Accrued Liabilities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Accrued Liabilities [Abstract]
Salaries, benefits and related expenses	$ 397.4	$ 520.6
Office and related expenses	46.7	57.9
Acquisition obligations	19.4	43.7
Interest	24.3	40.3
Professional fees	20.6	25.3
Other	141.6	139.3
Total accrued liabilities	$ 650.0	$ 827.1