Shareholders' Equity - Components of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	$ 2,649.9	$ 2,698.5	$ 2,939.0	$ 2,857.6
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	(253.8)	(223.2)
Translation gain (loss) on net investment hedge, net of income taxes of $(7.8) and $(12.9), respectively
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	12.7	(4.7)
Accumulated other comprehensive loss, income taxes	(7.8)	(12.9)
Translation loss on long-term intercompany loans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	(126.2)	(137.2)
Defined benefit pension plans and Retiree health care plan | Defined benefit pension plans, net of income taxes of $(23.1) and $(23.2), respectively
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	(37.6)	(37.9)
Accumulated other comprehensive loss, income taxes	(23.1)	(23.2)
Defined benefit pension plans and Retiree health care plan | Retiree health care plan, net of income taxes of $2.0 for both 2019 and 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	3.1	3.2
Accumulated other comprehensive loss, income taxes	2.0	2.0
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	$ (401.8)	$ (399.8)	$ (264.1)	$ (288.2)