CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net sales	$ 131,617	$ 131,622	$ 245,285	$ 252,805
Cost of sales	102,575	105,930	192,965	204,040
Gross profit	29,042	25,692	52,320	48,765
Selling, general and administrative expenses	21,858	17,966	43,010	35,636
Impairment of goodwill and other intangible assets	0	(2,611)	0	105,972
Impairment of property, plant and equipment	42	0	42	0
Restructuring charges	138	373	171	601
Income (loss) from operations	7,004	9,964	9,097	(93,444)
Interest expense	(1,586)	(1,505)	(3,010)	(3,706)
Interest income and other, net	(6)	184	48	224
Earnings (loss) before provision for (benefit from) income taxes	5,412	8,643	6,135	(96,926)
Provision for (benefit from) income taxes	2,292	(14,133)	2,269	(19,005)
Net earnings (loss) available to common shareholders	3,120	22,776	3,866	(77,921)
Class A Common Share [Member]
Net earnings (loss) available to common shareholders	$ 530	$ 3,987	$ 646	$ (13,718)
Net earnings (loss) per common share:
Common share - basic and diluted (in dollars per share)	$ 0.24	$ 1.83	$ 0.30	$ (6.31)
Weighted-average number of shares outstanding:
Common share - basic and diluted (in shares)	2,175	2,175	2,175	2,175
Dividends paid per common share:
Common share (in dollars per share)	$ 0.06	$ 0.06	$ 0.12	$ 0.12
Class B Common Share [Member]
Net earnings (loss) available to common shareholders	$ 2,590	$ 18,789	$ 3,220	$ (64,203)
Net earnings (loss) per common share:
Common share - basic and diluted (in dollars per share)	$ 0.26	$ 1.93	$ 0.33	$ (6.61)
Weighted-average number of shares outstanding:
Common share - basic and diluted (in shares)	9,859	9,729	9,852	9,715
Dividends paid per common share:
Common share (in dollars per share)	$ 0.07	$ 0.07	$ 0.14	$ 0.14