Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net income	$ 21,773	$ 13,862
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of intangible assets	6,873	7,092
Loss on sales of property and equipment	58
(Gains) losses on investments, net	(244)	256
Deferred taxes, net	12
Excess tax benefits from equity awards	(361)	(2,648)
Stock-based compensation expense	20,726	18,716
Changes in operating assets and liabilities:
Accounts receivable	(520)	(1,134)
Inventories	(6,758)	(24,029)
Other assets	(10,417)	405
Accounts payable	7,176	4,687
Accrued liabilities	769	2,807
Income tax liabilities	395	1,122
Accrued compensation and related benefits	4,386	2,213
Net cash provided by operating activities	43,868	23,349
Cash flows from investing activities:
Property and equipment purchases	(18,678)	(6,655)
Purchases of short-term investments	(106,004)	(129,663)
Proceeds from sales of short-term investments	87,919	91,962
Contributions to employee deferred compensation plan, net	(1,623)	(2,775)
Net cash used in investing activities	(38,386)	(47,131)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(150)	(150)
Proceeds from Stock Options Exercised	1,040	6,680
Proceeds from Stock Plans	1,285	1,121
Repurchases of common shares		(18,129)
Dividends and dividend equivalents paid	(16,480)	(13,842)
Excess tax benefits from equity awards	361	2,648
Net cash used in financing activities	(13,944)	(21,672)
Effect of change in exchange rates	(352)	56
Net decrease in cash and cash equivalents	(8,814)	(45,398)
Cash and cash equivalents, beginning of period	90,860	126,266
Cash and cash equivalents, end of period	82,046	80,868
Supplemental disclosures for cash flow information:
Cash paid for taxes and interest	712	1,755
Supplemental disclosures of non-cash investing and financing activities:
Liability accrued for property and equipment purchases	472	681
Liability accrued for dividends and dividend equivalents	$ 9,312	$ 9,121