Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
NET CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 28,998	$ 36,987
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,179	9,833
Share-based compensation expense	4,175	3,437
Excess tax benefit from share-based payment arrangements	(476)	(18)
Loss on disposal of assets		1
Deferred income taxes provision	1,341	(9,327)
Changes in operating assets and liabilities:
Accounts receivable	4,720	(16,939)
Inventories	(1,033)	(39)
Income taxes receivable	5,720	4,011
Other current assets	656	(1,276)
Accounts payable	(3,343)	2,963
Income taxes payable	290	2,889
Other current liabilities	(1,347)	6,658
Deferred income on shipments to distributors	(2,232)	19,623
Net cash provided by operating activities	46,648	58,803
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment, net	(6,324)	(6,390)
Purchases of investments	(54,355)	(2,001)
Proceeds from the sale of investments	32,785	1,000
Net cash used in investing activities	(27,894)	(7,391)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of long-term debt	(2,857)	(6,428)
Proceeds from the issuance of common stock	11,574	3,011
Repurchases of common stock	(12,529)	(13,127)
Payment of cash dividends	(6,848)	(6,508)
Excess tax benefit from share based payment arrangements	476	18
Net cash used in financing activities	(10,184)	(23,034)
NET INCREASE IN CASH AND CASH EQUIVALENTS	8,570	28,378
CASH AND CASH EQUIVALENTS--Beginning of period	74,738	70,898
CASH AND CASH EQUIVALENTS--End of period	$ 83,308	$ 99,276