Post Retirement Benefit Plans - Changes in Benefit Obligations and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in benefit obligation:
Benefit obligation at beginning of year	$ 199.2	$ 207.2
Service cost	6.8	7.2	$ 4.8
Interest cost	2.2	2.5	4.6
Plan participant contributions	4.0	3.9
Plan curtailments		(0.3)
Benefits paid	(7.1)	1.3
Actuarial loss (gain)	11.1	7.5
Plan amendments		14.7
Plan settlements		(39.7)
Premiums paid	(1.4)	(1.4)
Plan combinations		0.9
Impact of foreign currency exchange rates	(4.7)	(4.6)
Benefit obligation at end of year	210.1	199.2	207.2
Change in plan assets:
Fair value of plan assets at beginning of year	106.1	139.6
Return on plan assets	1.3	(3.7)
Plan participant and employer contributions	9.2	9.5
Benefits paid	(7.1)	1.3
Plan settlements		(39.7)
Premiums paid	(1.4)	(1.4)
Plan combinations		0.1
Impact of foreign currency exchange rates	(2.2)	0.4
Fair value of plan assets at end of year	105.9	106.1	$ 139.6
Net under funded status	(104.2)	(93.1)
Accumulated benefit obligation	$ 199.9	$ 189.7