Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Consolidated Statements Of Income (Loss) [Abstract]
Net sales	$ 555,229	$ 640,688	$ 1,759,651	$ 1,909,415
Cost of sales	502,346	587,911	1,599,970	1,744,021
Gross profit	52,883	52,777	159,681	165,394
Selling, general and administrative expenses	34,875	37,607	103,927	109,182
Amortization of intangible assets	2,367	2,368	7,095	7,101
Restructuring charges and other costs	5,843	1,845	10,833	5,838
Income from operations	9,798	10,957	37,826	43,273
Interest expense	(1,687)	(3,822)	(5,014)	(8,543)
Interest income	734	1,619	3,084	5,197
Other income (expense)	(136)	1,139	2,276	827
Income before income taxes	8,709	9,893	38,172	40,754
Income tax expense	1,573	2,094	7,816	45,653
Net income (loss)	$ 7,136	$ 7,799	$ 30,356	$ (4,899)
Earnings (loss) per share:
Basic	$ 0.19	$ 0.17	$ 0.78	$ (0.10)
Diluted	$ 0.19	$ 0.17	$ 0.77	$ (0.10)
Weighted-average number of shares outstanding:
Basic	37,419	46,301	38,813	47,415
Diluted	37,645	46,455	39,184	47,415