CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 32,909	$ 36,952	$ 17,956
Adjustments to reconcile net income to net cash and cash equivalents provided by operating activities:
Depreciation	3,990	3,677	3,951
Amortization of convertible note discount and issuance costs	0	2,154	3,766
Amortization of intangibles and other	1,940	2,320	2,145
Foreign currency exchange loss	457	592	293
Gain on disposal of property, plant and equipment	0	(946)	0
Change in fair value of contingent consideration	133	170	(630)
Share-based compensation	5,670	4,775	7,603
Provision for doubtful accounts and inventory valuation	3,608	2,971	3,826
Deferred income taxes	17,207	5,011	3,980
Change in operating assets and liabilities, excluding effects of business combinations:
Accounts receivable	430	(9,279)	(4,336)
Income taxes	(4,727)	(3,021)	2,626
Inventories	(4,218)	4,003	(12,529)
Prepaid expenses and other assets	(1,686)	2,038	953
Accounts payable	3,198	1,169	2,254
Deferred revenue	(1,122)	896	(1,535)
Other liabilities	6,582	(6,057)	3,486
Net cash and cash equivalents provided by operating activities	64,371	47,425	33,809
Cash flows from investing activities:
Purchases of marketable securities	(164,661)	(146,865)	(237,127)
Proceeds from sales of marketable securities	143,349	175,460	234,105
Purchases of property, plant and equipment	(10,210)	(3,291)	(3,359)
Purchase of intangible assets	(1,000)	(2,000)	(2,696)
Proceeds from sale of property, plant & equipment	0	1,165	0
Net cash and cash equivalents (used in) provided by investing activities	(32,522)	24,469	(9,077)
Cash flows from financing activities:
Payment of senior convertible debt	0	(60,000)	0
Redemption of stock warrants	(1,025)	(9,500)	0
Purchases of common stock	0	(8,044)	(20,668)
Tax payments related to shares withheld for share-based compensation plans	(1,358)	(1,587)	(1,916)
Payment of contingent consideration for acquired business	(992)	(622)	(731)
Issuance of shares through share-based compensation plans	623	850	330
Net cash and cash equivalents used in financing activities	(2,752)	(78,903)	(22,985)
Effect of exchange rate changes on cash and cash equivalents	814	314	(307)
Net increase (decrease) in cash and cash equivalents	29,911	(6,695)	1,440
Cash and cash equivalents at beginning of year	37,859	44,554	43,114
Cash and cash equivalents at end of year	67,770	37,859	44,554
Supplemental disclosure of cash flow information:
Income taxes paid, net	14,605	10,980	2,013
Interest paid	0	2,250	2,250
Litigation settlement received	13,000	14,643	0
Non-cash financing and investing activities:
Purchase of intangible assets	$ 0	$ 0	$ 3,000