Shareholders' Equity - Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	$ 27.0
Balance at end of period	17.0	$ 27.0
Accumulated Other Comprehensive Income
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	27.0	(75.9)	$ (44.2)
Other comprehensive income (loss)	(13.4)	98.1	(35.7)
Realized loss on reclassification	3.4	4.8	4.0
Balance at end of period	17.0	27.0	(75.9)
Foreign Currency Translation
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	72.2	(24.1)	3.2
Other comprehensive income (loss)	(25.3)	96.3	(27.3)
Balance at end of period	46.9	72.2	(24.1)
Pension Liability Adjustment
Summary of the components of accumulated other comprehensive income, net of tax
Balance at beginning of period	(45.2)	(51.8)	(47.4)
Other comprehensive income (loss)	11.9	1.8	(8.4)
Realized loss on reclassification	3.4	4.8	4.0
Balance at end of period	$ (29.9)	$ (45.2)	$ (51.8)