Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net income	$ 35,770	$ 14,055	$ 23,425
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation	35,003	37,739	37,112
Amortization	9,149	11,053	11,315
Provision for doubtful accounts	0	2,160	8,608
Deferred income taxes	(6,883)	(7,312)	(2,367)
Asset impairments	4,357	6,950	834
Insurance recoveries	0	0	(5,000)
(Gain) loss on the sale of property, plant and equipment	148	(155)	53
Stock-based compensation expense	15,262	10,398	10,194
Changes in operating assets and liabilities:
Accounts receivable	(46,967)	13,586	134,926
Contract assets	(12,464)	18,282	(20,979)
Inventories	(197,867)	(10,799)	(5,238)
Prepaid expenses and other assets	(12,201)	4,080	2,494
Accounts payable	139,952	(15,553)	(121,860)
Advance payments from customers	34,002	46,611	9,254
Accrued liabilities	(508)	(9,826)	19,623
Operating leases	(167)	724	1,029
Income taxes	792	(1,555)	(10,287)
Net cash provided by (used in) operations	(2,622)	120,438	93,136
Cash flows from investing activities:
Proceeds from sales of investments at par	0	0	50
Additions to property, plant and equipment	(38,794)	(34,584)	(32,576)
Proceeds from the sale of property, plant and equipment	239	368	259
Additions to purchased software	(3,383)	(4,935)	(2,542)
Cash received from business divestitures	0	4,714	0
Other	63	54	(54)
Net cash used in investing activities	(41,875)	(34,383)	(34,863)
Cash flows from financing activities:
Debt issuance costs	(1,150)	0	0
Proceeds from stock options exercised	346	958	1,585
Employee taxes paid for with shares withheld	(3,174)	(2,236)	(2,231)
Dividends paid	(23,260)	(23,041)	(23,287)
Borrowings under credit agreement	150,000	110,000	0
Borrowings under finance leases	0	864	0
Principal payments on credit agreement	(155,625)	(117,500)	(5,626)
Principal payments on finance leases	(873)	(1,351)	(1,168)
Share repurchases	(40,216)	(25,220)	(122,110)
Net cash used in financing activities	(73,952)	(57,526)	(152,837)
Effect of exchange rate changes	(5,792)	3,505	418
Net (decrease) increase in cash and cash equivalents and restricted cash	(124,241)	32,034	(94,146)
Cash and cash equivalents and restricted cash at beginning of year	395,990	363,956	458,102
Cash and cash equivalents and restricted cash at end of period	$ 271,749	$ 395,990	$ 363,956