Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ (31,965)	$ 64,047	$ 95,401
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	36,668	41,398	42,822
Amortization	12,004	13,741	6,850
Deferred income taxes	9,262	7,055	(12,781)
Asset impairments	42	142	1,201
Gain on the sale of property, plant and equipment	(202)	(224)	(85)
Stock-based compensation expense	7,815	5,322	7,709
Excess tax benefit from stock-based compensation	0	(663)	(481)
Changes in operating assets and liabilities, net of effects from business acquisitions:
Accounts receivable	6,354	37,573	52,847
Inventories	(14,015)	27,749	3,974
Prepaid expenses and other assets	(10,434)	3,147	(3,202)
Accounts payable	29,542	76,039	(41,388)
Accrued liabilities	13,519	(28)	(4,533)
Income taxes	87,252	(2,210)	(959)
Net cash provided by operations	145,842	273,088	147,375
Cash flows from investing activities:
Proceeds from sales of investments at par	250	200	50
Additions to property, plant and equipment	(50,786)	(30,478)	(37,128)
Proceeds from the sale of property, plant and equipment	280	357	605
Additions to purchased software	(3,720)	(1,856)	(934)
Business acquisitions, net of cash acquired		10,750
Business acquisitions, net of cash acquired	0		(229,582)
Other	(2,145)	(218)	188
Net cash used in investing activities	(56,121)	(21,245)	(266,801)
Cash flows from financing activities:
Proceeds from stock options exercised	11,208	18,825	1,976
Excess tax benefits from stock-based compensation	0	663	481
Employee taxes paid for shares withheld	(383)	(568)	(571)
Borrowings under credit agreement	100,000	25,000	250,000
Principal payments on long-term debt and capital lease obligations	(112,396)	(37,301)	(20,676)
Share repurchases	(29,348)	(41,929)	(68,365)
Debt issuance costs	(433)	0	(3,779)
Net cash provided by (used in) financing activities	(31,352)	(35,310)	159,066
Effect of exchange rate changes	2,744	(1,095)	(1,021)
Net increase in cash and cash equivalents	61,113	215,438	38,619
Cash and cash equivalents at beginning of year	681,433	465,995	427,376
Cash and cash equivalents at end of period	$ 742,546	$ 681,433	$ 465,995