CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 37,014	$ 33,713
Adjustments to reconcile net income to net cash and cash equivalents provided by operating activities:
Amortization of intangibles	1,147	1,516
Depreciation	3,634	2,925
Foreign currency exchange loss	217	533
Change in fair value of contingent consideration	603	132
Share-based compensation	4,879	4,413
Provision for doubtful accounts and inventory valuation	3,105	3,019
Patent litigation income		(13,000)
Changes in operating assets and liabilities	(26,160)	9,536
Net cash and cash equivalents provided by operating activities	24,439	42,787
Cash flows from investing activities:
Purchases of marketable securities	(113,353)	(103,224)
Proceeds from sales of marketable securities	152,588	99,931
Cash advanced on convertible note receivable	(1,000)
Purchases of property, plant and equipment	(4,127)	(7,447)
Net cash and cash equivalents provided by (used in) investing activities	34,108	(10,740)
Cash flows from financing activities:
Redemption of stock warrants	0	(1,025)
Purchase of common stock	(38)
Tax payments related to shares withheld for share-based compensation plans	(980)	(1,331)
Payment of contingent consideration for acquired business	(1,057)	(358)
Issuance of shares through share-based compensation plans	490	289
Net cash and cash equivalents used in financing activities	(1,585)	(2,425)
Effect of exchange rate changes on cash and cash equivalents	(398)	545
Net increase in cash and cash equivalents	56,564	30,167
Cash and cash equivalents at beginning of period	67,770	37,859
Cash and cash equivalents at end of period	124,334	68,026
Supplemental disclosure of cash flow information:
Income taxes paid	$ 2,389	$ 6,917