CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net sales	$ 491,611	$ 500,153	$ 567,080	[1]
Cost of sales	389,601	400,245	458,253
Gross profit	102,010	99,908	108,827
Selling, general and administrative expenses	85,067	71,005	77,952
Impairment of goodwill and other intangible assets	0	105,972	0
Loss (gain) on disposal of property, plant and equipment	297	(2,644)	161
Restructuring charges	308	2,087	2,114
Income (loss) from operations	16,338	(76,512)	28,600	[1]
Interest expense	(6,802)	(6,662)	(7,588)
Interest income and other, net	107	622	4,720
Earnings (loss) before provision for (benefit from) income taxes	9,643	(82,552)	25,732
Provision for (benefit from) income taxes	21,540	(17,718)	6,535
Net (loss) earnings available to common shareholders	(11,897)	(64,834)	19,197
Class A Common Stock [Member]
Net (loss) earnings available to common shareholders	$ (2,113)	$ (11,408)	$ 3,331
Net (loss) earnings per common share:
Common shares - basic and diluted (in dollars per share)	$ (0.97)	$ (5.25)	$ 1.53
Weighted-average shares outstanding:
Common shares - basic and diluted (in shares)	2,175	2,175	2,175
Dividends paid per common share:
Common shares (in dollars per share)	$ 0.24	$ 0.24	$ 0.24
Class B Common Stock [Member]
Net (loss) earnings available to common shareholders	$ (9,784)	$ (53,426)	$ 15,866
Net (loss) earnings per common share:
Common shares - basic and diluted (in dollars per share)	$ (0.99)	$ (5.48)	$ 1.64
Weighted-average shares outstanding:
Common shares - basic and diluted (in shares)	9,857	9,749	9,698
Dividends paid per common share:
Common shares (in dollars per share)	$ 0.28	$ 0.28	$ 0.28

[1] (Revised)