Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities
Net income	$ 39,657	$ 22,148
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,340	11,760
Amortization of debt issuance costs	20	0
Provision for losses on accounts receivable, net of adjustments	76	128
Provision for excess and obsolete inventories	(193)	1,153
Share-based compensation	5,694	7,786
Loss (gain) on disposal of assets	(62)	290
Foreign currency transaction loss (gain)	30	(13)
Interest income on note receivable	(12)	(26)
Deferred	5,061	3,318
Changes in assets and liabilities:
Accounts receivable	10,929	(14,983)
Income taxes	(4,382)	2,925
Inventories	(11,617)	(585)
Prepaid expenses and other	(568)	(650)
Accounts payable	2,893	(2,592)
Deferred revenue	473	172
Accrued liabilities	2,423	5,041
Net cash provided by operating activities	62,762	35,872
Investing Activities
Capital expenditures	(33,510)	(16,784)
Proceeds from sale of property, plant and equipment	61	59
Investment in certificates of deposits	0	(6,000)
Maturities of certificates of deposits	0	2,000
Principal payments from note receivable	25	28
Net cash used in investing activities	(33,424)	(20,697)
Financing Activities
Stock options exercised	14,173	7,685
Repurchase of stock	(15,937)	(10,191)
Employee taxes paid by withholding shares	(1,102)	(980)
Net cash used in financing activities	(2,866)	(3,486)
Net increase in cash, cash equivalents and restricted cash	26,472	11,689
Cash, cash equivalents and restricted cash, beginning of period	44,373	1,994
Cash, cash equivalents and restricted cash, end of period	$ 70,845	$ 13,683