Accrued Liabilities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accrued Liabilities [Abstract]
Salaries, benefits and related expenses	$ 370.9	$ 478.2
Office and related expenses	52.9	51.6
Acquisition obligations	9.2	29.5
Interest	15.9	42.4
Professional fees	17.6	21.7
Other	86.8	104.8
Total accrued liabilities	$ 553.3	$ 728.2