Employee Benefits (Amounts Recognized in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Retirement Income Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	$ 109,215	$ 121,052
Prior service benefit	(20,410)	(23,877)
Total	88,805	97,175
Other Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net loss	11,408	10,073
Prior service benefit	(146)	(185)
Total	$ 11,262	$ 9,888