Business Segments (Reconciliation of Operating Profit (Loss) from Segments to Consolidated) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting [Abstract]
Profit for reportable segments	$ 11,176	$ 9,118	$ 27,837	$ 19,485
Interest expense	(1,367)	(2,026)	(4,979)	(6,315)
Interest income	71	56	166	166
Other (expense) income	(153)	551	327	564
LIFO expense	(1,701)	(1,552)	(2,414)	(1,733)
Equity in (loss) income of nonconsolidated investments	(4)	50	(7)	(5)
Unallocated corporate expense and other unallocated charges	(3,297)	(3,183)	(12,089)	(7,640)
Income before income taxes	$ 4,725	$ 3,014	$ 8,841	$ 4,522