Supplementary Information - Quarterly Results of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 127,771	$ 88,132	$ 77,029	$ 113,252	$ 125,764	$ 80,818	$ 78,529	$ 120,928	$ 406,184	$ 406,039	$ 335,764
Gross profit	62,444	41,315	38,378	61,745	64,102	39,217	41,862	66,344	203,882	211,525	173,234
Operating income (loss)	6,406	13,365	3,849	12,683	19,310	8,211	6,573	19,300	36,303	53,394	40,271
Income from continuing operations	8,532	8,342	2,566	8,185	11,974	7,845	3,696	11,586	27,625	35,101	26,803
Income (loss) from discontinued operation	(88)	(101)	(77)	(1,092)	(364)	(251)	(166)	(142)	(1,358)	(923)	(201)
Net income	$ 8,444	$ 8,241	$ 2,489	$ 7,093	$ 11,610	$ 7,594	$ 3,530	$ 11,444	$ 26,267	$ 34,178	$ 26,602
Basic (in dollars per share)	$ 0.28	$ 0.27	$ 0.08	$ 0.23	$ 0.38	$ 0.24	$ 0.11	$ 0.37	$ 0.86	$ 1.10	$ 0.85
Diluted (in dollars per share)	$ 0.27	$ 0.27	$ 0.08	$ 0.23	$ 0.37	$ 0.24	$ 0.11	$ 0.37	$ 0.85	$ 1.09	$ 0.84
Asset impairment charge									$ 8,800	$ 0	$ 0
Tax Cuts And Jobs Act Of 2017, incomplete accounting, change in tax rate, deferred tax asset, provisional income tax expense	$ 5,600
Payments for legal settlements				$ 1,200					1,200
Additions for tax positions taken in prior years						$ 2,700			$ 38	$ 21	$ 1