Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Operating Activities
Net income	$ 52,572	$ 60,117
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	22,532	18,971
Amortization of debt issuance costs	31	31
Provision for credit losses on accounts receivable, net of adjustments	0	193
Provision for excess and obsolete inventories	378	1,776
Share-based compensation	8,784	8,546
Gain on disposal of assets	(15)	(61)
Foreign currency transaction (gain) loss	(1)	18
Interest income on note receivable	(19)	(19)
Deferred	2,766	7,676
Changes in assets and liabilities:
Accounts receivable	(11,369)	5,011
Income taxes	2,588	(3,142)
Inventories	(22,712)	(6,994)
Prepaid expenses and other	937	(598)
Accounts payable	16,390	3,654
Deferred revenue	316	1,128
Accrued liabilities	1,525	688
Net cash provided by operating activities	74,703	96,995
Investing Activities
Capital expenditures	(42,636)	(48,955)
Proceeds from sale of property, plant and equipment	19	61
Principal payments from note receivable	41	38
Net cash used in investing activities	(42,576)	(48,856)
Financing Activities
Stock options exercised	14,573	18,519
Repurchase of stock	(15,014)	(21,390)
Employee taxes paid by withholding shares	(1,537)	(1,130)
Cash dividends paid to stockholders	(9,964)	(9,910)
Net cash used in financing activities	(11,942)	(13,911)
Net increase in cash, cash equivalents and restricted cash	20,185	34,228
Cash, cash equivalents and restricted cash, beginning of period	82,288	44,373
Cash, cash equivalents and restricted cash, end of period	$ 102,473	$ 78,601