Other Assets - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Prepaid Expenses and Other Current Assets
Prepaid expenses	$ 67.4	$ 75.6
Income tax receivable	64.8	187.7
Inventories	56.2	53.1
Reinsurance receivable	32.3	25.7
Other non-trade receivables	21.5	34.4
Prepaid fees for cloud-based hosting arrangements, current	7.9	10.2
Other current assets	4.5	4.5
Total	$ 254.6	$ 391.2