Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 22,817	$ (31,901)	$ 63,933
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	38,439	36,668	41,398
Amortization	13,400	12,004	13,741
Provision for doubtful accounts	1,712	1,697	0
Deferred income taxes	7,628	7,422	8,390
Asset impairments	96	42	142
Gain on the sale of property, plant and equipment	(262)	(202)	(224)
Stock-based compensation expense	10,089	7,815	5,322
Excess tax benefits from stock-based compensation	0	0	(663)
Changes in operating assets and liabilities, net of effects from business acquisition:
Accounts receivable	(33,952)	4,657	37,573
Contract assets	6,414	9,710	(10,931)
Inventories	(43,264)	(24,570)	38,397
Prepaid expenses and other assets	10,238	(7,812)	2,207
Accounts payable	61,391	29,542	76,039
Accrued liabilities	5,778	13,519	(28)
Income taxes	(23,837)	87,251	(2,208)
Net cash provided by operations	76,687	145,842	273,088
Cash flows from investing activities:
Proceeds from sales of investments at par	522	250	200
Additions to property, plant and equipment	(62,808)	(50,786)	(30,478)
Proceeds from the sale of property, plant and equipment	239	280	357
Additions to purchased software	(3,924)	(3,720)	(1,856)
Business acquisition, net of cash acquired			10,750
Business acquisitions, net of cash acquired	(2,731)	0
Other	(147)	(2,145)	(218)
Net cash used in investing activities	(68,849)	(56,121)	(21,245)
Cash flows from financing activities:
Proceeds from stock options exercised	3,631	11,208	18,825
Excess tax benefits from stock-based compensation	0	0	663
Employee taxes paid for shares withheld	(1,408)	(383)	(568)
Dividends paid	(21,005)	0	0
Borrowings under credit agreement	50,000	100,000	25,000
Principal payments on long-term debt and capital lease obligations	(108,024)	(112,396)	(37,301)
Share repurchases	(211,858)	(29,348)	(41,929)
Debt issuance costs	(2,303)	(433)	0
Net used in financing activities	(290,967)	(31,352)	(35,310)
Effect of exchange rate changes	(1,315)	2,744	(1,095)
Net increase (decrease) in cash and cash equivalents	(284,444)	61,113	215,438
Cash and cash equivalents at beginning of year	742,546	681,433	465,995
Cash and cash equivalents at end of period	$ 458,102	$ 742,546	$ 681,433