Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Net income	$ 15,508	$ 10,848
Depreciation and amortization	6,866	6,550
Loss on disposal of property and equipment	79
Amortization and realized gain on debt instruments	145	357
Credit gain on auction-rate securities	(40)	0
Tax benefit from stock option transactions	2,606	1,907
Excess tax benefit from stock option transactions	(835)	(145)
Stock-based compensation	11,326	10,036
Accounts receivable	(6,464)	1,927
Inventories	(12,519)	2,240
Prepaid expenses and other current assets	(490)	363
Accounts payable	2,345	712
Accrued and other long-term liabilities	(345)	(387)
Accrued income taxes payable and noncurrent tax liabilities	(1,352)	(1,806)
Accrued compensation and related benefits	(3,380)	(2,183)
Net cash provided by operating activities	13,450	30,419
Property and equipment purchases	(18,735)	(18,795)
Proceeds from sale of property and equipment	13
Purchase of intangible assets	(459)
Purchases of short-term investments	(115,709)	(47,261)
Proceeds from sale of short-term investments	86,168	108,718
Proceeds from sale of long-term investments	2,100	3,750
Net cash provided by (used in) investing activities	(46,622)	46,412
Proceeds from issuance of common stock	12,233	4,334
Proceeds from employee stock purchase plan	1,852	1,773
Repurchase of common stock		(38,472)
Excess tax benefits from stock option transactions	835	145
Net cash provided by (used in) financing activities	14,920	(32,220)
Effect of change in exchange rates	128	351
Net increase (decrease) in cash and cash equivalents	(18,124)	44,962
Cash and cash equivalents, beginning of period	96,371	48,010
Cash and cash equivalents, end of period	78,247	92,972
Cash paid for taxes	732	581
Liability accrued for equipment purchases	1,687	462
Reversal of temporary impairment of auction-rate securities	$ (141)	$ (290)