Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		$ 2,698.5	$ 2,857.6	$ 2,446.4	$ 2,692.5
Reclassification of cumulative unrealized gain on Swiss franchise's investment portfolio	$ 15.3
Foreign currency translation
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		(223.2)	(87.7)
Translation loss on net investment hedge
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		(4.7)	(39.9)
Accumulated other comprehensive loss, income taxes		(12.9)	(23.1)
Translation loss on long-term intercompany loans
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		(137.2)	(128.8)
Unrealized gain on investments
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		0.0	15.3
Accumulated other comprehensive loss, income taxes		0.0	3.4
Defined benefit pension plans and Retiree health care plan | Defined benefit pension plans, net of income taxes of $(23.2) and $(27.8), respectively
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		(37.9)	(50.5)
Accumulated other comprehensive loss, income taxes		(23.2)	(27.8)
Defined benefit pension plans and Retiree health care plan | Retiree health care plan, net of income taxes of $2.0 for both 2018 and 2017
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		3.2	3.4
Accumulated other comprehensive loss, income taxes		2.0	2.0
Accumulated other comprehensive loss
Defined Benefit Plan Disclosure [Line Items]
Accumulated other comprehensive loss		$ (399.8)	$ (288.2)	$ (426.1)	$ (286.0)