Income Tax Unrecognized Tax Benefits Balance (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Estimated interest and penalties	$ 2.9	$ 2.3	$ 2.1
Unrecognized tax positions	72.4	51.6	41.9	$ 39.7
Total unrecognized tax benefits	75.3	53.9	44.0
Presented net against non-current deferred tax assets	68.4	47.8	37.9
Current (included in accounts payable and other current liabilities)	0.0	0.0	0.0
Unrecognized tax benefits	6.9	6.1	6.1
Amount of unrecognized tax benefits that would impact the effective tax rate, if recognized(1)	$ 72.4	$ 51.6	$ 41.9