Restatement of Unaudited Interim Condensed Consolidated Financial Statements - Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Addition from acquisitions	$ 66.9	$ 1,769.9
Goodwill	4,247.9	2,981.7	$ 4,021.9
As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Addition from acquisitions		1,697.1
Goodwill		2,908.9
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Addition from acquisitions		72.8
Goodwill		72.8
ArgoSolutions
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Addition from acquisitions	0.0	1,769.9
Goodwill	$ 1,996.0	2,059.6	$ 1,874.7
ArgoSolutions | As Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Addition from acquisitions		1,697.1
Goodwill		1,986.8
ArgoSolutions | Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Addition from acquisitions		72.8
Goodwill		$ 72.8