Defined Benefit Plans (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 1,305.0	$ 1,412.2	$ 1,198.7
Projected benefit obligation	1,217.5	1,335.4	1,205.1
Net asset (liability)	87.5	76.8	(6.4)
Net periodic pension cost	7.4	4.0	9.7
Service cost	24.4	$ 22.2	23.0
Curtailment gain	1.1		$ 1.4
Contributions expected in next fiscal year	26.1
Contributions by employer	50.6
Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	918.3
Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137.6
Significant unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 249.1