Retirement Benefits - Narrative (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($) employee	Sep. 30, 2019 USD ($) employee	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer		$ 0.1
Participants affected due to plan freeze | employee	60	60
Decrease in liability due to plan freeze		$ 1.2
Other (Income) Expense Net
Defined Benefit Plan Disclosure [Line Items]
Settlement loss recognized	$ (0.5)	$ 0.5
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected contribution for next fiscal year			$ 0.6
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected contribution for next fiscal year			$ 1.1