Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net income	$ 15,286	$ 445
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	17,735	18,813
Amortization	4,259	5,718
Provision for doubtful accounts	40	2,107
Deferred income taxes	(944)	(330)
Asset impairments	0	1,214
(Gain) loss on the sale of property, plant and equipment	14	(139)
Stock-based compensation expense	6,863	6,044
Changes in operating assets and liabilities
Accounts receivable	18,959	20,356
Contract assets	(11,850)	7,420
Inventories	(88,634)	(48,668)
Prepaid expenses and other assets	(8,372)	(1,234)
Accounts payable	92,677	6,980
Advance payments from customers	4,563	15,267
Accrued liabilities	(11,854)	(12,176)
Operating leases	(485)	236
Income taxes	2,016	(2,135)
Net cash provided by operations	40,273	19,918
Cash flows from investing activities:
Additions to property, plant and equipment	(16,681)	(21,402)
Proceeds from the sale of property, plant and equipment	116	307
Additions to purchased software	(1,938)	(1,888)
Cash received from business divestitures	0	2,214
Other	72	55
Net cash used in investing activities	(18,431)	(20,714)
Cash flows from financing activities:
Proceeds from stock options exercised	346	364
Employee taxes paid for with shares withheld	(2,973)	(1,801)
Dividends paid	(11,577)	(11,365)
Borrowings under credit agreement	0	110,000
Principal payments on credit agreement	(3,750)	(83,750)
Principal payments on finance leases	(793)	(642)
Share repurchases	(30,319)	(19,329)
Net cash provided by financing activities	(49,066)	(6,523)
Effect of exchange rate changes	1,677	(218)
Net increase in cash and cash equivalents and restricted cash	(25,547)	(7,537)
Cash and cash equivalents and restricted cash at beginning of year	395,990	363,956
Cash and cash equivalents and restricted cash at end of period	$ 370,443	$ 356,419