Investments - Additional Information (Detail) - USD ($)	12 Months Ended
Dec. 29, 2018	Dec. 30, 2017
Debt Securities, Available-for-sale [Line Items]
Investments maximum maturity period	5 years
Unrealized losses, net of unrealized gains, on the investments in the bond portfolio	$ 1,184,000	$ 223,000
Guarantee Payment of Insurance Claims
Debt Securities, Available-for-sale [Line Items]
Letters of credit outstanding	62,345,000
Current Investments
Debt Securities, Available-for-sale [Line Items]
Investments providing collateral for letters of credit to guarantee insurance claims	40,058,000
Non-Current Investments
Debt Securities, Available-for-sale [Line Items]
Investments providing collateral for letters of credit to guarantee insurance claims	29,214,000
Total non-current investments	$ 72,117,000

Investments maximum maturity period, years

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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.

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- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

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- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

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- Definition

The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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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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