Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Condensed Consolidated Statements Of Income (Loss) [Abstract]
Revenues	$ 608,136	$ 557,903
Cost of sales	549,818	510,371
Gross profit	58,318	47,532
Selling, general and administrative expenses	35,750	32,651
Amortization of intangible assets	2,366	2,481
Restructuring charges and other costs	2,235	1,511
Income from operations	17,967	10,889
Interest expense	(2,428)	(2,225)
Interest income	1,933	1,074
Other income (expense), net	43	(81)
Income before income taxes	17,515	9,657
Income tax expense	41,156	1,102
Net income (loss)	$ (23,641)	$ 8,555
Earnings (loss) per share:
Basic	$ (0.49)	$ 0.17
Diluted	$ (0.49)	$ 0.17
Weighted-average number of shares outstanding:
Basic	48,517	49,511
Diluted	48,517	50,080