Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities
Net income	$ 60,117	$ 36,438
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	18,971	17,627
Amortization of debt issuance costs	31	0
Provision for credit losses on accounts receivable, net of adjustments	193	91
Provision for excess and obsolete inventories	1,776	1,003
Share-based compensation	8,546	9,854
Loss (gain) on disposal of assets	(61)	296
Foreign currency transaction loss (gain)	18	(17)
Interest income on note receivable	(19)	(19)
Deferred	7,676	3,614
Changes in assets and liabilities:
Accounts receivable	5,011	(2,096)
Income taxes	(3,142)	2,283
Inventories	(6,994)	(4,014)
Prepaid expenses and other	(598)	(513)
Accounts payable	3,654	782
Deferred revenue	1,128	263
Accrued liabilities	688	4,991
Net cash provided by operating activities	96,995	70,583
Investing Activities
Capital expenditures	(48,955)	(30,831)
Proceeds from sale of property, plant and equipment	61	68
Investment in certificates of deposits	0	(6,000)
Maturities of certificates of deposits	0	6,000
Principal payments from note receivable	38	39
Net cash used in investing activities	(48,856)	(30,724)
Financing Activities
Stock options exercised	18,519	11,283
Repurchase of stock	(21,390)	(15,437)
Employee taxes paid by withholding shares	(1,130)	(1,023)
Cash dividends paid to stockholders	(9,910)	(8,303)
Net cash used in financing activities	(13,911)	(13,480)
Net increase in cash, cash equivalents and restricted cash	34,228	26,379
Cash, cash equivalents and restricted cash, beginning of period	44,373	1,994
Cash, cash equivalents and restricted cash, end of period	$ 78,601	$ 28,373