Employee Benefit Plans (Plans' Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in projected benefit obligation:
Amendments		$ 3.2
Changes in plan assets:
Fair value of plan assets at beginning of year	$ 292.5
Fair value of plan assets at end of year	318.6	292.5
Pension Benefits [Member]
Pension and Postretirement Benefit Plans recognized in financial statements
Accumulated benefit obligation	401.5	374.1
Changes in projected benefit obligation:
Benefit obligation at beginning of year	381.6	415.4
Service cost	5.0	4.4	$ 4.8
Interest cost	12.6	15.3	17.2
Plan participants' contributions	0.0	0.0
Amendments	0.0	0.1
Actuarial (gain) loss	22.1	22.8
Effect of exchange rates	4.3	(3.8)
Settlements and curtailments	(1.3)	(50.6)
Benefits paid	(18.8)	(22.0)
Benefit obligation at end of year	405.5	381.6	415.4
Changes in plan assets:
Fair value of plan assets at beginning of year	292.5	293.0
Actual gain return on plan assets	39.8	21.0
Employer contribution	3.5	53.9
Plan participants' contributions	0.0	0.0
Effect of exchange rates	2.9	(2.8)
Plan settlements	(1.3)	(50.6)
Benefits paid	(18.8)	(22.0)
Fair value of plan assets at end of year	318.6	292.5	293.0
Funded status / net amount recognized	(86.9)	(89.1)
Net amount recognized consists of:
Noncurrent assets	(1.6)	0.0
Current liability	(4.0)	(1.6)
Non-current liability	(84.5)	(87.5)
Net amount recognized	(86.9)	(89.1)
Other Benefits [Member]
Changes in projected benefit obligation:
Benefit obligation at beginning of year	3.3	4.9
Service cost	0.0	0.0	0.0
Interest cost	0.1	0.1	0.2
Plan participants' contributions	0.3	0.3
Amendments	0.0	0.0
Actuarial (gain) loss	(0.1)	(0.7)
Effect of exchange rates	0.0	0.0
Settlements and curtailments	0.0	0.0
Benefits paid	(0.5)	(1.3)
Benefit obligation at end of year	3.1	3.3	4.9
Changes in plan assets:
Fair value of plan assets at beginning of year	0.0	0.0
Actual gain return on plan assets	0.0	0.0
Employer contribution	0.3	1.0
Plan participants' contributions	0.2	0.3
Effect of exchange rates	0.0	0.0
Plan settlements	0.0	0.0
Benefits paid	(0.5)	(1.3)
Fair value of plan assets at end of year	0.0	0.0	$ 0.0
Funded status / net amount recognized	(3.1)	(3.3)
Net amount recognized consists of:
Noncurrent assets	0.0	0.0
Current liability	(0.5)	(0.5)
Non-current liability	(2.6)	(2.8)
Net amount recognized	$ (3.1)	$ (3.3)