Savings Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Domestic Tax Authority
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	$ 47.2	$ 47.0	$ 44.5
Discretionary Company Contribution
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	3.6	6.1	5.8
Defined Contribution Plans Participant Forfeitures
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	4.6	4.4	3.8
Foreign Tax Authority
Defined Benefit Plans and Other Postretirement Benefit Plans
Cost Recognized	$ 47.4	$ 44.5	$ 43.9