Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:
Net income	$ 26,635	$ 15,399
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,688	8,960
Amortization and realized gain/loss on investments	197	320
Stock-based compensation	24,872	15,081
Changes in operating assets and liabilities, net of effects of an acquisition:
Accounts receivable	(516)	(2,573)
Inventories	(1,800)	(10,851)
Prepaid expenses and other assets	(1,868)	463
Accounts payable	3,864	1,164
Accrued liabilities	(2,885)	3,492
Accrued income taxes payable and noncurrent tax liabilities	(801)	(215)
Accrued compensation and related benefits	(3,789)	(1,002)
Net cash provided by operating activities	53,597	30,238
Cash flows from investing activities:
Property and equipment purchases	(7,730)	(15,424)
Purchases of short-term investments	(100,706)	(62,374)
Proceeds from sale of short-term investments	98,752	55,700
Proceeds from sale of long-term investments		25
Investments related to deferred compensation plan	(4,860)	(309)
Cash paid for an acquisition, net of cash acquired	(11,590)
Net cash used in investing activities	(26,134)	(22,382)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(250)
Proceeds from issuance of common shares	10,403	32,654
Proceeds from employee stock purchase plan	2,078	2,145
Repurchases of common shares	(32,976)	(7,973)
Dividends and dividend equivalents paid	(5,817)
Net cash provided by (used in) financing activities	(26,562)	26,826
Effect of change in exchange rates	(302)	660
Net increase in cash and cash equivalents	599	35,342
Cash and cash equivalents, beginning of period	101,213	75,104
Cash and cash equivalents, end of period	101,812	110,446
Supplemental disclosures for cash flow information:
Cash paid for taxes	981	847
Supplemental disclosures of non-cash investing and financing activities:
Liability accrued for property and equipment purchases	783	2,081
Liability accrued for dividends and dividend equivalents	6,359
Sensima [Member]
Supplemental disclosures of non-cash investing and financing activities:
Fair value of contingent consideration related to an acquisition	$ 2,507