Fair Value Measurements (Summary Of Short-Term And Long-Term Investments) (Details) (USD $) In Thousands	Jul. 02, 2011	Dec. 31, 2010
Amortized Cost	$ 249,524	$ 211,247
Gross Unrealized Gains	917	753
Gross Unrealized Losses	(584)	(955)
Estimated Fair Value	249,857	211,045
U.S. Government And Agency Securities [Member]
Amortized Cost	27,556	21,226
Gross Unrealized Gains	95	98
Gross Unrealized Losses		(6)
Estimated Fair Value	27,651	21,318
Obligations Of Government-Sponsored Enterprises [Member]
Amortized Cost	3,805	5,731
Gross Unrealized Gains	31	54
Gross Unrealized Losses
Estimated Fair Value	3,836	5,785
State And Municipal Bonds [Member]
Amortized Cost	151,459	134,370
Gross Unrealized Gains	422	402
Gross Unrealized Losses	(8)	(463)
Estimated Fair Value	151,873	134,309
Corporate Securities [Member]
Amortized Cost	66,668	49,884
Gross Unrealized Gains	369	199
Gross Unrealized Losses	(576)	(486)
Estimated Fair Value	66,461	49,597
Other Investments [Member]
Amortized Cost	36	36
Gross Unrealized Gains
Gross Unrealized Losses
Estimated Fair Value	$ 36	$ 36

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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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.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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