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Postretirement Plans - Summary of Target Allocation and Weighted-Average Asset Allocation by Asset Category and Fair Value of Plan Assets (Detail) - U.S. Postretirement Health Care Plans - USD ($) $ in Millions | Jan. 02, 2021 | Dec. 28, 2019 | Dec. 29, 2018
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target allocation | 100.00% |  |
Actual weighted-average asset allocation | 100.00% | 100.00% |
Fair value of plan assets | $ 13.3 | $ 12.8 | $ 12.1
Debt securities and cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target allocation | 46.00% |  |
Actual weighted-average asset allocation | 46.00% | 51.00% |
Equity securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target allocation | 29.00% |  |
Actual weighted-average asset allocation | 35.00% | 31.00% |
Fair value of plan assets | $ 4.6 | $ 4.0 |
Hedge funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Target allocation | 25.00% |  |
Actual weighted-average asset allocation | 19.00% | 18.00% |
Fair value of plan assets | $ 2.5 | $ 2.3 |

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