Condensed Consolidated Statements of Operations - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Net sales		$ 436,952	$ 437,525
Costs and expenses:
Cost of sales		(392,433)	(387,060)
Selling, general and administrative expenses		(32,980)	(29,955)
Total operating costs and expenses		(425,413)	(417,015)
Income from operations		11,539	20,510
Interest expense, net		(8,020)	(8,043)
Non-operating pension and other postretirment benefit (costs) income	[1]	(1,279)	48
Earnings (loss) before income taxes		2,240	12,515
Income tax provision		360	(5,000)
Net earnings (loss)		$ 2,600	$ 7,515
Net earnings per common share:
Basic (in dollars per share)		$ 0.16	$ 0.46
Diluted (in dollars per share)		$ 0.16	$ 0.45

[1] 2 As a result of the adoption of ASU 2017-07, certain pension and OPEB (costs) income have been reclassified from operating to non-operating income. The service cost component of pension and OPEB costs remains within segment operating income. Refer to Note 2, "Recently Adopted and New Accounting Standards," and Note 10, "Pension and Other Postretirement Benefit Plans," for additional detail.