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PENSION AND POST-RETIREMENT PLANS - MULTI-EMPLOYER DEFINED BENEFIT PLANS (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Multiemployer Plans |  |  |
Estimated benefit plan withdrawal obligations | $ 260.0 |  |
Multiemployer Health and Benefit Plans |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 32.5 | $ 32.8 | $ 30.0
Multi-employer defined contribution pension plans |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | $ 28.4 | 27.3 | 25.5
Multi-employer defined contribution pension plans | Orange Zone |  |  |
Multiemployer Plans |  |  |
Expected funding deficiency period | 6 years |  |
Multi-employer defined contribution pension plans | Minimum | Green Zone |  |  |
Multiemployer Plans |  |  |
Funded status of multiemployer plan (as a percent) | 80.00% |  |
Multi-employer defined contribution pension plans | Maximum | Red Zone |  |  |
Multiemployer Plans |  |  |
Funded status of multiemployer plan (as a percent) | 65.00% |  |
Multi-employer defined contribution pension plans | Maximum | Yellow Zone |  |  |
Multiemployer Plans |  |  |
Funded status of multiemployer plan (as a percent) | 80.00% |  |
Multi-employer defined contribution pension plans | Maximum | Orange Zone |  |  |
Multiemployer Plans |  |  |
Funded status of multiemployer plan (as a percent) | 80.00% |  |
Multi-employer defined contribution pension plans | American Radio Association Pension Fund | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | $ 1.0 | 1.1 | 1.0
Multi-employer defined contribution pension plans | Hawaii Terminals Multiemployer Pension Plan | Yellow Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 5.8 |  | 5.7
Multi-employer defined contribution pension plans | Hawaii Terminals Multiemployer Pension Plan | Orange Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson |  | 5.7 |
Multi-employer defined contribution pension plans | Hawaii Stevedoring Multiemployer Retirement Plan | Yellow Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson |  | 4.4 | 4.3
Multi-employer defined contribution pension plans | Hawaii Stevedoring Multiemployer Retirement Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 4.6 |  |
Multi-employer defined contribution pension plans | Master Mates And Pilots Pension Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 3.2 | 3.4 | 3.0
Multi-employer defined contribution pension plans | Masters, Mates and Pilots Adjustable Pension Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 1.8 | 1.9 | 1.7
Multi-employer defined contribution pension plans | M E B A Pension Trust - Defined Benefit Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 4.1 | 4.3 | 4.0
Multi-employer defined contribution pension plans | OCU Pension Trust Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 0.2 | 0.2 | 0.2
Multi-employer defined contribution pension plans | M F O W Supplementary Pension Plan | Yellow Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 0.1 |  |
Multi-employer defined contribution pension plans | M F O W Supplementary Pension Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson |  | 0.1 |
Multi-employer defined contribution pension plans | SIU Pacific District Pension Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 1.3 | 1.5 | 1.2
Multi-employer defined contribution pension plans | Alaska Teamster - Employer Pension Plan | Red Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 3.3 | 1.9 | 1.9
Multi-employer defined contribution pension plans | All Alaska Longshore Pension Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 1.3 | 1.2 | 1.0
Multi-employer defined contribution pension plans | Western Conference of Teamsters Pension Plan | Green Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | 1.6 | 1.5 | 1.4
Multi-employer defined contribution pension plans | O P E I U Local 153 Pension Plan | Red Zone |  |  |
Multiemployer Plans |  |  |
Contributions of Matson | $ 0.1 | $ 0.1 | $ 0.1

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