Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Activities
Net income	$ 16,376	$ 21,853
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,398	6,002
Amortization of debt issuance costs	10	10
(Recovery of) provision for credit losses on accounts receivable, net of adjustments	(13)	294
Provision for excess and obsolete inventories	(194)	(274)
Share-based compensation	2,761	2,351
(Gain) loss on disposal of assets	0	(62)
Foreign currency transaction (gain) loss	(8)	51
Interest income on note receivable	(6)	(6)
Deferred	4,658	(167)
Changes in assets and liabilities:
Accounts receivable	(5,179)	(2,789)
Income taxes	(2,766)	772
Inventories	(1,627)	1,020
Prepaid expenses and other	108	(670)
Accounts payable	4,904	2,742
Deferred revenue	2,358	229
Accrued liabilities	58	6,241
Net cash provided by operating activities	28,838	37,597
Investing Activities
Capital expenditures	(16,404)	(21,877)
Proceeds from sale of property, plant and equipment	0	61
Principal payments from note receivable	14	12
Net cash used in investing activities	(16,390)	(21,804)
Financing Activities
Stock options exercised	9,438	4,497
Repurchase of stock	(5,185)	(11,565)
Employee taxes paid by withholding shares	(1,217)	(953)
Net cash provided by (used in) financing activities	3,036	(8,021)
Net increase in cash, cash equivalents and restricted cash	15,484	7,772
Cash, cash equivalents and restricted cash, beginning of period	82,288	44,373
Cash, cash equivalents and restricted cash, end of period	$ 97,772	$ 52,145