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Investments - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 30, 2017 | Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items] |  |
Investments maximum maturity period | 5 years |
Unrealized losses, net of unrealized gains, on the investments in the bond portfolio | $ (223) | $ (109)
Guarantee Payment of Insurance Claims |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Letters of credit outstanding | 59,436 |
Current Investments |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments providing collateral for letters of credit to guarantee insurance claims | 48,928 |
Non-Current Investments |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Investments providing collateral for letters of credit to guarantee insurance claims | 17,112 |
Total non-current investments | $ 61,991 |

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