Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected quarterly financial information [Abstract]
Net sales	$ 229,799	$ 300,795	$ 288,977	$ 238,911	$ 204,967	$ 270,037	$ 269,382	$ 227,589	$ 1,058,482	$ 971,975	$ 980,392
Gross profit	66,771	95,644	87,076	72,996	62,786	81,553	72,760	63,889	322,487	280,988	289,630
Earnings from continuing operations	8,839	21,055	19,862	12,656	5,779	19,194	13,808	9,339	62,412	48,120	52,899
Loss from discontinued operations, net of taxes	(487)	(425)	(618)	(452)	(553)	(728)	(430)	(391)	(1,982)	(2,102)	(9,870)
Net earnings	$ 8,352	$ 20,630	$ 19,244	$ 12,204	$ 5,226	$ 18,466	$ 13,378	$ 8,948	$ 60,430	$ 46,018	$ 43,029
Net earnings from continuing operations per common share [Abstract]
Basic (in dollars per share)	$ 0.39	$ 0.93	$ 0.87	$ 0.56	$ 0.26	$ 0.84	$ 0.60	$ 0.41	$ 2.75	$ 2.11	$ 2.31
Diluted (in dollars per share)	0.38	0.91	0.86	0.55	0.25	0.83	0.59	0.40	2.70	2.08	2.28
Net earnings per common share [Abstract]
Basic (in dollars per share)	0.37	0.91	0.85	0.54	0.23	0.81	0.58	0.39	2.66	2.02	1.88
Diluted (in dollars per share)	$ 0.36	$ 0.89	$ 0.84	$ 0.53	$ 0.23	$ 0.80	$ 0.58	$ 0.39	$ 2.62	$ 1.99	$ 1.85