Other Assets - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Prepaid Expenses and Other Current Assets
Prepaid expenses	$ 88.0	$ 75.6
Inventories	55.3	53.1
Other non-trade receivables	39.0	34.4
Reinsurance receivable	31.4	25.7
Income tax receivable	17.6	187.7
Prepaid fees for cloud-based hosting arrangements, current	11.8	10.2
Other current assets	12.3	4.5
Total	$ 255.4	$ 391.2