Other Assets (Prepaid Expenses and Other Current Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Income tax receivable	$ 187.7	$ 59.7
Prepaid expenses	85.8	78.6
Inventories	53.1	51.2
Other non-trade receivables	34.4	28.6
Reinsurance receivable	25.7	23.1
Other current assets	4.5	6.4
Total	$ 391.2	$ 247.6