Business Segments (Reconciliation of Operating Profit (Loss) from Segments to Consolidated) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Business Segments [Abstract]
(Loss) income for reportable segments	$ (124,207)	$ 11,929	$ (124,945)	$ 21,187
Interest expense	(1,652)	(1,288)	(2,822)	(1,901)
Interest income	52	37	107	94
Other (expense) income	(107)	(95)	(822)	708
LIFO income	452	406	525	400
Equity in loss of nonconsolidated investment	(487)	(186)	(683)	(13)
Corporate expense, cost of capital elimination and other unallocated charges	(3,476)	(2,980)	(4,934)	(5,985)
(Loss) income before income taxes	$ (129,425)	$ 7,823	$ (133,574)	$ 14,490