345.8
Repositioning Actions [Member]
Operating Expenses [Abstract]
Salary and service costs									92.8
Office and general expenses									38.5
Operating Expenses									131.3
Remeasurement Gain [Member]
Operating Expenses [Abstract]
Office and general expenses									(123.4)
Operating Expenses									$ (123.4)