Restructuring and Other Charges, Net - Expected, incurred and remaining pre-tax restructuring costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring reserve
Costs incurred	$ 3.4	$ 6.8	$ 4.7
Summary of total expected, incurred and remaining pre-tax costs
Costs incurred	$ 3.4	$ 6.8	$ 4.7