Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Net sales	$ 492,412	$ 548,184
Cost of sales	381,715	408,927
Gross profit	110,697	139,257
Research and development costs	26,925	29,487
Selling, general and administrative expenses	76,062	82,600
Impairment of goodwill	8,891
Restructuring expenses	2,593	222
Gain on sale of property	(4,257)
Income from operations	483	26,948
Interest expense	(5,448)	(5,317)
Other (expense) income, net	(2,337)	1,985
(Loss) earnings before provision for income taxes	(7,302)	23,616
Provision for income taxes	1,441	2,907
Net (loss) earnings available to common shareholders	(8,743)	20,709
Common Class A [Member]
Net (loss) earnings available to common shareholders	$ (1,531)	$ 3,521
Net (loss) earnings per common share:
Net earnings per share, basic and diluted (in dollars per share)	$ (0.71)	$ 1.62
Weighted-average shares outstanding:
Common shares - basic and diluted (in shares)	2,167	2,175
Common Class B [Member]
Net (loss) earnings available to common shareholders	$ (7,212)	$ 17,188
Net (loss) earnings per common share:
Net earnings per share, basic and diluted (in dollars per share)	$ (0.71)	$ 1.73
Weighted-average shares outstanding:
Common shares - basic and diluted (in shares)	10,117	9,939