Matson (MATX) 10-K 23 Feb 24 2023 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2023	Feb. 16, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2023
Entity File Number	001-34187
Entity Registrant Name	Matson, Inc.
Entity Incorporation, State or Country Code	HI
Entity Tax Identification Number	99-0032630
Entity Address, Address Line One	1411 Sand Island Parkway
Entity Address, City or Town	Honolulu
Entity Address, State or Province	HI
Entity Address, Postal Zip Code	96819
City Area Code	808
Local Phone Number	848-1211
Title of 12(b) Security	Common Stock, without par value
Trading Symbol	MATX
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		34,495,712
Entity Public Float			$ 2,687,446,747
Entity Central Index Key	0000003453
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Auditor Name	Deloitte & Touche LLP
Auditor Location	Honolulu, Hawaii
Auditor Firm ID	34

Consolidated Statements of Inco

Consolidated Statements of Income and Comprehensive Income - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Revenue:
Total Operating Revenue	$ 3,094.6	$ 4,343	$ 3,925.3
Costs and Expenses:
Operating costs	(2,470.7)	(2,811.5)	(2,557.6)
Income from SSAT	2.2	83.1	56.3
Selling, general and administrative	(283.3)	(261)	(236.5)
Total Costs and Expenses	(2,751.8)	(2,989.4)	(2,737.8)
Operating Income	342.8	1,353.6	1,187.5
Interest income	36	8.2
Interest expense	(12.2)	(18)	(22.6)
Other income (expense), net	6.4	8.5	6.4
Income before Taxes	373	1,352.3	1,171.3
Income taxes	(75.9)	(288.4)	(243.9)
Net Income	297.1	1,063.9	927.4
Other Comprehensive Income (Loss), Net of Income Taxes:
Net Income (Loss)	297.1	1,063.9	927.4
Other Comprehensive Income (Loss):
Net change in pension and post-retirement liabilities	(2.5)	23.8	20.4
Other adjustments	1.2	0.2	(0.5)
Total Other Comprehensive Income (Loss), Net of Income Taxes	(1.3)	24	19.9
Comprehensive Income	$ 295.8	$ 1,087.9	$ 947.3
Basic Earnings Per Share (in dollars per share)	$ 8.42	$ 27.28	$ 21.67
Diluted Earnings Per Share (in dollars per share)	$ 8.32	$ 27.07	$ 21.47
Weighted Average Number of Shares Outstanding:
Basic (in shares)	35.3	39	42.8
Diluted (in shares)	35.7	39.3	43.2
Ocean Transportation
Operating Revenue:
Total Operating Revenue	$ 2,477	$ 3,544.6	$ 3,132.8
Logistics
Operating Revenue:
Total Operating Revenue	$ 617.6	$ 798.4	$ 792.5

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 134	$ 249.8
Accounts receivable, net of allowance for credit losses of $9.9 million and $13.0 million, respectively	279.4	268.5
Prepaid expenses and other assets	188.9	241.3
Total current assets	602.3	759.6
Long-term Assets:
Investment in SSAT	85.5	81.2
Property and equipment, net	2,089.9	1,962.5
Operating lease right of use assets	289.6	396.9
Goodwill	327.8	327.8
Intangible assets, net	176.4	174.9
Capital Construction Fund	599.4	518.2
Deferred dry-docking costs, net	57.3	55.3
Other long-term assets	66.4	53.6
Total long-term assets	3,692.3	3,570.4
Total Assets	4,294.6	4,330
Current Liabilities:
Current portion of debt	39.7	76.9
Accounts payable and accruals	277.9	255.6
Operating lease liabilities	136.7	143.6
Other liabilities	108	105.5
Total current liabilities	562.3	581.6
Long-term Liabilities:
Long-term debt, net of deferred loan fees	389.3	427.7
Long-term operating lease liabilities	159.3	262.5
Deferred income taxes	669.3	646.5
Other long-term liabilities	113.7	114.8
Total long-term liabilities	1,331.6	1,451.5
Commitments and Contingencies (see Note 17)
Shareholders' Equity:
Common stock - common stock without par value; authorized, 150 million shares ($0.75 stated value per share): outstanding, 34.4 million shares in 2023 and 36.3 million shares in 2022	25.8	27.2
Additional paid in capital	293.4	290.4
Accumulated other comprehensive loss, net	(8.2)	(6.9)
Retained earnings	2,089.7	1,986.2
Total shareholders' equity	2,400.7	2,296.9
Total Liabilities and Shareholders' Equity	$ 4,294.6	$ 4,330

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Consolidated Balance Sheets
Accounts receivable, allowance for credit loss	$ 9.9	$ 13
Common stock, shares authorized	150	150
Common stock, stated value (in dollars per share)	$ 0.75	$ 0.75
Common stock, shares outstanding	34.4	36.3

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash Flows From Operating Activities:
Net income	$ 297.1	$ 1,063.9	$ 927.4
Reconciling adjustments:
Depreciation and amortization	144.4	141.3	135.9
Amortization of operating lease right of use assets	142	153	103.3
Deferred income taxes	19.6	90.2	33.2
Loss (Gain) on disposal of property and equipment	0.6	(1.5)	(0.8)
Share-based compensation expense	23.8	18.3	19.3
Income from SSAT	(2.2)	(83.1)	(56.3)
Distributions from SSAT		47.3	46.9
Other	(2.7)
Changes in assets and liabilities:
Accounts receivable, net	(10.9)	74.6	(90.3)
Deferred dry-docking payments	(24.1)	(25.7)	(36.3)
Deferred dry-docking amortization	25.3	24.9	24.3
Prepaid expenses and other assets	33.5	(45.2)	(48.1)
Accounts payable, accruals and other liabilities	10.9	(31.7)	39.6
Operating lease liabilities	(144.8)	(154.1)	(99.7)
Other long-term liabilities	(2)	(0.3)	(14.3)
Net cash provided by operating activities	510.5	1,271.9	984.1
Cash Flows From Investing Activities:
Capitalized vessel construction expenditures	(52.9)	(62.4)	(14.9)
Capital expenditures (excluding vessel construction expenditures)	(195.5)	(146.9)	(310.4)
Proceeds from disposal of property and equipment	1.2	1.2	1.9
Payments for intangible asset acquisitions	(12.4)	(3)
Cash and interest deposits into Capital Construction Fund	(128.5)	(582.8)	(31.2)
Withdrawals from Capital Construction Fund	49.9	64.6	31.2
Net cash used in investing activities	(338.2)	(729.3)	(323.4)
Cash Flows From Financing Activities:
Repayments of debt	(76.9)	(111.5)	(59.3)
Proceeds from revolving credit facility			304.3
Repayments of revolving credit facility			(376.1)
Payment of financing costs			(3)
Dividends paid	(45)	(48)	(45.9)
Repurchase of Matson common stock	(155.2)	(397)	(198.3)
Tax withholding related to net share settlements of restricted stock units	(12.6)	(20.1)	(14.4)
Net cash used in financing activities	(289.7)	(576.6)	(392.7)
Net (Decrease) Increase in Cash, Cash Equivalents and Restricted Cash	(117.4)	(34)	268
Cash, Cash Equivalents and Restricted Cash, Beginning of the Year	253.7	287.7	19.7
Cash, Cash Equivalents and Restricted Cash, End of the Year	136.3	253.7	287.7
Reconciliation of Cash, Cash Equivalents, and Restricted Cash, at End of the Year:
Cash and Cash Equivalents	134	249.8	282.4
Restricted Cash	2.3	3.9	5.3
Total Cash, Cash Equivalents and Restricted Cash, End of the Year	136.3	253.7	287.7
Supplemental Cash Flow Information:
Interest paid, net of capitalized interest	11.1	16.2	19.3
Income tax paid, net of income tax refunds	7.5	215.2	241.6
Non-cash Information:
Capital expenditures included in accounts payable, accruals and other liabilities	10.8	5.5	$ 6.4
Non-cash payments for intangible asset acquisitions	$ 2.7	$ 2.2

Consolidated Statements of Shar

Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Common Stock	Additional Paid In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Total
Balance at the beginning of the period at Dec. 31, 2020	$ 32.4	$ 321.5	$ (50.8)	$ 658.1	$ 961.2
Balance (in shares) at Dec. 31, 2020	43.2
Increase (Decrease) in Shareholders' Equity
Net income				927.4	927.4
Other comprehensive income (loss), net of tax			19.9		19.9
Share-based compensation		19.3			19.3
Shares issued, net of shares withheld for employee taxes	$ 0.2	(14.7)		0.1	(14.4)
Shares issued, net of shares withheld for employee taxes (in shares)	0.3
Share repurchase	$ (1.9)	(12)		(186.2)	$ (200.1)
Share repurchase (in shares)	(2.5)				(2.5)
Dividends				(45.9)	$ (45.9)
Balance at the end of the period at Dec. 31, 2021	$ 30.7	314.1	(30.9)	1,353.5	1,667.4
Balance (in shares) at Dec. 31, 2021	41
Increase (Decrease) in Shareholders' Equity
Net income				1,063.9	1,063.9
Other comprehensive income (loss), net of tax			24		24
Share-based compensation		18.3			18.3
Shares issued, net of shares withheld for employee taxes	$ 0.2	(20.3)			(20.1)
Shares issued, net of shares withheld for employee taxes (in shares)	0.3
Share repurchase	$ (3.7)	(21.7)		(371.6)	$ (397)
Share repurchase (in shares)	(5)				(5)
Equity interest in SSAT (see Note 4)				(11.6)	$ (11.6)
Dividends				(48)	(48)
Balance at the end of the period at Dec. 31, 2022	$ 27.2	290.4	(6.9)	1,986.2	$ 2,296.9
Balance (in shares) at Dec. 31, 2022	36.3				36.3
Increase (Decrease) in Shareholders' Equity
Net income				297.1	$ 297.1
Other comprehensive income (loss), net of tax			(1.3)		(1.3)
Share-based compensation		23.8			23.8
Shares issued, net of shares withheld for employee taxes	$ 0.2	(12.7)		(0.1)	(12.6)
Shares issued, net of shares withheld for employee taxes (in shares)	0.2
Share repurchase	$ (1.6)	(8.1)		(148.5)	$ (158.2)
Share repurchase (in shares)	(2.1)				(2.1)
Dividends				(45)	$ (45)
Balance at the end of the period at Dec. 31, 2023	$ 25.8	$ 293.4	$ (8.2)	$ 2,089.7	$ 2,400.7
Balance (in shares) at Dec. 31, 2023	34.4				34.4

Consolidated Statements of Sh_2

Consolidated Statements of Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Consolidated Statements of Shareholders' Equity
Dividends (in dollars per share)	$ 1.26	$ 1.22	$ 1.06

DESCRIPTION OF THE BUSINESS

DESCRIPTION OF THE BUSINESS	12 Months Ended
	Dec. 31, 2023
DESCRIPTION OF THE BUSINESS
DESCRIPTION OF THE BUSINESS	1. DESCRIPTION OF THE BUSINESS ​ Matson, Inc., a holding company incorporated in the State of Hawaii, and its subsidiaries (“Matson” or the “Company”), is a leading provider of ocean transportation and logistics services. The Company consists of segments, Ocean Transportation and Logistics. For financial information on the Company’s reportable segments for the three years ended December 31, 2023, see Note 3. ​ Ocean Transportation: Matson’s Ocean Transportation business is conducted through Matson Navigation Company, Inc. (“MatNav”), a wholly-owned subsidiary of Matson, Inc. Founded in 1882, MatNav provides a vital lifeline of ocean freight transportation services to the domestic non-contiguous economies of Hawaii, Alaska and Guam, and to other island economies in Micronesia. MatNav also operates premium, expedited services from China to Long Beach, California, provides services to Okinawa, Japan and various islands in the South Pacific, and operates an international export service from Dutch Harbor, Alaska to Asia. In addition, subsidiaries of MatNav provide stevedoring, refrigerated cargo services, inland transportation and other terminal services for MatNav on the Hawaiian islands of Oahu, Hawaii, Maui and Kauai, and for MatNav and other ocean carriers in Alaska. ​ Matson has a 35 percent ownership interest in SSA Terminals, LLC, a joint venture between Matson Ventures, Inc., a wholly-owned subsidiary of MatNav, and SSA Ventures, Inc., a subsidiary of Carrix, Inc. (“SSAT”). SSAT currently provides terminal and stevedoring services to various carriers at facilities dedicated for MatNav’s use. Matson records its share of income from SSAT in costs and expenses in the Consolidated Statements of Income and Comprehensive Income, and within the Ocean Transportation segment due to the nature of SSAT’s operations (see Note 4). ​ Logistics: Matson’s Logistics business is conducted through Matson Logistics, Inc. (“Matson Logistics”), a wholly-owned subsidiary of MatNav. Established in 1987, Matson Logistics extends the geographic reach of Matson’s transportation network throughout North America and Asia, and is an asset-light business that provides a variety of logistics services to its customers including: (i) multimodal transportation brokerage of domestic and international rail intermodal services, long-haul and regional highway trucking services, specialized hauling, flat-bed and project services, less-than-truckload services, and expedited freight services (collectively, “Transportation Brokerage” services); (ii) less-than-container load (“LCL”) consolidation and freight forwarding services (collectively, “Freight Forwarding” services); (iii) warehousing, trans-loading, value-added packaging and distribution services (collectively, “Warehousing” services); and (iv) supply chain management, non-vessel operating common carrier (“NVOCC”) freight forwarding and other services. ​

SIGNIFICANT ACCOUNTING POLICIES

SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
SIGNIFICANT ACCOUNTING POLICIES
SIGNIFICANT ACCOUNTING POLICIES	2. SIGNIFICANT ACCOUNTING POLICIES ​ Principles of Consolidation: The Consolidated Financial Statements include the accounts of Matson, Inc. and all wholly-owned subsidiaries, after elimination of intercompany amounts and transactions. Significant investments in businesses, partnerships, and limited liability companies in which the Company does not have a controlling financial interest, but has the ability to exercise significant influence, are accounted for under the equity method. The Company accounts for its investment in SSAT using the equity method of accounting (see Note 4). ​ Fiscal Year: The year end for Matson is December 31. The period end for MatNav occurred on the last Friday in December, except for certain Company subsidiaries whose period closed on December 31. Included in these Consolidated Financial Statements are 53 ​ Foreign Currency Transactions: The United States (U.S.) dollar is the functional currency for substantially all of the financial statements of the Company’s foreign subsidiaries. Foreign currency denominated assets and liabilities of the Company’s foreign subsidiaries are translated into U.S. dollars at exchange rates existing at the respective balance sheet dates. Translation adjustments resulting from fluctuations in exchange rates are recorded as a component of accumulated other comprehensive loss (gain) within shareholders’ equity. The Company translates the result of operations of its foreign subsidiaries at the average exchange rate during the respective periods. Gains and losses resulting from foreign currency transactions are included in Costs and Expenses in the Consolidated Statements of Income and Comprehensive Income. ​ Use of Estimates: The preparation of the Consolidated Financial Statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the amounts reported. Estimates and assumptions are used for, but not limited to: impairment of investments; impairment of long-lived assets, intangible assets and goodwill; capitalized interest; allowance for doubtful accounts and other receivables; legal contingencies; insurance reserves and other related liabilities; contingent acquisition related consideration; accrual estimates; pension and post-retirement estimates; multi-employer withdrawal liabilities; operating lease assets and liabilities; income (loss) from SSAT; and income taxes. Future results could be materially affected if actual results differ from these estimates and assumptions. ​ Cash, Cash Equivalents and Restricted Cash: Cash equivalents consist of highly-liquid investments with original maturities of three months or less. The Company carries these investments at cost, which approximates fair value. Restricted cash relates to amounts that are subject to contractual restrictions and are not readily available. Restricted cash was 31, 2023 and 2022, respectively, and are included in prepaid expenses and other assets in the Consolidated Balance Sheets. ​ Accounts Receivable, net: Accounts receivable represent amounts due from trade customers arising in the normal course of business. Accounts receivable are shown net of allowance for doubtful accounts receivable in the Consolidated Balance Sheets. Allowance for doubtful accounts receivable is established by management based on estimates of collectability. Estimates of collectability are principally based on an evaluation of the current financial condition of the customer and the potential risks to collection, the customer’s payment history, expected future credit losses and other factors which are regularly monitored by the Company. ​ Changes in the allowance for doubtful accounts receivable for the three years ended December 31, 2023, 2022 and 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Write-offs Balance at Year (in millions) Beginning of Year Expense (1) and Other End of Year 2023 ​ $ 13.0 ​ $ (2.1) ​ $ (1.0) ​ $ 9.9 2022 ​ $ 10.1 ​ $ 3.2 ​ $ (0.3) ​ $ 13.0 2021 ​ $ 6.3 ​ $ 4.2 ​ $ (0.4) ​ $ 10.1 (1) Expense is shown net of amounts recovered from previously reserved doubtful accounts receivable. ​ Prepaid Expenses and Other Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Prepaid Expenses and Other Assets (in millions) 2023 2022 Income tax receivables, net ​ $ 125.2 ​ $ 170.8 ​ Prepaid fuel ​ ​ 22.5 ​ ​ 26.3 ​ Prepaid insurance and insurance related receivables ​ 19.3 ​ 17.4 ​ Restricted cash - vessel construction obligations ​ ​ 2.3 ​ ​ 3.9 ​ Other ​ 19.6 ​ 22.9 ​ Total ​ $ 188.9 ​ $ 241.3 ​ ​ Income tax receivables primarily include a federal income tax refund related to the Company’s 2021 federal tax return of approximately $118.6 million, overpayments of federal and state taxes paid during the year ended December 31, 2023, and other income tax receivables. ​ Deferred Loan Fees: The Company records deferred loan fees, excluding those related to the revolving credit facility, as a reduction to Total Debt in the Company’s Consolidated Balance Sheets in accordance with Accounting Standards Update (“ASU”) 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”). These costs are being amortized over the life of the related debt using the effective interest method (see Note 8). ​ Deferred loan fees related to the Company’s revolving credit facility are recorded in other long-term assets in the Company’s Consolidated Balance Sheets and are amortized using the straight-line method, as the difference between that method and the use of the effective interest method is not material. ​ Other Long-Term Assets: Other long-term assets consist of the following at December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Long-Term Assets (in millions) 2023 2022 Vessel and equipment spare parts ​ $ 14.2 ​ $ 13.2 ​ Pension plan assets ​ ​ 34.8 ​ ​ 18.9 ​ Insurance related receivables ​ ​ 10.2 ​ ​ 12.1 ​ Other ​ ​ 7.2 ​ ​ 9.4 ​ Total ​ $ 66.4 ​ $ 53.6 ​ ​ Property and Equipment: Property and equipment is stated at cost. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives of property and equipment range up to the following maximum life as follows: ​ ​ ​ ​ Classification Life Vessels 40 years Terminal cranes 30 years Containers and chassis ​ 15 years Terminal facilities and other property 35 years ​ Capitalized Interest: The Company capitalizes interest costs during the period the qualified assets are being readied for their intended use. The Company determined that vessel construction costs are considered qualifying assets for the purposes of capitalizing interest on these assets. The amount of capitalized interest is calculated based on the amount of payments incurred related to the construction of these vessels using a weighted average interest rate. The weighted average interest rate is determined using the Company’s average borrowings outstanding during the period. Capitalized interest is included in vessel construction in progress in property and equipment in the Company’s Consolidated Balance Sheets (see Note 5). During the years ended December 31, 2023, 2022 and 2021, the Company capitalized ​ Leases: Accounting Standards Codification (“ASC”) 842, Leases requires lessees to record leases on their balance sheets but recognize the expenses in their income statements. ASC 842 states that a lessee would recognize a lease liability for the obligation to make lease payments, and a right-of-use asset for the underlying leased asset for the period of the lease term. Refer to Note 9 for additional information on the Company’s lease related disclosures. ​ Deferred Dry-docking Costs: U.S. flagged vessels must meet specified seaworthiness standards established by U.S. Coast Guard rules and classification society rules. These standards require U.S. flagged vessels to undergo between them. However, U.S. flagged vessels that are enrolled in the U.S. Coast Guard’s Underwater Survey in lieu of Dry-docking (“UWILD”) program are allowed to have their Intermediate Survey dry-docking requirement met with a less costly underwater inspection. Non-U.S. flagged vessels are required to meet applicable classification society rules and their own local standards for seaworthiness, which also mandate vessels to undergo . ​ The Company is responsible for maintaining its vessels in compliance with U.S. and international standards. As costs associated with dry-docking inspections provide future economic benefits to the Company through continued operation of the vessels, the costs are deferred and amortized until the scheduled date of the next required dry-docking, which is usually over a two period. Amortization of deferred dry-docking costs are charged to operating expenses of the Ocean Transportation segment in the Consolidated Statements of Income and Comprehensive Income. Routine vessel maintenance and repairs are charged to expense as incurred. ​ Goodwill and Intangible Assets: Goodwill and intangible assets arise as a result of acquisitions made by the Company (see Note 6). Intangible assets consist of customer relationships which are being amortized using the straight-line method over the expected useful lives ranging up to ​ Impairment Evaluation of Long-Lived Assets, Intangible Assets and Goodwill : The Company evaluates its long-lived assets, intangible assets and goodwill for possible impairment in the fourth quarter, or whenever events or changes in circumstances indicate that it is more likely than not that the fair value is less than its carrying amount. The Company has reporting units within the Ocean Transportation and Logistics reportable segments. ​ Long-lived assets and finite-lived intangible assets are grouped at the lowest level reporting unit for which identifiable cash flows are available. In evaluating for impairment, the estimated future undiscounted cash flows generated by each of these asset groups are compared with the carrying value recorded for each asset group to determine if its carrying value is recoverable. If this review determines that the amount recorded will not be recovered, the amount recorded for the asset group is reduced to its estimated fair value. ​ Indefinite-life intangible assets and goodwill are grouped at the lowest level reporting unit for which identifiable cash flows are available. In estimating the fair value of a reporting unit, the Company uses a combination of a discounted cash flow model and fair value based on market multiples of earnings before interest, taxes, depreciation and amortization. Based upon the Company’s evaluation of its indefinite-life intangible assets and goodwill for impairment, the Company determined that the fair value of each reporting unit exceeds book value. ​ Impairment Evaluation of SSAT: The Company’s investment in SSAT, a related party, is evaluated for impairment whenever there is evidence of impairment during the reporting period. If any impairment is identified, the Company evaluates if the decrease in the fair value of the investment below its carrying value is other-than-temporary. ​ Other Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Liabilities (in millions) 2023 2022 Payroll and vacation $ 38.3 $ 34.7 ​ Employee incentives and other benefits ​ ​ 33.9 ​ ​ 33.2 ​ Insurance reserves and other related liabilities - short term ​ ​ 17.5 ​ ​ 15.6 ​ Multi-employer withdrawal liabilities - short term ​ ​ 4.1 ​ ​ 4.1 ​ Income tax and other tax related liabilities ​ ​ 1.6 ​ ​ 2.2 ​ Other short-term liabilities ​ ​ 12.6 ​ ​ 15.7 ​ Total $ 108.0 $ 105.5 ​ ​ Other Long-Term Liabilities: Other long-term liabilities consist of the following at December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Long-Term Liabilities (in millions) 2023 2022 Multi-employer withdrawal liability ​ $ 46.5 ​ $ 48.6 ​ Insurance reserves and other related liabilities ​ ​ 23.8 ​ ​ 29.8 ​ Pension and post-retirement liabilities ​ ​ 21.8 ​ ​ 17.8 ​ Other long-term liabilities ​ 21.6 ​ 18.6 ​ Total ​ $ 113.7 ​ $ 114.8 ​ ​ Pension and Post-Retirement Plans: The Company is a member of the Pacific Maritime Association (“PMA”) and the Hawaii Stevedoring Industry Committee, which negotiate multi-employer pension plans covering certain shoreside bargaining unit personnel. The Company directly negotiates multi-employer pension plans covering other bargaining unit personnel. Pension costs are accrued in accordance with contribution rates established by the PMA, the parties to a plan or the trustees of a plan. Several trusteed, non-contributory, single-employer defined benefit plans and defined contribution plans cover substantially all other employees. ​ The estimation of the Company’s pension and post-retirement benefit expenses and liabilities requires that the Company make various assumptions. These assumptions include factors such as discount rates, expected long-term rates of return on pension plan assets, salary growth, health care cost trend rates, inflation, retirement rates, mortality rates, and expected contributions. Actual results that differ from the assumptions made could materially affect the Company’s financial condition or its future operating results. Additional information about the Company’s pension and post-retirement plans is included in Note 11. ​ Insurance Related Liabilities: The Company purchases insurance with deductibles or self-insured retentions to mitigate significant risks that it is exposed to. Such insurance includes, but is not limited to, employee health, workers’ compensation, marine liability, cybersecurity, auto liability and physical damage to property and equipment. For certain risks, the Company elects to not purchase insurance because of the excessive cost of insurance, the perceived remoteness of the risk or insurance coverage is not commercially available. The Company retains the risk of loss for insurance deductibles and self-insured retentions, for amounts that exceed the limits of the Company’s insurance policies, and for other risks not covered by insurance. ​ When estimating its reserves for retained risks and related liabilities, the Company considers a number of factors, including historical claims experience, demographic factors, current trends, and analyses provided by independent third parties. Periodically, management reviews its assumptions and estimates used to determine the adequacy of the Company’s reserves for retained risks and other related liabilities. ​ Recognition of Revenues and Expenses: Revenue in the Company’s Consolidated Financial Statements is presented net of elimination of intercompany transactions. The following is a description of the Company’s principal revenue generating activities by segment, and the Company’s revenue recognition policy for each activity for the periods presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Ocean Transportation (in millions) (1) ​ 2023 ​ 2022 ​ 2021 Ocean Transportation services ​ $ 2,420.8 ​ $ 3,508.0 ​ $ 3,101.9 Terminal and other related services ​ ​ 36.9 ​ ​ 18.5 ​ ​ 16.0 Fuel sales ​ ​ 12.3 ​ ​ 11.3 ​ ​ 7.2 Vessel management and related services ​ ​ 7.0 ​ ​ 6.8 ​ ​ 7.7 Total ​ $ 2,477.0 ​ $ 3,544.6 ​ $ 3,132.8 (1) Ocean Transportation revenue transactions are primarily denominated in U.S. dollars except for less than 3 percent of Ocean Transportation services revenue and fuel sales revenue categories which are denominated in foreign currencies. ​ ◾ Ocean Transportation services revenue is recognized ratably over the duration of a voyage based on the relative transit time completed in each reporting period. Vessel operating costs and other ocean transportation operating costs, such as terminal operating overhead and selling, general and administrative expenses, are charged to operating costs as incurred. ◾ Terminal and other related services revenue is recognized as the services are performed. Related costs are recognized as incurred. ◾ Fuel sales revenue and related costs are recognized when the Company has completed delivery of the product to the customer in accordance with the terms and conditions of the contract. ◾ Vessel management and related services revenue is recognized in proportion to the services completed. Related costs are recognized as incurred. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Logistics (in millions) (1) ​ 2023 ​ 2022 ​ 2021 Transportation Brokerage and Freight Forwarding services ​ $ 546.8 ​ $ 695.1 ​ $ 707.4 Warehousing and distribution services ​ ​ 42.5 ​ ​ 53.5 ​ ​ 44.7 Supply chain management and other services ​ 28.3 ​ 49.8 ​ 40.4 Total ​ $ 617.6 ​ $ 798.4 ​ $ 792.5 (1) Logistics revenue transactions are primarily denominated in U.S. dollars except for less than 3 percent of transportation brokerage and freight forwarding services revenue, and supply chain management and other services revenue categories which are denominated in foreign currencies. ​ ◾ Transportation Brokerage and Freight Forwarding services revenue consists of amounts billed to customers for services provided. The primary costs include third-party purchased transportation services, agent commissions, labor and equipment. Revenue and the related purchased third-party transportation costs are recognized over the duration of a delivery based upon the relative transit time completed in each reporting period. Labor, agent commissions, and other operating costs are expensed as incurred. The Company reports revenue on a gross basis as the Company serves as the principal in these transactions because it is responsible for fulfilling the contractual arrangements with the customer and has latitude in establishing prices. ◾ Warehousing and distribution services revenue consist of amounts billed to customers for storage, handling, and value-added packaging of customer merchandise. Storage revenue is recognized in the month the service is provided to the customer. Storage related costs are recognized as incurred. Other warehousing and distribution services revenue and related costs are recognized in proportion to the services performed. ◾ Supply chain management and other services revenue, and related costs are recognized in proportion to the services performed. ​ The Company generally invoices its customers at the commencement of the voyage or the transportation service being provided, or as other services are being performed. Revenue is deferred when services are invoiced in advance to the customer. The Company’s receivables are classified as short-term as collection terms are for periods of less than one year. The Company expenses sales commissions and contract acquisition costs as incurred because the amounts are generally immaterial. These expenses are included in selling, general and administration expenses in the Consolidated Statements of Income and Comprehensive Income. ​ Customer Concentration: The Ocean Transportation segment serves customers in numerous industries and carries a wide variety of cargo, mitigating its dependence upon any single customer or single type of cargo. In 2023, the Company’s percent of the Company’s Ocean Transportation operating revenue. ​ The Logistics segment serves customers in numerous industries and geographical locations. In 2023, the Company’s percent of the Company’s Logistics operating revenue. ​ Dividends: ​ Repurchase of Shares: During the years ended December 31, 2023, 2022 and 2021, the Company repurchased approximately million, respectively. As of December 31, 2023, the number of remaining shares that may be repurchased under the Company’s share repurchase program was approximately ​ Share-Based Compensation: The Company records compensation expense for all share-based awards made to employees and directors. The Company’s various stock-based compensation plans are more fully described in Note 15. ​ Income Taxes: The estimate of the Company’s income tax expense requires the Company to make various estimates and judgments. These estimates and judgments are applied in the calculation of taxable income, tax credits, tax benefits, CCF and other tax deductions, and in the calculation of certain deferred tax assets and liabilities, which arise from differences in the timing of recognition of revenue, costs and expenses for tax purposes. The Company also considers the impact of expected future events such as changes in tax rates, changes in tax laws, regulations and rulings. Deferred tax assets and liabilities are adjusted to the extent necessary to reflect tax rates expected to be in effect when the temporary differences reverse. ​ The Company records a valuation allowance if, based on the weight of available evidence, management believes that it is more likely than not that some portion or all of a recorded deferred tax asset would not be realized in future periods. The Company’s income taxes are more fully described in Note 10. ​ Rounding: Amounts in the Consolidated Financial Statements and Notes to the Consolidated Financial Statements are rounded to tenth of millions, except for per share calculations and percentages which were determined based on amounts before rounding. Accordingly, a recalculation of some per-share amounts and percentages, if based on the reported data, may be slightly different. ​ New Accounting Pronouncements: ​ In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”). ASU 2023-07 requires disclosure of incremental segment information on an annual and interim basis. The ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, and requires retrospective application to all prior periods presented in the financial statements. Early adoption is permitted. The Company is currently evaluating the effects of adopting ASU 2023-07 but does not expect it will have a material impact on the Company’s consolidated financial statements. ​ In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024, and interim periods within fiscal years beginning after December 15, 2025. The Company is currently evaluating the effects of adoption ASU 2023-09 but does not expect it to have a material impact on the Company’s consolidated financial statements.

REPORTABLE SEGMENTS

REPORTABLE SEGMENTS	12 Months Ended
	Dec. 31, 2023
REPORTABLE SEGMENTS
REPORTABLE SEGMENTS	3. REPORTABLE SEGMENTS ​ Reportable segments are components of an enterprise that engage in business activities from which it may earn revenues and incur expenses, whose operating results are regularly reviewed by the chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and for which discrete financial information is available. The Company’s chief operating decision maker is its Chief Executive Officer. ​ The Company consists of two reportable segments, Ocean Transportation and Logistics, which are further described in Note 1. Reportable segments are measured based on operating income. In arrangements where the customer purchases ocean transportation and logistics services, the revenues are allocated to each reportable segment based upon the contractual amounts for each type of service. The Company’s SSAT segment has been aggregated into the Company’s Ocean Transportation segment due to the operations of SSAT being an integral part of the Company’s Ocean Transportation business (see Note 4). ​ The Company’s Ocean Transportation segment provides ocean transportation services to the Logistics segment, and the Logistics segment provides logistics services to the Ocean Transportation segment in certain transactions. Accordingly, inter-segment revenue of million for the years ended December 31, 2023, 2022 and 2021, respectively, have been eliminated from operating revenues in the table below. ​ Reportable segment financial information for the years ended December 31, 2023, 2022 and 2021, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Operating Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation (1) ​ $ 2,477.0 ​ $ 3,544.6 ​ $ 3,132.8 Logistics (2) ​ 617.6 ​ 798.4 ​ 792.5 Total Operating Revenue ​ $ 3,094.6 ​ $ 4,343.0 ​ $ 3,925.3 Operating Income: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation (3) ​ $ 294.8 ​ $ 1,281.2 ​ $ 1,137.7 Logistics ​ 48.0 ​ 72.4 ​ 49.8 Total Operating Income ​ 342.8 ​ 1,353.6 ​ 1,187.5 Interest income ​ ​ 36.0 ​ ​ 8.2 ​ ​ — Interest expense ​ (12.2) ​ (18.0) ​ (22.6) Other income (expense), net ​ 6.4 ​ 8.5 ​ 6.4 Income before Taxes ​ 373.0 ​ 1,352.3 ​ 1,171.3 Income taxes ​ (75.9) ​ (288.4) ​ (243.9) Net Income ​ $ 297.1 ​ $ 1,063.9 ​ $ 927.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Capital Expenditures: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation ​ $ 240.2 ​ $ 190.9 ​ $ 322.4 Logistics ​ 8.2 ​ 18.4 ​ 2.9 Total Capital Expenditures ​ $ 248.4 ​ $ 209.3 ​ $ 325.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Depreciation and Amortization: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation ​ $ 132.8 ​ $ 133.2 ​ $ 128.6 Logistics ​ 11.6 ​ 8.1 ​ 7.3 ​ ​ ​ 144.4 ​ ​ 141.3 ​ ​ 135.9 Deferred dry-docking amortization - Ocean Transportation ​ ​ 25.3 ​ ​ 24.9 ​ ​ 24.3 Total Depreciation and Amortization ​ $ 169.7 ​ $ 166.2 ​ $ 160.2 (1) Ocean Transportation operating revenue excludes inter-segment revenue of $76.5 million, $93.6 million and $81.0 million for the years ended December 31, 2023, 2022 and 2021, respectively. (2) Logistics operating revenue excludes inter-segment revenue of $132.2 million, $177.3 million and $132.8 million for the years ended December 31, 2023, 2022 and 2021, respectively. (3) Ocean Transportation segment information includes $2.2 million, $83.1 million, and $56.3 million of income from the Company’s investment in SSAT for the years ended December 31, 2023, 2022 and 2021, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) 2023 2022 Identifiable Assets: ​ ​ ​ ​ ​ ​ Ocean Transportation (1) ​ $ 3,645.3 ​ $ 3,705.2 Logistics ​ 649.3 ​ 624.8 Total Assets ​ $ 4,294.6 ​ $ 4,330.0 (1) The Ocean Transportation segment includes $85.5 million and $81.2 million related to the Company’s investment in SSAT as of December 31, 2023 and 2022, respectively.

INVESTMENT IN SSAT

INVESTMENT IN SSAT	12 Months Ended
	Dec. 31, 2023
INVESTMENT IN SSAT
INVESTMENT IN SSAT	4. INVESTMENT IN SSAT ​ The Company accounts for its 35 percent ownership interest in SSAT using the equity method of accounting. The Company records its share of income from SSAT in costs and expenses within the Ocean Transportation segment due to operations of SSAT being an integral part of the Company’s Ocean Transportation business. The Company’s investment in SSAT was 31, 2023 and 2022, respectively. On September 16, 2022, SSAT completed the purchase of a percent equity interest in SSAT Terminals (Oakland), LLC (“SSAT Oakland”) from a third-party company. After completion of this transaction, SSAT Oakland became a wholly owned subsidiary of SSAT. The operating results of SSAT Oakland consolidate into the operating results of SSAT. As a result of this transaction, the Company recorded a decrease of 31, 2022. ​ The Company’s share of income recorded in the Consolidated Statements of Income and Comprehensive Income and dividends received by the Company during the years ended December 31, 2023, 2022 and 2021 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Company’s share of income from SSAT ​ $ 2.2 ​ $ 83.1 ​ $ 56.3 Distributions received from SSAT ​ $ — ​ $ 47.3 ​ $ 46.9 ​ The Company’s Ocean Transportation segment operating costs for terminal services provided by SSAT include $297.2 million, $308.3 million and $284.9 million for the years ended December 31, 2023, 2022 and 2021, respectively. Accounts payable and accrued liabilities in the Consolidated Balance Sheets for terminal services payable to SSAT include ​ A summary of the Condensed Balance Sheets of SSAT at December 31, 2023 and 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Condensed Balance Sheets (in millions) 2023 2022 Current assets ​ $ 304.0 ​ $ 324.7 Non-current assets ​ 1,510.2 ​ 1,436.0 Total Assets ​ $ 1,814.2 ​ $ 1,760.7 ​ ​ ​ ​ ​ ​ ​ Current liabilities ​ $ 271.8 ​ $ 342.1 Non-current liabilities ​ 1,255.3 ​ 1,199.5 Equity ​ 287.1 ​ 219.1 Total Liabilities and Equity ​ $ 1,814.2 ​ $ 1,760.7 ​ A summary of the Condensed Statements of Operating Income and Net Income of SSAT for the years ended December 31, 2023, 2022 and 2021 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Condensed Statements of Operating Income and Net Income (in millions) 2023 2022 2021 Operating revenue ​ $ 1,025.1 ​ $ 1,466.9 ​ $ 1,297.5 Operating costs and expenses ​ 1,019.6 ​ 1,168.8 ​ 1,113.8 Operating income ​ 5.5 ​ 298.1 ​ 183.7 Net Income (1)(2) ​ $ 11.9 ​ $ 249.6 ​ $ 161.7 (1) Includes earnings from equity method investments held by SSAT less earnings allocated to non-controlling interests. (2) Includes net income or loss attributable to noncontrolling interests. ​

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2023
PROPERTY AND EQUIPMENT
PROPERTY AND EQUIPMENT	5. PROPERTY AND EQUIPMENT ​ Property and equipment consists of the following as of December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2023 ​ As of December 31, 2022 ​ ​ ​ Accumulated ​ ​ ​ Accumulated ​ (In millions) ​ Cost ​ Depreciation ​ Net Book Value ​ Cost ​ Depreciation ​ Net Book Value Vessels ​ $ 2,323.4 ​ $ 886.8 ​ $ 1,436.6 ​ ​ $ 2,278.6 ​ $ 838.8 ​ $ 1,439.8 ​ Containers and equipment ​ 845.0 ​ ​ 451.9 ​ 393.1 ​ ​ 762.7 ​ 433.8 ​ 328.9 ​ Terminal facilities and other property ​ 148.0 ​ ​ 58.6 ​ 89.4 ​ ​ 131.5 ​ 53.6 ​ 77.9 ​ New vessel construction in progress ​ ​ 103.1 ​ ​ — ​ ​ 103.1 ​ ​ ​ 50.2 ​ ​ — ​ ​ 50.2 ​ Other construction in progress ​ 67.7 ​ ​ — ​ 67.7 ​ ​ 65.7 ​ — ​ 65.7 ​ Total ​ $ 3,487.2 ​ $ 1,397.3 ​ $ 2,089.9 ​ ​ $ 3,288.7 ​ $ 1,326.2 ​ $ 1,962.5 ​ ​ New vessel construction in progress at December 31, 2023 and 2022 includes milestone progress payments, capitalized interest and other costs related to the construction of three new Jones Act vessels. Delivery of the first vessel is currently anticipated to be in the fourth quarter of 2026, with subsequent deliveries expected in the second and fourth quarters of 2027. ​ Depreciation expense for the years ended December 31, 2023, 2022 and 2021 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Depreciation expense ​ $ 124.4 ​ $ 123.5 ​ $ 117.1 ​ ​

GOODWILL AND INTANGIBLES

GOODWILL AND INTANGIBLES	12 Months Ended
	Dec. 31, 2023
GOODWILL AND INTANGIBLES
GOODWILL AND INTANGIBLES	6. GOODWILL AND INTANGIBLE ASSETS ​ Goodwill by segment consists of the following as of December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean ​ ​ ​ ​ ​ ​ (In millions) Transportation Logistics Total Goodwill ​ $ 222.6 ​ $ 105.2 ​ $ 327.8 ​ Ocean Transportation goodwill of $222.6 million includes $221.8 million related to the acquisition of Horizon Lines, Inc. (“Horizon”) in May 2015. Logistics goodwill of ​ Intangible assets by segment consist of the following as of December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2023 ​ As of December 31, 2022 ​ ​ Gross ​ Accumulated ​ ​ ​ ​ Gross ​ Accumulated ​ ​ ​ (In millions) Amount Amortization Net Book Value Amount Amortization Net Book Value Ocean Transportation - Customer relationships ​ $ 140.6 ​ $ 57.9 ​ $ 82.7 ​ ​ $ 140.6 ​ $ 51.2 ​ $ 89.4 ​ Logistics: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer relationships ​ ​ 110.4 ​ ​ 44.0 ​ ​ 66.4 ​ ​ ​ 95.3 ​ ​ 37.1 ​ ​ 58.2 ​ Trade name ​ 27.3 ​ ​ — ​ ​ 27.3 ​ ​ 27.3 ​ ​ — ​ ​ 27.3 ​ Total Logistics ​ 137.7 ​ ​ 44.0 ​ ​ 93.7 ​ ​ 122.6 ​ ​ 37.1 ​ ​ 85.5 ​ Total ​ $ 278.3 ​ $ 101.9 ​ $ 176.4 ​ ​ $ 263.2 ​ $ 88.3 ​ $ 174.9 ​ ​ In February 2023, the Company completed an asset acquisition consisting of customer relationship intangible assets for $16.5 million, which are being amortized over seven years. ​ Ocean Transportation intangible assets of $140.6 million relate to customer relationships acquired as part of the acquisition of Horizon, and are being amortized over 21 years . Logistics intangible assets include acquired as part of the Span Alaska acquisition. The remaining Logistics customer relationships relate to various acquisitions and are being amortized over a period of ​ Intangible assets related amortization expense for the years ended December 31, 2023, 2022 and 2021, are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Amortization expense ​ $ 13.6 ​ $ 11.4 ​ $ 10.9 ​ ​ As of December 31, 2023, estimated amortization expense related to customer relationship intangible assets during the next five years and thereafter are as follows: ​ ​ ​ ​ ​ ​ ​ Customer ​ Year (in millions) ​ Relationships 2024 ​ $ 14.3 ​ 2025 ​ 13.6 ​ 2026 ​ 13.0 ​ 2027 ​ 13.0 ​ 2028 ​ 13.0 ​ Thereafter ​ 82.2 ​ Total ​ $ 149.1 ​ ​

CAPITAL CONSTRUCTION FUND

CAPITAL CONSTRUCTION FUND	12 Months Ended
	Dec. 31, 2023
CAPITAL CONSTRUCTION FUND
CAPITAL CONSTRUCTION FUND	7. CAPITAL CONSTRUCTION FUND ​ The Company is party to an agreement with the U.S. Department of Transportation, Maritime Administration (“MARAD”) that established a Capital Construction Fund (“CCF”) program under provisions of the Merchant Marine Act of 1936, as amended (the “Merchant Marine Act”). The CCF program was created to assist owners and operators of U.S. flagged vessels in raising capital necessary for the modernization and expansion of the U.S. merchant marine fleet. CCF funds may be used for the acquisition, construction, or reconstruction of vessels, and for repayment of existing vessel indebtedness through the deferment of federal income taxes on certain deposits of monies and other property placed into the CCF. Qualified withdrawals from the CCF must be used for investment in vessels built in the U.S. and used between covered U.S. ports as described by the Merchant Marine Act, and for other qualifying expenditures (see Item 1 of Part 1 for additional information on Maritime Laws and the Jones Act). Participants of the CCF must also meet certain U.S. citizenship requirements. ​ Cash deposits into the CCF are limited by certain applicable earnings and other conditions. Such cash deposits, once made, are available as tax deductions in the Company’s income tax provision. Qualified withdrawals from the CCF do not give rise to a current income tax liability, but reduce the depreciable basis of the vessels or certain related equipment for income tax purposes. However, if withdrawals are made from the CCF for general corporate purposes or other non-qualified purposes, or upon termination of the agreement, they are taxable with interest payable from the year of deposit. ​ Deposits not committed for qualified purposes within 25 years from the date of deposit will be treated as non-qualified withdrawals over the subsequent five years . Under the terms of the CCF agreement, the Company may designate certain qualified earnings as “accrued deposits” or may designate, as obligations of the CCF, qualified withdrawals to reimburse qualified expenditures initially made with operating funds. Such accrued deposits to, and withdrawals from, the CCF are reflected in the Consolidated Balance Sheets either as obligations of the Company’s current assets or as receivables from the CCF. ​ The Company may invest funds on deposit in the CCF in money market funds, U.S. Treasury Obligation Funds or other eligible credit-based investments for maturities of up to 3 years. ​ A summary of the activities within the CCF cash account for the years ended December 31, 2023 and 2022 consists of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, (In millions) ​ 2023 2022 CCF balance at beginning of period ​ $ 518.2 ​ $ — Cash deposits into CCF ​ ​ 100.0 ​ ​ 579.7 Interest earned on deposits ​ ​ 31.1 ​ ​ 3.1 Qualifying withdrawal payments ​ ​ (49.9) ​ ​ (64.6) CCF balance at end of period ​ $ 599.4 ​ $ 518.2 ​ Cash on deposit and assigned accounts receivables in the CCF as of December 31, 2023 and 2022 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) ​ 2023 2022 Capital Construction Fund: ​ ​ ​ ​ ​ ​ Cash on deposit ​ $ 599.4 ​ $ 518.2 Assigned accounts receivables ​ $ 218.1 ​ $ 9.9 ​ Cash on deposit in the CCF is invested in a U.S. Treasury obligations fund with daily liquidity. At December 31, 2023, securities held within the U.S. Treasury obligations fund had a weighted average life of 68 days . Cash on deposit in the CCF is classified as a long-term asset on the Company’s Condensed Consolidated Balance Sheets, as the Company intends to use withdrawals to fund qualified milestone progress payments for the construction of ​ In February 2024, the Company purchased approximately $450 million of fixed-rate U.S. Treasuries with CCF cash deposits. The fixed-rate investments have various maturity dates up to ​ Assigned accounts receivable in the CCF are classified as part of accounts receivable on the Company’s Consolidated Balance Sheets due to the nature of the assignment.

DEBT

DEBT	12 Months Ended
	Dec. 31, 2023
DEBT
DEBT	8. DEBT ​ The Company’s debt consists of the following as of December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) 2023 2022 Private Placement Term Loans: ​ ​ ​ ​ ​ ​ 3.66 %, payable through 2023 ​ $ — ​ $ 4.5 3.37 %, payable through 2027 ​ ​ 46.2 ​ ​ 57.7 3.14 %, payable through 2031 ​ ​ 114.4 ​ ​ 132.8 Title XI Debt: ​ ​ ​ ​ ​ ​ 5.34 %, payable through 2028 ​ — ​ 13.2 5.27 %, payable through 2029 ​ — ​ 15.4 1.22 %, payable through 2043 ​ ​ 158.2 ​ ​ 166.2 1.35 %, payable through 2044 ​ ​ 121.8 ​ ​ 127.7 Total Debt ​ 440.6 ​ 517.5 Less: Current portion ​ (39.7) ​ (76.9) Total Long-term Debt ​ ​ 400.9 ​ ​ 440.6 Less: Deferred loan fees ​ ​ (11.6) ​ ​ (12.9) Total Long-term Debt, net of deferred loan fees ​ $ 389.3 ​ $ 427.7 ​ The following is a description of the Company’s debt: ​ Private Placement Term Loans : During 2012, the Company issued tranches. The remaining tranche, at an interest rate of percent, payable semi-annually. In December 2016, the Company issued ​ Title XI Bonds: In September 2003, MatNav issued Manukai (the “Manukai Title XI Bonds”). In August 2004, MatNav issued Maunawili ​ In January 2023, the Company prepaid $14.3 million of outstanding principal on the Maunawili Title XI Bonds representing all of the remaining outstanding principal for this bond. In March 2023, the Company also prepaid the outstanding principal of approximately ​ In April 2020, MatNav issued $185.9 million in U.S. government guaranteed vessel financing bonds to partially refinance debt incurred in connection with the construction of Daniel K. Inouye (the “DKI Title XI Debt”). The secured DKI Title XI Debt matures in October 2043 and has a cash interest rate of percent, payable semi-annually in arrears. ​ In June 2020, MatNav issued $139.6 million in U.S. government guaranteed vessel financing bonds to partially refinance debt incurred in connection with the construction of Kaimana Hila (the “KMH Title XI Debt”, and together with the DKI Title XI Debt, the “2020 Title XI Debt”). The secured KMH Title XI Debt matures in March 2044 and has a cash interest rate of percent, payable semi-annually in arrears. ​ MatNav may prepay any amounts outstanding under the 2020 Title XI Debt agreements subject to a potential prepayment premium or other adjustment, in accordance with the 2020 Title XI Debt agreements. Once amounts under the 2020 Title XI Debt are repaid, they may not be reborrowed. Mandatory prepayments are required under certain limited circumstances, including specified casualty events with respect to Daniel K. Inouye Kaimana Hila (the “Vessels”). ​ Revolving Credit Facility: million. The Credit Agreement amended certain covenants and other terms including (i) amending the pricing grid to provide for pricing ranging from, at the Company’s election, LIBOR plus a margin between to 1.0 in connection with a material acquisition. The Company may prepay any amounts outstanding under the Credit Agreement without premium or penalty. The Credit Agreement contains affirmative, negative and financial covenants customary for financings of this type, including, among other things, limitations on certain other indebtedness, loans and investments, liens, mergers, asset sales, and transactions with affiliates. The Credit Agreement also contains customary events of default. ​ In February 2023, the Company further amended the Credit Agreement to replace LIBOR with a new benchmark interest rate, the Secured Overnight Financing Rate (“SOFR”). There were no other significant changes to the Credit Agreement as a result of this amendment. ​ As of December 31, 2023, the Company had $644.2 million of remaining borrowing availability under the revolving credit facility. The Company used 31, 2023. Borrowings under the revolving credit facility are classified as long-term debt in the Company’s Consolidated Balance Sheets, as principal payments are not required until the maturity date. ​ Amendments to Existing Private Placement Term Loan Facilities and New Shelf Facilities (“Private Loan Facilities”): ​ The 2021 Note Amendments amended certain covenants and other terms, including the reduction of the maximum permitted consolidated leverage ratio to 3.50 to 1.0, with an option for a one-time increase to 4.0 to 1.0 in connection with a material acquisition, with potential interest enhancement payments if leverage is over 3.25 to 1.0. The Company paid fees of approximately ​ Debt Maturities: At December 31, 2023, debt maturities during the next five years and thereafter are as follows: ​ ​ ​ ​ ​ ​ ​ As of Year (in millions) December 31, 2023 2024 ​ $ 39.7 2025 ​ 39.7 2026 ​ 39.7 2027 ​ 39.7 2028 ​ 28.2 Thereafter ​ 253.6 Total Debt ​ $ 440.6 ​ Deferred Loan Fees: Activity relating to deferred loan fees for the year ended December 31, 2023 are as follows: ​ ​ ​ ​ ​ Deferred Loan Fees (in millions) Amount Balance at December 31, 2022 ​ $ 12.9 Amortization expense for the year ended December 31, 2023 ​ (1.3) Balance at December 31, 2023 ​ $ 11.6 ​ As of December 31, 2023, amortization expense relating to deferred loan fees during the next five years and thereafter are as follows: ​ ​ ​ ​ ​ Year (in millions) Amount 2024 ​ $ 1.2 2025 ​ 1.1 2026 ​ 1.0 2027 ​ 0.9 2028 ​ 0.9 Thereafter ​ 6.5 Total amortization expense of deferred loan fees ​ $ 11.6 ​ Debt Covenants in 2020 Title XI Debt Agreements: The 2020 Title XI Debt agreements contain customary representations and warranties as well as affirmative and negative covenants, defaults and other provisions typical for MARAD-guaranteed financings of this type, with definitions, limitations and financial tests all as negotiated between MatNav and MARAD. The covenants in the 2020 Title XI Debt agreements include, among other things, limitations on certain other indebtedness, loans and investments, liens, mergers, asset sales, sale and leasebacks, and transactions with affiliates as defined within the 2020 Title XI Debt agreements. Certain of the covenants in the 2020 Title XI Debt agreements are applicable only upon and during the continuance of either (i) an event of default or (ii) the failure of either the Company or MatNav to meet certain supplemental financial tests, including the following: ​ ● The supplemental financial tests applicable to MatNav include maintenance of a working capital minimum of $1 , and maintenance of a long-term debt to net worth ratio of greater than or equal to 2.0 to 1.0; and ● The supplemental financial tests applicable to the Company include maintenance of a net worth greater than or equal to 90% of the net worth of the Company as set forth in the most recent audited financial statements prior to closing of the issuance of the 2020 Title XI Bonds and compliance with the leverage ratio set forth in the Credit Agreement. ​ Debt Security and Guarantees: ​ Under the 2020 Title XI Debt agreements, MARAD has guaranteed certain obligations of MatNav. MatNav has agreed to reimburse MARAD for any payments it makes under the MARAD guaranty, and MatNav’s obligations to MARAD with respect to the 2020 Title XI Debt are secured by a mortgage on the Vessels and certain other related assets (the “Collateral”). In addition, MatNav’s obligations to MARAD with respect to the 2020 Title XI Debt are guaranteed by the Company under an Affiliate Guaranty.

LEASES

LEASES	12 Months Ended
	Dec. 31, 2023
LEASES
LEASES	9. LEASES ​ Description of Operating Leases: The Company has different types of operating leases, the specific terms and conditions of which vary from lease to lease. Certain operating lease agreements include terms such as: (i) renewal and early termination options; (ii) early buy-out and purchase options; and (iii) rent escalation clauses. The lease agreements also include provisions for the maintenance of the leased asset and payment of lease related costs. The Company reviews the specific terms and conditions of each lease and, as appropriate, notifies the lessor of any intent to exercise any option in accordance with the terms of the lease. In the normal course of business, the Company expects to be able to renew or replace most of its operating leases with other similar leases as they expire. The Company’s leases do not contain any residual value guarantees. ​ The Company’s sub-lease income was nominal to the Company’s Consolidated Statements of Income and Comprehensive Income for the years ended December 31, 2023 and 2022. The Company did not have any finance leases during the years ended December 31, 2023 and 2022. Certain of the Company’s lease agreements include rental payments that may be adjusted in the future based on economic conditions and others include rental payments adjusted periodically for inflation. Variable lease expense is disclosed for the adjusted portion of such payments. ​ The lease type by underlying asset class and maximum terms of the Company’s operating leases are as follows: ​ ​ ​ ​ Lease Type: Term Real estate and terminal leases 50 years Vessel and barge charter leases 4 years Operations equipment and other leases 14 years ​ Incremental Borrowing Rate: As most of the Company’s operating leases do not provide an implicit rate, the Company uses an estimated incremental borrowing rate based on information available at the date of adoption and subsequent lease commencement dates in calculating the present value of its operating lease liabilities. The incremental borrowing rate is determined using the U.S. Treasury rate adjusted to account for the Company’s credit rating and the collateralized nature of operating leases. ​ Components of Lease Cost: Components of lease cost recorded in the Company’s Consolidated Statement of Income and Comprehensive Income consists of the following for the years ended December 31, 2023, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, (In millions) 2023 ​ 2022 ​ 2021 Operating lease cost ​ $ 151.0 ​ $ 162.2 ​ $ 110.7 Short-term lease cost ​ 7.7 ​ 0.6 ​ 3.1 Variable lease cost ​ 0.6 ​ 0.8 ​ 0.6 Total lease cost ​ $ 159.3 ​ $ 163.6 ​ $ 114.4 ​ Other Lease Information: Other information related to the Company’s operating leases consists of the following for the years ended December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, (In millions) 2023 ​ 2022 Cash paid for amounts included in operating lease liabilities ​ $ 154.3 ​ $ 163.4 Right of use assets obtained in the exchange for new operating lease liabilities ​ $ 40.0 ​ $ 131.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2023 2022 Weighted average remaining operating lease term ​ ​ 4.8 years ​ ​ 4.9 years Weighted average incremental borrowing rate ​ ​ 3.1% ​ ​ 2.4% ​ Maturities of operating lease liabilities consist of the following at December 31, 2023: ​ ​ ​ ​ ​ ​ As of Year (in millions) December 31, 2023 2024 ​ $ 143.3 2025 ​ 80.8 2026 ​ 32.1 2027 ​ 15.3 2028 ​ 6.7 Thereafter ​ 51.1 Total lease payments ​ ​ 329.3 Less: Interest ​ ​ (33.3) Present value of operating lease liabilities ​ ​ 296.0 Less: Short-term portion ​ ​ (136.7) Long-term operating lease liabilities ​ $ 159.3 ​

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2023
INCOME TAXES
INCOME TAXES	10. INCOME TAXES ​ Income Taxes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ 44.0 ​ $ 171.5 ​ $ 181.2 ​ State ​ 9.2 ​ 18.3 ​ 35.6 ​ Foreign ​ ​ 3.0 ​ ​ 1.3 ​ ​ 2.5 ​ Total current tax expense ​ 56.2 ​ 191.1 ​ 219.3 ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ 18.2 ​ ​ 71.1 ​ ​ 26.4 ​ State ​ ​ — ​ ​ 24.3 ​ ​ 0.4 ​ Foreign ​ ​ 1.5 ​ ​ 1.9 ​ ​ (2.2) ​ Total deferred tax expense ​ ​ 19.7 ​ ​ 97.3 ​ ​ 24.6 ​ Total income taxes ​ $ 75.9 ​ $ 288.4 ​ $ 243.9 ​ ​ Income taxes for the years ended December 31, 2023, 2022 and 2021 differ from amounts computed by applying the statutory federal rate to income before income taxes as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2023 2022 2021 Computed federal income tax expense 21.0 % 21.0 % 21.0 % State income tax 2.6 % 2.8 % 3.1 % Foreign-derived intangible income (FDII) (2.0) % (2.4) % (2.5) % Valuation allowance — % — % (0.3) % Foreign taxes 0.4 % 0.1 % 0.2 % Share-based payments 0.5 % — % (0.2) % Return to provision true-ups ​ (2.8) % 0.1 % (0.2) % Other — net 0.6 % (0.3) % (0.3) % Effective income tax rate 20.3 % 21.3 % 20.8 % ​ The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and deferred tax liabilities at December 31, 2023 and 2022, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) 2023 2022 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Operating lease liabilities ​ $ 77.4 ​ $ 102.9 ​ Multi-employer withdrawal liabilities ​ ​ 12.8 ​ ​ 13.3 ​ Deferred compensation ​ 11.8 ​ ​ 10.9 ​ U.S. state alternative minimum tax credits ​ ​ 7.4 ​ ​ 8.8 ​ Insurance reserves ​ ​ 6.3 ​ ​ 7.3 ​ Other ​ 12.9 ​ 15.4 ​ Total deferred tax assets ​ 128.6 ​ 158.6 ​ Valuation allowance ​ ​ (5.3) ​ ​ (7.4) ​ Total deferred tax assets, net of valuation allowance ​ ​ 123.3 ​ ​ 151.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Basis differences for property and equipment ​ 451.4 ​ 433.1 ​ Capital Construction Fund ​ 206.9 ​ ​ 194.0 ​ Operating lease right of use assets ​ 75.8 ​ 100.7 ​ Intangibles ​ ​ 42.3 ​ ​ 42.0 ​ Other ​ ​ 16.2 ​ ​ 27.9 ​ Total deferred tax liabilities ​ 792.6 ​ 797.7 ​ Deferred tax liability, net ​ $ 669.3 ​ $ 646.5 ​ ​ Valuation Allowance: 31, 2023 and 2022, respectively. The Company believes that it is more likely than not that the benefit from these deferred assets will not be realized. ​ Income Tax Receivables: The Company has income tax receivables, net of income tax payables, of approximately 31, 2023, and other income tax receivables. These income tax receivable amounts have been included in prepaid expenses and other assets in the Company’s Consolidated Balance Sheets (see Note 2). ​ Net Operating Losses and Tax Credit Carryforwards: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (In millions) ​ Expiration Date 2023 2022 U.S. federal income tax NOLs ​ Various dates beginning in 2027 ​ $ — ​ $ 0.8 U.S. state income tax NOLs (1) ​ Various dates beginning in 2032 ​ $ 152.3 ​ $ 157.9 U.S. state alternative minimum tax credit ​ No expiration date ​ $ 7.3 ​ $ 8.6 (1) U.S. State income tax NOLs are presented on a gross tax basis. The Company does not expect to benefit from $152.3 million of U.S. state income tax NOLs as of December 31, 2023. ​ The U.S. federal and state income tax NOLs in the Company’s filed income tax returns include unrecognized tax benefits. The deferred tax assets recognized for those NOLs are presented net of these unrecognized tax benefits. As a result of changes in tax legislation, the use of a portion of the Company’s domestic NOL and tax credit carryforwards may be limited in future periods. Further, a portion of the federal and state income tax NOLs and tax credit carryforwards may expire before being applied to reduce future income tax liabilities. ​ Unrecognized Tax Benefits: Total unrecognized benefits represent the amount that, if recognized, would favorably affect the Company’s income taxes and effective tax rate in future periods. The Company does not expect a material change in gross unrecognized benefits in the next twelve months. ​ ​ ​ ​ ​ ​ Unrecognized Tax Benefits (in millions) Amount Balance at December 31, 2020 ​ $ 18.3 ​ Tax position changes in current year ​ 2.3 ​ Tax position changes in prior years ​ ​ (1.2) ​ Reductions for lapse of statute of limitations ​ ​ (0.2) ​ Balance at December 31, 2021 ​ 19.2 ​ Tax position changes in current year ​ 5.8 ​ Tax position changes in prior years ​ ​ 0.3 ​ Reductions for lapse of statute of limitations ​ ​ (0.2) ​ Balance at December 31, 2022 ​ 25.1 ​ Tax position changes in current year ​ 3.6 ​ Tax position changes in prior years ​ ​ (0.1) ​ Reductions for lapse of statute of limitations ​ ​ (0.2) ​ Balance at December 31, 2023 ​ $ 28.4 ​ ​ Included in the balance of unrecognized tax benefits at December 31, 2023 are potential benefits of $24.2 million that, if recognized, would affect the Company’s income taxes and effective tax rate. The Company recognizes potential accrued interest and penalties related to unrecognized tax benefits in income taxes. To the extent interest and penalties are not ultimately assessed with respect to the settlement of uncertain tax positions, amounts accrued will be reduced and reflected as a reduction of the Company’s income taxes. Interest and penalties accrued related to the balance of unrecognized tax benefits were million as of December 31, 2022, respectively. During the years ended December 31, 2023 and 2022, the Company recognized ​ The Company is no longer subject to U.S. federal income tax audits for years before 2016. The Company is routinely involved in federal, state, local income and excise tax audits, and foreign tax audits. ​

PENSION AND POST-RETIREMENT PLA

PENSION AND POST-RETIREMENT PLANS	12 Months Ended
	Dec. 31, 2023
PENSION AND POST-RETIREMENT PLANS
PENSION AND POST-RETIREMENT PLANS	11. PENSION AND POST-RETIREMENT PLANS ​ Qualified Pension and Post-retirement Benefits Plans: The Company provides a funded qualified single-employer defined benefit pension plan that covers most non-bargaining employees and certain clerical bargaining unit employees. The Company also provides a post-retirement benefit plan that provides health and life insurance benefits, and covers substantially all salaried, non-bargaining employees hired before 2008, and certain bargaining unit employees. Employees are generally eligible for such benefits upon retirement and completion of a specified number of years of service. The Company does not pre-fund the post-retirement benefit plan and has the right to modify or terminate the plan in the future, with the exception of the benefits pertaining to the bargaining unit employees. Most non-bargaining retirees pay a portion of these post-retirement benefit costs. ​ Plan Administration, Investments and Asset Allocations: The Company has a Benefits Investment Committee that meets regularly with investment advisors to establish investment policies, direct investments and select investment options for the qualified plan. The Benefits Investment Committee is also responsible for appointing investment managers and monitoring their performance. The Company’s investment policy permits investments in marketable equity securities, such as domestic and foreign stocks, domestic and foreign bonds, venture capital, real estate investments, and cash equivalents. The Company’s investment policy does not permit direct investment in certain types of assets, such as options or commodities, or the use of certain strategies, such as short selling or the purchase of securities on margin. ​ The Company’s investment strategy for its qualified pension plan assets is to achieve a diversified mix of investments that provides for long-term growth at an acceptable level of risk, and to provide sufficient liquidity to fund ongoing benefit payments. The Company has engaged a number of investment managers to implement various investment strategies to achieve the desired asset class mix, liquidity and risk diversification objectives. ​ The Company’s target and actual asset allocations at December 31, 2023 and 2022 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ Asset Categories Target 2023 2022 Domestic equity securities 53 % 57 % 53 % International equity securities 15 % 16 % 16 % Debt securities 22 % 19 % 20 % Real estate 5 % 5 % 7 % Other and cash 5 % 3 % 4 % Total 100 % 100 % 100 % ​ The Company’s investments in equity securities primarily include domestic large-cap and mid-cap companies, but also includes an allocation to small-cap and international equity securities. Equity investments do not include any direct holdings of the Company’s stock but may include such holdings to the extent that the stock is included as part of certain mutual fund holdings. Debt securities include investment-grade and high-yield corporate bonds from diversified industries, mortgage-backed securities, and U.S. Treasuries. Other types of investments include funds that invest in commercial real estate assets. All assets within specific funds are allocated to the target asset allocation of the fund. ​ The expected return on plan assets is principally based on the Company’s historical returns combined with the Company’s long-term future expectations regarding asset class returns, the mix of plan assets, and inflation assumptions. Actual return on plan assets for the periods presented are as follows: ​ ​ ​ ​ ​ Actual Return on Plan Assets Returns One-year return 12.8 % Three-year return 4.6 % Five-year return 9.5 % Long-term average return (since plan inception in 1989) 8.2 % ​ The Company’s pension plan assets are held in a trust and are stated at estimated fair values of the underlying investments. Purchases and sales of securities are recorded on a trade-date basis. Interest income is recorded on an accrual basis. Dividends are recorded on the ex-dividend date. ​ Equity Securities: Domestic and international common stocks are valued by obtaining quoted prices on recognized and highly liquid exchanges. ​ Fixed Income Securities: Corporate bonds and U.S. government treasury and agency securities are valued based on the closing price reported in the market in which the security is traded. U.S. government agency and corporate asset-backed securities may utilize models, such as a matrix pricing model, that incorporate other observable inputs when broker/dealer quotes are not available, such as cash flow, security structure, or market information. ​ Real Estate and Certain International Equity Funds: The fair value of real estate and certain developed and emerging market equity funds is determined by the issuer based on their net asset value (“NAV”). NAV is determined by dividing the fund’s net assets, as recorded in the fund’s audited financial statements, by the number of units outstanding at the valuation date. Fair value for the underlying investments in real estate is determined through independent property appraisals. ​ The fair values of the Company’s pension plan assets at December 31, 2023 and 2022 by asset category were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2023 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets ​ Observable ​ Unobservable Asset Category (in millions) ​ Total ​ (Level 1) ​ Inputs (Level 2) ​ Inputs (Level 3) Cash ​ $ 6.1 ​ $ 6.1 ​ $ — ​ $ — ​ Equity securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. large-cap ​ 82.8 ​ 82.8 ​ — ​ — ​ U.S. mid- and small-cap ​ 46.0 ​ 46.0 ​ — ​ — ​ International large-cap ​ 7.1 ​ 7.1 ​ — ​ — ​ Fixed income securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ 19.2 ​ — ​ 19.2 ​ — ​ Municipal bonds ​ 0.2 ​ — ​ 0.2 ​ — ​ Investment grade U.S. corporate bonds ​ ​ 24.7 ​ — ​ 24.7 ​ — ​ Convertible bonds ​ 0.1 ​ — ​ 0.1 ​ — ​ International fixed income securities ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ — ​ Total ​ ​ 186.3 ​ $ 142.0 ​ $ 44.3 ​ $ — ​ Investment measured at NAV (1) ​ ​ 41.6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total plan assets ​ $ 227.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2022 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets ​ Observable ​ Unobservable Asset Category (in millions) ​ Total ​ (Level 1) ​ Inputs (Level 2) ​ Inputs (Level 3) Cash ​ $ 8.8 ​ $ 8.8 ​ $ — ​ $ — ​ Equity securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. large-cap ​ 69.1 ​ 69.1 ​ — ​ — ​ U.S. mid- and small-cap ​ 41.5 ​ 41.5 ​ — ​ — ​ International large-cap ​ 6.2 ​ 6.2 ​ — ​ — ​ Fixed income securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ 17.4 ​ — ​ 17.4 ​ — ​ Municipal bonds ​ 0.2 ​ — ​ 0.2 ​ — ​ Investment grade U.S. corporate bonds ​ 22.8 ​ — ​ 22.8 ​ — ​ Convertible bonds ​ ​ 0.3 ​ — ​ ​ 0.3 ​ ​ ​ ​ International fixed income securities ​ 0.1 ​ — ​ 0.1 ​ — ​ Total ​ ​ 166.4 ​ $ 125.6 ​ $ 40.8 ​ $ — ​ Investment measured at NAV (1) ​ ​ 40.0 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total plan assets ​ $ 206.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Certain funds for which fair value is measured using the NAV per share as a practical expedient are not leveled within the fair value hierarchy and are included as a reconciling item to total plan assets. These investments include real estate and certain developed and emerging market equity funds. ​ Contributions to the qualified single-employer defined benefit pension plan are determined annually by the Company, taking into consideration recommendations from the actuary based upon the actuarially determined minimum required contributions under the Employee Retirement Income Security Act of 1974 (“ERISA”), as amended, the Pension Protection Act of 2006, and the maximum deductible contribution allowed for tax purposes. The Company’s funding policy is to contribute cash so that it meets at least the minimum required contributions, with an allowance for discretionary contributions. In 2023, 2022 and 2021, the Company contributed million, respectively, in pension contributions to this plan, which were in excess of the minimum required contributions. ​ The benefit formulas for employees who are members of collective bargaining units are determined according to the collective bargaining agreements, either using final average pay as the base, a flat dollar amount per year of service, or a cash balance formula. ​ Effective December 31, 2011, the Company froze benefit accruals under the final average pay formula for salaried, non-bargaining unit employees hired before January 1, 2008 and transitioned them to the same cash balance formula for employees hired on or after January 1, 2008. Retirement benefits under the cash balance formula are based on a fixed percentage of employee eligible compensation, plus interest. The plan interest credit rate will vary from year to year based on the ten-year U.S. Treasury rate. ​ Effective December 31, 2022, the Matson Pension Plan for Clerical Bargaining Unit Employees was merged into the Retirement Plan for Employees of Matson. ​ Benefit Plan Assets and Obligations: 31 of each year. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post-retirement ​ ​ Pension Benefits ​ Benefits ​ ​ December 31, ​ December 31, ​ (In millions) 2023 2022 2023 2022 Change in Benefit Obligation: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at beginning of year ​ $ 187.4 ​ $ 249.5 ​ $ 15.3 ​ $ 29.3 ​ Service cost ​ 3.1 ​ 4.8 ​ 0.2 ​ 0.7 ​ Interest cost ​ 10.0 ​ 7.0 ​ 0.8 ​ 0.8 ​ Participant contributions ​ — ​ — ​ 0.7 ​ 0.7 ​ Actuarial loss (gain) ​ 5.5 ​ (59.0) ​ 4.5 ​ (14.2) ​ Benefits paid, net of subsidies received ​ (12.9) ​ (14.1) ​ (2.0) ​ (2.0) ​ Expenses paid ​ — ​ (0.8) ​ — ​ — ​ Benefit obligation at end of year ​ ​ 193.1 ​ ​ 187.4 ​ ​ 19.5 ​ ​ 15.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in Plan Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at beginning of year ​ ​ 206.3 ​ ​ 238.9 ​ ​ — ​ ​ — ​ Actual return on plan assets ​ 25.5 ​ (26.7) ​ — ​ — ​ Participant contributions ​ — ​ — ​ 0.7 ​ 0.7 ​ Employer contributions ​ 9.0 ​ 9.0 ​ 1.3 ​ 1.3 ​ Benefits paid, net of subsidies received ​ (12.9) ​ (14.1) ​ (2.0) ​ (2.0) ​ Expenses paid ​ — ​ (0.8) ​ — ​ — ​ Fair value of plan assets at end of year ​ 227.9 ​ 206.3 ​ — ​ — ​ Funded Status and Recognized Plan Assets and Benefit Obligations ​ $ 34.8 ​ $ 18.9 ​ $ (19.5) ​ $ (15.3) ​ ​ Qualified pension and post-retirement benefit plan assets and liabilities recognized in the Consolidated Balance Sheets and expenses recognized in accumulated other comprehensive income (loss) at December 31, 2023 and 2022 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post-retirement ​ ​ Pension Benefits ​ Benefits ​ ​ December 31, ​ December 31, ​ (In millions) 2023 2022 2023 2022 Non-current assets ​ $ 34.8 ​ $ 18.9 ​ $ — ​ $ — ​ Current liabilities ​ ​ — ​ ​ — ​ ​ (1.1) ​ ​ (0.9) ​ Non-current liabilities ​ — ​ — ​ (18.4) ​ (14.4) ​ Total ​ $ 34.8 ​ $ 18.9 ​ $ (19.5) ​ $ (15.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (loss) gain, net of taxes ​ $ (20.3) ​ $ (25.8) ​ $ 2.7 ​ $ 7.6 ​ Prior service credit, net of taxes ​ — ​ — ​ 8.3 ​ 11.1 ​ Total ​ $ (20.3) ​ $ (25.8) ​ $ 11.0 ​ $ 18.7 ​ ​ Unrecognized gains and losses of the post-retirement benefit plans are amortized over five years . Although current health care costs are expected to increase, the Company attempts to mitigate these increases by maintaining caps on certain of its benefit plans, using lower cost health care plan options where possible, requiring that certain groups of employees pay a portion of their benefit costs, self-insuring for certain insurance plans, encouraging wellness programs for employees, and implementing measures to mitigate future benefit cost increases. ​ Components of the net periodic benefit cost and other amounts recognized in other comprehensive income (loss) for the qualified pension plan and the post-retirement benefit plan during 2023, 2022 and 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension Benefits ​ Post-retirement Benefits ​ ​ December 31, ​ December 31, ​ (In millions) 2023 2022 2021 2023 2022 2021 Components of Net Periodic Benefit Cost (Credit): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service cost ​ $ 3.1 ​ $ 4.8 ​ $ 4.8 ​ $ 0.2 ​ $ 0.7 ​ $ 0.7 ​ Interest cost ​ 10.0 ​ 7.0 ​ 6.4 ​ 0.8 ​ 0.8 ​ 0.7 ​ Expected return on plan assets ​ (13.9) ​ (16.0) ​ (14.7) ​ — ​ — ​ — ​ Amortization of net loss (gain) ​ 1.3 ​ 2.4 ​ 5.2 ​ (2.0) ​ 0.8 ​ 1.0 ​ Amortization of prior service credit ​ — ​ (1.0) ​ (2.3) ​ (3.7) ​ (3.6) ​ (3.7) ​ Net periodic benefit cost (credit) ​ ​ 0.5 ​ ​ (2.8) ​ ​ (0.6) ​ ​ (4.7) ​ ​ (1.3) ​ ​ (1.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income, net of tax: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (gain) loss ​ ​ (4.5) ​ ​ (12.3) ​ ​ (20.4) ​ ​ 3.4 ​ ​ (10.7) ​ ​ — ​ Amortization of net (loss) gain ​ (1.0) ​ (1.8) ​ (3.9) ​ 1.5 ​ (0.6) ​ (0.7) ​ Amortization of prior service credit ​ — ​ 0.8 ​ 1.7 ​ 2.8 ​ 2.7 ​ 2.8 ​ Total recognized in other comprehensive (income) loss ​ ​ (5.5) ​ ​ (13.3) ​ ​ (22.6) ​ ​ 7.7 ​ ​ (8.6) ​ ​ 2.1 ​ Total recognized in net periodic benefit cost and other comprehensive (income) loss ​ $ (5.0) ​ $ (16.1) ​ $ (23.2) ​ $ 3.0 ​ $ (9.9) ​ $ 0.8 ​ ​ The weighted average assumptions used to determine benefit information during 2023, 2022 and 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension Benefits ​ Post-retirement Benefits ​ ​ December 31, ​ December 31, ​ ​ 2023 2022 2021 2023 2022 2021 Discount rate (1) 5.30 % 5.60 % 2.90 % 5.40 % 5.50 % 3.00 % Expected return on plan assets 6.85 % 6.75 % 7.00 % ​ ​ ​ ​ ​ ​ Rate of compensation increase 3.50 % 4.00 % - 3.50 % 3.00 % 3.50 % 4.00 % - 3.50 % 3.00 % Cash balance interest credit rate ​ 4.50 % - 3.25 % 3.50 % - 3.25 % 1.50 % - 3.25 % ​ ​ ​ ​ ​ ​ Immediate health care cost trend rate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-65 group ​ ​ ​ ​ ​ ​ ​ 6.80 % 6.60 % 5.70 % Post-65 group ​ ​ ​ ​ ​ ​ ​ 7.10 % 6.10 % 5.80 % Ultimate health care cost trend rate ​ ​ ​ ​ ​ ​ ​ 3.90 % 4.00 % 4.00 % Year ultimate health care cost trend rate is reached ​ ​ ​ ​ ​ ​ ​ 2048 ​ 2046 ​ 2045 ​ (1) The Company derives a single equivalent rate utilizing a yield curve constructed from a portfolio of high-quality corporate bonds with various maturities. ​ Non-qualified Pension Plans: The Company has non-qualified supplemental pension plans covering certain employees and retirees, which provide for incremental pension payments from the Company’s general funds so that total pension benefits would be substantially equal to amounts that would have been payable from the Company’s qualified pension plans if it were not for limitations imposed by income tax law. A few employees and retirees receive additional supplemental pension benefits. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-qualified ​ Pension Benefits ​ December 31, ​ (In millions) ​ 2023 2022 Current liabilities ​ $ (1.2) ​ $ (0.7) ​ Non-current liabilities ​ ​ (3.4) ​ ​ (3.4) ​ Total ​ $ (4.6) ​ $ (4.1) ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (loss), net of taxes ​ $ (0.2) ​ $ 0.1 ​ Total ​ $ (0.2) ​ $ 0.1 ​ ​ Discount rates of 5.2 percent and 5.5 percent were used in determining the 2023 and 2022 non-qualified pension plan obligations, respectively. ​ Estimated Benefit Payments: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-qualified ​ ​ ​ ​ Pension ​ Pension ​ Post-retirement ​ Year (in millions) ​ Benefits ​ Benefits ​ Benefits (1) 2024 ​ $ 14.7 ​ $ 1.2 ​ $ 1.1 ​ 2025 ​ 15.0 ​ 0.4 ​ 1.1 ​ 2026 ​ 15.2 ​ 0.5 ​ 1.2 ​ 2027 ​ 15.4 ​ 0.5 ​ 1.2 ​ 2028 ​ 15.6 ​ 0.4 ​ 1.2 ​ 2029-2033 ​ ​ 77.0 ​ ​ 2.6 ​ ​ 6.1 ​ Total ​ $ 152.9 ​ $ 5.6 ​ $ 11.9 ​ (1) Net of participant contributions and Medicare Part D subsidies. ​ Defined Contribution Plans: The Company sponsors defined contribution plans that qualify under Sections 401(a) and 401(k) of the Internal Revenue Code. The Company may make discretionary matching contributions equal to a specified percentage of each participant’s 401(k) contributions and makes other non-discretionary contributions. For the year ended December 31, 2023, the Company provided discretionary matching contributions of up to percent of eligible employee compensation. The Company’s matching contributions and other contributions expensed in 2023, 2022 and 2021 were million, respectively. ​ The Company may also provide a discretionary profit sharing contribution under the qualified defined contribution plans to non-bargaining unit employees, if both a minimum threshold of Company performance is achieved and the Board has approved the profit sharing contribution. For certain eligible employees, supplemental profit sharing contributions are credited under a non-qualified plan to be paid after separation from service from the Company’s general funds so that total profit sharing contributions would be substantially equal to amounts that would have been contributed to the Company’s qualified defined contribution plans if it were not for limitations imposed by income tax law. Discretionary profit sharing contributions expensed in 2023, 2022 and 2021 were million, respectively. ​ Multi-employer Bargaining Plans: ​ The Company contributes to multi-employer defined benefit pension plans under the terms of collective-bargaining agreements that cover its bargaining unit employees. Contributions are generally based on amounts paid for union labor or cargo volume. The risks of participating in multi-employer plans are different from single-employer plans because assets contributed to the multi-employer plan by one employer may be used to provide benefits to employees of other participating employers. Additionally, if one employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers. ​ The multi-employer pension plans are subject to the plan termination insurance provisions of ERISA and are paying premiums to the Pension Benefit Guaranty Corporation (“PBGC”). The statutes provide that an employer who withdraws from, or significantly reduces its contribution obligation to, a multi-employer plan generally will be required to continue funding its proportional share of the plan’s unfunded vested benefits. As of December 31, 2023, the Company’s estimated benefit plan withdrawal obligations were million. Except as described in Note 12, no withdrawal obligations have been recorded by the Company in the Consolidated Balance Sheets at December 31, 2023 and 2022, as the Company has no present intention of withdrawing from and does not anticipate termination of any of these plans. ​ Information regarding the Company’s participation in multi-employer pension plans is outlined in the table below. The “EIN/Pension Plan Number” column provides the Employer Identification Number (“EIN”) and the three-digit plan number, if applicable. Unless otherwise noted, the most recent Pension Protection Act zone status available in 2023 and 2022 is for the plan’s year-end at December 31, 2023 and 2022, respectively. The zone status is based on information that the Company received from the plan and is certified by the plan’s actuary. Among other factors, plans in the red zone are generally less than b) have an accumulated/expected funding deficiency in any of the next six one percent funded. The funding improvement plan (“FIP”) or rehabilitation plan (“RP”) column indicates the status which is either pending or has been implemented. The last column lists the expiration dates of the collective-bargaining agreements to which the plans are subject. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Protection Act ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Zone as of ​ FIP/RP Status ​ 5% ​ Contributions of Matson ​ ​ ​ ​ ​ ​ EIN/Pension ​ ​ ​ December 31, ​ Pending/ ​ Contributor ​ (in millions) ​ Surcharge ​ Expiration Pension Funds Plan Number Notes 2023 2022 Implemented in 2023 2023 2022 2021 Imposed Date (1) American Radio Association Pension Fund 13-6161999-001 ​ ​ Green Green Implemented ​ Yes ​ $ 1.0 ​ $ 1.1 ​ $ 1.1 No 6/15/2028 ​ Hawaii Longshore Pension Plan ​ 99-0314293-001 ​ ​ ​ Green ​ Green ​ No ​ Yes ​ ​ 12.1 ​ ​ 11.9 ​ ​ 11.1 ​ No ​ 6/30/2028 ​ Master, Mates and Pilots Pension Plan 13-6372630-001 ​ ​ ​ Green Green No ​ Yes ​ 3.6 ​ 3.8 ​ 3.5 No ​ 6/15/2027, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/15/2028 ​ Masters, Mates and Pilots Adjustable Pension Plan 37-1719247-001 ​ ​ ​ Green Green No ​ Yes ​ 2.0 ​ 2.1 ​ 2.0 No ​ 6/15/2027, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/15/2028 ​ MEBA Pension Trust - Defined Benefit Plan 51-6029896-001 ​ ​ ​ Green Green No ​ Yes ​ 4.2 ​ 4.5 ​ 4.3 No 6/15/2028 ​ OCU Pension Trust Plan 26-1574440-001 ​ ​ ​ Green Green No ​ No ​ 0.4 ​ 0.5 ​ 0.3 No 6/30/2030 ​ MFOW Supplementary Pension Plan ​ 94-6201677-001 ​ ​ ​ Yellow ​ Yellow ​ No ​ Yes ​ ​ 0.1 ​ ​ 0.1 ​ ​ 0.1 ​ No ​ 6/30/2026 ​ SIU Pacific District Pension Plan ​ 94-6061923-001 ​ ​ ​ Green ​ Green ​ No ​ Yes ​ ​ 1.3 ​ ​ 1.5 ​ ​ 1.4 ​ No ​ 6/30/2026 ​ Alaska Teamster - Employer Pension Plan ​ 92-6003463-024 ​ ​ ​ Red ​ Red ​ Implemented ​ Yes ​ ​ 3.9 ​ ​ 4.0 ​ ​ 3.6 ​ No ​ 6/30/2024, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/30/2025, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/30/2026, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/30/2027 ​ All Alaska Longshore Pension Plan ​ 91-6085352-001 ​ ​ ​ Green ​ Green ​ No ​ Yes ​ ​ 1.8 ​ ​ 2.0 ​ ​ 1.6 ​ No ​ 6/30/2028 ​ Western Conference of Teamsters Pension Plan ​ 91-6145047-001 ​ ​ ​ Green ​ Green ​ No ​ No ​ ​ 2.1 ​ ​ 2.1 ​ ​ 1.9 ​ No ​ 3/31/2028 ​ Western Conference of Teamsters Supplemental Benefit Trust ​ 95-3746907-001 ​ ​ ​ Green ​ Green ​ No ​ No ​ ​ 0.1 ​ ​ 0.1 ​ ​ — ​ No ​ 3/31/2028 ​ OPEIU Local 153 Pension Plan ​ 13-2864289-001 ​ ​ ​ Red ​ Red ​ Implemented ​ No ​ ​ 0.1 ​ ​ 0.1 ​ ​ 0.1 ​ No ​ 11/9/2028 ​ Seafarers Pension Plan ​ 13-6100329-001 ​ (2) ​ Green ​ Green ​ No ​ No ​ ​ — ​ ​ — ​ ​ — ​ No ​ 6/30/2027 ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 32.7 ​ $ 33.8 ​ $ 31.0 ​ ​ ​ ​ ​ (1) Represents the expiration date of the collective bargaining agreement. (2) The Company does not make contributions directly to the Seafarers Pension Plan. Instead, contributions are made to the Seafarers Health and Benefits Plan, and are subsequently re-allocated to the Seafarers Pension Plan at the discretion of the plan Trustees. ​ The Company also contributes to multi-employer plans that provide post-retirement health and other benefits other than pensions under the terms of collective-bargaining agreements. Benefits provided to active and retired employees and their eligible dependents under these plans include medical, dental, vision and prescription drugs. These plans are not subject to the PBGC plan termination and withdrawal liability provisions of ERISA applicable to multi-employer defined benefit pension plans. Contributions made to these plans were ​ Multi-employer Defined Contribution Plans: multi-employer defined contribution pension plans. These plans are not subject to the withdrawal liability provisions of ERISA or the PBGC applicable to multi-employer defined benefit pension plans. Contributions made to these plans by the Company were

MULTI-EMPLOYER WITHDRAWAL LIABI

MULTI-EMPLOYER WITHDRAWAL LIABILITIES	12 Months Ended
	Dec. 31, 2023
MULTI-EMPLOYER WITHDRAWAL LIABILITIES
MULTI-EMPLOYER WITHDRAWAL LIABILITIES	12. MULTI-EMPLOYER WITHDRAWAL LIABILITIES ​ Horizon ceased all of its operations in Puerto Rico during the first quarter of 2015, which resulted in a mass withdrawal from its multi-employer ILA-PRSSA pension fund. The Company assumed this liability as part of the acquisition of Horizon on May 29, 2015. The Company estimated the mass withdrawal liability based upon the required undiscounted quarterly payment of approximately million to be paid to the ILA-PRSSA pension fund over a period which ends in March 2040, discounted to present value using the Company’s incremental borrowing rate. Future estimated annual payments to be paid to the ILA-PRSSA pension fund as of December 31, 2023 were as follows: ​ ​ ​ ​ ​ Year (in millions) ​ Total 2024 $ 4.1 2025 ​ ​ 4.1 2026 ​ ​ 4.1 2027 ​ ​ 4.1 2028 ​ ​ 4.1 Thereafter ​ ​ 47.3 Total remaining future undiscounted payments due to the ILA-PRSSA pension fund ​ ​ 67.8 Less: amount representing interest ​ ​ (17.2) Present value of multi-employer withdrawal liability ​ ​ 50.6 Current portion of multi-employer withdrawal liability (see Note 2) ​ ​ (4.1) Long-term portion of multi-employer withdrawal liability (see Note 2) $ 46.5 ​

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
	Dec. 31, 2023
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	13. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ​ Changes in accumulated other comprehensive income (loss) by component, net of tax, consist of the following for the years ended December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non- ​ ​ Accumulated ​ ​ ​ ​ ​ Post- ​ Qualified ​ ​ ​ ​ Other ​ ​ Pension ​ Retirement ​ Pension ​ ​ ​ ​ Comprehensive (In millions) ​ Benefits ​ Benefits ​ Benefits ​ Other ​ Income (Loss) Balance at December 31, 2021 ​ $ (39.1) ​ $ 10.1 ​ $ (0.7) ​ $ (1.2) ​ $ (30.9) ​ Amortization of prior service cost ​ (0.8) ​ ​ (2.7) ​ ​ — ​ ​ — ​ (3.5) ​ Amortization of net gain (loss) ​ ​ 14.1 ​ ​ 11.3 ​ ​ 0.8 ​ ​ 1.1 ​ 27.3 ​ Foreign currency exchange ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.4) ​ ​ (0.4) ​ Other adjustments ​ ​ — ​ — ​ — ​ 0.6 ​ 0.6 ​ Balance at December 31, 2022 ​ (25.8) ​ 18.7 ​ 0.1 ​ 0.1 ​ (6.9) ​ Amortization of prior service cost ​ — ​ ​ (2.8) ​ ​ — ​ ​ — ​ (2.8) ​ Amortization of net gain (loss) ​ 5.5 ​ ​ (4.9) ​ ​ (0.3) ​ ​ — ​ 0.3 ​ Foreign currency exchange ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.5) ​ ​ (0.5) ​ Other adjustments ​ — ​ ​ — ​ ​ — ​ ​ 1.7 ​ 1.7 ​ Balance at December 31, 2023 ​ $ (20.3) ​ $ 11.0 ​ $ (0.2) ​ $ 1.3 ​ $ (8.2) ​ ​ Other comprehensive income (loss) in the Consolidated Statements of Income and Comprehensive Income is shown net of tax benefit (expense) of $(1.2) million, $(9.3) million and $(8.1) million for the years ended December 2023, 2022 and 2021, respectively.

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2023
EARNINGS PER SHARE
EARNINGS PER SHARE	14. EARNINGS PER SHARE ​ Basic earnings per share are determined by dividing net income by the weighted-average common shares outstanding during the year. The calculation of diluted earnings per share includes the dilutive effect of unexercised non-qualified stock options and non-vested stock units. The computation of weighted average dilutive shares outstanding excluded a nominal amount of anti-dilutive non-qualified stock options for each of the years 2023, 2022 and 2021. ​ The denominators used to compute basic and diluted earnings per share for the years ended December 31, 2023, 2022 and 2021 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2023 ​ Year Ended December 31, 2022 ​ Year Ended December 31, 2021 ​ ​ ​ Weighted Per ​ ​ Weighted Per ​ ​ Weighted Per ​ ​ ​ ​ ​ Average ​ Common ​ ​ ​ ​ Average ​ Common ​ ​ ​ ​ Average ​ Common ​ ​ Net ​ Common ​ Share ​ Net ​ Common ​ Share ​ Net ​ Common ​ Share (In millions, except per share amounts) ​ Income ​ Shares ​ Amount ​ Income ​ Shares ​ Amount ​ Income ​ Shares ​ Amount Basic: ​ $ 297.1 35.3 ​ $ 8.42 ​ $ 1,063.9 39.0 ​ $ 27.28 ​ $ 927.4 42.8 ​ $ 21.67 ​ Effect of Dilutive Securities: ​ ​ — 0.4 ​ ​ (0.10) ​ ​ — 0.3 ​ ​ (0.21) ​ ​ — 0.4 ​ ​ (0.20) ​ Diluted: ​ $ 297.1 ​ 35.7 ​ $ 8.32 ​ $ 1,063.9 ​ 39.3 ​ $ 27.07 ​ $ 927.4 ​ 43.2 ​ $ 21.47 ​ ​

SHARE-BASED AWARDS

SHARE-BASED AWARDS	12 Months Ended
	Dec. 31, 2023
SHARE-BASED AWARDS
SHARE-BASED AWARDS	15. SHARE-BASED AWARDS ​ The Company has share-based compensation plans which are described as follows: ​ 2016 Incentive Compensation Plan: The Amended and Restated Matson, Inc. 2016 Incentive Compensation Plan (the “2016 Plan”) serves as a successor to the 2007 Incentive Compensation Plan and all other predecessor plans. further grants were made under the predecessor stock option plans. Under the 2016 Plan, ​ The 2016 Plan consists of four separate incentive compensation programs: (i) the discretionary grant program, (ii) the stock issuance program, (iii) the incentive bonus program, and (iv) the automatic grant program for the non- employee members of the Company’s Board of Directors. Share-based compensation is generally awarded under ​ Discretionary Grant Program percent of the fair market value (defined as the closing market price) of the Company’s common stock on the date of the grant. No stock options have been granted under the 2016 Plan. ​ Stock Issuance Program — Under the Stock Issuance Program, shares of common stock, restricted stock units or performance shares may be granted. Time-based equity awards generally vest ratably over . Provided certain anniversary date of the grant. ​ Automatic Grant Program — At each annual shareholder meeting, non-employee directors will receive an award of restricted stock units that entitle the holder to an equivalent number of shares of common stock upon vesting, under the Automatic Grant Program. Awards of restricted stock units granted under the program generally vest on the ​ The shares of common stock authorized to be issued under the 2016 Plan may be drawn from shares of the Company’s authorized but unissued common stock or from shares of its common stock that the Company acquires, including shares purchased on the open market or in private transactions. ​ Share-based compensation expense and other information related to share-based awards for the years ended December 31, 2023, 2022 and 2021 are as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Share-based compensation expense, net of estimated forfeitures (in millions) 2023 2022 2021 Share-based compensation expense ​ $ 23.8 ​ $ 18.3 ​ $ 19.3 ​ Tax benefit realized upon stock vesting ​ $ 6.1 ​ $ 10.6 ​ $ 8.0 ​ Fair value of stock vested ​ $ 27.8 ​ $ 44.0 ​ $ 33.5 ​ ​ As of December 31, 2023, unrecognized compensation cost related to non-vested restricted stock units and performance-based equity awards was $24.8 million. Unrecognized compensation cost is expected to be recognized over a weighted average period of approximately ​ The following table summarizes non-vested restricted stock unit activity through December 31, 2023 (in thousands, except weighted average grant-date fair value amounts): ​ ​ ​ ​ ​ ​ ​ ​ 2016 Plan Weighted ​ ​ Restricted ​ Average Grant- ​ ​ ​ Stock Units ​ Date Fair Value Outstanding at December 31, 2022 546 $ 68.38 ​ Granted ​ 269 ​ ​ 66.05 ​ Vested ​ (439) ​ ​ 46.96 ​ Canceled ​ (10) ​ ​ 70.07 ​ Added by performance factor (1) ​ 167 ​ ​ 39.61 ​ Outstanding at December 31, 2023 533 $ 75.82 ​ (1) Represents shares paid out above target.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2023
FAIR VALUE OF FINANCIAL INSTRUMENTS
FAIR VALUE OF FINANCIAL INSTRUMENTS	16. FAIR VALUE OF FINANCIAL INSTRUMENTS ​ The Company values its financial instruments based on the fair value hierarchy of valuation techniques for fair value measurements. Level 1 inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 inputs include quoted prices for similar assets and liabilities in active markets and inputs other than quoted prices observable for the asset or liability. Level 3 inputs are unobservable inputs for the asset or liability. If the technique used to measure fair value includes inputs from multiple levels of the fair value hierarchy, the lowest level of significant input determines the placement of the entire fair value measurement in the hierarchy. ​ The Company uses Level 1 inputs for the fair values of its cash and cash equivalents, restricted cash and cash on deposit in the CCF, and Level 2 inputs for its fixed rate debt. The fair values of cash and cash equivalents, restricted cash and cash on deposit in the CCF approximate their carrying values due to the nature of the instruments. The fair value of fixed rate debt is calculated based upon interest rates available for debt with terms and maturities similar to the Company’s existing debt arrangements. ​ The carrying value and fair value of the Company’s financial instruments consists of the following as of December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ Significant ​ Significant ​ ​ ​ Total ​ ​ ​ Active Markets ​ Observable ​ Unobservable ​ ​ Carrying Value Total (Level 1) Inputs (Level 2) Inputs (Level 3) ​ (In millions) ​ December 31, 2023 ​ Fair Value Measurements at December 31, 2023 ​ Cash and cash equivalents ​ $ 134.0 ​ $ 134.0 ​ $ 134.0 ​ $ — ​ $ — ​ Restricted cash ​ $ 2.3 ​ $ 2.3 ​ $ 2.3 ​ $ — ​ $ — ​ Capital Construction Fund ​ $ 599.4 ​ $ 599.4 ​ $ 599.4 ​ $ — ​ $ — ​ Fixed rate debt ​ $ 440.6 ​ $ 359.9 ​ $ — ​ $ 359.9 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (In millions) December 31, 2022 ​ Fair Value Measurements at December 31, 2022 ​ Cash and cash equivalents ​ $ 249.8 ​ $ 249.8 $ 249.8 ​ $ — ​ $ — ​ Restricted cash ​ $ 3.9 ​ $ 3.9 ​ $ 3.9 ​ $ — ​ $ — ​ Capital Construction Fund ​ $ 518.2 ​ $ 518.2 ​ $ 518.2 ​ $ — ​ $ — ​ Fixed rate debt ​ $ 517.5 ​ $ 427.3 ​ $ — ​ $ 427.3 ​ $ — ​ ​

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2023
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	17. COMMITMENTS AND CONTINGENCIES ​ Commitments and contractual obligations, excluding debt obligations (see Note 8), lease commitments (see Note 9), pension and post-retirement plan obligations (see Note 11), and multi-employer withdrawal liabilities (see Note 12), are as follows as of December 31, 2023: ​ ​ ​ ​ ​ ​ Commitments and Contractual Obligations (in millions) Total Standby letters of credit (1) ​ $ 5.8 ​ Bonds (2) ​ $ 56.4 ​ Vessel construction obligations (3) ​ $ 899.1 ​ Vendor and other obligations (4) ​ $ 77.1 ​ (1) Standby letters of credit are required for the Company’s uninsured workers’ compensation and other insurance programs, and other needs. (2) Bonds are required for U.S. Customs and other related matters. (3) Vessel construction obligations represent remaining contractual obligations entered into for the construction of three new Jones Act vessels. (4) Vendor and other obligations include: (i) non-cancellable contractual capital project obligations; (ii) dry-docking related obligations; and (iii) other contractual obligations. Amounts are considered obligations if a contract has been agreed to specifying significant terms of the contract, and the amounts are not reflected in the Consolidated Balance Sheets as of December 31, 2023. ​ These amounts are not recorded on the Company’s Consolidated Balance Sheets as of December 31, 2023 and it is not expected that the Company or its subsidiaries will be called upon to advance funds under these commitments and contractual obligations. ​ Contingencies: Contingencies and other litigation related matters are described as follows: ​ Environmental Matters: The Company faces certain risks that could result in material expenditures related to environmental remediation. The Company believes, that based on all information currently available to it, the Company is currently in compliance, in all material respects, with applicable environmental laws and regulations. ​ Other Matters: The Company and its subsidiaries are parties to, or may be contingently liable in connection with, other legal actions arising in the normal course of their businesses, the outcomes of which, in the opinion of management after consultation with counsel, would not have a material effect on the Company’s financial condition, results of operations, or cash flows.

SIGNIFICANT ACCOUNTING POLICI_2

SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
SIGNIFICANT ACCOUNTING POLICIES
Principles of Consolidation	Principles of Consolidation: The Consolidated Financial Statements include the accounts of Matson, Inc. and all wholly-owned subsidiaries, after elimination of intercompany amounts and transactions. Significant investments in businesses, partnerships, and limited liability companies in which the Company does not have a controlling financial interest, but has the ability to exercise significant influence, are accounted for under the equity method. The Company accounts for its investment in SSAT using the equity method of accounting (see Note 4).
Fiscal Year	Fiscal Year: The year end for Matson is December 31. The period end for MatNav occurred on the last Friday in December, except for certain Company subsidiaries whose period closed on December 31. Included in these Consolidated Financial Statements are 53
Foreign Currency Transactions	Foreign Currency Transactions: The United States (U.S.) dollar is the functional currency for substantially all of the financial statements of the Company’s foreign subsidiaries. Foreign currency denominated assets and liabilities of the Company’s foreign subsidiaries are translated into U.S. dollars at exchange rates existing at the respective balance sheet dates. Translation adjustments resulting from fluctuations in exchange rates are recorded as a component of accumulated other comprehensive loss (gain) within shareholders’ equity. The Company translates the result of operations of its foreign subsidiaries at the average exchange rate during the respective periods. Gains and losses resulting from foreign currency transactions are included in Costs and Expenses in the Consolidated Statements of Income and Comprehensive Income.
Use of Estimates	Use of Estimates: The preparation of the Consolidated Financial Statements in conformity with accounting principles generally accepted in the U.S. requires management to make estimates and assumptions that affect the amounts reported. Estimates and assumptions are used for, but not limited to: impairment of investments; impairment of long-lived assets, intangible assets and goodwill; capitalized interest; allowance for doubtful accounts and other receivables; legal contingencies; insurance reserves and other related liabilities; contingent acquisition related consideration; accrual estimates; pension and post-retirement estimates; multi-employer withdrawal liabilities; operating lease assets and liabilities; income (loss) from SSAT; and income taxes. Future results could be materially affected if actual results differ from these estimates and assumptions.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash: Cash equivalents consist of highly-liquid investments with original maturities of three months or less. The Company carries these investments at cost, which approximates fair value. Restricted cash relates to amounts that are subject to contractual restrictions and are not readily available. Restricted cash was 31, 2023 and 2022, respectively, and are included in prepaid expenses and other assets in the Consolidated Balance Sheets.
Accounts Receivable, net	Accounts Receivable, net: Accounts receivable represent amounts due from trade customers arising in the normal course of business. Accounts receivable are shown net of allowance for doubtful accounts receivable in the Consolidated Balance Sheets. Allowance for doubtful accounts receivable is established by management based on estimates of collectability. Estimates of collectability are principally based on an evaluation of the current financial condition of the customer and the potential risks to collection, the customer’s payment history, expected future credit losses and other factors which are regularly monitored by the Company. ​ Changes in the allowance for doubtful accounts receivable for the three years ended December 31, 2023, 2022 and 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Write-offs Balance at Year (in millions) Beginning of Year Expense (1) and Other End of Year 2023 ​ $ 13.0 ​ $ (2.1) ​ $ (1.0) ​ $ 9.9 2022 ​ $ 10.1 ​ $ 3.2 ​ $ (0.3) ​ $ 13.0 2021 ​ $ 6.3 ​ $ 4.2 ​ $ (0.4) ​ $ 10.1 (1) Expense is shown net of amounts recovered from previously reserved doubtful accounts receivable.
Prepaid Expenses and Other Assets	Prepaid Expenses and Other Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Prepaid Expenses and Other Assets (in millions) 2023 2022 Income tax receivables, net ​ $ 125.2 ​ $ 170.8 ​ Prepaid fuel ​ ​ 22.5 ​ ​ 26.3 ​ Prepaid insurance and insurance related receivables ​ 19.3 ​ 17.4 ​ Restricted cash - vessel construction obligations ​ ​ 2.3 ​ ​ 3.9 ​ Other ​ 19.6 ​ 22.9 ​ Total ​ $ 188.9 ​ $ 241.3 ​ ​ Income tax receivables primarily include a federal income tax refund related to the Company’s 2021 federal tax return of approximately $118.6 million, overpayments of federal and state taxes paid during the year ended December 31, 2023, and other income tax receivables.
Deferred Loan Fees	Deferred Loan Fees: The Company records deferred loan fees, excluding those related to the revolving credit facility, as a reduction to Total Debt in the Company’s Consolidated Balance Sheets in accordance with Accounting Standards Update (“ASU”) 2015-03, Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”). These costs are being amortized over the life of the related debt using the effective interest method (see Note 8). ​ Deferred loan fees related to the Company’s revolving credit facility are recorded in other long-term assets in the Company’s Consolidated Balance Sheets and are amortized using the straight-line method, as the difference between that method and the use of the effective interest method is not material. ​
Other Long-Term Assets	Other Long-Term Assets: Other long-term assets consist of the following at December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Long-Term Assets (in millions) 2023 2022 Vessel and equipment spare parts ​ $ 14.2 ​ $ 13.2 ​ Pension plan assets ​ ​ 34.8 ​ ​ 18.9 ​ Insurance related receivables ​ ​ 10.2 ​ ​ 12.1 ​ Other ​ ​ 7.2 ​ ​ 9.4 ​ Total ​ $ 66.4 ​ $ 53.6 ​
Property and Equipment	Property and Equipment: Property and equipment is stated at cost. Property and equipment is depreciated using the straight-line method over the estimated useful lives of the assets. The estimated useful lives of property and equipment range up to the following maximum life as follows: ​ ​ ​ ​ Classification Life Vessels 40 years Terminal cranes 30 years Containers and chassis ​ 15 years Terminal facilities and other property 35 years ​
Capitalized Interest	Capitalized Interest: The Company capitalizes interest costs during the period the qualified assets are being readied for their intended use. The Company determined that vessel construction costs are considered qualifying assets for the purposes of capitalizing interest on these assets. The amount of capitalized interest is calculated based on the amount of payments incurred related to the construction of these vessels using a weighted average interest rate. The weighted average interest rate is determined using the Company’s average borrowings outstanding during the period. Capitalized interest is included in vessel construction in progress in property and equipment in the Company’s Consolidated Balance Sheets (see Note 5). During the years ended December 31, 2023, 2022 and 2021, the Company capitalized
Leases	Leases: Accounting Standards Codification (“ASC”) 842, Leases requires lessees to record leases on their balance sheets but recognize the expenses in their income statements. ASC 842 states that a lessee would recognize a lease liability for the obligation to make lease payments, and a right-of-use asset for the underlying leased asset for the period of the lease term. Refer to Note 9 for additional information on the Company’s lease related disclosures.
Deferred Dry-docking Costs	Deferred Dry-docking Costs: U.S. flagged vessels must meet specified seaworthiness standards established by U.S. Coast Guard rules and classification society rules. These standards require U.S. flagged vessels to undergo between them. However, U.S. flagged vessels that are enrolled in the U.S. Coast Guard’s Underwater Survey in lieu of Dry-docking (“UWILD”) program are allowed to have their Intermediate Survey dry-docking requirement met with a less costly underwater inspection. Non-U.S. flagged vessels are required to meet applicable classification society rules and their own local standards for seaworthiness, which also mandate vessels to undergo . ​ The Company is responsible for maintaining its vessels in compliance with U.S. and international standards. As costs associated with dry-docking inspections provide future economic benefits to the Company through continued operation of the vessels, the costs are deferred and amortized until the scheduled date of the next required dry-docking, which is usually over a two period. Amortization of deferred dry-docking costs are charged to operating expenses of the Ocean Transportation segment in the Consolidated Statements of Income and Comprehensive Income. Routine vessel maintenance and repairs are charged to expense as incurred.
Goodwill and Intangible Assets	Goodwill and Intangible Assets: Goodwill and intangible assets arise as a result of acquisitions made by the Company (see Note 6). Intangible assets consist of customer relationships which are being amortized using the straight-line method over the expected useful lives ranging up to ​
Impairment Evaluation of Long-Lived Assets, Intangible Assets and Goodwill	Impairment Evaluation of Long-Lived Assets, Intangible Assets and Goodwill : The Company evaluates its long-lived assets, intangible assets and goodwill for possible impairment in the fourth quarter, or whenever events or changes in circumstances indicate that it is more likely than not that the fair value is less than its carrying amount. The Company has reporting units within the Ocean Transportation and Logistics reportable segments. ​ Long-lived assets and finite-lived intangible assets are grouped at the lowest level reporting unit for which identifiable cash flows are available. In evaluating for impairment, the estimated future undiscounted cash flows generated by each of these asset groups are compared with the carrying value recorded for each asset group to determine if its carrying value is recoverable. If this review determines that the amount recorded will not be recovered, the amount recorded for the asset group is reduced to its estimated fair value. ​ Indefinite-life intangible assets and goodwill are grouped at the lowest level reporting unit for which identifiable cash flows are available. In estimating the fair value of a reporting unit, the Company uses a combination of a discounted cash flow model and fair value based on market multiples of earnings before interest, taxes, depreciation and amortization. Based upon the Company’s evaluation of its indefinite-life intangible assets and goodwill for impairment, the Company determined that the fair value of each reporting unit exceeds book value.
Impairment Evaluation of SSAT	Impairment Evaluation of SSAT: The Company’s investment in SSAT, a related party, is evaluated for impairment whenever there is evidence of impairment during the reporting period. If any impairment is identified, the Company evaluates if the decrease in the fair value of the investment below its carrying value is other-than-temporary.
Other Liabilities	Other Liabilities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Liabilities (in millions) 2023 2022 Payroll and vacation $ 38.3 $ 34.7 ​ Employee incentives and other benefits ​ ​ 33.9 ​ ​ 33.2 ​ Insurance reserves and other related liabilities - short term ​ ​ 17.5 ​ ​ 15.6 ​ Multi-employer withdrawal liabilities - short term ​ ​ 4.1 ​ ​ 4.1 ​ Income tax and other tax related liabilities ​ ​ 1.6 ​ ​ 2.2 ​ Other short-term liabilities ​ ​ 12.6 ​ ​ 15.7 ​ Total $ 108.0 $ 105.5 ​
Other long-term Liabilities	Other Long-Term Liabilities: Other long-term liabilities consist of the following at December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Long-Term Liabilities (in millions) 2023 2022 Multi-employer withdrawal liability ​ $ 46.5 ​ $ 48.6 ​ Insurance reserves and other related liabilities ​ ​ 23.8 ​ ​ 29.8 ​ Pension and post-retirement liabilities ​ ​ 21.8 ​ ​ 17.8 ​ Other long-term liabilities ​ 21.6 ​ 18.6 ​ Total ​ $ 113.7 ​ $ 114.8 ​
Pension and Post-Retirement Plans	Pension and Post-Retirement Plans: The Company is a member of the Pacific Maritime Association (“PMA”) and the Hawaii Stevedoring Industry Committee, which negotiate multi-employer pension plans covering certain shoreside bargaining unit personnel. The Company directly negotiates multi-employer pension plans covering other bargaining unit personnel. Pension costs are accrued in accordance with contribution rates established by the PMA, the parties to a plan or the trustees of a plan. Several trusteed, non-contributory, single-employer defined benefit plans and defined contribution plans cover substantially all other employees. ​ The estimation of the Company’s pension and post-retirement benefit expenses and liabilities requires that the Company make various assumptions. These assumptions include factors such as discount rates, expected long-term rates of return on pension plan assets, salary growth, health care cost trend rates, inflation, retirement rates, mortality rates, and expected contributions. Actual results that differ from the assumptions made could materially affect the Company’s financial condition or its future operating results. Additional information about the Company’s pension and post-retirement plans is included in Note 11.
Insurance Related Liabilities	Insurance Related Liabilities: The Company purchases insurance with deductibles or self-insured retentions to mitigate significant risks that it is exposed to. Such insurance includes, but is not limited to, employee health, workers’ compensation, marine liability, cybersecurity, auto liability and physical damage to property and equipment. For certain risks, the Company elects to not purchase insurance because of the excessive cost of insurance, the perceived remoteness of the risk or insurance coverage is not commercially available. The Company retains the risk of loss for insurance deductibles and self-insured retentions, for amounts that exceed the limits of the Company’s insurance policies, and for other risks not covered by insurance. ​ When estimating its reserves for retained risks and related liabilities, the Company considers a number of factors, including historical claims experience, demographic factors, current trends, and analyses provided by independent third parties. Periodically, management reviews its assumptions and estimates used to determine the adequacy of the Company’s reserves for retained risks and other related liabilities.
Recognition of Revenues and Expenses	Recognition of Revenues and Expenses: Revenue in the Company’s Consolidated Financial Statements is presented net of elimination of intercompany transactions. The following is a description of the Company’s principal revenue generating activities by segment, and the Company’s revenue recognition policy for each activity for the periods presented: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Ocean Transportation (in millions) (1) ​ 2023 ​ 2022 ​ 2021 Ocean Transportation services ​ $ 2,420.8 ​ $ 3,508.0 ​ $ 3,101.9 Terminal and other related services ​ ​ 36.9 ​ ​ 18.5 ​ ​ 16.0 Fuel sales ​ ​ 12.3 ​ ​ 11.3 ​ ​ 7.2 Vessel management and related services ​ ​ 7.0 ​ ​ 6.8 ​ ​ 7.7 Total ​ $ 2,477.0 ​ $ 3,544.6 ​ $ 3,132.8 (1) Ocean Transportation revenue transactions are primarily denominated in U.S. dollars except for less than 3 percent of Ocean Transportation services revenue and fuel sales revenue categories which are denominated in foreign currencies. ​ ◾ Ocean Transportation services revenue is recognized ratably over the duration of a voyage based on the relative transit time completed in each reporting period. Vessel operating costs and other ocean transportation operating costs, such as terminal operating overhead and selling, general and administrative expenses, are charged to operating costs as incurred. ◾ Terminal and other related services revenue is recognized as the services are performed. Related costs are recognized as incurred. ◾ Fuel sales revenue and related costs are recognized when the Company has completed delivery of the product to the customer in accordance with the terms and conditions of the contract. ◾ Vessel management and related services revenue is recognized in proportion to the services completed. Related costs are recognized as incurred. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Logistics (in millions) (1) ​ 2023 ​ 2022 ​ 2021 Transportation Brokerage and Freight Forwarding services ​ $ 546.8 ​ $ 695.1 ​ $ 707.4 Warehousing and distribution services ​ ​ 42.5 ​ ​ 53.5 ​ ​ 44.7 Supply chain management and other services ​ 28.3 ​ 49.8 ​ 40.4 Total ​ $ 617.6 ​ $ 798.4 ​ $ 792.5 (1) Logistics revenue transactions are primarily denominated in U.S. dollars except for less than 3 percent of transportation brokerage and freight forwarding services revenue, and supply chain management and other services revenue categories which are denominated in foreign currencies. ​ ◾ Transportation Brokerage and Freight Forwarding services revenue consists of amounts billed to customers for services provided. The primary costs include third-party purchased transportation services, agent commissions, labor and equipment. Revenue and the related purchased third-party transportation costs are recognized over the duration of a delivery based upon the relative transit time completed in each reporting period. Labor, agent commissions, and other operating costs are expensed as incurred. The Company reports revenue on a gross basis as the Company serves as the principal in these transactions because it is responsible for fulfilling the contractual arrangements with the customer and has latitude in establishing prices. ◾ Warehousing and distribution services revenue consist of amounts billed to customers for storage, handling, and value-added packaging of customer merchandise. Storage revenue is recognized in the month the service is provided to the customer. Storage related costs are recognized as incurred. Other warehousing and distribution services revenue and related costs are recognized in proportion to the services performed. ◾ Supply chain management and other services revenue, and related costs are recognized in proportion to the services performed. ​ The Company generally invoices its customers at the commencement of the voyage or the transportation service being provided, or as other services are being performed. Revenue is deferred when services are invoiced in advance to the customer. The Company’s receivables are classified as short-term as collection terms are for periods of less than one year. The Company expenses sales commissions and contract acquisition costs as incurred because the amounts are generally immaterial. These expenses are included in selling, general and administration expenses in the Consolidated Statements of Income and Comprehensive Income.
Customer Concentration	Customer Concentration: The Ocean Transportation segment serves customers in numerous industries and carries a wide variety of cargo, mitigating its dependence upon any single customer or single type of cargo. In 2023, the Company’s percent of the Company’s Ocean Transportation operating revenue. ​ The Logistics segment serves customers in numerous industries and geographical locations. In 2023, the Company’s percent of the Company’s Logistics operating revenue.
Dividends	Dividends:
Repurchase of Shares	Repurchase of Shares: During the years ended December 31, 2023, 2022 and 2021, the Company repurchased approximately million, respectively. As of December 31, 2023, the number of remaining shares that may be repurchased under the Company’s share repurchase program was approximately
Share-Based Compensation	Share-Based Compensation: The Company records compensation expense for all share-based awards made to employees and directors. The Company’s various stock-based compensation plans are more fully described in Note 15.
Income Taxes	Income Taxes: The estimate of the Company’s income tax expense requires the Company to make various estimates and judgments. These estimates and judgments are applied in the calculation of taxable income, tax credits, tax benefits, CCF and other tax deductions, and in the calculation of certain deferred tax assets and liabilities, which arise from differences in the timing of recognition of revenue, costs and expenses for tax purposes. The Company also considers the impact of expected future events such as changes in tax rates, changes in tax laws, regulations and rulings. Deferred tax assets and liabilities are adjusted to the extent necessary to reflect tax rates expected to be in effect when the temporary differences reverse. ​ The Company records a valuation allowance if, based on the weight of available evidence, management believes that it is more likely than not that some portion or all of a recorded deferred tax asset would not be realized in future periods. The Company’s income taxes are more fully described in Note 10.
Rounding	Rounding: Amounts in the Consolidated Financial Statements and Notes to the Consolidated Financial Statements are rounded to tenth of millions, except for per share calculations and percentages which were determined based on amounts before rounding. Accordingly, a recalculation of some per-share amounts and percentages, if based on the reported data, may be slightly different. ​
New Accounting Pronouncements	New Accounting Pronouncements: ​ In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”). ASU 2023-07 requires disclosure of incremental segment information on an annual and interim basis. The ASU is effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024, and requires retrospective application to all prior periods presented in the financial statements. Early adoption is permitted. The Company is currently evaluating the effects of adopting ASU 2023-07 but does not expect it will have a material impact on the Company’s consolidated financial statements. ​ In December 2023, the FASB issued ASU 2023-09, Improvements to Income Tax Disclosures (“ASU 2023-09”). ASU 2023-09 requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as information on income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024, and interim periods within fiscal years beginning after December 15, 2025. The Company is currently evaluating the effects of adoption ASU 2023-09 but does not expect it to have a material impact on the Company’s consolidated financial statements.

SIGNIFICANT ACCOUNTING POLICI_3

SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
Schedule of changes in the allowance for doubtful accounts receivable	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Balance at ​ Write-offs Balance at Year (in millions) Beginning of Year Expense (1) and Other End of Year 2023 ​ $ 13.0 ​ $ (2.1) ​ $ (1.0) ​ $ 9.9 2022 ​ $ 10.1 ​ $ 3.2 ​ $ (0.3) ​ $ 13.0 2021 ​ $ 6.3 ​ $ 4.2 ​ $ (0.4) ​ $ 10.1 (1) Expense is shown net of amounts recovered from previously reserved doubtful accounts receivable.
Schedule of prepaid expenses and other assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Prepaid Expenses and Other Assets (in millions) 2023 2022 Income tax receivables, net ​ $ 125.2 ​ $ 170.8 ​ Prepaid fuel ​ ​ 22.5 ​ ​ 26.3 ​ Prepaid insurance and insurance related receivables ​ 19.3 ​ 17.4 ​ Restricted cash - vessel construction obligations ​ ​ 2.3 ​ ​ 3.9 ​ Other ​ 19.6 ​ 22.9 ​ Total ​ $ 188.9 ​ $ 241.3 ​
Schedule of other long-term assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Long-Term Assets (in millions) 2023 2022 Vessel and equipment spare parts ​ $ 14.2 ​ $ 13.2 ​ Pension plan assets ​ ​ 34.8 ​ ​ 18.9 ​ Insurance related receivables ​ ​ 10.2 ​ ​ 12.1 ​ Other ​ ​ 7.2 ​ ​ 9.4 ​ Total ​ $ 66.4 ​ $ 53.6 ​
Schedule of estimated useful lives of property and equipment	​ ​ ​ ​ Classification Life Vessels 40 years Terminal cranes 30 years Containers and chassis ​ 15 years Terminal facilities and other property 35 years
Schedule of other liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Liabilities (in millions) 2023 2022 Payroll and vacation $ 38.3 $ 34.7 ​ Employee incentives and other benefits ​ ​ 33.9 ​ ​ 33.2 ​ Insurance reserves and other related liabilities - short term ​ ​ 17.5 ​ ​ 15.6 ​ Multi-employer withdrawal liabilities - short term ​ ​ 4.1 ​ ​ 4.1 ​ Income tax and other tax related liabilities ​ ​ 1.6 ​ ​ 2.2 ​ Other short-term liabilities ​ ​ 12.6 ​ ​ 15.7 ​ Total $ 108.0 $ 105.5 ​
Schedule of other long-term liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Other Long-Term Liabilities (in millions) 2023 2022 Multi-employer withdrawal liability ​ $ 46.5 ​ $ 48.6 ​ Insurance reserves and other related liabilities ​ ​ 23.8 ​ ​ 29.8 ​ Pension and post-retirement liabilities ​ ​ 21.8 ​ ​ 17.8 ​ Other long-term liabilities ​ 21.6 ​ 18.6 ​ Total ​ $ 113.7 ​ $ 114.8 ​
Ocean Transportation
Schedule of principal revenue generating activities by segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Ocean Transportation (in millions) (1) ​ 2023 ​ 2022 ​ 2021 Ocean Transportation services ​ $ 2,420.8 ​ $ 3,508.0 ​ $ 3,101.9 Terminal and other related services ​ ​ 36.9 ​ ​ 18.5 ​ ​ 16.0 Fuel sales ​ ​ 12.3 ​ ​ 11.3 ​ ​ 7.2 Vessel management and related services ​ ​ 7.0 ​ ​ 6.8 ​ ​ 7.7 Total ​ $ 2,477.0 ​ $ 3,544.6 ​ $ 3,132.8 (1) Ocean Transportation revenue transactions are primarily denominated in U.S. dollars except for less than 3 percent of Ocean Transportation services revenue and fuel sales revenue categories which are denominated in foreign currencies. ​
Logistics
Schedule of principal revenue generating activities by segment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Logistics (in millions) (1) ​ 2023 ​ 2022 ​ 2021 Transportation Brokerage and Freight Forwarding services ​ $ 546.8 ​ $ 695.1 ​ $ 707.4 Warehousing and distribution services ​ ​ 42.5 ​ ​ 53.5 ​ ​ 44.7 Supply chain management and other services ​ 28.3 ​ 49.8 ​ 40.4 Total ​ $ 617.6 ​ $ 798.4 ​ $ 792.5 (1) Logistics revenue transactions are primarily denominated in U.S. dollars except for less than 3 percent of transportation brokerage and freight forwarding services revenue, and supply chain management and other services revenue categories which are denominated in foreign currencies. ​

REPORTABLE SEGMENTS (Tables)

REPORTABLE SEGMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
REPORTABLE SEGMENTS
Schedule of reportable segment financial information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Operating Revenue: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation (1) ​ $ 2,477.0 ​ $ 3,544.6 ​ $ 3,132.8 Logistics (2) ​ 617.6 ​ 798.4 ​ 792.5 Total Operating Revenue ​ $ 3,094.6 ​ $ 4,343.0 ​ $ 3,925.3 Operating Income: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation (3) ​ $ 294.8 ​ $ 1,281.2 ​ $ 1,137.7 Logistics ​ 48.0 ​ 72.4 ​ 49.8 Total Operating Income ​ 342.8 ​ 1,353.6 ​ 1,187.5 Interest income ​ ​ 36.0 ​ ​ 8.2 ​ ​ — Interest expense ​ (12.2) ​ (18.0) ​ (22.6) Other income (expense), net ​ 6.4 ​ 8.5 ​ 6.4 Income before Taxes ​ 373.0 ​ 1,352.3 ​ 1,171.3 Income taxes ​ (75.9) ​ (288.4) ​ (243.9) Net Income ​ $ 297.1 ​ $ 1,063.9 ​ $ 927.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Capital Expenditures: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation ​ $ 240.2 ​ $ 190.9 ​ $ 322.4 Logistics ​ 8.2 ​ 18.4 ​ 2.9 Total Capital Expenditures ​ $ 248.4 ​ $ 209.3 ​ $ 325.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Depreciation and Amortization: ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean Transportation ​ $ 132.8 ​ $ 133.2 ​ $ 128.6 Logistics ​ 11.6 ​ 8.1 ​ 7.3 ​ ​ ​ 144.4 ​ ​ 141.3 ​ ​ 135.9 Deferred dry-docking amortization - Ocean Transportation ​ ​ 25.3 ​ ​ 24.9 ​ ​ 24.3 Total Depreciation and Amortization ​ $ 169.7 ​ $ 166.2 ​ $ 160.2 (1) Ocean Transportation operating revenue excludes inter-segment revenue of $76.5 million, $93.6 million and $81.0 million for the years ended December 31, 2023, 2022 and 2021, respectively. (2) Logistics operating revenue excludes inter-segment revenue of $132.2 million, $177.3 million and $132.8 million for the years ended December 31, 2023, 2022 and 2021, respectively. (3) Ocean Transportation segment information includes $2.2 million, $83.1 million, and $56.3 million of income from the Company’s investment in SSAT for the years ended December 31, 2023, 2022 and 2021, respectively. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) 2023 2022 Identifiable Assets: ​ ​ ​ ​ ​ ​ Ocean Transportation (1) ​ $ 3,645.3 ​ $ 3,705.2 Logistics ​ 649.3 ​ 624.8 Total Assets ​ $ 4,294.6 ​ $ 4,330.0 (1) The Ocean Transportation segment includes $85.5 million and $81.2 million related to the Company’s investment in SSAT as of December 31, 2023 and 2022, respectively.

INVESTMENT IN SSAT (Tables)

INVESTMENT IN SSAT (Tables)	12 Months Ended
	Dec. 31, 2023
INVESTMENT IN SSAT
Schedule of condensed income statement information for SSAT	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Company’s share of income from SSAT ​ $ 2.2 ​ $ 83.1 ​ $ 56.3 Distributions received from SSAT ​ $ — ​ $ 47.3 ​ $ 46.9
Unaudited condensed financial information for SSAT - Balance Sheet	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, Condensed Balance Sheets (in millions) 2023 2022 Current assets ​ $ 304.0 ​ $ 324.7 Non-current assets ​ 1,510.2 ​ 1,436.0 Total Assets ​ $ 1,814.2 ​ $ 1,760.7 ​ ​ ​ ​ ​ ​ ​ Current liabilities ​ $ 271.8 ​ $ 342.1 Non-current liabilities ​ 1,255.3 ​ 1,199.5 Equity ​ 287.1 ​ 219.1 Total Liabilities and Equity ​ $ 1,814.2 ​ $ 1,760.7 ​
Unaudited condensed financial information for SSAT - Statement of Operating Income and Net Income	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Condensed Statements of Operating Income and Net Income (in millions) 2023 2022 2021 Operating revenue ​ $ 1,025.1 ​ $ 1,466.9 ​ $ 1,297.5 Operating costs and expenses ​ 1,019.6 ​ 1,168.8 ​ 1,113.8 Operating income ​ 5.5 ​ 298.1 ​ 183.7 Net Income (1)(2) ​ $ 11.9 ​ $ 249.6 ​ $ 161.7 (1) Includes earnings from equity method investments held by SSAT less earnings allocated to non-controlling interests. (2) Includes net income or loss attributable to noncontrolling interests. ​

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2023
PROPERTY AND EQUIPMENT
Schedule of property and equipment	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2023 ​ As of December 31, 2022 ​ ​ ​ Accumulated ​ ​ ​ Accumulated ​ (In millions) ​ Cost ​ Depreciation ​ Net Book Value ​ Cost ​ Depreciation ​ Net Book Value Vessels ​ $ 2,323.4 ​ $ 886.8 ​ $ 1,436.6 ​ ​ $ 2,278.6 ​ $ 838.8 ​ $ 1,439.8 ​ Containers and equipment ​ 845.0 ​ ​ 451.9 ​ 393.1 ​ ​ 762.7 ​ 433.8 ​ 328.9 ​ Terminal facilities and other property ​ 148.0 ​ ​ 58.6 ​ 89.4 ​ ​ 131.5 ​ 53.6 ​ 77.9 ​ New vessel construction in progress ​ ​ 103.1 ​ ​ — ​ ​ 103.1 ​ ​ ​ 50.2 ​ ​ — ​ ​ 50.2 ​ Other construction in progress ​ 67.7 ​ ​ — ​ 67.7 ​ ​ 65.7 ​ — ​ 65.7 ​ Total ​ $ 3,487.2 ​ $ 1,397.3 ​ $ 2,089.9 ​ ​ $ 3,288.7 ​ $ 1,326.2 ​ $ 1,962.5 ​
Schedule of depreciation expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Depreciation expense ​ $ 124.4 ​ $ 123.5 ​ $ 117.1 ​ ​

GOODWILL AND INTANGIBLES (Table

GOODWILL AND INTANGIBLES (Tables)	12 Months Ended
	Dec. 31, 2023
GOODWILL AND INTANGIBLES
Schedule of goodwill	Goodwill by segment consists of the following as of December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Ocean ​ ​ ​ ​ ​ ​ (In millions) Transportation Logistics Total Goodwill ​ $ 222.6 ​ $ 105.2 ​ $ 327.8
Schedule of intangible assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, 2023 ​ As of December 31, 2022 ​ ​ Gross ​ Accumulated ​ ​ ​ ​ Gross ​ Accumulated ​ ​ ​ (In millions) Amount Amortization Net Book Value Amount Amortization Net Book Value Ocean Transportation - Customer relationships ​ $ 140.6 ​ $ 57.9 ​ $ 82.7 ​ ​ $ 140.6 ​ $ 51.2 ​ $ 89.4 ​ Logistics: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Customer relationships ​ ​ 110.4 ​ ​ 44.0 ​ ​ 66.4 ​ ​ ​ 95.3 ​ ​ 37.1 ​ ​ 58.2 ​ Trade name ​ 27.3 ​ ​ — ​ ​ 27.3 ​ ​ 27.3 ​ ​ — ​ ​ 27.3 ​ Total Logistics ​ 137.7 ​ ​ 44.0 ​ ​ 93.7 ​ ​ 122.6 ​ ​ 37.1 ​ ​ 85.5 ​ Total ​ $ 278.3 ​ $ 101.9 ​ $ 176.4 ​ ​ $ 263.2 ​ $ 88.3 ​ $ 174.9 ​
Schedule of intangible asset related amortization expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Amortization expense ​ $ 13.6 ​ $ 11.4 ​ $ 10.9 ​
Schedule of estimated amortization expenses related to intangible assets	As of December 31, 2023, estimated amortization expense related to customer relationship intangible assets during the next five years and thereafter are as follows: ​ ​ ​ ​ ​ ​ ​ Customer ​ Year (in millions) ​ Relationships 2024 ​ $ 14.3 ​ 2025 ​ 13.6 ​ 2026 ​ 13.0 ​ 2027 ​ 13.0 ​ 2028 ​ 13.0 ​ Thereafter ​ 82.2 ​ Total ​ $ 149.1 ​ ​

CAPITAL CONSTRUCTION FUND (Tabl

CAPITAL CONSTRUCTION FUND (Tables)	12 Months Ended
	Dec. 31, 2023
CAPITAL CONSTRUCTION FUND
Schedule of capital construction fund	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, (In millions) ​ 2023 2022 CCF balance at beginning of period ​ $ 518.2 ​ $ — Cash deposits into CCF ​ ​ 100.0 ​ ​ 579.7 Interest earned on deposits ​ ​ 31.1 ​ ​ 3.1 Qualifying withdrawal payments ​ ​ (49.9) ​ ​ (64.6) CCF balance at end of period ​ $ 599.4 ​ $ 518.2
Schedule of assigned eligible accounts receivable, and on deposit to the Capital Construction Fund	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) ​ 2023 2022 Capital Construction Fund: ​ ​ ​ ​ ​ ​ Cash on deposit ​ $ 599.4 ​ $ 518.2 Assigned accounts receivables ​ $ 218.1 ​ $ 9.9

DEBT (Tables)

DEBT (Tables)	12 Months Ended
	Dec. 31, 2023
DEBT
Schedule of debt	The Company’s debt consists of the following as of December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) 2023 2022 Private Placement Term Loans: ​ ​ ​ ​ ​ ​ 3.66 %, payable through 2023 ​ $ — ​ $ 4.5 3.37 %, payable through 2027 ​ ​ 46.2 ​ ​ 57.7 3.14 %, payable through 2031 ​ ​ 114.4 ​ ​ 132.8 Title XI Debt: ​ ​ ​ ​ ​ ​ 5.34 %, payable through 2028 ​ — ​ 13.2 5.27 %, payable through 2029 ​ — ​ 15.4 1.22 %, payable through 2043 ​ ​ 158.2 ​ ​ 166.2 1.35 %, payable through 2044 ​ ​ 121.8 ​ ​ 127.7 Total Debt ​ 440.6 ​ 517.5 Less: Current portion ​ (39.7) ​ (76.9) Total Long-term Debt ​ ​ 400.9 ​ ​ 440.6 Less: Deferred loan fees ​ ​ (11.6) ​ ​ (12.9) Total Long-term Debt, net of deferred loan fees ​ $ 389.3 ​ $ 427.7
Schedule of maturities of debt	​ ​ ​ ​ ​ ​ ​ As of Year (in millions) December 31, 2023 2024 ​ $ 39.7 2025 ​ 39.7 2026 ​ 39.7 2027 ​ 39.7 2028 ​ 28.2 Thereafter ​ 253.6 Total Debt ​ $ 440.6
Schedule of deferred loan fees	​ ​ ​ ​ ​ Deferred Loan Fees (in millions) Amount Balance at December 31, 2022 ​ $ 12.9 Amortization expense for the year ended December 31, 2023 ​ (1.3) Balance at December 31, 2023 ​ $ 11.6
Schedule of estimated amortization expense relating to deferred laon fees	​ ​ ​ ​ ​ Year (in millions) Amount 2024 ​ $ 1.2 2025 ​ 1.1 2026 ​ 1.0 2027 ​ 0.9 2028 ​ 0.9 Thereafter ​ 6.5 Total amortization expense of deferred loan fees ​ $ 11.6

LEASES (Tables)

LEASES (Tables)	12 Months Ended
	Dec. 31, 2023
LEASES
Summary of lease type by underlying asset class and maximum terms	​ ​ ​ ​ Lease Type: Term Real estate and terminal leases 50 years Vessel and barge charter leases 4 years Operations equipment and other leases 14 years
Components of Lease Cost	Components of Lease Cost: Components of lease cost recorded in the Company’s Consolidated Statement of Income and Comprehensive Income consists of the following for the years ended December 31, 2023, 2022 and 2021: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, (In millions) 2023 ​ 2022 ​ 2021 Operating lease cost ​ $ 151.0 ​ $ 162.2 ​ $ 110.7 Short-term lease cost ​ 7.7 ​ 0.6 ​ 3.1 Variable lease cost ​ 0.6 ​ 0.8 ​ 0.6 Total lease cost ​ $ 159.3 ​ $ 163.6 ​ $ 114.4 ​ Other Lease Information: Other information related to the Company’s operating leases consists of the following for the years ended December 31, 2023 and 2022: ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended ​ ​ December 31, (In millions) 2023 ​ 2022 Cash paid for amounts included in operating lease liabilities ​ $ 154.3 ​ $ 163.4 Right of use assets obtained in the exchange for new operating lease liabilities ​ $ 40.0 ​ $ 131.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, ​ ​ 2023 2022 Weighted average remaining operating lease term ​ ​ 4.8 years ​ ​ 4.9 years Weighted average incremental borrowing rate ​ ​ 3.1% ​ ​ 2.4% ​
Summary of maturities of operating lease liabilities	​ ​ ​ ​ ​ ​ As of Year (in millions) December 31, 2023 2024 ​ $ 143.3 2025 ​ 80.8 2026 ​ 32.1 2027 ​ 15.3 2028 ​ 6.7 Thereafter ​ 51.1 Total lease payments ​ ​ 329.3 Less: Interest ​ ​ (33.3) Present value of operating lease liabilities ​ ​ 296.0 Less: Short-term portion ​ ​ (136.7) Long-term operating lease liabilities ​ $ 159.3 ​

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2023
INCOME TAXES
Schedule of income tax expense	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, (In millions) 2023 2022 2021 Current: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ $ 44.0 ​ $ 171.5 ​ $ 181.2 ​ State ​ 9.2 ​ 18.3 ​ 35.6 ​ Foreign ​ ​ 3.0 ​ ​ 1.3 ​ ​ 2.5 ​ Total current tax expense ​ 56.2 ​ 191.1 ​ 219.3 ​ Deferred: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Federal ​ ​ 18.2 ​ ​ 71.1 ​ ​ 26.4 ​ State ​ ​ — ​ ​ 24.3 ​ ​ 0.4 ​ Foreign ​ ​ 1.5 ​ ​ 1.9 ​ ​ (2.2) ​ Total deferred tax expense ​ ​ 19.7 ​ ​ 97.3 ​ ​ 24.6 ​ Total income taxes ​ $ 75.9 ​ $ 288.4 ​ $ 243.9 ​ ​
Schedule of effective income tax rate	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, ​ 2023 2022 2021 Computed federal income tax expense 21.0 % 21.0 % 21.0 % State income tax 2.6 % 2.8 % 3.1 % Foreign-derived intangible income (FDII) (2.0) % (2.4) % (2.5) % Valuation allowance — % — % (0.3) % Foreign taxes 0.4 % 0.1 % 0.2 % Share-based payments 0.5 % — % (0.2) % Return to provision true-ups ​ (2.8) % 0.1 % (0.2) % Other — net 0.6 % (0.3) % (0.3) % Effective income tax rate 20.3 % 21.3 % 20.8 %
Schedule of tax effects of temporary differences	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of December 31, (In millions) 2023 2022 Deferred tax assets: ​ ​ ​ ​ ​ ​ ​ Operating lease liabilities ​ $ 77.4 ​ $ 102.9 ​ Multi-employer withdrawal liabilities ​ ​ 12.8 ​ ​ 13.3 ​ Deferred compensation ​ 11.8 ​ ​ 10.9 ​ U.S. state alternative minimum tax credits ​ ​ 7.4 ​ ​ 8.8 ​ Insurance reserves ​ ​ 6.3 ​ ​ 7.3 ​ Other ​ 12.9 ​ 15.4 ​ Total deferred tax assets ​ 128.6 ​ 158.6 ​ Valuation allowance ​ ​ (5.3) ​ ​ (7.4) ​ Total deferred tax assets, net of valuation allowance ​ ​ 123.3 ​ ​ 151.2 ​ ​ ​ ​ ​ ​ ​ ​ ​ Deferred tax liabilities: ​ ​ ​ ​ ​ ​ ​ Basis differences for property and equipment ​ 451.4 ​ 433.1 ​ Capital Construction Fund ​ 206.9 ​ ​ 194.0 ​ Operating lease right of use assets ​ 75.8 ​ 100.7 ​ Intangibles ​ ​ 42.3 ​ ​ 42.0 ​ Other ​ ​ 16.2 ​ ​ 27.9 ​ Total deferred tax liabilities ​ 792.6 ​ 797.7 ​ Deferred tax liability, net ​ $ 669.3 ​ $ 646.5 ​
Schedule of company's net operating losses ("NOLs") and tax credit carryforwards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (In millions) ​ Expiration Date 2023 2022 U.S. federal income tax NOLs ​ Various dates beginning in 2027 ​ $ — ​ $ 0.8 U.S. state income tax NOLs (1) ​ Various dates beginning in 2032 ​ $ 152.3 ​ $ 157.9 U.S. state alternative minimum tax credit ​ No expiration date ​ $ 7.3 ​ $ 8.6 (1) U.S. State income tax NOLs are presented on a gross tax basis. The Company does not expect to benefit from $152.3 million of U.S. state income tax NOLs as of December 31, 2023. ​
Reconciliation of unrecognized tax benefits	​ ​ ​ ​ ​ ​ Unrecognized Tax Benefits (in millions) Amount Balance at December 31, 2020 ​ $ 18.3 ​ Tax position changes in current year ​ 2.3 ​ Tax position changes in prior years ​ ​ (1.2) ​ Reductions for lapse of statute of limitations ​ ​ (0.2) ​ Balance at December 31, 2021 ​ 19.2 ​ Tax position changes in current year ​ 5.8 ​ Tax position changes in prior years ​ ​ 0.3 ​ Reductions for lapse of statute of limitations ​ ​ (0.2) ​ Balance at December 31, 2022 ​ 25.1 ​ Tax position changes in current year ​ 3.6 ​ Tax position changes in prior years ​ ​ (0.1) ​ Reductions for lapse of statute of limitations ​ ​ (0.2) ​ Balance at December 31, 2023 ​ $ 28.4 ​

PENSION AND POST-RETIREMENT P_2

PENSION AND POST-RETIREMENT PLANS (Tables)	12 Months Ended
	Dec. 31, 2023
PENSION AND POST-RETIREMENT PLANS
Schedule of the Company's target and actual asset allocations	​ ​ ​ ​ ​ ​ ​ ​ ​ Asset Categories Target 2023 2022 Domestic equity securities 53 % 57 % 53 % International equity securities 15 % 16 % 16 % Debt securities 22 % 19 % 20 % Real estate 5 % 5 % 7 % Other and cash 5 % 3 % 4 % Total 100 % 100 % 100 %
Schedule of the Company's actual return on plan assets	​ ​ ​ ​ ​ Actual Return on Plan Assets Returns One-year return 12.8 % Three-year return 4.6 % Five-year return 9.5 % Long-term average return (since plan inception in 1989) 8.2 %
Schedule of the fair values of the Company's pension plan assets, by asset category	The fair values of the Company’s pension plan assets at December 31, 2023 and 2022 by asset category were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2023 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets ​ Observable ​ Unobservable Asset Category (in millions) ​ Total ​ (Level 1) ​ Inputs (Level 2) ​ Inputs (Level 3) Cash ​ $ 6.1 ​ $ 6.1 ​ $ — ​ $ — ​ Equity securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. large-cap ​ 82.8 ​ 82.8 ​ — ​ — ​ U.S. mid- and small-cap ​ 46.0 ​ 46.0 ​ — ​ — ​ International large-cap ​ 7.1 ​ 7.1 ​ — ​ — ​ Fixed income securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ 19.2 ​ — ​ 19.2 ​ — ​ Municipal bonds ​ 0.2 ​ — ​ 0.2 ​ — ​ Investment grade U.S. corporate bonds ​ ​ 24.7 ​ — ​ 24.7 ​ — ​ Convertible bonds ​ 0.1 ​ — ​ 0.1 ​ — ​ International fixed income securities ​ ​ 0.1 ​ ​ — ​ ​ 0.1 ​ ​ — ​ Total ​ ​ 186.3 ​ $ 142.0 ​ $ 44.3 ​ $ — ​ Investment measured at NAV (1) ​ ​ 41.6 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total plan assets ​ $ 227.9 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair Value Measurements at December 31, 2022 ​ ​ ​ Quoted Prices in Significant Significant ​ ​ ​ ​ ​ Active Markets ​ Observable ​ Unobservable Asset Category (in millions) ​ Total ​ (Level 1) ​ Inputs (Level 2) ​ Inputs (Level 3) Cash ​ $ 8.8 ​ $ 8.8 ​ $ — ​ $ — ​ Equity securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. large-cap ​ 69.1 ​ 69.1 ​ — ​ — ​ U.S. mid- and small-cap ​ 41.5 ​ 41.5 ​ — ​ — ​ International large-cap ​ 6.2 ​ 6.2 ​ — ​ — ​ Fixed income securities: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. Treasuries ​ 17.4 ​ — ​ 17.4 ​ — ​ Municipal bonds ​ 0.2 ​ — ​ 0.2 ​ — ​ Investment grade U.S. corporate bonds ​ 22.8 ​ — ​ 22.8 ​ — ​ Convertible bonds ​ ​ 0.3 ​ — ​ ​ 0.3 ​ ​ ​ ​ International fixed income securities ​ 0.1 ​ — ​ 0.1 ​ — ​ Total ​ ​ 166.4 ​ $ 125.6 ​ $ 40.8 ​ $ — ​ Investment measured at NAV (1) ​ ​ 40.0 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Total plan assets ​ $ 206.4 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (1) Certain funds for which fair value is measured using the NAV per share as a practical expedient are not leveled within the fair value hierarchy and are included as a reconciling item to total plan assets. These investments include real estate and certain developed and emerging market equity funds.
Schedule of change in benefit obligation and plan assets	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post-retirement ​ ​ Pension Benefits ​ Benefits ​ ​ December 31, ​ December 31, ​ (In millions) 2023 2022 2023 2022 Change in Benefit Obligation: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Benefit obligation at beginning of year ​ $ 187.4 ​ $ 249.5 ​ $ 15.3 ​ $ 29.3 ​ Service cost ​ 3.1 ​ 4.8 ​ 0.2 ​ 0.7 ​ Interest cost ​ 10.0 ​ 7.0 ​ 0.8 ​ 0.8 ​ Participant contributions ​ — ​ — ​ 0.7 ​ 0.7 ​ Actuarial loss (gain) ​ 5.5 ​ (59.0) ​ 4.5 ​ (14.2) ​ Benefits paid, net of subsidies received ​ (12.9) ​ (14.1) ​ (2.0) ​ (2.0) ​ Expenses paid ​ — ​ (0.8) ​ — ​ — ​ Benefit obligation at end of year ​ ​ 193.1 ​ ​ 187.4 ​ ​ 19.5 ​ ​ 15.3 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Change in Plan Assets: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Fair value of plan assets at beginning of year ​ ​ 206.3 ​ ​ 238.9 ​ ​ — ​ ​ — ​ Actual return on plan assets ​ 25.5 ​ (26.7) ​ — ​ — ​ Participant contributions ​ — ​ — ​ 0.7 ​ 0.7 ​ Employer contributions ​ 9.0 ​ 9.0 ​ 1.3 ​ 1.3 ​ Benefits paid, net of subsidies received ​ (12.9) ​ (14.1) ​ (2.0) ​ (2.0) ​ Expenses paid ​ — ​ (0.8) ​ — ​ — ​ Fair value of plan assets at end of year ​ 227.9 ​ 206.3 ​ — ​ — ​ Funded Status and Recognized Plan Assets and Benefit Obligations ​ $ 34.8 ​ $ 18.9 ​ $ (19.5) ​ $ (15.3) ​
Schedule of amounts recognized on the consolidated balance sheets and in accumulated other comprehensive income (loss)	Qualified pension and post-retirement benefit plan assets and liabilities recognized in the Consolidated Balance Sheets and expenses recognized in accumulated other comprehensive income (loss) at December 31, 2023 and 2022 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Post-retirement ​ ​ Pension Benefits ​ Benefits ​ ​ December 31, ​ December 31, ​ (In millions) 2023 2022 2023 2022 Non-current assets ​ $ 34.8 ​ $ 18.9 ​ $ — ​ $ — ​ Current liabilities ​ ​ — ​ ​ — ​ ​ (1.1) ​ ​ (0.9) ​ Non-current liabilities ​ — ​ — ​ (18.4) ​ (14.4) ​ Total ​ $ 34.8 ​ $ 18.9 ​ $ (19.5) ​ $ (15.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (loss) gain, net of taxes ​ $ (20.3) ​ $ (25.8) ​ $ 2.7 ​ $ 7.6 ​ Prior service credit, net of taxes ​ — ​ — ​ 8.3 ​ 11.1 ​ Total ​ $ (20.3) ​ $ (25.8) ​ $ 11.0 ​ $ 18.7 ​
Schedule of components of the net periodic benefit cost and other changes in plan assets and benefit obligations recognized in other comprehensive income (loss)	Components of the net periodic benefit cost and other amounts recognized in other comprehensive income (loss) for the qualified pension plan and the post-retirement benefit plan during 2023, 2022 and 2021 were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension Benefits ​ Post-retirement Benefits ​ ​ December 31, ​ December 31, ​ (In millions) 2023 2022 2021 2023 2022 2021 Components of Net Periodic Benefit Cost (Credit): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Service cost ​ $ 3.1 ​ $ 4.8 ​ $ 4.8 ​ $ 0.2 ​ $ 0.7 ​ $ 0.7 ​ Interest cost ​ 10.0 ​ 7.0 ​ 6.4 ​ 0.8 ​ 0.8 ​ 0.7 ​ Expected return on plan assets ​ (13.9) ​ (16.0) ​ (14.7) ​ — ​ — ​ — ​ Amortization of net loss (gain) ​ 1.3 ​ 2.4 ​ 5.2 ​ (2.0) ​ 0.8 ​ 1.0 ​ Amortization of prior service credit ​ — ​ (1.0) ​ (2.3) ​ (3.7) ​ (3.6) ​ (3.7) ​ Net periodic benefit cost (credit) ​ ​ 0.5 ​ ​ (2.8) ​ ​ (0.6) ​ ​ (4.7) ​ ​ (1.3) ​ ​ (1.3) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income, net of tax: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (gain) loss ​ ​ (4.5) ​ ​ (12.3) ​ ​ (20.4) ​ ​ 3.4 ​ ​ (10.7) ​ ​ — ​ Amortization of net (loss) gain ​ (1.0) ​ (1.8) ​ (3.9) ​ 1.5 ​ (0.6) ​ (0.7) ​ Amortization of prior service credit ​ — ​ 0.8 ​ 1.7 ​ 2.8 ​ 2.7 ​ 2.8 ​ Total recognized in other comprehensive (income) loss ​ ​ (5.5) ​ ​ (13.3) ​ ​ (22.6) ​ ​ 7.7 ​ ​ (8.6) ​ ​ 2.1 ​ Total recognized in net periodic benefit cost and other comprehensive (income) loss ​ $ (5.0) ​ $ (16.1) ​ $ (23.2) ​ $ 3.0 ​ $ (9.9) ​ $ 0.8 ​
Schedule of weighted average assumptions used to determine benefit information	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension Benefits ​ Post-retirement Benefits ​ ​ December 31, ​ December 31, ​ ​ 2023 2022 2021 2023 2022 2021 Discount rate (1) 5.30 % 5.60 % 2.90 % 5.40 % 5.50 % 3.00 % Expected return on plan assets 6.85 % 6.75 % 7.00 % ​ ​ ​ ​ ​ ​ Rate of compensation increase 3.50 % 4.00 % - 3.50 % 3.00 % 3.50 % 4.00 % - 3.50 % 3.00 % Cash balance interest credit rate ​ 4.50 % - 3.25 % 3.50 % - 3.25 % 1.50 % - 3.25 % ​ ​ ​ ​ ​ ​ Immediate health care cost trend rate: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pre-65 group ​ ​ ​ ​ ​ ​ ​ 6.80 % 6.60 % 5.70 % Post-65 group ​ ​ ​ ​ ​ ​ ​ 7.10 % 6.10 % 5.80 % Ultimate health care cost trend rate ​ ​ ​ ​ ​ ​ ​ 3.90 % 4.00 % 4.00 % Year ultimate health care cost trend rate is reached ​ ​ ​ ​ ​ ​ ​ 2048 ​ 2046 ​ 2045 ​ (1) The Company derives a single equivalent rate utilizing a yield curve constructed from a portfolio of high-quality corporate bonds with various maturities.
Schedule of amounts recognized on balance sheet and accumulated comprehensive income (loss)	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-qualified ​ Pension Benefits ​ December 31, ​ (In millions) ​ 2023 2022 Current liabilities ​ $ (1.2) ​ $ (0.7) ​ Non-current liabilities ​ ​ (3.4) ​ ​ (3.4) ​ Total ​ $ (4.6) ​ $ (4.1) ​ ​ ​ ​ ​ ​ ​ ​ ​ Net (loss), net of taxes ​ $ (0.2) ​ $ 0.1 ​ Total ​ $ (0.2) ​ $ 0.1 ​
Schedule of estimated benefit payments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-qualified ​ ​ ​ ​ Pension ​ Pension ​ Post-retirement ​ Year (in millions) ​ Benefits ​ Benefits ​ Benefits (1) 2024 ​ $ 14.7 ​ $ 1.2 ​ $ 1.1 ​ 2025 ​ 15.0 ​ 0.4 ​ 1.1 ​ 2026 ​ 15.2 ​ 0.5 ​ 1.2 ​ 2027 ​ 15.4 ​ 0.5 ​ 1.2 ​ 2028 ​ 15.6 ​ 0.4 ​ 1.2 ​ 2029-2033 ​ ​ 77.0 ​ ​ 2.6 ​ ​ 6.1 ​ Total ​ $ 152.9 ​ $ 5.6 ​ $ 11.9 ​ (1) Net of participant contributions and Medicare Part D subsidies.
Schedule of information regarding the entity's participation in the multi-employer pension plans	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Pension ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Protection Act ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Zone as of ​ FIP/RP Status ​ 5% ​ Contributions of Matson ​ ​ ​ ​ ​ ​ EIN/Pension ​ ​ ​ December 31, ​ Pending/ ​ Contributor ​ (in millions) ​ Surcharge ​ Expiration Pension Funds Plan Number Notes 2023 2022 Implemented in 2023 2023 2022 2021 Imposed Date (1) American Radio Association Pension Fund 13-6161999-001 ​ ​ Green Green Implemented ​ Yes ​ $ 1.0 ​ $ 1.1 ​ $ 1.1 No 6/15/2028 ​ Hawaii Longshore Pension Plan ​ 99-0314293-001 ​ ​ ​ Green ​ Green ​ No ​ Yes ​ ​ 12.1 ​ ​ 11.9 ​ ​ 11.1 ​ No ​ 6/30/2028 ​ Master, Mates and Pilots Pension Plan 13-6372630-001 ​ ​ ​ Green Green No ​ Yes ​ 3.6 ​ 3.8 ​ 3.5 No ​ 6/15/2027, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/15/2028 ​ Masters, Mates and Pilots Adjustable Pension Plan 37-1719247-001 ​ ​ ​ Green Green No ​ Yes ​ 2.0 ​ 2.1 ​ 2.0 No ​ 6/15/2027, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/15/2028 ​ MEBA Pension Trust - Defined Benefit Plan 51-6029896-001 ​ ​ ​ Green Green No ​ Yes ​ 4.2 ​ 4.5 ​ 4.3 No 6/15/2028 ​ OCU Pension Trust Plan 26-1574440-001 ​ ​ ​ Green Green No ​ No ​ 0.4 ​ 0.5 ​ 0.3 No 6/30/2030 ​ MFOW Supplementary Pension Plan ​ 94-6201677-001 ​ ​ ​ Yellow ​ Yellow ​ No ​ Yes ​ ​ 0.1 ​ ​ 0.1 ​ ​ 0.1 ​ No ​ 6/30/2026 ​ SIU Pacific District Pension Plan ​ 94-6061923-001 ​ ​ ​ Green ​ Green ​ No ​ Yes ​ ​ 1.3 ​ ​ 1.5 ​ ​ 1.4 ​ No ​ 6/30/2026 ​ Alaska Teamster - Employer Pension Plan ​ 92-6003463-024 ​ ​ ​ Red ​ Red ​ Implemented ​ Yes ​ ​ 3.9 ​ ​ 4.0 ​ ​ 3.6 ​ No ​ 6/30/2024, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/30/2025, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/30/2026, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 6/30/2027 ​ All Alaska Longshore Pension Plan ​ 91-6085352-001 ​ ​ ​ Green ​ Green ​ No ​ Yes ​ ​ 1.8 ​ ​ 2.0 ​ ​ 1.6 ​ No ​ 6/30/2028 ​ Western Conference of Teamsters Pension Plan ​ 91-6145047-001 ​ ​ ​ Green ​ Green ​ No ​ No ​ ​ 2.1 ​ ​ 2.1 ​ ​ 1.9 ​ No ​ 3/31/2028 ​ Western Conference of Teamsters Supplemental Benefit Trust ​ 95-3746907-001 ​ ​ ​ Green ​ Green ​ No ​ No ​ ​ 0.1 ​ ​ 0.1 ​ ​ — ​ No ​ 3/31/2028 ​ OPEIU Local 153 Pension Plan ​ 13-2864289-001 ​ ​ ​ Red ​ Red ​ Implemented ​ No ​ ​ 0.1 ​ ​ 0.1 ​ ​ 0.1 ​ No ​ 11/9/2028 ​ Seafarers Pension Plan ​ 13-6100329-001 ​ (2) ​ Green ​ Green ​ No ​ No ​ ​ — ​ ​ — ​ ​ — ​ No ​ 6/30/2027 ​ Total ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ $ 32.7 ​ $ 33.8 ​ $ 31.0 ​ ​ ​ ​ ​ (1) Represents the expiration date of the collective bargaining agreement. (2) The Company does not make contributions directly to the Seafarers Pension Plan. Instead, contributions are made to the Seafarers Health and Benefits Plan, and are subsequently re-allocated to the Seafarers Pension Plan at the discretion of the plan Trustees. ​

MULTI-EMPLOYER WITHDRAWAL LIA_2

MULTI-EMPLOYER WITHDRAWAL LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2023
MULTI-EMPLOYER WITHDRAWAL LIABILITIES
Schedule of future estimated annual payments to the multi-employer pension plan	​ ​ ​ ​ ​ Year (in millions) ​ Total 2024 $ 4.1 2025 ​ ​ 4.1 2026 ​ ​ 4.1 2027 ​ ​ 4.1 2028 ​ ​ 4.1 Thereafter ​ ​ 47.3 Total remaining future undiscounted payments due to the ILA-PRSSA pension fund ​ ​ 67.8 Less: amount representing interest ​ ​ (17.2) Present value of multi-employer withdrawal liability ​ ​ 50.6 Current portion of multi-employer withdrawal liability (see Note 2) ​ ​ (4.1) Long-term portion of multi-employer withdrawal liability (see Note 2) $ 46.5 ​

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2023
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
Schedule of changes in accumulated other comprehensive income (loss) by component, net of tax	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non- ​ ​ Accumulated ​ ​ ​ ​ ​ Post- ​ Qualified ​ ​ ​ ​ Other ​ ​ Pension ​ Retirement ​ Pension ​ ​ ​ ​ Comprehensive (In millions) ​ Benefits ​ Benefits ​ Benefits ​ Other ​ Income (Loss) Balance at December 31, 2021 ​ $ (39.1) ​ $ 10.1 ​ $ (0.7) ​ $ (1.2) ​ $ (30.9) ​ Amortization of prior service cost ​ (0.8) ​ ​ (2.7) ​ ​ — ​ ​ — ​ (3.5) ​ Amortization of net gain (loss) ​ ​ 14.1 ​ ​ 11.3 ​ ​ 0.8 ​ ​ 1.1 ​ 27.3 ​ Foreign currency exchange ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.4) ​ ​ (0.4) ​ Other adjustments ​ ​ — ​ — ​ — ​ 0.6 ​ 0.6 ​ Balance at December 31, 2022 ​ (25.8) ​ 18.7 ​ 0.1 ​ 0.1 ​ (6.9) ​ Amortization of prior service cost ​ — ​ ​ (2.8) ​ ​ — ​ ​ — ​ (2.8) ​ Amortization of net gain (loss) ​ 5.5 ​ ​ (4.9) ​ ​ (0.3) ​ ​ — ​ 0.3 ​ Foreign currency exchange ​ ​ — ​ ​ — ​ ​ — ​ ​ (0.5) ​ ​ (0.5) ​ Other adjustments ​ — ​ ​ — ​ ​ — ​ ​ 1.7 ​ 1.7 ​ Balance at December 31, 2023 ​ $ (20.3) ​ $ 11.0 ​ $ (0.2) ​ $ 1.3 ​ $ (8.2) ​ ​

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2023
EARNINGS PER SHARE
Schedule of basic and diluted earnings per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Year Ended December 31, 2023 ​ Year Ended December 31, 2022 ​ Year Ended December 31, 2021 ​ ​ ​ Weighted Per ​ ​ Weighted Per ​ ​ Weighted Per ​ ​ ​ ​ ​ Average ​ Common ​ ​ ​ ​ Average ​ Common ​ ​ ​ ​ Average ​ Common ​ ​ Net ​ Common ​ Share ​ Net ​ Common ​ Share ​ Net ​ Common ​ Share (In millions, except per share amounts) ​ Income ​ Shares ​ Amount ​ Income ​ Shares ​ Amount ​ Income ​ Shares ​ Amount Basic: ​ $ 297.1 35.3 ​ $ 8.42 ​ $ 1,063.9 39.0 ​ $ 27.28 ​ $ 927.4 42.8 ​ $ 21.67 ​ Effect of Dilutive Securities: ​ ​ — 0.4 ​ ​ (0.10) ​ ​ — 0.3 ​ ​ (0.21) ​ ​ — 0.4 ​ ​ (0.20) ​ Diluted: ​ $ 297.1 ​ 35.7 ​ $ 8.32 ​ $ 1,063.9 ​ 39.3 ​ $ 27.07 ​ $ 927.4 ​ 43.2 ​ $ 21.47 ​ ​

SHARE-BASED AWARDS (Tables)

SHARE-BASED AWARDS (Tables)	12 Months Ended
	Dec. 31, 2023
SHARE-BASED AWARDS
Summary of Compensation Expense and Other Information Related to Share-Based awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Years Ended December 31, Share-based compensation expense, net of estimated forfeitures (in millions) 2023 2022 2021 Share-based compensation expense ​ $ 23.8 ​ $ 18.3 ​ $ 19.3 ​ Tax benefit realized upon stock vesting ​ $ 6.1 ​ $ 10.6 ​ $ 8.0 ​ Fair value of stock vested ​ $ 27.8 ​ $ 44.0 ​ $ 33.5 ​
Non-Vested Restricted Stock Unit Activity	The following table summarizes non-vested restricted stock unit activity through December 31, 2023 (in thousands, except weighted average grant-date fair value amounts): ​ ​ ​ ​ ​ ​ ​ ​ 2016 Plan Weighted ​ ​ Restricted ​ Average Grant- ​ ​ ​ Stock Units ​ Date Fair Value Outstanding at December 31, 2022 546 $ 68.38 ​ Granted ​ 269 ​ ​ 66.05 ​ Vested ​ (439) ​ ​ 46.96 ​ Canceled ​ (10) ​ ​ 70.07 ​ Added by performance factor (1) ​ 167 ​ ​ 39.61 ​ Outstanding at December 31, 2023 533 $ 75.82 ​ (1) Represents shares paid out above target.

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
FAIR VALUE OF FINANCIAL INSTRUMENTS
Schedule of fair value measurement	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Quoted Prices in ​ Significant ​ Significant ​ ​ ​ Total ​ ​ ​ Active Markets ​ Observable ​ Unobservable ​ ​ Carrying Value Total (Level 1) Inputs (Level 2) Inputs (Level 3) ​ (In millions) ​ December 31, 2023 ​ Fair Value Measurements at December 31, 2023 ​ Cash and cash equivalents ​ $ 134.0 ​ $ 134.0 ​ $ 134.0 ​ $ — ​ $ — ​ Restricted cash ​ $ 2.3 ​ $ 2.3 ​ $ 2.3 ​ $ — ​ $ — ​ Capital Construction Fund ​ $ 599.4 ​ $ 599.4 ​ $ 599.4 ​ $ — ​ $ — ​ Fixed rate debt ​ $ 440.6 ​ $ 359.9 ​ $ — ​ $ 359.9 ​ $ — ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (In millions) December 31, 2022 ​ Fair Value Measurements at December 31, 2022 ​ Cash and cash equivalents ​ $ 249.8 ​ $ 249.8 $ 249.8 ​ $ — ​ $ — ​ Restricted cash ​ $ 3.9 ​ $ 3.9 ​ $ 3.9 ​ $ — ​ $ — ​ Capital Construction Fund ​ $ 518.2 ​ $ 518.2 ​ $ 518.2 ​ $ — ​ $ — ​ Fixed rate debt ​ $ 517.5 ​ $ 427.3 ​ $ — ​ $ 427.3 ​ $ — ​ ​

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2023
COMMITMENTS AND CONTINGENCIES
Schedule of Commitments and Contractual Obligations	Commitments and contractual obligations, excluding debt obligations (see Note 8), lease commitments (see Note 9), pension and post-retirement plan obligations (see Note 11), and multi-employer withdrawal liabilities (see Note 12), are as follows as of December 31, 2023: ​ ​ ​ ​ ​ ​ Commitments and Contractual Obligations (in millions) Total Standby letters of credit (1) ​ $ 5.8 ​ Bonds (2) ​ $ 56.4 ​ Vessel construction obligations (3) ​ $ 899.1 ​ Vendor and other obligations (4) ​ $ 77.1 ​ (1) Standby letters of credit are required for the Company’s uninsured workers’ compensation and other insurance programs, and other needs. (2) Bonds are required for U.S. Customs and other related matters. (3) Vessel construction obligations represent remaining contractual obligations entered into for the construction of three new Jones Act vessels. (4) Vendor and other obligations include: (i) non-cancellable contractual capital project obligations; (ii) dry-docking related obligations; and (iii) other contractual obligations. Amounts are considered obligations if a contract has been agreed to specifying significant terms of the contract, and the amounts are not reflected in the Consolidated Balance Sheets as of December 31, 2023. ​

DESCRIPTION OF THE BUSINESS (De

DESCRIPTION OF THE BUSINESS (Details)	12 Months Ended
	Dec. 31, 2023 facility segment
DESCRIPTION OF THE BUSINESS
Number of reportable segments | segment	2
Ocean Transportation | SSAT
DESCRIPTION OF THE BUSINESS
Ownership interest in SSAT (as a percent)	35%
Number of terminal facilities on which SSAT provides terminal and stevedoring services on the U.S. West Coast	8
MatNav | SSAT
DESCRIPTION OF THE BUSINESS
Number of terminal facilities on which SSAT provides terminal and stevedoring services on the U.S. West Coast	3

SIGNIFICANT ACCOUNTING POLICI_4

SIGNIFICANT ACCOUNTING POLICIES - FISCAL YEAR (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SIGNIFICANT ACCOUNTING POLICIES
Fiscal Period Duration	364 days	364 days	364 days

SIGNIFICANT ACCOUNTING POLICI_5

SIGNIFICANT ACCOUNTING POLICIES - CASH AND ACCOUNTS RECEIVABLE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
CAPITAL CONSTRUCTION FUND
Restricted Cash	$ 2.3	$ 3.9
Allowance for doubtful accounts
Balance at Beginning of year	13	10.1	$ 6.3
Expense	(2.1)	3.2	4.2
Write-offs and Other	(1)	(0.3)	(0.4)
Balance at End of Year	$ 9.9	$ 13	$ 10.1

SIGNIFICANT ACCOUNTING POLICI_6

SIGNIFICANT ACCOUNTING POLICIES - PREPAID EXPENSES AND OTHER ASSETS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Prepaid Expenses and Other Assets:
Income tax receivables, net	$ 125.2	$ 170.8
Prepaid fuel	22.5	26.3
Prepaid insurance and insurance related receivables	19.3	17.4
Restricted cash - vessel construction obligations	2.3	3.9
Other	19.6	22.9
Total	188.9	241.3
Other Long-term Assets
Vessel and equipment spare parts	14.2	13.2
Pension plan assets	34.8	18.9
Insurance related receivables	10.2	12.1
Other	7.2	9.4
Total	66.4	$ 53.6
Income taxes receivable	$ 118.6

SIGNIFICANT ACCOUNTING POLICI_7

SIGNIFICANT ACCOUNTING POLICIES - PROPERTY AND EQUIPMENT AND OTHER (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Impairment of Investment
Impairment charges related to investment in SSAT	$ 0	$ 0	$ 0
Capitalized Interest
Interest Costs Capitalized	$ 2.6	$ 0.7	$ 0.2
Dry-docking
Number of dry-docking inspections to be made within a specified period | item	2
Dry-dock inspections interval, maximum	36 months
Minimum
Dry-docking
Period within which number of specified dry-docking inspections to be made	2 years
Maximum
Dry-docking
Period within which number of specified dry-docking inspections to be made	5 years
Vessels
Depreciation
Useful life	40 years
Terminal cranes
Depreciation
Useful life	30 years
Containers and chassis
Depreciation
Useful life	15 years
Terminal facilities and other property
Depreciation
Useful life	35 years

SIGNIFICANT ACCOUNTING POLICI_8

SIGNIFICANT ACCOUNTING POLICIES - ACCRUED AND OTHER LIABILITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Intangible assets
Impairment charges related to finite-lived intangible assets	$ 0	$ 0	$ 0
Impairment charges related to indefinite-lived intangible assets and goodwill for impairment	0	0	$ 0
Accrued and other liabilities
Payroll and vacation	38.3	34.7
Employee incentives and other benefits	33.9	33.2
Insurance reserves and other related liabilities - short term	17.5	15.6
Multi-employer withdrawal liability - short-term	4.1	4.1
Income tax and other tax related liabilities	1.6	2.2
Other short-term liabilities	12.6	15.7
Total	108	105.5
Other long-term liabilities
Multi-employer withdrawal liability	46.5	48.6
Pension and post-retirement liabilities	21.8	17.8
Insurance reserves and other related liabilities	23.8	29.8
Other long-term liabilities	21.6	18.6
Total	$ 113.7	$ 114.8
Customer Relationships | Maximum
Intangible assets
Expected useful lives	21 years

SIGNIFICANT ACCOUNTING POLICI_9

SIGNIFICANT ACCOUNTING POLICIES - RECOGNITION OF REVENUES AND EXPENSES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Total	$ 3,094.6	$ 4,343	$ 3,925.3
Ocean Transportation
Ocean Transportation services	2,420.8	3,508	3,101.9
Terminal and other related services	36.9	18.5	16
Fuel sales	12.3	11.3	7.2
Vessel management and related services	7	6.8	7.7
Total	$ 2,477	$ 3,544.6	$ 3,132.8
Percentage of ocean transportation revenues and fuel sales denominated in foreign currency	3%	3%	3%
Logistics
Transportation Brokerage and Freight Forwarding services	$ 546.8	$ 695.1	$ 707.4
Warehousing and distribution services	42.5	53.5	44.7
Supply chain management and other services	28.3	49.8	40.4
Total	$ 617.6	$ 798.4	$ 792.5
Percentage of transportation brokerage and freight forwarding services revenue denominated in foreign currency	3%	3%	3%

SIGNIFICANT ACCOUNTING POLIC_10

SIGNIFICANT ACCOUNTING POLICIES - CUSTOMER CONCENTRATION (Details) - Serves customers	12 Months Ended
	Dec. 31, 2023 customer
Ocean Transportation
Number of largest customers	10
Ocean Transportation | Revenue
Concentration percentage	16%
Logistics
Number of largest customers	10
Logistics | Revenue
Concentration percentage	21%

SIGNIFICANT ACCOUNTING POLIC_11

SIGNIFICANT ACCOUNTING POLICIES - DIVIDENDS AND OTHERS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Per Common Share Amount
Dividends (in dollars per share)	$ 1.26	$ 1.22	$ 1.06
Shares repurchased (in shares)	2.1	5	2.5
Shares repurchased	$ 158.2	$ 397	$ 200.1
Maximum number of shares remaining to be repurchased	2.5

REPORTABLE SEGMENTS (Details)

REPORTABLE SEGMENTS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Segment results
Number of segments | segment	2
Fiscal Period Duration	364 days	364 days	364 days
Total Operating Revenue	$ 3,094.6	$ 4,343	$ 3,925.3
Total Operating Income	342.8	1,353.6	1,187.5
Interest income	36	8.2
Interest expense	(12.2)	(18)	(22.6)
Other income (expense), net	6.4	8.5	6.4
Income before Taxes	373	1,352.3	1,171.3
Income taxes	(75.9)	(288.4)	(243.9)
Net Income	297.1	1,063.9	927.4
Deferred dry-docking amortization	25.3	24.9	24.3
Total Depreciation and Amortization	169.7	166.2	160.2
Total Assets	4,294.6	4,330
Income from SSAT	2.2	83.1	56.3
Operating segments
Segment results
Total Operating Revenue	3,094.6	4,343	3,925.3
Total Operating Income	342.8	1,353.6	1,187.5
Total Capital Expenditures	248.4	209.3	325.3
Depreciation and Amortization	144.4	141.3	135.9
Total Assets	4,294.6	4,330
Intersegment Eliminations
Segment results
Total Operating Revenue	208.7	270.9	213.8
Ocean Transportation | SSAT
Segment results
Income from SSAT	2.2	83.1	56.3
Equity method investments	85.5	81.2
Ocean Transportation | Operating segments
Segment results
Total Operating Revenue	2,477	3,544.6	3,132.8
Total Operating Income	294.8	1,281.2	1,137.7
Total Capital Expenditures	240.2	190.9	322.4
Depreciation and Amortization	132.8	133.2	128.6
Deferred dry-docking amortization	25.3	24.9	24.3
Total Assets	3,645.3	3,705.2
Ocean Transportation | Intersegment Eliminations
Segment results
Total Operating Revenue	76.5	93.6	81
Logistics | Operating segments
Segment results
Total Operating Revenue	617.6	798.4	792.5
Total Operating Income	48	72.4	49.8
Total Capital Expenditures	8.2	18.4	2.9
Depreciation and Amortization	11.6	8.1	7.3
Total Assets	649.3	624.8
Logistics | Intersegment Eliminations
Segment results
Total Operating Revenue	$ 132.2	$ 177.3	$ 132.8

INVESTMENT IN SSAT (Details)

INVESTMENT IN SSAT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 16, 2022
Investments in affiliates
Investment in SSAT	$ 85.5	$ 81.2
Financial information for equity method investment
Company's share of net income	2.2	83.1	$ 56.3
Distributions Received		47.3	46.9
Total Current assets	602.3	759.6
Total Non-current assets	3,692.3	3,570.4
Total Assets	4,294.6	4,330
Total Current liabilities	562.3	581.6
Total Non-current liabilities	1,331.6	1,451.5
Total Liabilities and Shareholders' Equity	4,294.6	4,330
SSAT Terminals Oakland | SSAT
Investments in affiliates
Investment in SSAT, interest acquired (as a percent)				20%
SSAT
Investments in affiliates
Equity method investment decrease in investment in subsidiary	15.5
Equity method investment decrease in deferred tax assets in subsidiary	3.9
Equity method investment decrease in retained earnings in subsidiary	11.6
Ocean Transportation | SSAT
Financial information for equity method investment
Total Current assets	304	324.7
Total Non-current assets	1,510.2	1,436
Total Assets	1,814.2	1,760.7
Total Current liabilities	271.8	342.1
Total Non-current liabilities	1,255.3	1,199.5
Equity	287.1	219.1
Total Liabilities and Shareholders' Equity	1,814.2	1,760.7
Operating revenue	1,025.1	1,466.9	1,297.5
Operating costs and expenses	1,019.6	1,168.8	1,113.8
Operating (loss) income	5.5	298.1	183.7
Net Income	$ 11.9	249.6	161.7
Ocean Transportation | SSAT
Investments in affiliates
Ownership interest accounted in the related party terminal joint venture (as a percent)	35%
Cost of services from transactions with unconsolidated affiliate	$ 297.2	308.3	284.9
Accounts payable and accrued liabilities	43.4	43.6
Financial information for equity method investment
Company's share of net income	$ 2.2	$ 83.1	$ 56.3

PROPERTY AND EQUIPMENT (Details

PROPERTY AND EQUIPMENT (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($) item	Dec. 31, 2021 USD ($)
Property and equipment
Property and Equipment	$ 3,487.2	$ 3,288.7
Less: Accumulated Depreciation	(1,397.3)	(1,326.2)
Property and equipment, net	$ 2,089.9	1,962.5
Number of vessels under agreements for construction | item	3
Depreciation Expense	$ 124.4	123.5	$ 117.1
Vessels
Property and equipment
Property and Equipment	2,323.4	2,278.6
Less: Accumulated Depreciation	(886.8)	(838.8)
Property and equipment, net	1,436.6	1,439.8
Containers and equipment
Property and equipment
Property and Equipment	845	762.7
Less: Accumulated Depreciation	(451.9)	(433.8)
Property and equipment, net	393.1	328.9
Terminal facilities and other property
Property and equipment
Property and Equipment	148	131.5
Less: Accumulated Depreciation	(58.6)	(53.6)
Property and equipment, net	89.4	77.9
Vessel construction in progress
Property and equipment
Property and Equipment	103.1	50.2
Property and equipment, net	$ 103.1	$ 50.2
Number of vessels under agreements for construction | item	3	3
Other construction in progress
Property and equipment
Property and Equipment	$ 67.7	$ 65.7
Property and equipment, net	$ 67.7	$ 65.7

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS - GOODWILL (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Goodwill [Line Items]
Total Goodwill	$ 327.8	$ 327.8
Ocean Transportation
Goodwill [Line Items]
Total Goodwill	222.6
Ocean Transportation | Horizon
Goodwill [Line Items]
Total Goodwill	221.8
Logistics
Goodwill [Line Items]
Total Goodwill	105.2
Logistics | Span Alaska
Goodwill [Line Items]
Total Goodwill	78.6
Logistics | Other Acquisitions
Goodwill [Line Items]
Total Goodwill	$ 26.6

GOODWILL AND INTANGIBLES - INTA

GOODWILL AND INTANGIBLES - INTANGIBLE ASSETS (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 28, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Intangible assets
Gross Amount		$ 278.3	$ 263.2
Total Intangible Assets, net		176.4	174.9
Aggregate intangible asset amortization		13.6	11.4	$ 10.9
Less: Accumulated Amortization		(101.9)	(88.3)
Total estimated amortization expense related to intangibles		149.1
Estimated amortization expenses related to intangibles
2024		14.3
2025		13.6
2026		13
2027		13
2028		13
Thereafter		82.2
Total estimated amortization expense related to intangibles		$ 149.1
Customer Relationships | Maximum
Intangible assets
Expected useful life		21 years
Ocean Transportation | Customer Relationships
Intangible assets
Gross Amount		$ 140.6	140.6
Total Intangible Assets, net		82.7	89.4
Less: Accumulated Amortization		$ (57.9)	(51.2)
Ocean Transportation | Customer Relationships | Horizon
Intangible assets
Expected useful life		21 years
Finite-Lived intangible assets acquired		$ 140.6
Logistics
Intangible assets
Gross Amount		137.7	122.6
Total Intangible Assets, net		93.7	85.5
Less: Accumulated Amortization		(44)	(37.1)
Logistics | Trade Names
Intangible assets
Indefinite-Lived intangible asset		27.3	27.3
Logistics | Span Alaska | Trade Names
Intangible assets
Indefinite-Lived intangible asset acquired		27.3
Logistics | Customer Relationships
Intangible assets
Gross Amount		110.4	95.3
Total Intangible Assets, net		66.4	58.2
Expected useful life	7 years
Finite-Lived intangible assets acquired	$ 16.5
Less: Accumulated Amortization		$ (44)	$ (37.1)
Logistics | Customer Relationships | Minimum
Intangible assets
Expected useful life		3 years
Logistics | Customer Relationships | Maximum
Intangible assets
Expected useful life		13 years
Logistics | Customer Relationships | Span Alaska
Intangible assets
Total Intangible Assets, net		$ 79.3
Expected useful life		20 years

CAPITAL CONSTRUCTION FUND (Deta

CAPITAL CONSTRUCTION FUND (Details) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 29, 2024 USD ($)	Dec. 31, 2023 USD ($) item	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Maximum Period to Commit Fund Deposits for Qualified Purposes		25 years
Period over which deposits will be treated as non-qualified withdrawals		5 years
Cash deposits into CCF		$ 128.5	$ 582.8	$ 31.2
Qualifying cash withdrawal payments		49.9	64.6	$ 31.2
Accounts receivable, net		$ 279.4	268.5
Number of vessels under agreements for construction | item		3
Purchase price	$ 450
Fixed rate investments, Maturity date	3 years
Eligible Accounts Receivable Assigned to CCF
Capital construction fund		$ 599.4	518.2
Cash deposits into CCF		100	579.7
Interest earned on deposits		31.1	3.1
Qualifying cash withdrawal payments		(49.9)	(64.6)
Accounts receivable, net		$ 218.1	$ 9.9
Weighted average life of securities held within the fund		68 days

DEBT - SUMMARY (Details)

DEBT - SUMMARY (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt
Total Debt	$ 440.6	$ 517.5
Less: Current portion	(39.7)	(76.9)
Total Long-term Debt	400.9	440.6
Less: Deferred loan fees	(11.6)	(12.9)
Total Long-term Debt, net of deferred loan fees	$ 389.3	427.7
3.66 %, payable through 2023
Debt
Total Debt		$ 4.5
Interest rate (as a percent)	3.66%	3.66%
3.37 %, payable through 2027
Debt
Total Debt	$ 46.2	$ 57.7
Interest rate (as a percent)	3.37%	3.37%
3.14%, payable through 2031
Debt
Total Debt	$ 114.4	$ 132.8
Interest rate (as a percent)	3.14%	3.14%
5.34 %, payable through 2028
Debt
Total Debt		$ 13.2
Interest rate (as a percent)	5.34%	5.34%
5.27 %, payable through 2029
Debt
Total Debt		$ 15.4
Interest rate (as a percent)	5.27%	5.27%
1.22 %, payable through 2043
Debt
Total Debt	$ 158.2	$ 166.2
Interest rate (as a percent)	1.22%	1.22%
1.35 %, payable through 2044
Debt
Total Debt	$ 121.8	$ 127.7
Interest rate (as a percent)	1.35%	1.35%

DEBT - REVOLVING CREDIT FACILIT

DEBT - REVOLVING CREDIT FACILITY (Details)

1 Months Ended

Mar. 31, 2023 USD ($)

Mar. 31, 2021 USD ($)

Dec. 31, 2016 USD ($)

Sep. 30, 2016 USD ($)

Dec. 31, 2023 USD ($)

Jan. 31, 2023 USD ($)

Dec. 31, 2022

Jun. 30, 2020 USD ($)

Apr. 30, 2020 USD ($)

Dec. 31, 2012 USD ($) item

Aug. 31, 2004 USD ($)

Sep. 30, 2003 USD ($)

Unsecured Debt

Debt

Unsecured Long-term Debt, Number of Tranches | item

3

Debt issued

$ 170,000,000

Unsecured debt, tranche maturing in 2023

Debt

Debt Instrument, Interest Rate, Stated Percentage

3.66%

Senior Unsecured Series A Notes

Debt

Debt Instrument, Interest Rate, Stated Percentage

3.37%

Debt issued

$ 75,000,000

Debt instrument term

11 years

5.34 %, payable through 2028

Debt

Debt Instrument, Interest Rate, Stated Percentage

5.34%

5.34%

Revolving Credit Facility

Debt

Maximum borrowing capacity under revolving credit facility

$ 650,000,000

Ratio of debt instrument covenant threshold leverage

3.50

Ratio of debt instrument covenant threshold leverage connection with material acquisition

4

Funds available under the revolving credit facility

$ 644,200,000

Standby commercial letters of credit

Debt

Used portion of revolving credit facility

5,800,000

Amendment to 2021 Private Placement Term Loan

Debt

Ratio of debt instrument covenant threshold leverage

3.50

Ratio of debt instrument covenant threshold leverage connection with material acquisition

4

Fees paid

$ 800,000

Debt Instrument, Threshold Leverage Ratio To Trigger Interest Enhancement Payments

3.25

The Senior Unsecured Notes (The "Series D Notes")

Debt

Debt Instrument, Interest Rate, Stated Percentage

3.14%

Debt issued

$ 200,000,000

Debt instrument term

15 years

LIBOR | Revolving Credit Facility | Minimum

Debt

Variable rate margin

1%

LIBOR | Revolving Credit Facility | Maximum

Debt

Variable rate margin

1.75%

Base rate | Revolving Credit Facility | Minimum

Debt

Variable rate margin

0%

Base rate | Revolving Credit Facility | Maximum

Debt

Variable rate margin

0.75%

MatNav

Debt

Extinguishment of Debt, Amount

$ 12,100,000

Annual principal payments

$ 14,300,000

MatNav | Title XI Notes

Debt

Debt Instrument, Interest Rate, Stated Percentage

1.35%

1.22%

Minimum working capital covenant

$ 1

Debt instrument covenant ratio, maintenance of net worth

90%

Debt issued

$ 139,600,000

$ 185,900,000

MatNav | 5.34 %, payable through 2028

Debt

Debt issued

$ 55,000,000

$ 55,000,000

MatNav | Minimum | Title XI Notes

Debt

Debt instrument covenant, long-term debt to net worth

2%

DEBT - MATURITIES (Details)

DEBT - MATURITIES (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt maturities
2024	$ 39.7
2025	39.7
2026	39.7
2027	39.7
2028	28.2
Thereafter	253.6
Total Debt	$ 440.6	$ 517.5

DEBT - DEFERRED LOAN FEES (Deta

DEBT - DEFERRED LOAN FEES (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($)
DEBT
Deferred financing costs related to Title XI bonds and private placement debt amendments	$ 12.9
Amortization expense	(1.3)
Ending Balance	$ 11.6

DEBT - AMORTIZATION EXPENSE (De

DEBT - AMORTIZATION EXPENSE (Details) $ in Millions	Dec. 31, 2023 USD ($)
DEBT
2024	$ 1.2
2025	1.1
2026	1
2027	0.9
2028	0.9
Thereafter	6.5
Total amortization expense of deferred loan fees	$ 11.6

LEASES - LEASE TERM (Details)

LEASES - LEASE TERM (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Retained earnings	$ 2,089.7	$ 1,986.2
Real estate and terminal leases
Lessee, Lease, Description [Line Items]
Base term	50 years
Vessel and barge charter leases
Lessee, Lease, Description [Line Items]
Base term	4 years
Operations equipment and other leases
Lessee, Lease, Description [Line Items]
Base term	14 years

LEASES - COMPONENTS OF LEASE CO

LEASES - COMPONENTS OF LEASE COST (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Components of Lease Cost
Operating lease cost	$ 151	$ 162.2	$ 110.7
Short-term lease cost	7.7	0.6	3.1
Variable lease cost	0.6	0.8	0.6
Total lease cost	$ 159.3	$ 163.6	$ 114.4

LEASES - OTHER INFORMATION (Det

LEASES - OTHER INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Components of Lease Cost
Cash paid for amounts included in operating lease liabilities	$ 154.3	$ 163.4
Right of use assets obtained in the exchange for new operating lease liabilities	$ 40	$ 131.4
Weighted-average remaining operating lease term	4 years 9 months 18 days	4 years 10 months 24 days
Weighted-average incremental borrowing rate	3.10%	2.40%

LEASES - MATURITIES OF OPERATIN

LEASES - MATURITIES OF OPERATING LEASE LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Maturities of operating lease liabilities
2024	$ 143.3
2025	80.8
2026	32.1
2027	15.3
2028	6.7
Thereafter	51.1
Total lease payments	329.3
Less: Interest	(33.3)
Present value of operating lease liabilities	296
Less: Short-term portion	(136.7)	$ (143.6)
Long-term operating lease liabilities	$ 159.3	$ 262.5
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Liabilities, Current

INCOME TAXES - SUMMARY (Details

INCOME TAXES - SUMMARY (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 44	$ 171.5	$ 181.2
State	9.2	18.3	35.6
Foreign	3	1.3	2.5
Total	56.2	191.1	219.3
Deferred:
Federal	18.2	71.1	26.4
State		24.3	0.4
Foreign	1.5	1.9	(2.2)
Total deferred tax expense	19.7	97.3	24.6
Total income taxes	$ 75.9	$ 288.4	$ 243.9
Difference of Income tax expense from amounts computed by applying the statutory federal rate to income from continuing operations before income taxes
Computed federal income tax expense (as a percent)	21%	21%	21%
State income tax (as a percent)	2.60%	2.80%	3.10%
Foreign-derived intangible income (FDII) (as a percent)	(2.00%)	(2.40%)	(2.50%)
Valuation allowance (as a percent)			(0.30%)
Foreign taxes (as a percent)	0.40%	0.10%	0.20%
Share-based payments (as a percent)	0.50%		(0.20%)
Return to provision true-ups (as a percent)	(2.80%)	0.10%	(0.20%)
Other-net (as a percent)	0.60%	(0.30%)	(0.30%)
Effective income tax rate , Percent, Total	20.30%	21.30%	20.80%
Valuation allowances	$ 5.3	$ 7.4
Deferred tax assets:
Operating lease liabilities	77.4	102.9
Multi-employer withdrawal liabilities	12.8	13.3
Deferred compensation	11.8	10.9
U.S. State alternative minimum tax credits	7.4	8.8
Insurance reserves	6.3	7.3
Other	12.9	15.4
Total deferred tax assets	128.6	158.6
Valuation allowance	(5.3)	(7.4)
Total Deferred tax assets, net of valuation allowance	123.3	151.2
Deferred tax liabilities:
Basis differences for property and equipment	451.4	433.1
Operating lease right of use assets	75.8	100.7
Intangibles	42.3	42
Capital Construction Fund	206.9	194
Other	16.2	27.9
Total deferred tax liabilities	792.6	797.7
Deferred tax liability, net , Total	$ 669.3	$ 646.5

INCOME TAXES - OPERATING LOSS A

INCOME TAXES - OPERATING LOSS AND TAX CREDIT CARRYFORWARDS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Operating Loss and Tax Credit Carryforwards
Valuation allowances	$ 5.3	$ 7.4
Operating loss carryforwards, not expected to benefit the entity	152.3
Income tax receivables, net	125.2	170.8
U.S. Federal Income Tax
Operating Loss and Tax Credit Carryforwards
Net operating losses carryforwards		0.8
Income tax receivables, net	118.6
State Income Tax
Operating Loss and Tax Credit Carryforwards
Net operating losses carryforwards	152.3	157.9
Alternative minimum tax credit carryforwards	$ 7.3	$ 8.6

INCOME TAXES - UNRECOGNIZED TAX

INCOME TAXES - UNRECOGNIZED TAX BENEFITS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of the beginning and ending amount of gross unrecognized tax benefits
Balance at beginning of the period	$ 25.1	$ 19.2	$ 18.3
Tax position changes in current year	3.6	5.8	2.3
Tax position changes in prior years	(0.1)		(1.2)
Tax position changes in prior years		0.3
Reductions for lapse of statute of limitations	(0.2)	(0.2)	(0.2)
Balance at the end of the period	28.4	25.1	$ 19.2
Unrecognized tax benefits that, if recognized, would impact the effective rate	24.2
Interest accrued related to unrecognized tax benefits	0.9	0.2
Accrued for a tax position claimed	1.5	$ 1.2
Income taxes related to interest	0.7
Income taxes related to penalties	$ 0.8

PENSION AND POST-RETIREMENT P_3

PENSION AND POST-RETIREMENT PLANS - ASSET ALLOCATION (Details) - Pension Benefits	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Employee benefit plans
Target allocation (as a percent)	100%
Asset allocations (as a percent)	100%	100%
One year returns (losses) on plan assets (as a percent)	12.80%
Three year returns (losses) on plan assets (as a percent)	4.60%
Five year returns (losses) on plan assets (as a percent)	9.50%
Long-term average return on plan assets since inception (as a percent)	8.20%
Domestic equity securities
Employee benefit plans
Target allocation (as a percent)	53%
Asset allocations (as a percent)	57%	53%
International equity securities
Employee benefit plans
Target allocation (as a percent)	15%
Asset allocations (as a percent)	16%	16%
Debt securities
Employee benefit plans
Target allocation (as a percent)	22%
Asset allocations (as a percent)	19%	20%
Real estate
Employee benefit plans
Target allocation (as a percent)	5%
Asset allocations (as a percent)	5%	7%
Other and cash
Employee benefit plans
Target allocation (as a percent)	5%
Asset allocations (as a percent)	3%	4%

PENSION AND POST-RETIREMENT P_4

PENSION AND POST-RETIREMENT PLANS - FAIR VALUE (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and Post-retirement Plans
Total	$ 227.9	$ 206.3	$ 238.9
Fair Value Measurement
Pension and Post-retirement Plans
Total	186.3	166.4
Total plan assets	227.9	206.4
Fair Value Measurement | Cash
Pension and Post-retirement Plans
Total	6.1	8.8
Fair Value Measurement | U S large-cap
Pension and Post-retirement Plans
Total	82.8	69.1
Fair Value Measurement | U S mid and small-cap
Pension and Post-retirement Plans
Total	46	41.5
Fair Value Measurement | International large-cap
Pension and Post-retirement Plans
Total	7.1	6.2
Fair Value Measurement | U S Treasuries
Pension and Post-retirement Plans
Total	19.2	17.4
Fair Value Measurement | Municipal bonds
Pension and Post-retirement Plans
Total	0.2	0.2
Fair Value Measurement | Investment grade U S corporate bonds
Pension and Post-retirement Plans
Total	24.7	22.8
Fair Value Measurement | Convertible Bonds
Pension and Post-retirement Plans
Total	0.1	0.3
Fair Value Measurement | International Fixed Income
Pension and Post-retirement Plans
Total	0.1	0.1
Fair Value Measurement | Quoted Prices in Active Markets (Level 1)
Pension and Post-retirement Plans
Total	142	125.6
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | Cash
Pension and Post-retirement Plans
Total	6.1	8.8
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | U S large-cap
Pension and Post-retirement Plans
Total	82.8	69.1
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | U S mid and small-cap
Pension and Post-retirement Plans
Total	46	41.5
Fair Value Measurement | Quoted Prices in Active Markets (Level 1) | International large-cap
Pension and Post-retirement Plans
Total	7.1	6.2
Fair Value Measurement | Significant Observable Inputs (Level 2)
Pension and Post-retirement Plans
Total	44.3	40.8
Fair Value Measurement | Significant Observable Inputs (Level 2) | U S Treasuries
Pension and Post-retirement Plans
Total	19.2	17.4
Fair Value Measurement | Significant Observable Inputs (Level 2) | Municipal bonds
Pension and Post-retirement Plans
Total	0.2	0.2
Fair Value Measurement | Significant Observable Inputs (Level 2) | Investment grade U S corporate bonds
Pension and Post-retirement Plans
Total	24.7	22.8
Fair Value Measurement | Significant Observable Inputs (Level 2) | Convertible Bonds
Pension and Post-retirement Plans
Total	0.1	0.3
Fair Value Measurement | Significant Observable Inputs (Level 2) | International Fixed Income
Pension and Post-retirement Plans
Total	0.1	0.1
Fair Value Measurement | Investment measured at NAV
Pension and Post-retirement Plans
Total	$ 41.6	$ 40

PENSION AND POST-RETIREMENT P_5

PENSION AND POST-RETIREMENT PLANS - STATUS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Change in Benefit Obligation:
Benefit obligation at beginning of year	$ 187.4	$ 249.5
Service cost	3.1	4.8	$ 4.8
Interest cost	10	7	6.4
Actuarial (gain) loss	5.5	(59)
Benefits paid, net of subsidies received	(12.9)	(14.1)
Expenses paid		(0.8)
Benefit obligation at end of year	193.1	187.4	249.5
Change in Plan Assets:
Balance at the beginning of the period	206.3	238.9
Actual return on plan assets	25.5	(26.7)
Employer contribution	9	9	9
Benefits paid, net of subsidies received	(12.9)	(14.1)
Expenses paid		(0.8)
Balance at the end of the period	227.9	206.3	238.9
Funded Status and Recognized Plan Assets and Benefit Obligations	34.8	18.9
Post-retirement benefits
Change in Benefit Obligation:
Benefit obligation at beginning of year	15.3	29.3
Service cost	0.2	0.7	0.7
Interest cost	0.8	0.8	0.7
Participant contributions	0.7	0.7
Actuarial (gain) loss	4.5	(14.2)
Benefits paid, net of subsidies received	(2)	(2)
Benefit obligation at end of year	19.5	15.3	$ 29.3
Change in Plan Assets:
Participant contributions	0.7	0.7
Employer contribution	1.3	1.3
Benefits paid, net of subsidies received	(2)	(2)
Funded Status and Recognized Plan Assets and Benefit Obligations	$ (19.5)	$ (15.3)

PENSION AND POST-RETIREMENT P_6

PENSION AND POST-RETIREMENT PLANS - AMOUNTS INCLUDED IN FINANCIAL STATEMENTS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Employee benefit plans
Non-current assets	$ 34.8	$ 18.9
Non-current liabilities	(21.8)	(17.8)
Pension Benefits
Employee benefit plans
Projected benefit obligations	193.1	187.4	$ 249.5
Fair value of plan assets at end of year	227.9	206.3	238.9
Pension Benefits | Qualified Plan
Employee benefit plans
Non-current assets	34.8	18.9
Total	34.8	18.9
Net (loss) gain, net of taxes	(20.3)	(25.8)
Total	(20.3)	(25.8)
Pension Benefits | Nonqualified Plan
Employee benefit plans
Current liabilities	(1.2)	(0.7)
Non-current liabilities	(3.4)	(3.4)
Total	(4.6)	(4.1)
Net (loss) gain, net of taxes	(0.2)	0.1
Total	(0.2)	0.1
Post-retirement benefits
Employee benefit plans
Projected benefit obligations	$ 19.5	15.3	$ 29.3
Amortization period of unrecognized gains and losses	5 years
Post-retirement benefits | Qualified Plan
Employee benefit plans
Current liabilities	$ (1.1)	(0.9)
Non-current liabilities	(18.4)	(14.4)
Total	(19.5)	(15.3)
Net (loss) gain, net of taxes	2.7	7.6
Prior service credit, net of taxes	8.3	11.1
Total	$ 11	$ 18.7

PENSION AND POST-RETIREMENT P_7

PENSION AND POST-RETIREMENT PLANS - COMPONENTS OF NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income, net of tax:
Total recognized in other comprehensive (income) loss	$ 2.5	$ (23.8)	$ (20.4)
Qualified Pension Plans, Non-qualified Pension Plans and Post-retirement Plans
Discount rate used to determine obligation (as a percent)	5.20%	5.50%
Pension Benefits
Components of Net Periodic Benefit Cost (Credit):
Service cost	$ 3.1	$ 4.8	4.8
Interest cost	10	7	6.4
Expected return on plan assets	(13.9)	(16)	(14.7)
Amortization of net loss (gain)	1.3	2.4	5.2
Amortization of prior service credit		(1)	(2.3)
Net periodic benefit cost (credit)	0.5	(2.8)	(0.6)
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income, net of tax:
Net loss (gain)	(4.5)	(12.3)	(20.4)
Amortization of net loss (gain)	(1)	(1.8)	(3.9)
Amortization of prior service credit		0.8	1.7
Total recognized in other comprehensive (income) loss	(5.5)	(13.3)	(22.6)
Total recognized in net periodic benefit cost and other comprehensive (income) loss	$ (5)	$ (16.1)	$ (23.2)
Weighted Average Assumptions:
Discount rate (as a percent)	5.30%	5.60%	2.90%
Expected return plan assets (as a percent)	6.85%	6.75%	7%
Rate of compensation increase (as a percent)	3.50%		3%
Qualified Pension Plans, Non-qualified Pension Plans and Post-retirement Plans
Benefit obligation at end of year	$ 193.1	$ 187.4	$ 249.5
Pension Benefits | Minimum
Weighted Average Assumptions:
Rate of compensation increase (as a percent)		3.50%
Cash balance interest credit rate	3.25%	3.25%	1.50%
Pension Benefits | Maximum
Weighted Average Assumptions:
Rate of compensation increase (as a percent)		4%
Cash balance interest credit rate	4.50%	3.50%	3.25%
Post-retirement benefits
Components of Net Periodic Benefit Cost (Credit):
Service cost	$ 0.2	$ 0.7	$ 0.7
Interest cost	0.8	0.8	0.7
Amortization of net loss (gain)	(2)	0.8	1
Amortization of prior service credit	(3.7)	(3.6)	(3.7)
Net periodic benefit cost (credit)	(4.7)	(1.3)	(1.3)
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income, net of tax:
Net loss (gain)	3.4	(10.7)
Amortization of net loss (gain)	1.5	(0.6)	(0.7)
Amortization of prior service credit	2.8	2.7	2.8
Total recognized in other comprehensive (income) loss	7.7	(8.6)	2.1
Total recognized in net periodic benefit cost and other comprehensive (income) loss	$ 3	$ (9.9)	$ 0.8
Weighted Average Assumptions:
Discount rate (as a percent)	5.40%	5.50%	3%
Rate of compensation increase (as a percent)	3.50%		3%
Immediate health care cost trend rate, Pre-65 group (as a percent)	6.80%	6.60%	5.70%
Immediate health care cost trend rate, Post-65 group (as a percent)	7.10%	6.10%	5.80%
Ultimate health care cost trend rate (as a percent)	3.90%	4%	4%
Qualified Pension Plans, Non-qualified Pension Plans and Post-retirement Plans
Benefit obligation at end of year	$ 19.5	$ 15.3	$ 29.3
Post-retirement benefits | Minimum
Weighted Average Assumptions:
Rate of compensation increase (as a percent)		3.50%
Post-retirement benefits | Maximum
Weighted Average Assumptions:
Rate of compensation increase (as a percent)		4%
Qualified Plan | Pension Benefits
Qualified Pension Plans, Non-qualified Pension Plans and Post-retirement Plans
Amounts recognized in accumulated other comprehensive income for net loss, net of tax	(20.3)	$ (25.8)
Total	(20.3)	(25.8)
Qualified Plan | Post-retirement benefits
Components of Net Periodic Benefit Cost (Credit):
Current liabilities	1.1	0.9
Qualified Pension Plans, Non-qualified Pension Plans and Post-retirement Plans
Amounts recognized in accumulated other comprehensive income for net loss, net of tax	2.7	7.6
Amount recognized as prior service credit, net of tax	8.3	11.1
Total	11	18.7
Nonqualified Plan | Pension Benefits
Components of Net Periodic Benefit Cost (Credit):
Current liabilities	1.2	0.7
Qualified Pension Plans, Non-qualified Pension Plans and Post-retirement Plans
Amounts recognized in accumulated other comprehensive income for net loss, net of tax	(0.2)	0.1
Total	$ (0.2)	$ 0.1

PENSION AND POST-RETIREMENT P_8

PENSION AND POST-RETIREMENT PLANS - ESTIMATED BENEFIT PAYMENTS (Details) $ in Millions	Dec. 31, 2023 USD ($)
Pension Benefits
Estimated future benefit payments
2024	$ 14.7
2025	15
2026	15.2
2027	15.4
2028	15.6
2029-2033	77
Total remaining future undiscounted payments due	152.9
Post-retirement benefits
Estimated future benefit payments
2024	1.1
2025	1.1
2026	1.2
2027	1.2
2028	1.2
2029-2033	6.1
Total remaining future undiscounted payments due	11.9
Nonqualified Plan | Pension Benefits
Estimated future benefit payments
2024	1.2
2025	0.4
2026	0.5
2027	0.5
2028	0.4
2029-2033	2.6
Total remaining future undiscounted payments due	$ 5.6

PENSION AND POST-RETIREMENT P_9

PENSION AND POST-RETIREMENT PLANS - DEFINED CONTRIBUTION PLANS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
401 K plan
Defined Contribution Plans
Employer matching contribution (as a percent)	4%
Employer matching contribution expenses	$ 4.2	$ 3.6	$ 3.2
Profit sharing plan
Defined Contribution Plans
Profit sharing expense recorded	$ 3.1	$ 2.8	$ 2.5

PENSION AND POST-RETIREMENT _10

PENSION AND POST-RETIREMENT PLANS - MULTI-EMPLOYER DEFINED BENEFIT PLANS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Multiemployer Plans
Estimated benefit plan withdrawal obligations	$ 182.1
Pension Benefits | Hawaii Longshore Pension Plan | Green Zone
Multiemployer Plans
Contributions of Matson	12.1	$ 11.9	$ 11.1
Multiemployer Health and Benefit Plans
Multiemployer Plans
Contributions of Matson	37.7	37.7	34.7
Multi-employer defined contribution pension plans
Multiemployer Plans
Contributions of Matson	$ 32.7	33.8	31
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%
Multi-employer defined contribution pension plans | Maximum | Red Zone
Multiemployer Plans
Funded status of multiemployer plan (as a percent)	65%
Multi-employer defined contribution pension plans | Maximum | Yellow Zone
Multiemployer Plans
Funded status of multiemployer plan (as a percent)	80%
Multi-employer defined contribution pension plans | Maximum | Orange Zone
Multiemployer Plans
Funded status of multiemployer plan (as a percent)	80%
Multi-employer defined contribution pension plans | American Radio Association Pension Fund | Green Zone
Multiemployer Plans
Contributions of Matson	$ 1	1.1	1.1
Multi-employer defined contribution pension plans | Master Mates And Pilots Pension Plan | Green Zone
Multiemployer Plans
Contributions of Matson	3.6	3.8	3.5
Multi-employer defined contribution pension plans | Masters, Mates and Pilots Adjustable Pension Plan | Green Zone
Multiemployer Plans
Contributions of Matson	2	2.1	2
Multi-employer defined contribution pension plans | MEBA Pension Trust - Defined Benefit Plan | Green Zone
Multiemployer Plans
Contributions of Matson	4.2	4.5	4.3
Multi-employer defined contribution pension plans | OCU Pension Trust Plan | Green Zone
Multiemployer Plans
Contributions of Matson	0.4	0.5	0.3
Multi-employer defined contribution pension plans | MFOW Supplementary Pension Plan | Yellow Zone
Multiemployer Plans
Contributions of Matson	0.1	0.1	0.1
Multi-employer defined contribution pension plans | SIU Pacific District Pension Plan | Green Zone
Multiemployer Plans
Contributions of Matson	1.3	1.5	1.4
Multi-employer defined contribution pension plans | Alaska Teamster - Employer Pension Plan | Red Zone
Multiemployer Plans
Contributions of Matson	3.9	4	3.6
Multi-employer defined contribution pension plans | All Alaska Longshore Pension Plan | Green Zone
Multiemployer Plans
Contributions of Matson	1.8	2	1.6
Multi-employer defined contribution pension plans | Western Conference of Teamsters Pension Plan | Green Zone
Multiemployer Plans
Contributions of Matson	2.1	2.1	1.9
Multi-employer defined contribution pension plans | Western Conference Of Teamsters Supplemental Benefit Trust | Green Zone
Multiemployer Plans
Contributions of Matson	0.1	0.1
Multi-employer defined contribution pension plans | OPEIU Local 153 Pension Plan | Red Zone
Multiemployer Plans
Contributions of Matson	$ 0.1	$ 0.1	$ 0.1

PENSION AND POST-RETIREMENT _11

PENSION AND POST-RETIREMENT PLANS - MULTI-EMPLOYER DEFINED CONTRIBUTION PLANS (Details) - Multi-employer defined contribution pension plans $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) plan	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Defined Contribution Plans
Number of Multiemployer Plans | plan	6
Employer contributions | $	$ 5.7	$ 6	$ 5.6

MULTI-EMPLOYER WITHDRAWAL LIA_3

MULTI-EMPLOYER WITHDRAWAL LIABILITIES (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Multi-employer withdrawal liability
Quarterly payments to ILA-PRSSA over an estimated period	$ 1
Estimated future benefit payments
Current portion of multi-employer withdrawal liability	(4.1)	$ (4.1)
Long-term portion of multi-employer withdrawal liability	46.5	$ 48.6
Horizon | ILA-PRSSA Pension Fund
Estimated future benefit payments
2024	4.1
2025	4.1
2026	4.1
2027	4.1
2028	4.1
Thereafter	47.3
Total remaining future undiscounted payments due	67.8
Less: amount representing interest	(17.2)
Present value of multi-employer withdrawal liability	50.6
Current portion of multi-employer withdrawal liability	(4.1)
Long-term portion of multi-employer withdrawal liability	$ 46.5

ACCUMULATED OTHER COMPREHENSI_3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	$ 2,296.9	$ 1,667.4	$ 961.2
Other adjustments	1.2	0.2	(0.5)
Balance at the end of the period	2,400.7	2,296.9	1,667.4
Comprehensive Income (Loss):
Tax benefit (expense) on other comprehensive income (loss)	(1.2)	(9.3)	(8.1)
Pensions
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	(25.8)	(39.1)
Amortization of prior service cost		(0.8)
Amortization of net gain (loss)	5.5	14.1
Balance at the end of the period	(20.3)	(25.8)	(39.1)
Post Retirement
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	18.7	10.1
Amortization of prior service cost	(2.8)	(2.7)
Amortization of net gain (loss)	(4.9)	11.3
Balance at the end of the period	11	18.7	10.1
Non-Qualified Plans
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	0.1	(0.7)
Amortization of net gain (loss)	(0.3)	0.8
Balance at the end of the period	(0.2)	0.1	(0.7)
Other
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	0.1	(1.2)
Amortization of net gain (loss)		1.1
Foreign currency exchange	(0.5)	(0.4)
Other adjustments	1.7	0.6
Balance at the end of the period	1.3	0.1	(1.2)
Accumulated Other Comprehensive Income (Loss)
Changes in accumulated other comprehensive income (loss) by component, net of taxes
Balance at the beginning of the period	(6.9)	(30.9)	(50.8)
Amortization of prior service cost	(2.8)	(3.5)
Amortization of net gain (loss)	0.3	27.3
Foreign currency exchange	(0.5)	(0.4)
Other adjustments	1.7	0.6
Balance at the end of the period	$ (8.2)	$ (6.9)	$ (30.9)

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net Income
Net Income, Basic	$ 297.1	$ 1,063.9	$ 927.4
Net Income, Diluted	$ 297.1	$ 1,063.9	$ 927.4
Weighted Average Common Shares
Basic (in shares)	35.3	39	42.8
Effect of Dilutive Securities (in shares)	0.4	0.3	0.4
Diluted (in shares)	35.7	39.3	43.2
Per Common Share Amount
Net income, Basic (in dollars per share)	$ 8.42	$ 27.28	$ 21.67
Effect of dilutive securities (in dollars per shares)	(0.10)	(0.21)	(0.20)
Net income, Diluted (in dollars per share)	$ 8.32	$ 27.07	$ 21.47

SHARE-BASED AWARDS - SUMMARY (D

SHARE-BASED AWARDS - SUMMARY (Details) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) plan shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Share-based expense (net of estimated forfeitures)
Share-based compensation expense	$ 23.8	$ 18.3	$ 19.3
Tax benefit realized upon stock vesting	6.1	10.6	8
Fair value of stock vested	27.8	$ 44	$ 33.5
Non-vested restricted stock units and performance-based equity awards
Share-based expense (net of estimated forfeitures)
Unrecognized compensation cost	$ 24.8
Unrecognized compensation cost, weighted average period for recognition	1 year 8 months 12 days
2016 Plan
SHARE-BASED AWARDS
Common stock initially available for future issuance (in shares) | shares	4,350
Additional shares authorized for issuance | shares	0
Number of separate incentive compensation programs | plan	4
Number of share based compensation plans within the entity's incentive compensation programs | plan	3
2016 Plan | Discretionary Grant Program
SHARE-BASED AWARDS
Minimum exercise price as a percentage of fair market value of common stock	100%
2016 Plan | Time Based Restricted Stock Units | Stock Issuance Program
SHARE-BASED AWARDS
Vesting period of awards granted	3 years
2016 Plan | Time Based Restricted Stock Units | Automatic Grant Program
SHARE-BASED AWARDS
Vesting period of awards granted	1 year
2016 Plan | Performance Based Restricted Stock Units | Stock Issuance Program
SHARE-BASED AWARDS
Vesting period of awards granted	3 years
2016 Plan | Restricted Stock Units
Activity in the entity's stock option plans
Added by performance factor (in shares) | shares	167

SHARE-BASED AWARDS - RESTRICTED

SHARE-BASED AWARDS - RESTRICTED STOCK UNIT ACTIVITY (Details) - Restricted Stock Units shares in Thousands	12 Months Ended
	Dec. 31, 2023 $ / shares shares
Weighted Average Grant-Date Fair Value
Outstanding, weighted average grant-date fair value, beginning of period (in dollars per share) | $ / shares	$ 68.38
Granted, weighted average grant-date fair value (in dollars per share) | $ / shares	66.05
Vested, weighted average grant-date fair value (in dollars per share) | $ / shares	46.96
Cancelled, weighted average grant-date fair value (in dollars per shares) | $ / shares	70.07
Added by performance factor , weighted average grant-date fair value (in dollars per share) | $ / shares	39.61
Outstanding, weighted average grant-date fair value, end of period (in dollars per shares) | $ / shares	$ 75.82
2016 Plan
Non-vested restricted stock unit activity
Outstanding, beginning of period (in shares) | shares	546
Granted (in shares) | shares	269
Vested (in shares) | shares	(439)
Cancelled (in shares) | shares	(10)
Added by performance factor (in shares) | shares	167
Outstanding, end of period (in shares) | shares	533

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair value of financial instruments
Restricted Cash	$ 2.3	$ 3.9	$ 5.3
Carrying value
Fair value of financial instruments
Cash and cash equivalents	134	249.8
Restricted Cash	2.3	3.9
Capital construction fund	599.4	518.2
Fixed rate debt	440.6	517.5
Fair Value Measurement
Fair value of financial instruments
Cash and cash equivalents	134	249.8
Restricted Cash	2.3	3.9
Capital construction fund	599.4	518.2
Fixed rate debt	359.9	427.3
Fair Value Measurement | Quoted Prices in Active Markets (Level 1)
Fair value of financial instruments
Cash and cash equivalents	134	249.8
Restricted Cash	2.3	3.9
Capital construction fund	599.4	518.2
Fair Value Measurement | Significant Observable Inputs (Level 2)
Fair value of financial instruments
Fixed rate debt	$ 359.9	$ 427.3

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Dec. 31, 2023 USD ($) item	Dec. 31, 2022 item
Commitments, Guarantees and Contingencies
Standby letters of credit	$ 5.8
Vessel construction obligations	899.1
Vendor and other obligations	$ 77.1
Number of vessels under agreements for construction | item	3
Vessel construction in progress
Commitments, Guarantees and Contingencies
Number of vessels under agreements for construction | item	3	3
U.S. Custom Bond
Commitments, Guarantees and Contingencies
Bonds	$ 56.4

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss)	$ 297.1	$ 1,063.9	$ 927.4

Insider Trading Arrangements

Insider Trading Arrangements - shares			3 Months Ended
	Feb. 23, 2024	Feb. 22, 2024	Dec. 31, 2023
Trading Arrangements, by Individual
Material Terms of Trading Arrangement			Trading Plans : During the quarter ended December 31, 2023, no director or Section 16 officer ​ On February 23, 2024, Matthew J. Cox, Chairman and Chief Executive Officer, adopted a trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) to sell up to 39,204 shares of Matson common stock through December 31, 2024, subject to certain pricing and other conditions. ​ On February 22, 2024, Joel M. Wine, Executive Vice President and Chief Financial Officer, adopted a trading plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) to sell up to 76,156 shares of Matson common stock through July 31, 2024, subject to certain pricing and other conditions.
Rule 10b5-1 Arrangement Adopted			false
Non-Rule 10b5-1 Arrangement Adopted			false
Rule 10b5-1 Arrangement Terminated			false
Non-Rule 10b5-1 Arrangement Terminated			false
Matthew J. Cox
Trading Arrangements, by Individual
Name	Matthew J. Cox
Title	Chairman and Chief Executive Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	February 23, 2024
Aggregate Available	39,204
Expiration Date	December 31, 2024
Joel M. Wine
Trading Arrangements, by Individual
Name		Joel M. Wine
Title		Executive Vice President and Chief Financial Officer
Rule 10b5-1 Arrangement Adopted		true
Adoption Date		February 22, 2024
Aggregate Available		76,156
Expiration Date		July 31, 2024