Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Consolidated Statements Of Income [Abstract]
Sales	$ 574,341	$ 630,191	$ 1,702,908	$ 1,915,154
Cost of sales	521,519	575,627	1,546,915	1,752,809
Gross profit	52,822	54,564	155,993	162,345
Selling, general and administrative expenses	28,085	26,216	85,082	80,689
Amortization of intangible assets	3,170	1,104	8,945	3,039
Restructuring charges and other costs	3,485	1,096	9,876	7,553
Income from operations	18,082	26,148	52,090	71,064
Interest expense	(2,302)	(495)	(6,935)	(1,427)
Interest income	577	246	1,170	971
Other expense	(383)	(1,121)	(535)	(1,582)
Income before income taxes	15,974	24,778	45,790	69,026
Income tax expense (benefit)	(5,768)	4,213	311	13,046
Net income	$ 21,742	$ 20,565	$ 45,479	$ 55,980
Earnings per share:
Basic	$ 0.44	$ 0.4	$ 0.92	$ 1.08
Diluted	$ 0.44	$ 0.4	$ 0.91	$ 1.07
Weighted-average number of shares outstanding:
Basic	48,965	51,192	49,377	51,940
Diluted	49,414	51,588	49,878	52,448