Benefit Plans Benefit Plans - Change in Plan Assets Unobservable Inputs (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.24%	4.62%
U.S. Plans | Level 3
Defined Benefit Plan Disclosure [Line Items]
Balance, January 1	$ 47.4	$ 53.3
Dispositions	(4.3)	(8.3)
Realized and unrealized gain, net	4.1	2.4
Balance, December 31	47.2	47.4
Acquisition	$ 0.0	$ 0.0
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	1.47%	1.16%
Foreign Plan [Member] | Level 3
Defined Benefit Plan Disclosure [Line Items]
Balance, January 1	$ 230.6	$ 0.0
Dispositions	(175.3)	0.0
Realized and unrealized gain, net	26.5	0.1
Balance, December 31	81.8	230.6
Acquisition	$ 0.0	$ 230.5