Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 22,898	$ 15,756	$ 13,301
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,160	9,332	8,732
Loss on disposal of property and equipment	31	81	33
Amortization and loss on investments	443	254	376
Gain on auction-rate securities		(40)
Deferred income tax assets	(81)	(8)	(403)
Excess tax benefit from stock option transactions		(869)	(27)
Stock-based compensation	20,701	18,652	13,126
Changes in operating assets and liabilities:
Accounts receivable	(4,347)	(4,286)	3,250
Inventories	(7,606)	(12,004)	5,699
Prepaid expenses and other current assets	121	(456)	673
Accounts payable	1,440	754	(957)
Accrued liabilities	12,149	(2,097)	(438)
Accrued income taxes payable and long-term income tax liabilities	86	1,476	(169)
Accrued compensation and related benefits	2,691	(1,633)	489
Net cash provided by operating activities	60,686	24,912	43,685
Cash flows from investing activities:
Property and equipment purchases	(15,764)	(21,059)	(21,022)
Proceeds from sale of property and equipment	88	13
Premiums paid on deferred compensation plan	(617)
Purchases of short-term investments	(125,756)	(143,094)	(78,250)
Proceeds from sale of short-term investments	85,700	135,183	129,719
Proceeds from sale of long-term investments	2,025	2,100	5,775
Change in restricted assets		20
Net cash provided by (used in) investing activities	(54,324)	(26,837)	36,222
Cash flows from financing activities:
Property and equipment purchased on extended payment terms	(557)
Proceeds from issuance of common shares	37,877	13,390	4,697
Proceeds from employee stock purchase plan	2,145	1,852	1,773
Repurchases of common shares	(20,615)		(38,472)
Dividend payment		(35,664)
Excess tax benefits from stock option transactions		869	27
Net cash provided by (used in) financing activities	18,850	(19,553)	(31,975)
Effect of change in exchange rates	897	211	429
Net increase (decrease) in cash and cash equivalents	26,109	(21,267)	48,361
Cash and cash equivalents, beginning of period	75,104	96,371	48,010
Cash and cash equivalents, end of period	101,213	75,104	96,371
Supplemental disclosures for cash flow information:
Cash paid for taxes	1,116	807	675
Supplemental disclosures of non-cash activities:
Liability accrued for property and equipment purchases	$ 1,941	$ 1,728	$ 1,483