CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Net sales	$ 500,153	$ 567,080	[1]	$ 487,076	[1]
Cost of sales	400,245	458,253		399,721
Gross profit	99,908	108,827		87,355
Selling, general and administrative expenses	71,005	77,952		72,061
Impairment of goodwill and other intangible assets	105,972	0		0
(Gain) loss on sale of property, plant and equipment	(2,644)	161		(10)
Restructuring charges	2,087	2,114		1,832
(Loss) income from operations	(76,512)	28,600	[1]	13,472	[1]
Interest expense	(6,662)	(7,588)		(3,978)
Interest income and other, net	622	4,720		276
(Loss) earnings before (benefit) provision for income taxes	(82,552)	25,732		9,770
(Benefit) provision for income taxes	(17,718)	6,535		1,167
Net (loss) earnings available to common shareholders	(64,834)	19,197		8,603
Class A [Member]
Net (loss) earnings available to common shareholders	$ (11,408)	$ 3,331		$ 1,492
Net (loss) earnings per common share:
Common shares - basic and diluted (in dollars per share)	$ (5.25)	$ 1.53		$ 0.69
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 [Member]
Net (loss) earnings available to common shareholders	$ (53,426)	$ 15,866		$ 7,111
Net (loss) earnings per common share:
Common shares - basic and diluted (in dollars per share)	$ (5.48)	$ 1.64		$ 0.75
Weighted-average shares outstanding:
Common shares - basic and diluted (in shares)	9,749	9,698		9,491
Dividends paid per common share:
Common shares (in dollars per share)	$ 0.28	$ 0.28		$ 0.28

[1] (Revised)