Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income	$ 9,587	$ 5,375
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	4,453	4,375
Loss on disposal of property and equipment	79
Amortization and realized gain on debt instruments	87	308
Deferred income tax assets	(2)
Credit gain on auction-rate securities	(40)
Tax benefit from stock option transactions	1,929	1,845
Excess tax benefit from stock option transactions	(767)	(474)
Stock-based compensation	7,144	6,662
Changes in operating assets and liabilities:
Accounts receivable	(6,318)	758
Inventories	(9,350)	1,082
Prepaid expenses and other current assets	(297)	661
Accounts payable	5,912	2,062
Accrued and other long-term liabilities	(999)	1,290
Accrued income taxes payable and noncurrent tax liabilities	(834)	(1,612)
Accrued compensation and related benefits	1,708	(818)
Net cash provided by operating activities	12,292	21,514
Cash flows from investing activities:
Property and equipment purchases	(13,184)	(5,271)
Proceeds from sale of property and equipment	13
Purchases of short-term investments	(86,774)	(22,957)
Proceeds from sale of short-term investments	61,518	86,719
Proceeds from sale of long-term investments	2,100	2,100
Net cash provided by (used in) investing activities	(36,327)	60,591
Cash flows from financing activities:
Proceeds from issuance of common stock	7,341	4,262
Proceeds from employee stock purchase plan	1,036	928
Repurchase of common stock		(38,472)
Excess tax benefits from stock option transactions	767	474
Net cash provided by (used in) financing activities	9,144	(32,808)
Effect of change in exchange rates	164	378
Net increase (decrease) in cash and cash equivalents	(14,727)	49,675
Cash and cash equivalents, beginning of period	96,371	48,010
Cash and cash equivalents, end of period	81,644	97,685
Supplemental disclosures for cash flow information:
Cash paid for taxes	423	381
Supplemental disclosures of non-cash investing and financing activities:
Liability accrued for equipment purchases	4,414	527
Temporary impairment reversal of auction-rate securities	$ (99)	$ (140)