Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating activities
Net income	$ 24,286	$ 21,353
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,700	8,147
Share-based Compensation	3,958	3,541
Deferred taxes	1,608	403
Loss on impairment of assets		455
Amortization of held-to-maturity securities	592	590
Other	77	(1,095)
Changes in operating assets and liabilities:
Accounts receivable	(6,914)	1,201
Inventories	175	(187)
Prepaid expenses and other	(775)	(1,146)
Income taxes	1,769	5,984
Accounts payable	2,534	(1,368)
Accrued liabilities and other	3,417	600
Net cash provided by operating activities	39,427	38,478
Investing activities
Purchases of property and equipment	(13,301)	(22,416)
Purchases of marketable securities	(20,037)	(38,304)
Proceeds from maturities of marketable securities	25,194	28,759
Purchases of other investments	(514)
Net cash used in investing activities	(8,658)	(31,961)
Financing activities
Acquisition-related contingent consideration		(400)
Proceeds from exercises of stock options and other	3,791	3,729
Repurchases of common stock	(4,410)
Net cash (used in) provided by financing activities	(619)	3,329
Effect of exchange rate changes on cash and cash equivalents	251	(168)
Net increase in cash and cash equivalents	30,401	9,678
Cash and cash equivalents, beginning of period	68,795	47,653
Cash and cash equivalents, end of period	$ 99,196	$ 57,331