Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Consolidated Statements Of Income (Loss) [Abstract]
Net sales	$ 2,566,465	$ 2,454,479	$ 2,322,285
Cost of sales	2,345,872	2,228,559	2,107,600
Gross profit	220,593	225,920	214,685
Selling, general and administrative expenses	143,205	130,401	113,448
Amortization of intangible assets	9,485	10,065	11,838
Restructuring charges and other costs	9,365	8,628	12,539
Income from operations	58,538	76,826	76,860
Interest expense	(10,473)	(9,405)	(9,304)
Interest income	6,848	5,370	2,136
Other income (expense)	628	(1,786)	(282)
Income before income taxes	55,541	71,005	69,410
Income tax expense	32,724	102,906	5,477
Net income (loss)	$ 22,817	$ (31,901)	$ 63,933
Earnings (loss) per share:
Basic	$ 0.49	$ (0.64)	$ 1.3
Diluted	$ 0.49	$ (0.64)	$ 1.28
Weighted-average number of shares outstanding:
Basic	46,332	49,680	49,298
Diluted	46,655	49,680	49,825