Shareholders' Equity - Components of Accumulated Other Comprehensive Loss, Net of Tax (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	$ 2,716.1	$ 2,694.5	$ 2,649.9	$ 2,698.5	$ 2,810.2	$ 2,847.5	$ 2,939.0	$ 2,857.6
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	(323.3)			(223.2)
Translation gain (loss) on derivative instruments, net of income taxes of $(10.9) and $(12.9), respectively
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	38.5			(4.7)
Translation loss on long-term intercompany loans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	(133.6)			(137.2)
Defined benefit pension plans and Retiree health care plan | Defined benefit pension plans, net of income taxes of $(23.0) and $(23.2), respectively
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	(36.9)			(37.9)
Defined benefit pension plans and Retiree health care plan | Retiree health care plan, net of income taxes of $1.9 and $2.0 for 2019 and 2018, respectively
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	2.8			3.2
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Total shareholders' equity	$ (452.5)	$ (416.5)	$ (401.8)	$ (399.8)	$ (393.2)	$ (375.9)	$ (264.1)	$ (288.2)