Benefit Plans (Changes in Projected Benefit Obligation, Fair Value of Plan Assets and Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in Benefit Obligation [Roll Forward]
Balance		$ (313.6)
Settlement			$ 139.4
Balance			(313.6)
Change in Fair Value of Plan Assets [Roll Forward]
Balance	$ 192.4
Balance	239.5	192.4
Pension Plan [Member]
Change in Benefit Obligation [Roll Forward]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	9.0	(19.2)	(17.7)
Balance	(262.2)	(246.3)
Service cost	(10.4)	(10.2)	(10.6)
Interest cost	(9.8)	(10.5)	(13.8)
Participants' contributions	(0.7)	(0.6)
Actuarial (loss) gain	(11.8)	(23.4)
Amendments/transfers in	0.0	0.0
Benefits/expenses paid	14.2	16.2
Curtailment	0.0	5.2
Foreign currency translation	(7.3)	7.4
Balance	(288.0)	(262.2)	(246.3)
Change in Fair Value of Plan Assets [Roll Forward]
Balance	192.4	188.9
Actual return on assets	34.4	16.8
Employer contribution	23.2	6.8
Participants' contributions	0.7	0.6
Benefits/expenses paid	(14.2)	(16.2)
Foreign currency translation	3.0	(4.5)
Balance	239.5	192.4	188.9
Funded status at end of year	(48.5)	(69.8)
Other Postretirement Benefits Plan [Member]
Change in Benefit Obligation [Roll Forward]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	1.1	0.1	0.8
Balance	(8.0)	(10.2)
Service cost	0.0	(0.5)	(0.5)
Interest cost	(0.3)	(0.5)	(0.4)
Participants' contributions	(0.5)	(0.5)
Actuarial (loss) gain	1.2	0.1
Amendments/transfers in	0.0	3.0
Benefits/expenses paid	0.5	0.6
Curtailment	0.0	0.0
Foreign currency translation	0.0	0.0
Balance	(7.1)	(8.0)	(10.2)
Change in Fair Value of Plan Assets [Roll Forward]
Balance	0.0	0.0
Actual return on assets	0.0	0.0
Employer contribution	0.0	0.1
Participants' contributions	0.5	0.5
Benefits/expenses paid	(0.5)	(0.6)
Foreign currency translation	0.0	0.0
Balance	0.0	0.0	$ 0.0
Funded status at end of year	$ (7.1)	$ (8.0)