CAPITAL CONSTRUCTION FUND - Investment maturity (Details) $ in Millions	Mar. 31, 2025 USD ($) item	Dec. 31, 2024 USD ($)	Mar. 31, 2024 USD ($)
CAPITAL CONSTRUCTION FUND
2025	$ 173.0
2026	169.3
2027	52.3
Total CCF investments	394.6	$ 411.9	$ 450.0
2025	173.2
2026	169.9
2027	52.6
Total CCF investments	$ 395.7
Number of vessels under agreements for construction \| item	3

No definition available.

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- Definition

Cost of capital construction fund investments maturing maturing in third fiscal year following current fiscal year.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestments
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cost of capital construction fund investments maturing in remainder of current fiscal year.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestmentsCostMaturitiesRemainderOfFiscalYear
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cost of capital construction fund investments maturing maturing in next fiscal year following current fiscal year.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestmentsCostMaturitiesYearOne
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Cost of capital construction fund investments maturing maturing in second fiscal year following current fiscal year.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestmentsCostMaturitiesYearTwo
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of investments made under capital construction fund.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestmentsFairValue
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of capital construction fund investments maturing in remainder of current fiscal year.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestmentsFairValueMaturitiesRemainderOfFiscalYear
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of capital construction fund investments maturing maturing in next fiscal year following current fiscal year.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestmentsFairValueMaturitiesYearOne
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of capital construction fund investments maturing maturing in second fiscal year following current fiscal year.

+ References

No definition available.

+ Details

Name:	matx_CapitalConstructionFundInvestmentsFairValueMaturitiesYearTwo
Namespace Prefix:	matx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of vessels under agreements for construction.

+ References

No definition available.

+ Details

Name:	matx_NumberOfVesselsUnderAgreementForConstruction
Namespace Prefix:	matx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant