Employees - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Current Fiscal Quarter	$ 0.5
Defined Benefit Plan, Expected Future Benefit Payment, Year 2020	2.0
Defined Benefit Plan, Expected Future Benefit Payment, Year 2021	2.0
Defined Benefit Plan, Expected Future Benefit Payment, Year 2020	0.1
Benefit plan settlements	0.1
Union Agreement [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Expected Future Benefit Payment, Total	6.9
Defined Benefit Plan, Expected Future Benefit Payment, Remainder of 2018	1.5
Defined Benefit Plan, Expected Future Benefit Payment, Year 2019	$ 2.0