CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 29,079	$ 24,575
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	7,847	7,968
Amortization of intangibles	3,374	3,684
Loss on sale of property and equipment	159	17
Gain on sale of assets held for sale	0	(497)
Stock-based compensation expense	8,090	7,964
Amortization of premium on marketable securities	815	251
Deferred income taxes	135	(2,388)
Reduction in accounts receivable allowances	(15)	(153)
Excess tax benefit from employee stock plans	(213)	0
Tax benefit associated with employee stock plans	364	0
Change in operating assets and liabilities:
Accounts receivable	(4,039)	(8,294)
Inventories	(8,946)	1,421
Prepaid expenses and other assets	5,300	5,198
Accounts payable	1,870	3,457
Taxes payable and accrued liabilities	(4,743)	(480)
Deferred income on sales to distributors	3,401	3,484
Net cash provided by operating activities	42,478	46,207
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(9,885)	(6,892)
Proceeds from sale of property and equipment	0	36
Proceeds from sale of assets held for sale	0	959
Purchases of marketable securities	(24,751)	(45,223)
Proceeds from maturities of marketable securities	0	16,850
Net cash used in investing activities	(34,636)	(34,270)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	9,867	14,749
Repurchase of common stock	(25,731)	0
Payments of dividends to stockholders	(6,059)	(4,654)
Excess tax benefit from employee stock plans	213	0
Net cash (used in) provided by financing activities	(21,710)	10,095
NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS	(13,868)	22,032
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	92,928	63,394
CASH AND CASH EQUIVALENTS AT END OF PERIOD	79,060	85,426
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	3,022	2,447
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash refund for income taxes, net of payments	$ (1,148)	$ (3,133)