Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Net sales	$ 516,159	$ 542,273	$ 522,219	$ 463,661	$ 443,674	$ 467,891	$ 460,086	$ 418,463	$ 2,044,312	$ 1,790,114
Gross profit	155,618	154,037	146,267	134,437	133,151	135,883	130,729	122,426	590,359	522,189
Net (loss) income from continuing operations	$ 1,925	$ (37,553)	$ 1,473	$ (2,264)	$ 74,759	$ 122	$ (146)	$ 3,171	$ 68,413	$ 51,464
Net income per share - basic (in dollars per share)	$ 0.04	$ (0.88)	$ 0.03	$ (0.05)	$ 1.74	$ 0.00	$ 0.00	$ 0.09	$ (0.28)	$ 1.99
Net income per share - diluted (in dollars per share)	$ 0.04	$ (0.88)	$ 0.03	$ (0.05)	$ 1.74	$ 0.00	$ 0.00	$ 0.09	$ (0.28)	$ 1.99