Fair Value Measurements (Summary Of Short-Term And Long-Term Investments) (Details) (USD $) In Thousands	Oct. 01, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	$ 255,854	$ 211,247
Gross Unrealized Gains	5,017	753
Gross Unrealized Losses	(5,670)	(955)
Estimated Fair Value	255,201	211,045
U.S. Government And Agency Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	43,404	21,226
Gross Unrealized Gains	93	98
Gross Unrealized Losses	(36)	(6)
Estimated Fair Value	43,461	21,318
Obligations Of Government-Sponsored Enterprises [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	14,091	5,731
Gross Unrealized Gains	28	54
Gross Unrealized Losses	(2)
Estimated Fair Value	14,117	5,785
State And Municipal Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	122,864	134,370
Gross Unrealized Gains	384	402
Gross Unrealized Losses	(34)	(463)
Estimated Fair Value	123,214	134,309
Corporate Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	75,459	49,884
Gross Unrealized Gains	4,512	199
Gross Unrealized Losses	(5,598)	(486)
Estimated Fair Value	74,373	49,597
Other Investments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized Cost	36	36
Gross Unrealized Gains
Gross Unrealized Losses
Estimated Fair Value	$ 36	$ 36

- Definition

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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