Condensed Consolidated Statements Of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 15,415	$ 7,989
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,300	5,711
Amortization and realized loss (gain) on investments	134	204
Stock-based compensation	16,013	9,850
Changes in operating assets and liabilities:
Accounts receivable	2,310	(936)
Inventories	(1,457)	(8,140)
Prepaid expenses and other current assets	(1,447)	452
Accounts payable	2,968	4,057
Accrued liabilities	(4,955)	1,775
Accrued income taxes payable and noncurrent tax liabilities	134	(1,137)
Accrued compensation and related benefits	2,173	2,392
Net cash provided by operating activities	37,588	22,217
Cash flows from investing activities:
Property and equipment purchases	(5,958)	(10,801)
Investments related to deferred compensation plan	(2,396)
Purchases of short-term investments	(86,558)	(40,385)
Proceeds from sale of short-term investments	78,502	37,800
Proceeds from sale of long-term investments		25
Net cash used in investing activities	(16,410)	(13,361)
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(250)
Proceeds from issuance of common shares	8,623	16,184
Proceeds from employee stock purchase plan	1,053	1,167
Repurchases of common shares	(23,796)
Net cash provided by (used in) financing activities	(14,370)	17,351
Effect of change in exchange rates	(158)	424
Net increase in cash and cash equivalents	6,650	26,631
Cash and cash equivalents, beginning of period	101,213	75,104
Cash and cash equivalents, end of period	107,863	101,735
Supplemental disclosures for cash flow information:
Cash paid for taxes	633	581
Supplemental disclosures of non-cash investing and financing activities:
Liability accrued for property and equipment purchases	611	3,744
Dividends and dividend equivalents payable	$ 6,083