Retirement Plans, Amounts Recognized in Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Pension Plan [Member]
Amounts recognized in the consolidated balance sheets [Abstract]
Noncurrent asset	$ 0	$ 0
Current liability	0	0
Long-term liability	(78,332)	(59,999)
SERP [Member]
Amounts recognized in the consolidated balance sheets [Abstract]
Noncurrent asset	0	0
Current liability	(158)	(159)
Long-term liability	(1,087)	(1,253)
Other Postretirement Benefits [Member]
Amounts recognized in the consolidated balance sheets [Abstract]
Noncurrent asset	0	0
Current liability	(65)	(54)
Long-term liability	$ (678)	$ (625)