Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
NET CASH FLOWS PROVIDED BY OPERATING ACTIVITIES:
Net income	$ 19,786	$ 22,067
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,295	6,539
Share-based compensation expense	2,685	2,237
Excess tax benefit from share-based payment arrangements	(463)	(18)
Loss on disposal of assets		1
Deferred income taxes provision	2,067	(6,042)
Changes in operating assets and liabilities:
Accounts receivable	(2,911)	(17,472)
Inventories	(1,548)	559
Income taxes receivable	5,057	4,011
Other current assets	479	(31)
Accounts payable	(4,460)	1,960
Income taxes payable	759	11,749
Other current liabilities	673	5,466
Deferred income on shipments to distributors	(913)	13,646
Net cash provided by operating activities	27,506	44,672
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property, plant and equipment, net	(4,818)	(4,071)
Purchases of investments	(23,939)	(2,001)
Proceeds from the sale of investments	27,045	850
Net cash used in investing activities	(1,712)	(5,222)
CASH FLOWS FROM FINANCING ACTIVITIES:
Repayments of long-term debt	(2,857)	(4,285)
Proceeds from the issuance of common stock	10,858	2,700
Repurchases of common stock	(7,228)	(2,239)
Payment of cash dividends	(4,350)	(4,327)
Excess tax benefit from share based payment arrangements	463	18
Net cash used in financing activities	(3,114)	(8,133)
NET INCREASE IN CASH AND CASH EQUIVALENTS	22,680	31,317
CASH AND CASH EQUIVALENTS - Beginning of period	74,738	70,898
CASH AND CASH EQUIVALENTS - End of period	$ 97,418	$ 102,215