Employee Benefit Plans (Amounts Recognized in Consolidated Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Amounts recognized in the consolidated balance sheets
Employee benefit plan obligations	$ (22,542)	$ (26,716)
Pension Benefits
Amounts recognized in the consolidated balance sheets
Accrued expenses	(1,516)	(1,232)
Employee benefit plan obligations	(2,846)	(4,600)
Net amount recognized	(4,362)	(5,832)
Postretirement Benefits
Amounts recognized in the consolidated balance sheets
Accrued expenses	(1,162)	(1,098)
Employee benefit plan obligations	(19,476)	(21,504)
Net amount recognized	$ (20,638)	$ (22,602)