Fair Value of Financial Instruments (Details) (USD $) In Thousands	Oct. 01, 2011	Jan. 01, 2011
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	$ 108,183	$ 138,567
Total short-term investments	174,915	227,295
Money market funds \| Assets and liabilities measured at fair value on recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	66,328	45,167
Money market funds \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	66,328	45,167
Corporate bonds \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	80,060	88,518
Corporate bonds \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	80,060	88,518
U.S. government agency \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	10,048	34,680
U.S. government agency \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	10,048	34,680
U.S. Treasury bills \| Assets and liabilities measured at fair value on recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents		50,097
Total short-term investments	8,600	6,999
U.S. Treasury bills \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents		50,097
Total short-term investments	8,600	6,999
International government bonds \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	2,792	10,830
International government bonds \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	2,792	10,830
Certificates of deposit \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	1,569	5,742
Certificates of deposit \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	1,569	5,742
Asset-backed securities \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	1,244
Asset-backed securities \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	1,244
Commercial paper \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents		2,659
Total short-term investments	1,000	2,687
Commercial paper \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents		2,659
Total short-term investments	1,000	2,687
Variable-rate demand notes \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	13,200	39,425
Variable-rate demand notes \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	13,200	39,425
Municipal bonds \| Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	56,402	38,414
Municipal bonds \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total short-term investments	56,402	38,414
Auction rate securities \| Assets and liabilities measured at fair value on recurring basis \| Significant Unobservable Inputs (Level 3)
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	17,840	17,500
Auction rate securities \| Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	17,840	17,500
Assets and liabilities measured at fair value on recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	66,328	95,264
Total short-term investments	8,600	6,999
Total assets at fair value	74,928	102,263
Assets and liabilities measured at fair value on recurring basis \| Significant Other Observable Inputs (Level 2)
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents		2,659
Total short-term investments	166,315	220,296
Total assets at fair value	166,315	222,955
Derivative instruments	2,526	3,811
Total liabilities at fair value	2,526	3,811
Assets and liabilities measured at fair value on recurring basis \| Significant Unobservable Inputs (Level 3)
Financial assets and liabilities measured at fair value on a recurring basis
Total long-term investments	17,840	17,500
Total assets at fair value	17,840	17,500
Contingent consideration	1,523	1,780
Total liabilities at fair value	1,523	1,780
Assets and liabilities measured at fair value on recurring basis \| Fair Value
Financial assets and liabilities measured at fair value on a recurring basis
Total cash equivalents	66,328	97,923
Total short-term investments	174,915	227,295
Total long-term investments	17,840	17,500
Total assets at fair value	259,083	342,718
Derivative instruments	2,526	3,811
Contingent consideration	1,523	1,780
Total liabilities at fair value	$ 4,049	$ 5,591

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

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