DESCRIPTION OF THE BUSINESS (Details)	9 Months Ended
Sep. 30, 2020 facility segment	Sep. 30, 2019 segment
DESCRIPTION OF THE BUSINESS
Number of reportable segments \| segment	2	2
Ocean Transportation \| SSAT
DESCRIPTION OF THE BUSINESS
Ownership interest in SSAT (as a percent)	35.00%
Number of terminal facilities on which SSAT provided terminal and stevedoring services on the U.S. West Coast	7
MatNav \| SSAT
DESCRIPTION OF THE BUSINESS
Number of terminal facilities on which SSAT provided terminal and stevedoring services on the U.S. West Coast	3

Line items represent description about business.

No definition available.

Name:	matx_DescriptionOfBusinessLineItems
Namespace Prefix:	matx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of ports terminal facilities on which the investee provides terminal and stevedoring services.

+ References

No definition available.

+ Details

Name:	matx_NumberOfTerminalFacilitiesOnWhichInvesteeProvidesTerminalAndStevedoringServices
Namespace Prefix:	matx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8672-108599

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=matx_OceanTransportationSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=matx_SsaTerminalsLlcMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=matx_MatNavMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: