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Investments - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 27, 2015	Dec. 27, 2014
Schedule of Available-for-sale Securities [Line Items]
Investments maximum maturity period	5 years
Unrealized gains, net of unrealized losses, on the investments in the bond portfolio	$ 262,000	$ 163,000

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- Definition

Investments maximum maturity period, years

+ References

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- Definition

Amount before tax of unrealized gain (loss) in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

No definition available.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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