CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 45,096	$ 32,909	$ 36,952
Adjustments to reconcile net income to net cash and cash equivalents provided by operating activities:
Depreciation	4,848	3,990	3,677
Amortization of convertible note discount and issuance costs			2,154
Amortization of intangibles	1,534	1,940	2,320
Foreign currency exchange loss	255	457	592
Gain on disposal of property, plant and equipment			(946)
Change in fair value of contingent consideration	1,010	133	170
Share-based compensation	6,062	5,670	4,775
Provision for doubtful accounts and inventory valuation	3,335	3,608	2,971
Deferred income taxes	2,163	17,207	5,011
Change in operating assets and liabilities:
Accounts receivable	706	430	(9,279)
Income taxes	1,056	(4,727)	(3,021)
Inventories	(31,545)	(4,218)	4,003
Prepaid expenses and other assets	(3,101)	(1,686)	2,038
Accounts payable	3,512	3,198	1,169
Deferred revenue	545	(1,122)	896
Other liabilities	(382)	6,382	(6,057)
Net cash and cash equivalents provided by operating activities	35,094	64,171	47,425
Cash flows from investing activities:
Purchases of marketable securities	(140,018)	(164,661)	(146,865)
Proceeds from sales of marketable securities	186,332	143,349	175,460
Purchases of property, plant and equipment	(7,542)	(10,210)	(3,291)
Cash advance on convertible note receivable	(5,000)
Purchase of intangible assets		(1,000)	(2,000)
Proceeds from sale of property, plant & equipment			1,165
Net cash and cash equivalents provided by (used in) investing activities	33,772	(32,522)	24,469
Cash flows from financing activities:
Payment of senior convertible debt			(60,000)
Redemption of stock warrants		(1,025)	(9,500)
Purchases of common stock	(21,069)		(8,044)
Tax payments related to shares withheld for share-based compensation plans	(1,921)	(1,358)	(1,587)
Payment of contingent consideration for acquired business	(1,543)	(792)	(622)
Issuance of shares through share-based compensation plans	624	623	850
Net cash and cash equivalents used in financing activities	(23,909)	(2,552)	(78,903)
Effect of exchange rate changes on cash and cash equivalents	(339)	814	314
Net increase (decrease) in cash and cash equivalents	44,618	29,911	(6,695)
Cash and cash equivalents at beginning of year	67,770	37,859	44,554
Cash and cash equivalents at end of year	112,388	67,770	37,859
Supplemental disclosure of cash flow information:
Income taxes paid, net	$ 4,301	14,605	10,980
Interest paid			2,250
Litigation settlement received		$ 13,000	$ 14,643