Retirement Plans - Assumptions Used to Determine the Net Periodic Benefit Cost and Benefit Obligations (Details) - Pension Plans, Defined Benefit [Member]	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Discount rate for net periodic pension cost	3.50%	4.00%	4.30%
Discount rate for benefit obligations	4.20%	3.50%	4.00%
Expected long-term return of plan assets	7.50%	7.75%	7.75%