Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating Activities
Net income	$ 23,863	$ 15,951
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	11,760	8,438
Amortization of bond premiums	0	8
Provision for losses on accounts receivable, net of adjustments	128	89
Provision for excess and obsolete inventories	1,153	299
Share-based compensation	5,073	3,699
Loss (gain) on disposal of assets	290	(11)
Foreign currency transaction gain	(13)	15
Interest income on note receivable	(26)	14
Deferred	4,112	438
Changes in assets and liabilities:
Accounts receivable	(14,983)	(2,087)
Income taxes	2,858	(3,328)
Inventories	(585)	1,400
Prepaid expenses and other	(650)	(935)
Accounts payable	(2,592)	12,974
Deferred revenue	172	(931)
Accrued liabilities	5,312	213
Net cash provided by operating activities	35,872	36,246
Investing Activities
Capital expenditures	(16,784)	(25,925)
Cash paid in business combination	0	(6,377)
Proceeds from sale of property, plant and equipment	59	11
Investment in certificates of deposits	(6,000)	(7,200)
Maturities of certificates of deposits	2,000	4,560
Purchases of investments held to maturity	0	(9,001)
Maturities of investments	0	11,620
Proceeds from called investments	0	495
Principal payments from note receivable	28	16
Net cash used in investing activities	(20,697)	(31,801)
Financing Activities
Stock options exercised	7,685	2,299
Repurchase of stock	(10,191)	(11,539)
Employee taxes paid by withholding shares	(980)	(808)
Net cash used in financing activities	(3,486)	(10,048)
Net increase (decrease) in cash and cash equivalents	11,689	(5,603)
Cash and cash equivalents, beginning of period	1,994	21,457
Cash and cash equivalents, end of period	$ 13,683	$ 15,854