Supplementary Data Accrued Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts Payable, Current [Abstract]
Salaries, benefits and related expenses	$ 433.2	$ 510.6
Office and related expenses	47.4	51.5
Acquisition obligations	62.5	88.1
Interest	17.5	18.3
Restructuring and other reorganization-related	3.6	5.5
Other	124.7	122.0
Total accrued liabilities	$ 688.9	$ 796.0