Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 15,756	$ 13,301	$ 29,563
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,332	8,732	8,016
Loss on disposal of property and equipment	81	33	1
Amortization and realized gain on available-for-sale securities	254	376	688
Deferred income tax assets	(8)	(403)	(56)
Gain on auction-rate securities	(40)	0
Tax benefit from stock option transactions	3,009	1,958	3,349
Excess tax benefit from stock option transactions	(869)	(27)	(1,256)
Stock-based compensation	18,652	13,126	16,810
Changes in operating assets and liabilities:
Accounts receivable	(4,286)	3,250	(2,826)
Inventories	(12,004)	5,699	(6,184)
Prepaid expenses and other current assets	(456)	673	378
Accounts payable	754	(957)	1,155
Accrued and other long-term liabilities	(2,097)	(438)	556
Accrued income taxes payable and noncurrent tax liabilities	(1,533)	(2,127)	(1,995)
Accrued compensation and related benefits	(1,633)	489	295
Net cash provided by operating activities	24,912	43,685	48,494
Cash flows from investing activities:
Property and equipment purchases	(21,059)	(21,022)	(22,779)
Proceeds from sale of property and equipment	13
Purchases of short-term investments	(143,094)	(78,250)	(208,621)
Proceeds from sale of short-term investments	135,183	129,719	197,243
Proceeds from sale of long-term investments	2,100	5,775	425
Changes in restricted assets	20		(19)
Net cash provided by (used in) investing activities	(26,837)	36,222	(33,751)
Cash flows from financing activities:
Proceeds from issuance of common stock	13,390	4,697	14,339
Proceeds from employee stock purchase plan	1,852	1,773	1,885
Repurchase of common stock		(38,472)	(31,527)
Dividend payment	(35,664)
Excess tax benefits from stock option transactions	869	27	1,256
Net cash used in financing activities	(19,553)	(31,975)	(14,047)
Effect of change in exchange rates	211	429	597
Net increase (decrease) in cash and cash equivalents	(21,267)	48,361	1,293
Cash and cash equivalents, beginning of period	96,371	48,010	46,717
Cash and cash equivalents, end of period	75,104	96,371	48,010
Supplemental disclosures for cash flow information:
Cash paid for taxes	807	675	35
Supplemental disclosures of non-cash investing and financing activities:
Liability accrued for equipment purchases	1,728	1,483	4,264
Reversal of temporary impairment of auction-rate securities	$ (140)	$ (270)	$ (160)