Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities
Net income	$ 33,335	$ 34,521
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,831	10,422
Share-based Compensation	5,260	4,515
Deferred taxes	495	(310)
Excess tax benefit from stock-based compensation	(1,965)	(5,212)
Loss on impairment of assets	455
Amortization of held-to-maturity securities	881	936
Other	(1,381)
Changes in operating assets and liabilities:
Accounts receivable	(1,626)	(8,827)
Inventories	(203)	(1,117)
Prepaid expenses and other	(1,107)	(2,596)
Income taxes	8,114	(546)
Accounts payable	(2,043)	3,744
Accrued liabilities and other	3,131	5,754
Net cash provided by operating activities	56,177	41,284
Investing activities
Purchases of property and equipment	(30,981)	(27,259)
Purchases of marketable securities	(56,213)	(42,674)
Proceeds from maturities of marketable securities	45,907	40,899
Net cash used in investing activities	(41,287)	(29,034)
Financing activities
Payments on debt		(107)
Acquisition-related contingent consideration	(400)	(1,400)
Proceeds from exercises of stock options and other	4,168	5,165
Excess tax benefit from stock-based compensation	1,965	5,212
Net cash provided by financing activities	5,733	8,870
Effect of exchange rate changes on cash and cash equivalents	(58)	(318)
Net increase in cash and cash equivalents	20,565	20,802
Cash and cash equivalents, beginning of period	47,653	43,329
Cash and cash equivalents, end of period	$ 68,218	$ 64,131