CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 47,890	$ 39,147	$ 59,544
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	16,812	16,464	15,884
Amortization of intangibles	6,663	7,039	6,072
Loss on disposal of property and equipment	332	361	250
Stock-based compensation expense	20,885	14,767	14,282
Accretion (Amortization) of Discounts and Premiums, Investments	555	1,063	1,694
Deferred income taxes	(660)	(5,416)	157
Allowance for Doubtful Accounts Receivable, Period Increase (Decrease)	207	127	70
Excess tax benefit from employee stock plans	0	0	(437)
Tax (Shortfall) Benefit Associated With Employee Stock Plans	0	(189)	815
Change in operating assets and liabilities:
Accounts receivable	650	4,131	2,133
Inventories	(630)	13,500	(21,703)
Prepaid expenses and other assets	(2,499)	3,391	8,211
Accounts payable	7,714	(2,000)	2,337
Taxes payable and accrued liabilities	(1,124)	(76)	(3,242)
Deferred income on sales to distributors	1,106	(122)	(505)
Net cash provided by operating activities	97,901	92,187	85,562
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(12,198)	(11,359)	(23,071)
Other assets	0	0	(1,261)
Payment for purchase of building (Note 11)	0	(10,389)	0
Payment for acquisition, net of cash acquired (Note 11)	0	(15,549)	0
Loans to third parties (Notes 11)	0	0	(6,600)
Purchases of marketable securities	(188,654)	(29,748)	(45,269)
Proceeds from sales and maturities of marketable securities	83,423	59,309	38,052
Net cash used in investing activities	(117,429)	(7,736)	(38,149)
CASH FLOWS FROM FINANCING ACTIVITIES:
Issuance of common stock under employee stock plans	13,059	12,580	13,855
Repurchase of common stock	(6,435)	(53,731)	(80,760)
Payments of dividends to stockholders	(15,054)	(13,916)	(13,165)
Excess tax benefit from employee stock plans	0	0	437
Net cash used in financing activities	(8,430)	(55,067)	(79,633)
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	(27,958)	29,384	(32,220)
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	90,092	60,708	92,928
CASH AND CASH EQUIVALENTS AT END OF PERIOD	62,134	90,092	60,708
SUPPLEMENTAL DISCLOSURE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Unpaid property and equipment	1,825	1,472	1,733
Loan applied to CamSemi purchase price (Note 11)	0	6,600	0
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid (refund) for income taxes, net of refunds (Note 8)	$ 6,613	$ 473	$ (3,121)