Retirement Benefits - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2019 employee
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer			$ 100
Participants affected due to plan freeze (fewer than) | employee					60
Funded percentage	108.00%		108.00%
Defined benefit plan, assets	$ 94,800		$ 94,800
Defined benefit plan, liability	87,600		87,600
Other (Income) Expense Net
Defined Benefit Plan Disclosure [Line Items]
Settlement loss recognized			400
Reduction in net periodic benefit cost			600
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected contribution for next fiscal year	3,000		3,000
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Expected contribution for next fiscal year		$ 1,100		$ 1,100
Reduction in net periodic benefit cost	$ (175)	$ (194)	$ (350)	$ (387)