Income Taxes - Schedule of Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Currently payable
U.K.	$ 0.2	$ (0.2)	$ 0.3
International	5.1	6.2	3.6
Total current taxes	5.3	6.0	3.9
Deferred
U.K.	3.4	(0.1)	3.4
International	(3.2)	(2.6)	(0.5)
Total deferred taxes	0.2	(2.7)	2.9
Total provision for income taxes	$ 5.5	$ 3.3	$ 6.8