Employee Benefits (Defined Benefit Plan, Amounts Recognized in Balance Sheet) (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]
Current liabilities	$ 0	$ 0
Noncurrent liabilities	(57,600)	(68,002)
Total	(57,600)	(68,002)
Other Pension Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current liabilities	(2,154)	(2,696)
Noncurrent liabilities	(26,238)	(24,766)
Total	(28,392)	(27,462)
Other Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Current liabilities	0	0
Noncurrent liabilities	(26,417)	(34,400)
Total	$ (26,417)	$ (34,400)