CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 10,903	$ 7,461
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	3,975	3,732
Amortization of intangibles	1,842	189
Gain on sale of property and equipment	0	(1)
Stock-based compensation expense	3,636	3,031
Amortization of premium on marketable securities	104	309
Non-cash interest income from SemiSouth note	0	(157)
Deferred income taxes	(3,236)	(327)
Reduction in accounts receivable allowances	(20)	0
Excess tax benefit from stock options exercised	0	(198)
Tax benefit associated with employee stock plans	0	782
Change in operating assets and liabilities:
Accounts receivable	(7,393)	(7,300)
Inventories	893	9,161
Prepaid expenses and other assets	3,928	1,306
Accounts payable	2,832	1,485
Taxes payable and accrued liabilities	1,172	604
Deferred income on sales to distributors	2,936	1,490
Net cash provided by operating activities	21,572	21,567
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(3,950)	(7,471)
Proceeds from sale of property and equipment	0	2
Increase in financing lease receivable	0	(383)
Collections of financing lease receivable	0	299
Loan to SemiSouth	0	(18,000)
Purchases of marketable securities	(19,422)	0
Proceeds from maturities of marketable securities	1,500	6,065
Net cash used in investing activities	(21,872)	(19,488)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	8,705	6,457
Payments of dividends to stockholders	(2,310)	(1,415)
Excess tax benefit from stock options exercised	0	198
Net cash provided by financing activities	6,395	5,240
NET INCREASE IN CASH AND CASH EQUIVALENTS	6,095	7,319
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	63,394	139,836
CASH AND CASH EQUIVALENTS AT END OF PERIOD	69,489	147,155
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	1,469	965
Receipt of SemiSouth purchase option	0	6,216
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid (received) for income taxes, net of refunds	$ (3,698)	$ 630