CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 45,190	$ 41,229
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	11,849	12,062
Amortization of intangibles	4,723	5,526
Loss on sale of property and equipment	170	17
Gain on sale of assets held for sale	0	(497)
Stock-based compensation expense	10,670	12,155
Amortization of premium on marketable securities	1,296	472
Deferred income taxes	(782)	(4,806)
Provision for (reduction in) accounts receivable allowances	75	(127)
Excess tax benefit from employee stock plans	(437)	0
Tax benefit associated with employee stock plans	815	0
Change in operating assets and liabilities:
Accounts receivable	1,933	(7,648)
Inventories	(14,639)	4,359
Prepaid expenses and other assets	9,955	1,595
Accounts payable	2,509	2,952
Taxes payable and accrued liabilities	(3,257)	2,608
Deferred income on sales to distributors	3,017	5,311
Net cash provided by operating activities	73,087	75,208
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(17,394)	(11,250)
Proceeds from sale of property and equipment	0	36
Proceeds from sale of assets held for sale	0	959
Other assets	(1,261)	0
Purchases of marketable securities	(45,269)	(96,271)
Proceeds from maturities of marketable securities	0	25,450
Net cash used in investing activities	(63,924)	(81,076)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	13,104	27,638
Repurchase of common stock	(45,258)	0
Payments of dividends to stockholders	(9,654)	(7,046)
Excess tax benefit from employee stock plans	437	0
Net cash (used in) provided by financing activities	(41,371)	20,592
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(32,208)	14,724
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	92,928	63,394
CASH AND CASH EQUIVALENTS AT END OF PERIOD	60,720	78,118
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	4,359	1,871
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash refund for income taxes, net of payments	$ (3,707)	$ (569)