Quarterly Unaudited Financial Data (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	$ 258,112	$ 274,574	$ 247,627	$ 206,605	$ 231,838	$ 272,734	$ 265,738	$ 237,671	$ 986,918	$ 1,007,981	$ 1,040,873
Gross profit	56,729	68,735	61,825	49,255	53,882	67,887	68,843	54,150	236,544	244,762	186,976
Income (loss) from operations:	22,547	35,693	24,930	9,679	629	26,522	28,576	17,761	92,849	73,488	48,732
Interest expense	3,420	3,486	3,550	3,576	3,595	3,625	3,666	3,691	14,032	14,577	15,003
Income from continuing operations	25,176	20,619	13,174	3,996	(7,708)	13,786	18,612	9,029	62,965	33,719	23,476
Loss from discontinued operations	0	0	(405)	0	(44)	0	0	0	(405)	(44)	(28)
Net income	$ 25,176	$ 20,619	$ 12,769	$ 3,996	$ (7,752)	$ 13,786	$ 18,612	$ 9,029	$ 62,560	$ 33,675	$ 23,448
(Loss) income per share from continuing operations:
Basic (in dollars per share)	$ 0.79	$ 0.65	$ 0.41	$ 0.13	$ (0.24)	$ 0.44	$ 0.59	$ 0.29	$ 1.98	$ 1.07	$ 0.75
Diluted (in dollars per share)	0.78	0.64	0.41	0.12	(0.24)	0.43	0.58	0.28	1.95	1.05	0.74
Loss per share from discontinued operations:
Basic (in dollars per share)	0.00	0.00	(0.01)	0.00	0.00	0.00	0.00	0.00	(0.01)	0.00	0.00
Diluted (in dollars per share)	$ 0.00	$ 0.00	$ (0.01)	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ 0.00	$ (0.01)	$ 0.00	$ 0.00