Benefit Plans, Pension and Other Postretirement Benefit Liabilities in Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Total Pension and Other Postretirement Benefit Liabilities Included in Balance Sheets [Abstract]
Other assets	$ 4.6	$ 0.0
Accrued liabilities	(2.0)	(1.7)
Pension and other postretirement benefits	$ (99.8)	$ (122.7)