Repositioning Actions and Supplemental Data (Details) (USD $) In Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Mar. 31, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
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		131.3
Severance payments related to repositioning actions				83.3
Severance liability related to repositioning actions	9.5			9.5
Repositioning actions, non-cash charges				23.2
Operating Expenses [Abstract]
Salary and service costs	2,504.7		2,210.8	7,395.8	6,526.5
Office and general expenses	502.8		469.7	1,440.1	1,408.6
Total operating expenses	3,007.5		2,680.5	8,835.9	7,935.1
Changes in Operating Capital [Abstract]
Decrease in accounts receivable				85.1	143.4
Increase in work in progress and other current assets				(208.2)	(267.1)
Decrease in accounts payable				(780.7)	(646.2)
Decrease in customer advances and other current liabilities				(266.4)	(112.1)
Change in other assets and liabilities, net				266.3	82.7
Change in operating capital				(903.9)	(799.3)
Income taxes paid				246.9	223.6
Interest paid				101.5	103.8
Repositioning Actions [Member]
Operating Expenses [Abstract]
Salary and service costs				92.8
Office and general expenses				38.5
Total operating expenses				131.3
Remeasurement Gain [Member]
Operating Expenses [Abstract]
Office and general expenses				(123.4)
Total operating expenses				$ (123.4)