Condensed Consolidated Statements Of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 9,018	$ 2,499
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,182	2,709
Amortization and realized loss (gain) on investments	71	98
Excess tax benefit from stock option transactions		(132)
Stock-based compensation	7,598	4,660
Changes in operating assets and liabilities:
Accounts receivable	1,673	(3,285)
Inventories	(81)	(2,836)
Prepaid expenses and other current assets	(2,036)	315
Accounts payable	1,058	2,135
Accrued liabilities	(8,473)	1,889
Accrued income taxes payable and noncurrent tax liabilities	38	(526)
Accrued compensation and related benefits	(63)	(822)
Net cash provided by operating activities	11,985	6,704
Cash flows from investing activities:
Property and equipment purchases	(4,516)	(3,435)
Purchases of short-term investments	(41,977)	(17,590)
Proceeds from sale of short-term investments	27,252	21,250
Proceeds from sale of long-term investments		25
Net cash provided by (used in) investing activities	(19,241)	250
Cash flows from financing activities:
Proceeds from issuance of common shares	5,554	9,839
Proceeds from employee stock purchase plan	1,053	1,167
Repurchases of common shares	(11,358)
Excess tax benefits from stock option transactions		132
Net cash provided by (used in) financing activities	(4,751)	11,138
Effect of change in exchange rates	(321)	91
Net increase (decrease) in cash and cash equivalents	(12,328)	18,183
Cash and cash equivalents, beginning of period	101,213	75,104
Cash and cash equivalents, end of period	88,885	93,287
Supplemental disclosures for cash flow information:
Cash paid for taxes	217	324
Supplemental disclosures of non-cash activities:
Liability accrued for property and equipment purchases	$ 445	$ 4,230