Retirement Benefits - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 employee
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer	$ 0.1
Participants affected due to plan freeze | employee			60
Funded percentage	105.00%
Defined benefit plan, assets	$ 89.1
Defined benefit plan, liability	$ 84.6
Other (Income) Expense Net
Defined Benefit Plan Disclosure [Line Items]
Settlement loss recognized		$ 0.3
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected contribution for next fiscal year		3.0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected contribution for next fiscal year		$ 1.1