Fair Value Measurements - Additional Information (Detail) (Fixed income securities, USD $)	9 Months Ended
Sep. 28, 2012	Dec. 30, 2011
Fixed income securities
Fair Value Measurements [Line Items]
State and municipal bonds, fair value	$ 22,086,000	$ 25,260,000
State and municipal bonds, amortized cost	22,008,000	25,173,000
State and municipal bonds, unrealized gain recorded in accumulated other comprehensive income	78,000
Fair value of available-for-sale securities with contractual maturities of less than one year	20,548,000
Amortized cost of available-for-sale securities with contractual maturities of less than one year	20,476,000
Fair value of available-for-sale securities with contractual maturities of between one and two years	1,538,000
Amortized cost of available-for-sale securities with contractual maturities of between one and two years	$ 1,532,000

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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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the next fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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- 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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