Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating Activities
Net income	$ 36,991	$ 39,657
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,924	12,340
Amortization of debt issuance costs	20	20
Provision for credit losses on accounts receivable, net of adjustments	12	76
Provision (recoveries) for excess and obsolete inventories	292	(193)
Share-based compensation	5,793	5,694
Gain on disposal of assets	0	(62)
Foreign currency transaction (gain) loss	(11)	30
Interest income on note receivable	(19)	(12)
Deferred	2,747	5,061
Changes in assets and liabilities:
Accounts receivable	(5,936)	10,929
Income taxes	1,248	(4,382)
Inventories	(5,472)	(11,617)
Prepaid expenses and other	799	(568)
Accounts payable	10,650	2,893
Deferred revenue	574	473
Accrued liabilities	300	2,423
Net cash provided by operating activities	62,912	62,762
Investing Activities
Capital expenditures	(33,157)	(33,510)
Proceeds from sale of property, plant and equipment	2	61
Principal payments from note receivable	29	25
Net cash used in investing activities	(33,126)	(33,424)
Financing Activities
Stock options exercised	11,848	14,173
Repurchase of stock	(10,271)	(15,937)
Employee taxes paid by withholding shares	(1,532)	(1,102)
Net cash provided by (used in) financing activities	45	(2,866)
Net increase in cash, cash equivalents and restricted cash	29,831	26,472
Cash, cash equivalents and restricted cash, beginning of period	82,288	44,373
Cash, cash equivalents and restricted cash, end of period	$ 112,119	$ 70,845