Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net income	$ 37,690	$ 30,036
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	17,627	12,865
Amortization of bond premiums	0	11
Provision for losses on accounts receivable, net of adjustments	91	67
Provision for excess and obsolete inventories	1,003	55
Share-based compensation	7,858	5,614
Loss (gain) on disposal of assets	296	(9)
Foreign currency transaction gain	(17)	(20)
Interest income on note receivable	(19)	27
Deferred	4,208	864
Changes in assets and liabilities:
Accounts receivable	(2,096)	146
Income taxes	2,234	(649)
Inventories	(4,014)	(7,071)
Prepaid expenses and other	(513)	(792)
Accounts payable	782	4,328
Deferred revenue	263	(1,644)
Accrued liabilities	5,190	364
Net cash provided by operating activities	70,583	44,192
Investing Activities
Capital expenditures	(30,831)	(34,328)
Cash paid in business combination	0	(6,377)
Proceeds from sale of property, plant and equipment	68	11
Investment in certificates of deposits	(6,000)	(7,200)
Maturities of certificates of deposits	6,000	7,920
Purchases of investments held to maturity	0	(9,001)
Maturities of investments	0	13,320
Proceeds from called investments	0	495
Principal payments from note receivable	39	32
Net cash used in investing activities	(30,724)	(35,128)
Financing Activities
Stock options exercised	11,283	3,504
Repurchase of stock	(15,437)	(17,500)
Employee taxes paid by withholding shares	(1,023)	(860)
Cash dividends paid to stockholders	(8,303)	(8,400)
Net cash used in financing activities	(13,480)	(23,256)
Net increase (decrease) in cash and cash equivalents	26,379	(14,192)
Cash and cash equivalents, beginning of period	1,994	21,457
Cash and cash equivalents, end of period	$ 28,373	$ 7,265