Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance		$ 59.0	$ 33.6	$ 25.7
Additions Charged to Costs and Expenses		16.8	15.6	10.5
Additions Charged to Other Accounts	[1]	6.0	13.0	0.3
Deductions		(6.5)	(3.2)	(2.9)
Ending balance		75.3	59.0	33.6
Valuation allowance for deferred tax assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance		460.7	355.7	304.5
Additions Charged to Costs and Expenses		194.1	108.8	75.6
Additions Charged to Other Accounts	[1]	18.9	3.4	6.1
Deductions		(10.9)	(7.2)	(30.5)
Ending balance		$ 662.8	$ 460.7	$ 355.7

[1] In 2016, this amount includes opening balances of businesses acquired in the period.