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Investments - Additional Information (Detail) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 26, 2015 | Dec. 27, 2014
Schedule of Available-for-sale Securities [Line Items] |  |
Investments maximum maturity period | 5 years |
Unrealized (loss) gain, net of unrealized gains/losses, on the investments in the bond portfolio | $ (145,000) | $ 163,000
Guarantee Payment Of Insurance Claims |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Letters of credit outstanding | 57,610,000 |
Current Investments |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments providing collateral for letters of credit to guarantee insurance claims | 48,823,000 |
Non-Current Investments |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments providing collateral for letters of credit to guarantee insurance claims | 15,188,000 |
Total non-current investments | $ 59,261,000 |

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