Pension and Other Postretirement Benefits (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Employer contribution	$ 18.0	$ 18.0	$ 16.0
Nonqualified supplemental pension plan
Pension and Other Postretirement Benefits
Accrued expenses	2.0	2.0
Other noncurrent liability	15.0	16.0
Expenses recognized	$ 1.0	$ 2.0	3.0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement			$ 1.0