Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ 23,425	$ 22,817	$ (31,901)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation	37,112	38,439	36,668
Amortization	11,315	13,400	12,004
Provision for doubtful accounts	8,608	1,712	1,697
Deferred income taxes	(2,367)	7,628	7,422
Asset impairments	834	96	42
Insurance recoveries	(5,000)	0	0
Gain on the sale of property, plant and equipment	53	(262)	(202)
Stock-based compensation expense	10,194	10,089	7,815
Changes in operating assets and liabilities, net of effects from business acquisition:
Accounts receivable	134,926	(33,952)	4,657
Contract assets	(20,979)	6,414	9,710
Inventories	(5,238)	(43,264)	(24,570)
Prepaid expenses and other assets	2,494	10,238	(7,812)
Accounts payable	(121,860)	61,391	29,542
Accrued liabilities	28,877	5,778	13,519
Increase (Decrease) in operating lease	1,029	0	0
Income taxes	(10,287)	(23,837)	87,251
Net cash provided by (used in) operations	93,136	76,687	145,842
Cash flows from investing activities:
Proceeds from sales of investments at par	50	522	250
Additions to property, plant and equipment	(32,576)	(62,808)	(50,786)
Proceeds from the sale of property, plant and equipment	259	239	280
Additions to purchased software	(2,542)	(3,924)	(3,720)
Business acquisitions, net of cash acquired	0	(2,731)	0
Other	(54)	(147)	(2,145)
Net cash used in investing activities	(34,863)	(68,849)	(56,121)
Cash flows from financing activities:
Proceeds from stock options exercised	1,585	3,631	11,208
Employee taxes paid for shares withheld	(2,231)	(1,408)	(383)
Dividends paid	(23,287)	(21,005)	0
Borrowings under credit agreement	0	50,000	100,000
Principal payments on long-term debt and capitallease obligations	(6,794)	(108,024)	(112,396)
Share repurchases	(122,110)	(211,858)	(29,348)
Debt issuance costs	0	(2,303)	(433)
Net cash used in financing activities	(152,837)	(290,967)	(31,352)
Effect of exchange rate changes	418	(1,315)	2,744
Net increase (decrease) in cash and cash equivalents and restricted cash	(94,146)	(284,444)	61,113
Cash and cash equivalents and restricted cash at beginning of year	458,102	742,546	681,433
Cash and cash equivalents and restricted cash at end of year	$ 363,956	$ 458,102	$ 742,546