Cleveland-Cliffs (CLF) 10-K 8 Feb 24 2023 FY Annual report Financial data

Cover

Cover - USD ($)	12 Months Ended
	Dec. 31, 2023	Feb. 08, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	1-8944
Entity Registrant Name	CLEVELAND-CLIFFS INC.
Entity Incorporation, State or Country Code	OH
Entity Tax Identification Number	34-1464672
Entity Address, Address Line One	200 Public Square,
Entity Address, City or Town	Cleveland,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	44114-2315
City Area Code	216
Local Phone Number	694-5700
Title of 12(b) Security	Common Shares, par value $0.125 per share
Trading Symbol	CLF
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 Public Float			$ 8,390,625,983
Entity Common Stock, Shares Outstanding		498,289,476
Documents Incorporated by Reference [Text Block]	Portions of the registrant’s proxy statement for its 2024 annual meeting of shareholders are incorporated by reference into Part III.
Entity Central Index Key	0000764065
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false

Audit Information

Audit Information	12 Months Ended
	Dec. 31, 2023
Audit Information [Abstract]
Auditor Location	Cleveland, Ohio
Auditor Name	Deloitte & Touche LLP
Auditor Firm ID	34

Statements of Consolidated Fina

Statements of Consolidated Financial Position - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 198	$ 26
Accounts receivable, net	1,840	1,960
Inventories	4,460	5,130
Other current assets	138	306
Total current assets	6,636	7,422
Non-current assets:
Property, plant and equipment, net	8,895	9,070
Goodwill	1,005	1,130
Pension and OPEB assets	329	356
Other non-current assets	672	777
TOTAL ASSETS	17,537	18,755
Current liabilities:
Accounts payable	2,099	2,186
Accrued employment costs	511	429
Accrued expenses	380	383
Other current liabilities	518	551
Total current liabilities	3,508	3,549
Non-current liabilities:
Long-term debt	3,137	4,249
Pension and OPEB liabilities	821	1,058
Deferred income taxes	639	590
Other non-current liabilities	1,310	1,267
TOTAL LIABILITIES	9,415	10,713
Commitments and contingencies (See NOTE 20)
Equity:
Common Shares - par value $0.125 per share	66	66
Capital in excess of par value of shares	4,861	4,871
Retained earnings	1,733	1,334
Cost of 26,164,757 common shares in treasury (2022 - 17,710,751 shares)	(430)	(310)
Accumulated other comprehensive income	1,657	1,830
Total Cliffs shareholders' equity	7,887	7,791
Noncontrolling interests	235	251
TOTAL EQUITY	8,122	8,042
TOTAL LIABILITIES AND EQUITY	$ 17,537	$ 18,755

Statements of Consolidated Fi_2

Statements of Consolidated Financial Position (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Common shares, par value (in dollars per share)	$ 0.125	$ 0.125
Common shares, authorized (in shares)	1,200,000,000	1,200,000,000
Common shares, issued (in shares)	531,051,530	531,051,530
Common shares, outstanding (in shares)	504,886,773	513,340,779
Common shares in treasury (in shares)	26,164,757	17,710,751

Statements Of Consolidated Oper

Statements Of Consolidated Operations - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Revenues	$ 21,996	$ 22,989	$ 20,444
Operating costs:
Cost of goods sold	(20,605)	(20,471)	(15,910)
Selling, general and administrative expenses	(577)	(465)	(422)
Acquisition-related costs	(12)	(4)	(20)
Goodwill impairment	(125)	0	0
Miscellaneous – net	0	(110)	(80)
Total operating costs	(21,319)	(21,050)	(16,432)
Operating income	677	1,939	4,012
Other income (expense):
Interest expense, net	(289)	(276)	(337)
Loss on extinguishment of debt	0	(75)	(88)
Net periodic benefit credits other than service cost component	204	212	210
Other non-operating income (loss)	5	(4)	6
Total other expense	(80)	(143)	(209)
Income from continuing operations before income taxes	597	1,796	3,803
Income tax expense	(148)	(423)	(773)
Income from continuing operations	449	1,373	3,030
Income from discontinued operations, net of tax	1	3	3
Net income	450	1,376	3,033
Net income attributable to noncontrolling interests	(51)	(41)	(45)
Net income attributable to Cliffs shareholders	$ 399	$ 1,335	$ 2,988
Earnings per common share attributable to Cliffs shareholders - basic
Continuing operations (in dollars per share)	$ 0.78	$ 2.57	$ 5.62
Discontinued operations (in dollars per share)	0	0	0.01
Earnings (loss) per common share attributable to Cliffs common shareholders - basic (in dollars per share)	0.78	2.57	5.63
Earnings per common share attributable to Cliffs shareholders - diluted
Continuing operations (in dollars per share)	0.78	2.55	5.35
Discontinued operations (in dollars per share)	0	0	0.01
Earnings (loss) per common share attributable to Cliffs common shareholders - diluted (in dollars per share)	$ 0.78	$ 2.55	$ 5.36

Statements Of Consolidated Comp

Statements Of Consolidated Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 450	$ 1,376	$ 3,033
Other comprehensive income (loss):
Changes in pension and OPEB, net of tax	(20)	1,298	684
Changes in derivative financial instruments, net of tax	(154)	(84)	69
Changes in foreign currency translation	1	(2)	(2)
Total other comprehensive income (loss)	(173)	1,212	751
Comprehensive income	277	2,588	3,784
Comprehensive income attributable to noncontrolling interests	(51)	(41)	(45)
Comprehensive income attributable to Cliffs shareholders	$ 226	$ 2,547	$ 3,739

Statements Of Consolidated Cash

Statements Of Consolidated Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
OPERATING ACTIVITIES
Net income	$ 450	$ 1,376	$ 3,033
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	973	1,034	897
Deferred income taxes	114	90	767
Pension and OPEB credits	(163)	(132)	(103)
Goodwill impairment	125	0	0
Loss on extinguishment of debt	0	75	88
Amortization of inventory step-up	0	0	161
Other	76	151	139
Changes in operating assets and liabilities, net of business combination:
Accounts receivable, net	120	197	(754)
Inventories	670	64	(1,370)
Income taxes	122	(22)	(136)
Pension and OPEB payments and contributions	(94)	(204)	(343)
Payables, accrued employment and accrued expenses	4	(70)	457
Other, net	(130)	(136)	(51)
Net cash provided by operating activities	2,267	2,423	2,785
INVESTING ACTIVITIES
Purchase of property, plant and equipment	(646)	(943)	(705)
Other investing activities	55	38	33
Net cash used by investing activities	(591)	(936)	(1,379)
FINANCING ACTIVITIES
Repurchase of common shares	(152)	(240)	0
Series B Redeemable Preferred Stock redemption	0	0	(1,343)
Proceeds from issuance of common shares	0	0	322
Proceeds from issuance of debt	750	0	1,000
Repayments of senior notes	0	(1,358)	(1,372)
Borrowings under credit facilities	3,004	5,749	5,962
Repayments under credit facilities	(4,868)	(5,494)	(5,889)
Debt issuance costs	(34)	0	(20)
Other financing activities	(204)	(166)	(130)
Net cash used by financing activities	(1,504)	(1,509)	(1,470)
Net increase (decrease) in cash and cash equivalents	172	(22)	(64)
Cash and cash equivalents at beginning of year	26	48	112
Cash and cash equivalents at end of year	198	26	48
Ferrous Processing and Trading
INVESTING ACTIVITIES
Acquisition, net of cash acquired	0	(31)	(761)
ArcelorMittal USA
INVESTING ACTIVITIES
Acquisition, net of cash acquired	$ 0	$ 0	$ 54

Statements of Consolidated Chan

Statements of Consolidated Changes in Equity - USD ($) $ in Millions	Total	ArcelorMittal USA	Common Stock	Capital in Excess of Par Value of Shares	Retained Earnings (Deficit)	Common Shares in Treasury	AOCI (Loss)	Non- controlling Interests	Non- controlling Interests ArcelorMittal USA
Balance, beginning of period (in shares) at Dec. 31, 2020			477,500,000
Balance, beginning of period at Dec. 31, 2020	$ 2,341		$ 63	$ 5,431	$ (2,989)	$ (354)	$ (133)	$ 323
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	3,784				2,988		751	45
Issuance of common shares (in shares)			20,000,000
Issuance of common shares	322			78		244
Stock and other incentive plans (in shares)			2,600,000
Stock and other incentive plans, APIC				(8)
Stock and other incentive plans	20					28
Series B Redeemable Preferred Stock redemption	(604)			(604)
1.500% 2025 Convertible Senior Notes redemption	(5)			(5)
Acquisition of ArcelorMittal USA - Measurement period adjustments		$ (22)							$ (22)
Net distributions to noncontrolling interests	(62)							(62)
Balance, end of period (in shares) at Dec. 31, 2021			500,100,000
Balance, end of period at Dec. 31, 2021	5,774		$ 63	4,892	(1)	(82)	618	284
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	2,588				1,335		1,212	41
Stock and other incentive plans (in shares)			1,500,000
Stock and other incentive plans, APIC				7
Stock and other incentive plans	19					12
1.500% 2025 Convertible Senior Notes redemption (in shares)			24,200,000
1.500% 2025 Convertible Senior Notes redemption			$ 3
1.500% 2025 Convertible Senior Notes redemption	(25)			(28)
Common stock repurchases (in shares)			(12,500,000)
Common share repurchases, net of excise tax	(240)					(240)
Net distributions to noncontrolling interests	$ (74)							(74)
Balance, end of period (in shares) at Dec. 31, 2022	513,340,779		513,300,000
Balance, end of period at Dec. 31, 2022	$ 8,042		$ 66	4,871	1,334	(310)	1,830	251
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income (loss)	277				399		(173)	51
Stock and other incentive plans (in shares)			2,000,000
Stock and other incentive plans, APIC				(10)
Stock and other incentive plans	23					33
Common stock repurchases (in shares)			(10,400,000)
Common share repurchases, net of excise tax	(153)					(153)
Net distributions to noncontrolling interests	$ (67)							(67)
Balance, end of period (in shares) at Dec. 31, 2023	504,886,773		504,900,000
Balance, end of period at Dec. 31, 2023	$ 8,122		$ 66	$ 4,861	$ 1,733	$ (430)	$ 1,657	$ 235

BASIS OF PRESENTATION AND SIGNI

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Significant Accounting Policies	NOTE 1 - BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES BUSINESS, CONSOLIDATION AND PRESENTATION NATURE OF BUSINESS We are the largest flat-rolled steel producer in North America. Founded in 1847 as a mine operator, we are also the largest manufacturer of iron ore pellets in North America. We are vertically integrated from mined raw materials, direct reduced iron and ferrous scrap to primary steelmaking and downstream finishing, stamping, tooling and tubing. We are the largest supplier of steel to the automotive industry in North America and serve a diverse range of other markets due to our comprehensive offering of flat-rolled steel products. Headquartered in Cleveland, Ohio, we employ approximately 28,000 people across our operations in the United States and Canada, of which approximately 20,000 were represented by labor unions under various agreements. More than 90% of our hourly workforce is represented by three prominent unions - USW, UAW and IAM. Unless otherwise noted, discussion of our business and results of operations in this Annual Report on Form 10-K refers to our continuing operations. BUSINESS OPERATIONS We are organized into four operating segments based on differentiated products, Steelmaking, Tubular, Tooling and Stamping and European Operations. We primarily operate through one reportable segment – the Steelmaking segment. BASIS OF CONSOLIDATION The consolidated financial statements consolidate our accounts and the accounts of our wholly owned subsidiaries, all subsidiaries in which we have a controlling interest and VIEs for which we are the primary beneficiary. All intercompany transactions and balances are eliminated upon consolidation. INVESTMENTS IN AFFILIATES We have investments in several businesses accounted for using the equity method of accounting. These investments are included within our Steelmaking segment. We review an investment for impairment when circumstances indicate that a loss in value below its carrying amount is other than temporary. Our investment in affiliates of $123 million and $133 million as of December 31, 2023 and 2022, respectively, was classified in Other non-current assets. SIGNIFICANT ACCOUNTING POLICIES We consider the following policies to be beneficial in understanding the judgments involved in the preparation of our consolidated financial statements and the uncertainties that could impact our financial condition, results of operations and cash flows. Certain prior period amounts have been reclassified to conform with the current year presentation. USE OF ESTIMATES The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Our mineral reserves; future realizable cash flow; environmental, reclamation and closure obligations; valuation of business combinations, goodwill, long-lived assets, inventory, tax assets and post-employment, post-retirement and other employee benefit liabilities; reserves for contingencies and litigation require the use of various management estimates and assumptions. Actual results could differ from estimates. Management reviews its estimates on an ongoing basis. Changes in facts and circumstances may alter such estimates and affect the results of operations and financial position in future periods. BUSINESS COMBINATIONS Assets acquired and liabilities assumed in a business combination are recognized and measured based on their estimated fair values at the acquisition date, while the acquisition-related costs are expensed as incurred. Any excess of the purchase consideration when compared to the fair value of the net tangible and intangible assets acquired is recorded as goodwill. We engaged independent valuation specialists to assist with the determination of the fair value of assets acquired, liabilities assumed, noncontrolling interest, and goodwill, for the acquisitions. If the initial accounting for the business combination is incomplete by the end of the reporting period in which the acquisition occurs, an estimate will be recorded. Subsequent to the acquisition date, and not later than one year from the acquisition date, we will record any material adjustments to the initial estimate based on new information obtained that would have existed as of the date of the acquisition. Any adjustment that arises from information obtained that did not exist as of the date of the acquisition will be recorded in the period the adjustment arises. CASH AND CASH EQUIVALENTS Cash and cash equivalents include cash on hand and on deposit as well as all short-term securities held for the primary purpose of general liquidity. We routinely monitor and evaluate counterparty credit risk related to the financial institutions in which our short-term investment securities are held. Where right of offset exists, we report cash balances net. TRADE ACCOUNTS RECEIVABLE AND ALLOWANCE FOR CREDIT LOSS Trade accounts receivable are recorded at the point control transfers and represent the amount of consideration we expect to receive in exchange for transferred goods and do not bear interest. We establish provisions for expected lifetime losses on accounts receivable at the time a receivable is recorded based on historical experience, customer credit quality and forecasted economic conditions. We regularly review our accounts receivable balances and the allowance for credit loss and establish or adjust the allowance as necessary using the specific identification method. We evaluate the aggregation and risk characteristics of receivable pools and develop loss rates that reflect historical collections, current forecasts of future economic conditions over the time horizon we are exposed to credit risk, and payment terms or conditions that may materially affect future forecasts. INVENTORIES Inventories are generally stated at the lower of cost or net realizable value using average cost, excluding depreciation and amortization. Certain iron ore inventories are stated at the lower of cost or market using the LIFO method. DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES We are exposed to certain risks related to the ongoing operations of our business, including those caused by changes in commodity prices and energy rates. We have established policies and procedures, including the use of certain derivative instruments, to manage such risks. Derivative financial instruments are recognized as either assets or liabilities on the Statements of Consolidated Financial Position and measured at fair value. On the date a qualifying hedging instrument is executed, we designate the hedging instrument as a hedge of the variability of cash flows to be received or paid related to a forecasted transaction (cash flow hedge). We formally document all relationships between hedging instruments and hedged items, as well as our risk-management objective and strategy for undertaking various hedge transactions. This process includes linking all derivatives that are designated as cash flow hedges to specific firm commitments or forecasted transactions. We also formally assess, both at the hedge's inception and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows of the related hedged items. When it is determined that a derivative is not highly effective as a hedge, we discontinue hedge accounting prospectively and record all future changes in fair value in the period of the instrument's earnings or losses. For derivative instruments that have been designated as cash flow hedges, the changes in fair value are recorded in Accumulated other comprehensive income . Amounts recorded in Accumulated other comprehensive income are reclassified to earnings or losses in the period the underlying hedged transaction affects earnings or when the underlying hedged transaction is no longer reasonably possible of occurring. The cash flows resulting from these derivative instruments are classified in Other, net in operating activities on the Statements of Consolidated Cash Flows. For derivative instruments that have not been designated as cash flow hedges, changes in fair value are recorded in the period of the instrument's earnings or losses. PROPERTY, PLANT AND EQUIPMENT Our properties are stated at cost less accumulated depreciation. Depreciation of plant and equipment is computed principally by the straight-line method based on estimated useful lives. Depreciation continues to be recognized when operations are idled temporarily. Depreciation and depletion are recorded over the following estimated useful lives: Asset Class Basis Life Land, land improvements and mineral rights Land and mineral rights Units of production Life of mine Land improvements Straight line 20 to 45 years Buildings Straight line 20 to 45 years Equipment Straight line/Double declining balance 3 to 45 years GOODWILL Goodwill represents the excess purchase price paid over the fair value of the net assets from an acquisition. Goodwill is not amortized for financial statement purposes. Goodwill is tested on a qualitative or quantitative basis for impairment at the reporting unit level on an annual basis on October 1 and between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying value. We have an unconditional option to bypass the qualitative test for any reporting unit in any period and proceed directly to performing the quantitative test. Should our qualitative test indicate that it is more likely than not that the fair value of a reporting unit is less than its carrying value, we perform a quantitative test to determine the amount of impairment, if any, to the carrying value of the reporting unit and its associated goodwill. OTHER INTANGIBLE ASSETS AND LIABILITIES Intangible assets and liabilities are subject to periodic amortization on a straight-line basis over their estimated useful lives. LEASES We determine if an arrangement contains a lease at inception. We recognize right-of-use assets and lease liabilities associated with leases based on the present value of the future minimum lease payments over the lease term at the commencement date. Lease terms reflect options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Short-term leases (leases with an initial lease term of 12 months or less) are not recognized on the Statements of Consolidated Financial Position. Operating lease expense is recognized on a straight-line basis over the lease term. ASSET IMPAIRMENT We monitor conditions that may affect the carrying value of our long-lived tangible and intangible assets when events and circumstances indicate that the carrying value of the asset groups may not be recoverable. In order to determine if assets have been impaired, assets are grouped and tested at the lowest level for which identifiable, independent cash flows are available ("asset group"). The measurement of the impairment loss to be recognized is based on the difference between the fair value and the carrying value of the asset group. Fair value can be determined using a market approach, income approach or cost approach. FAIR VALUE MEASUREMENTS ASC Topic 820, Fair Value Measurements and Disclosures , establishes a three-level valuation hierarchy for classification of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. Inputs refer broadly to the assumptions that market participants would use in pricing an asset or liability. Inputs may be observable or unobservable. Observable inputs are inputs that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our own views about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. The three-tier hierarchy of inputs is summarized below: • Level 1 — Valuation is based upon quoted prices (unadjusted) for identical assets or liabilities in active markets. • Level 2 — Valuation is based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument. • Level 3 — Valuation is based upon other unobservable inputs that are significant to the fair value measurement. The classification of assets and liabilities within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement in its entirety. PENSION AND OTHER POSTRETIREMENT BENEFITS We offer defined benefit pension plans, defined contribution pension plans and OPEB plans, primarily consisting of retiree healthcare benefits as part of our total compensation and benefits programs. We recognize the funded or unfunded status of our pension and OPEB obligations on the Statements of Consolidated Financial Position based on the difference between the market value of plan assets and the actuarial present value of our retirement obligations on that date, on a plan-by-plan basis. If the plan assets exceed the pension and OPEB obligations, the amount of the surplus is recorded as an asset; if the pension and OPEB obligations exceed the plan assets, the amount of the underfunded obligations is recorded as a liability. Year-end balance sheet adjustments to pension and OPEB assets and obligations are recorded as Accumulated other comprehensive income on the Statements of Consolidated Financial Position. The actuarial estimates of the PBO (Projected benefit obligation) and APBO (Accumulated postretirement benefit obligation) incorporate various assumptions including the discount rates, the rates of increases in compensation, healthcare cost trend rates, mortality, retirement timing, employee turnover and other demographic assumptions. The discount rate is determined based on the prevailing year-end rates for high-grade corporate bonds with a duration matching the expected cash flow timing of the benefit payments from the various plans. The remaining assumptions are based on our estimates of future events by incorporating historical trends and future expectations. The amount of net periodic cost that is recorded in the Statements of Consolidated Operations consists of several components including service cost, interest cost, expected return on plan assets, and amortization of previously unrecognized amounts. Service cost represents the value of the benefits earned in the current year by the participants. Interest cost represents the cost associated with the passage of time. Certain items, such as plan amendments, gains and/or losses resulting from differences between actual and assumed results for demographic and economic factors affecting the obligations and assets of the plans, and changes in other assumptions are subject to deferred recognition for income and expense purposes. The expected return on plan assets is calculated on a plan-by-plan basis using each plan's strategic asset allocation and our expected long-term capital market return assumptions. Service costs are classified within Cost of goods sold, Selling, general and administrative expenses and Miscellaneous – net while the interest cost, expected return on assets, amortization of prior service costs/credits, net actuarial gain/loss, and other costs are classified within Net periodic benefit credits other than service cost component. Cumulative actuarial gains and losses will be amortized to expense using the corridor method, where gains and losses are recognized if they exceed 10% of the greater of the fair value of plan assets or the plans' benefit obligations. The amortization period varies by plan. ASSET RETIREMENT OBLIGATIONS An asset retirement obligation is recognized when incurred if a reasonable estimate of fair value can be made, and is initially measured at fair value. The fair value of the liability is determined as the discounted value of the expected future cash flows. The asset retirement obligation is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized and amortized over the life of the related asset. Reclamation costs are adjusted periodically to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation costs. We review, on an annual basis, unless otherwise deemed necessary, the asset retirement obligation for each applicable operation in accordance with the provisions of ASC Topic 410, Asset Retirement and Environmental Obligations . We perform an in-depth evaluation of the liability every three years in addition to our routine annual assessments. Future reclamation costs for inactive operations are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at a site. Such cost estimates include, where applicable, ongoing maintenance and monitoring costs. Changes in estimates at inactive operations are reflected in Miscellaneous – net on the Statements of Consolidated Operations in the period an estimate is revised. ENVIRONMENTAL REMEDIATION COSTS Our operating activities are subject to various laws and regulations governing protection of the environment. We conduct our operations to protect the public health and environment and believe our operations are in compliance with applicable laws and regulations in all material respects. Our environmental liabilities, including obligations for known environmental remediation exposures, have been recognized based on the estimated cost of investigation and remediation at each site. If the cost can only be estimated as a range of possible amounts with no point in the range being more likely, the minimum of the range is accrued. Future expenditures are discounted unless the amount and timing of the cash disbursements cannot be reasonably estimated. It is possible that additional environmental obligations could be incurred, the extent of which cannot be assessed. Potential insurance recoveries have not been reflected in the determination of the liabilities. REVENUE RECOGNITION Sales are recognized when our performance obligations are satisfied. Generally, our performance obligations are satisfied, control of our products is transferred and revenue is recognized at a single point in time, according to shipping terms. Shipping and other transportation costs charged to customers are treated as fulfillment activities and are recorded in both revenue and cost of sales at the time control is transferred to the customer. REPAIRS AND MAINTENANCE Repairs, maintenance and replacement of components are expensed as incurred. The cost of major equipment overhauls is capitalized and depreciated over the estimated useful life, which is the period until the next scheduled overhauls. All other planned and unplanned repairs and maintenance costs are expensed when incurred. INCOME TAXES Income taxes are based on income for financial reporting purposes, calculated using tax rates by jurisdiction, and reflect a current tax liability or asset for the estimated taxes payable or recoverable on the current year tax return and expected annual changes in deferred taxes. Any interest or penalties on income tax are recognized as a component of Income tax expense . We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized within Net income in the period that includes the enactment date. We record net deferred tax assets to the extent we believe these assets will more likely than not be realized. In making such determination, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies and recent financial results of operations. Accounting for uncertainty in income taxes recognized in the financial statements requires that a tax benefit from an uncertain tax position be recognized when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on technical merits. FOREIGN CURRENCY Our financial statements are prepared with the U.S. dollar as the reporting currency, and the functional currency of all subsidiaries is the U.S. dollar, except for our European Operations for which the functional currency is the Euro. EARNINGS PER SHARE We present both basic and diluted EPS amounts for continuing operations and discontinued operations. Total basic EPS amounts are calculated by dividing Net income attributable to Cliffs shareholders , less the earnings allocated to any of our outstanding Series B Participating Redeemable Preferred Stock, by the weighted average number of common shares outstanding during the period presented. Total diluted EPS amounts are calculated by dividing Net income attributable to Cliffs shareholders by the weighted average number of common shares, common share equivalents under stock plans using the treasury-stock method, common share equivalents of the Series B Participating Redeemable Preferred Stock using the if-converted method and the calculated common share equivalents in excess of the conversion rate related to our 1.500% 2025 Convertible Senior Notes using the treasury-stock method. Common share equivalents are excluded from EPS computations in the periods in which they have an anti-dilutive effect. VARIABLE INTEREST ENTITIES We assess whether we have a variable interest in legal entities in which we have a financial relationship and, if so, whether or not those entities are VIEs. A VIE is an entity with insufficient equity at risk for the entity to finance its activities without additional subordinated financial support or in which equity investors lack the characteristics of a controlling financial interest. If an entity is determined to be a VIE, we evaluate whether we are the primary beneficiary. The primary beneficiary analysis is a qualitative analysis based on power and economics. We conclude that we are the primary beneficiary and consolidate the VIE if we have both (i) the power to direct the activities of the VIE that most significantly influence the VIE's economic performance and (ii) the obligation to absorb losses of, or the right to receive benefits from, the VIE that could potentially be significant to the VIE. RECENT ACCOUNTING PRONOUNCEMENTS AND LEGISLATION ACCOUNTING PRONOUNCEMENTS In September 2022, the FASB issued ASU No. 2022-04, Liabilities - Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations . This guidance requires annual and interim disclosure of the key terms of outstanding supplier finance programs and a roll-forward of the related obligations. The new standard does not affect the recognition, measurement or financial statement presentation of the supplier finance program obligations. We have adopted this standard, except for the roll-forward information, which is effective for fiscal years beginning after December 31, 2023. Refer to NOTE 2 - SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION for further information. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . This guidance requires additional annual and interim disclosures for reportable segments. This new standard does not affect the recognition, measurement or financial statement presentation. The amendments are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . This guidance requires additional annual and interim disclosures for income taxes. This new standard does not affect the recognition, measurement or financial statement presentation. The amendments are effective for fiscal years beginning after December 15, 2024. LEGISLATION In August 2022, the U.S. government signed the Inflation Reduction Act into law. The Inflation Reduction Act introduced, among other legislation, a 1% excise tax on the fair market value of stock repurchases net of the fair market value of stock issuances during the tax year and a 15% U.S. corporate alternative minimum tax on adjusted financial statement income. The excise tax and corporate alternative minimum tax, both of which are immaterial to our financial statements, are effective on transactions occurring after December 31, 2022. The excise tax is recorded in equity as a cost of common shares in treasury. In addition, a 15% global minimum corporate tax under Pillar Two of the Organization for Economic Cooperation and Development’s Global Anti-Base Erosion Rules has been adopted by the European Union requiring its Member States to implement national legislation applicable for fiscal years starting on or after December 31, 2023. This global minimum corporate tax is expected to be immaterial to our 2024 financial statements.

SUPPLEMENTARY FINANCIAL STATEME

SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION	12 Months Ended
	Dec. 31, 2023
Disclosure Text Block [Abstract]
Supplementary Financial Statement Information	NOTE 2 - SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION ALLOWANCE FOR CREDIT LOSSES The following is a roll-forward of our allowance for credit losses associated with Accounts receivable, net : (In millions) 2023 2022 Allowance for credit losses as of January 1 $ (4) $ (4) Increase in allowance (1) — Allowance for credit losses as of December 31 $ (5) $ (4) INVENTORIES The following table presents the detail of our Inventories on the Statements of Consolidated Financial Position: December 31, (In millions) 2023 2022 Product inventories Finished and semi-finished goods $ 2,573 $ 2,971 Raw materials 1,476 1,794 Total product inventories 4,049 4,765 Manufacturing supplies and critical spares 411 365 Inventories $ 4,460 $ 5,130 The excess of current cost over LIFO cost of iron ore inventories was $131 million and $169 million at December 31, 2023 and 2022, respectively. As of December 31, 2023, the product inventory balance for iron ore inventories increased, resulting in a LIFO increment in 2023. The effect of the inventory build was an increase in Inventories of $21 million on the Statements of Consolidated Financial Position for the year ended December 31, 2023. As of December 31, 2022, the product inventory balance for iron ore inventories decreased, resulting in a liquidation of a LIFO layer in 2022. The effect of the inventory reduction was an increase in Cost of goods sold of $36 million on the Statements of Consolidated Operations for the year ended December 31, 2022. SUPPLY CHAIN FINANCE PROGRAMS We negotiate payment terms directly with our suppliers for the purchase of goods and services. We currently offer voluntary supply chain finance programs that enable our suppliers to sell their Company receivables to financial intermediaries, at the sole discretion of both the suppliers and financial intermediaries. No guarantees are provided by us or our subsidiaries under the supply chain finance programs. The supply chain finance programs allow our suppliers to be paid by the financial intermediaries earlier than the due date on the applicable invoice. Supply chain finance programs that extend terms or provide us an economic benefit are classified as short-term financings. As of December 31, 2023 and 2022, we had $21 million and $19 million, respectively, deemed as short-term financings that are classified in Other current liabilities . Additionally , as of December 31, 2023 and 2022, we had $91 million and $112 million, respectively, classified as Accounts payable SALE OF BUSINESS On October 6, 2023, we entered into a membership interest purchase agreement for the sale of the legal entities owning, among other things, our closed coal mines in Pennsylvania. As a result of the sale, we recorded a gain of $63 million classified in Miscellaneous – net in the Statements of Consolidated Operations and as Other in operating activities on the Statements of Consolidated Cash Flows. As part of this transaction, we received $35 million in proceeds related to the sale that is classified as Other investing activities on the Statements of Consolidated Cash Flows. CASH FLOW INFORMATION A reconciliation of capital additions to cash paid for capital expenditures is as follows: Year Ended December 31, (In millions) 2023 2022 2021 Capital additions $ 785 $ 1,033 $ 857 Less: Non-cash accruals (13) 35 102 Equipment financed with seller 59 — — Right-of-use assets - finance leases 93 55 50 Cash paid for capital expenditures including deposits $ 646 $ 943 $ 705 Additionally, included within Other investing activities on the Statements of Consolidated Cash Flows are grant reimbursements related to governmental funded capital projects. For the years ended December 31, 2023, 2022 and 2021, grant reimbursements were $13 million, $27 million and $2 million, respectively. Cash payments (receipts) for interest and income taxes are as follows: Year Ended December 31, (In millions) 2023 2022 2021 Income taxes paid $ 94 $ 334 $ 166 Income tax refunds (205) (3) (16) Interest paid on debt obligations net of capitalized interest 1 256 249 299 1 Capitalized interest was $12 million, $9 million and $6 million for the years ended December 31, 2023, 2022 and 2021, respectively. Other non-cash investing and financing activities are as follows: Year Ended December 31, (In millions) 2023 2022 2021 1.500% 2025 Convertible Senior Notes redemption $ — $ 25 $ — Fair value of settlement of a pre-existing relationship as part of consideration in connection with FPT Acquisition — — (20)

ACQUISITIONS

ACQUISITIONS	12 Months Ended
	Dec. 31, 2023
Business Combinations [Abstract]
Acquisitions	NOTE 3 - ACQUISITIONS FPT ACQUISITION OVERVIEW On November 18, 2021, pursuant to the FPT Acquisition Agreement, we completed the FPT Acquisition, in which we were the acquirer. The FPT Acquisition entered us into the scrap business and provides us a competitive advantage in sourcing prime scrap, a key raw material for our steelmaking facilities. The fair value of the total purchase consideration was determined as follows: (In millions) Cash consideration: Cash consideration pursuant to the FPT Acquisition Agreement $ 778 Cash consideration paid related to IRC Section 338(h)(10) 23 Total cash consideration 801 Fair value of settlement of a pre-existing relationship (20) Total purchase consideration $ 781 We made certain elections under Section 338(h)(10) of the IRC with respect to entities acquired in connection with the FPT Acquisition that were finalized during the third quarter of 2022, which changed the final cash consideration. VALUATION ASSUMPTION AND PURCHASE PRICE ALLOCATION The allocation of consideration to the net tangible and intangible assets acquired and liabilities assumed in connection with the FPT Acquisition was based on estimated fair values at November 18, 2021, and was finalized during the quarter ended December 31, 2022. The following is a summary of the purchase price allocation to assets acquired and liabilities assumed in the FPT Acquisition: (In millions) Initial Allocation of Consideration Measurement Final Allocation of Consideration as of December 31, 2022 Cash and cash equivalents $ 9 $ — $ 9 Accounts receivable, net 233 2 235 Inventories 137 (2) 135 Other current assets 4 (1) 3 Property, plant and equipment 179 12 191 Other non-current assets 74 (2) 72 Accounts payable (122) — (122) Accrued employment costs (8) — (8) Other current liabilities (9) 3 (6) Other non-current liabilities (21) — (21) Net identifiable assets acquired 476 12 488 Goodwill 279 14 293 Total net assets acquired $ 755 $ 26 $ 781 The goodwill resulting from the FPT Acquisition primarily represents the incremental benefit of providing substantial access to prime scrap for our vertically integrated steelmaking business, as well as any synergistic benefits to be realized from the FPT Acquisition within our Steelmaking segment. We have $296 million in goodwill that is deductible for tax purposes from the FPT Acquisition. The purchase price allocated to identifiable intangible assets acquired was: (In millions) Weighted Average Life (In years) Customer relationships $ 13 15 Supplier relationships 29 18 Trade names and trademarks 7 15 Total identifiable intangible assets $ 49 17 Intangible assets are classified as Other non-current assets on the Statements of Consolidated Financial Position. PRO FORMA RESULTS The following table provides unaudited pro forma financial information, prepared in accordance with Topic 805, as if FPT had been acquired as of January 1, 2020: Year Ended (In millions) December 31, 2021 Revenues $ 21,701 Net income attributable to Cliffs shareholders 3,074 The unaudited pro forma financial information has been calculated after applying our accounting policies and adjusting the historical results with pro forma adjustments, net of tax, that assume the FPT Acquisition occurred on January 1, 2020. There were no significant pro forma adjustments for the FPT Acquisition. The unaudited pro forma financial information does not reflect the potential realization of synergies or cost savings, nor does it reflect other costs relating to the integration of the acquired company. This unaudited pro forma financial information should not be considered indicative of the results that would have actually occurred if the FPT Acquisition had been consummated on January 1, 2020, nor are they indicative of future results.

REVENUES

REVENUES	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Revenues	NOTE 4 - REVENUES We generate our revenue through product sales, in which shipping terms indicate when we have fulfilled our performance obligations and transferred control of products to our customer. Our revenue transactions consist of a single performance obligation to transfer promised goods. Our contracts with customers define the mechanism for determining the sales price, which is generally fixed upon transfer of control, but the contracts generally do not impose a specific quantity on either party. Quantities to be delivered to the customer are determined at a point near the date of delivery through purchase orders or other written instructions we receive from the customer. Spot market sales are made through purchase orders or other written instructions. We consider our performance obligation to be complete and recognize revenue when control transfers in accordance with shipping terms. Revenue is measured as the amount of consideration we expect to receive in exchange for transferring product. We reduce the amount of revenue recognized for estimated returns and other customer credits, such as discounts and volume rebates, based on the expected value to be realized. Payment terms are consistent with terms standard to the markets we serve. Sales taxes collected from customers are excluded from revenues. The following table represents our Revenues by market: Year Ended December 31, (In millions) 2023 2022 2021 Steelmaking: Automotive $ 7,440 $ 6,661 $ 4,726 Infrastructure and manufacturing 5,612 5,869 5,380 Distributors and converters 5,330 6,388 7,671 Steel producers 2,949 3,465 2,124 Total Steelmaking 21,331 22,383 19,901 Other Businesses: Automotive 545 478 426 Infrastructure and manufacturing 38 52 47 Distributors and converters 82 76 70 Total Other Businesses 665 606 543 Total revenues $ 21,996 $ 22,989 $ 20,444 The following table represents our Revenues by product line: Year Ended December 31, (In millions) 2023 2022 2021 Steelmaking: Hot-rolled steel $ 4,864 $ 4,529 $ 5,615 Cold-rolled steel 2,658 3,193 3,186 Coated steel 6,661 6,905 5,864 Stainless and electrical steel 2,281 2,284 1,622 Plate 1,444 1,651 1,316 Slab and other steel products 1,329 1,492 1,247 Other 2,094 2,329 1,051 Total Steelmaking 21,331 22,383 19,901 Other Businesses: Other 665 606 543 Total revenues $ 21,996 $ 22,989 $ 20,444

SEGMENT REPORTING

SEGMENT REPORTING	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Segment Reporting	NOTE 5 - SEGMENT REPORTING We are vertically integrated from mined raw materials and direct reduced iron and ferrous scrap to primary steelmaking and downstream finishing, stamping, tooling and tubing. We are organized into four operating segments based on our differentiated products - Steelmaking, Tubular, Tooling and Stamping, and European Operations. We have one reportable segment - Steelmaking. The operating segment results of our Tubular, Tooling and Stamping, and European Operations that do not constitute reportable segments are combined and disclosed in the Other Businesses category. Our Steelmaking segment operates as the largest flat-rolled steel producer supported by being the largest iron ore pellet producer as well as a leading prime scrap processor in North America, primarily serving the automotive, infrastructure and manufacturing, and distributors and converters markets. Our Other Businesses primarily include the operating segments that provide customer solutions with carbon and stainless steel tubing products, advanced-engineered solutions, tool design and build, hot- and cold-stamped steel components, and complex assemblies. All intersegment transactions were eliminated in consolidation. We allocate Corporate Selling, general and administrative expenses to our operating segments. We evaluate performance on an operating segment basis, as well as a consolidated basis, based on Adjusted EBITDA, which is a non-GAAP measure. This measure is used by management, investors, lenders and other external users of our financial statements to assess our operating performance and to compare operating performance to other companies in the steel industry. In addition, management believes Adjusted EBITDA is a useful measure to assess the earnings power of the business without the impact of capital structure and can be used to assess our ability to service debt and fund future capital expenditures in the business. Our results by segment are as follows: Year Ended December 31, (In millions) 2023 2022 2021 Revenues: Steelmaking $ 21,331 $ 22,383 $ 19,901 Other Businesses 665 606 543 Total revenues $ 21,996 $ 22,989 $ 20,444 Adjusted EBITDA: Steelmaking $ 1,873 $ 3,089 $ 5,280 Other Businesses 43 69 9 Eliminations (5) 11 (12) Total Adjusted EBITDA $ 1,911 $ 3,169 $ 5,277 The following table provides a reconciliation of our consolidated Net income to total Adjusted EBITDA: Year Ended December 31, (In millions) 2023 2022 2021 Net income $ 450 $ 1,376 $ 3,033 Less: Interest expense, net (289) (276) (337) Income tax expense (148) (423) (773) Depreciation, depletion and amortization (973) (1,034) (897) 1,860 3,109 5,040 Less: EBITDA from noncontrolling interests 1 83 74 75 Acquisition-related expenses and adjustments (12) (1) (197) Goodwill impairment (125) — — Non-cash gain on sale of business 28 — — Loss on extinguishment of debt — (75) (88) Asset impairment — (29) — Other, net (25) (29) (27) Total Adjusted EBITDA $ 1,911 $ 3,169 $ 5,277 1 EBITDA of noncontrolling interests includes the following: Net income attributable to noncontrolling interests $ 51 $ 41 $ 45 Depreciation, depletion and amortization 32 33 30 EBITDA of noncontrolling interests $ 83 $ 74 $ 75 The following table summarizes our depreciation, depletion and amortization and capital additions by segment: Year Ended December 31, (In millions) 2023 2022 2021 Depreciation, depletion and amortization: Steelmaking $ (938) $ (994) $ (860) Other Businesses (35) (40) (37) Total depreciation, depletion and amortization $ (973) $ (1,034) $ (897) Capital additions 1: Steelmaking $ 778 $ 997 $ 787 Other Businesses 3 30 52 Corporate 4 6 18 Total capital additions $ 785 $ 1,033 $ 857 1 Refer to NOTE 2 - SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION for additional information. The following summarizes our assets by segment: December 31, (In millions) 2023 2022 Assets: Steelmaking $ 16,880 $ 18,070 Other Businesses 657 836 Intersegment eliminations (507) (521) Total segment assets 17,030 18,385 Corporate/Eliminations 507 370 Total assets $ 17,537 $ 18,755 Included in the consolidated financial statements are the following amounts relating to geographic location based on product destination: (In millions) 2023 2022 2021 Revenues: United States $ 20,000 $ 20,991 $ 18,881 Canada 1,046 963 803 Other countries 950 1,035 760 Total revenues $ 21,996 $ 22,989 $ 20,444 Property, plant and equipment, net: United States $ 8,816 $ 8,981 $ 9,092 Canada 78 88 93 Other countries 1 1 1 Total property, plant and equipment, net $ 8,895 $ 9,070 $ 9,186

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	NOTE 6 - PROPERTY, PLANT AND EQUIPMENT The following table indicates the carrying value of each of the major classes of our depreciable assets: December 31, (In millions) 2023 2022 Land, land improvements and mineral rights $ 1,389 $ 1,388 Buildings 946 921 Equipment 9,680 9,289 Other 302 238 Construction in progress 590 552 Total property, plant and equipment 1 12,907 12,388 Allowance for depreciation and depletion (4,012) (3,318) Property, plant and equipment, net $ 8,895 $ 9,070 1 Includes right-of-use assets related to finance leases of $306 million and $408 million as of December 31, 2023 and 2022, respectively. We recorded depreciation expense of $932 million, $988 million and $848 million for the years ended December 31, 2023, 2022 and 2021, respectively. Depreciation expense for the year ended December 31, 2022 includes $23 million of accelerated depreciation related to the decision to indefinitely idle the coke facility at Middletown Works and $68 million of accelerated depreciation related to the indefinite idle of the Indiana Harbor #4 blast furnace. During the year ended December 31, 2022, we announced the permanent closure of Mountain State Carbon, which resulted in a $29 million asset impairment charge. The net book value of the mineral and land rights are as follows: December 31, (In millions) 2023 2022 Mineral rights: Cost $ 783 $ 780 Depletion (258) (225) Net mineral rights $ 525 $ 555 Land rights $ 427 $ 434 We recorded depletion expense of $33 million, $38 million and $46 million for the years ended December 31, 2023, 2022, and 2021, respectively.

GOODWILL AND INTANGIBLE ASSETS

GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets and Liabilities	NOTE 7 - GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES GOODWILL The following is a summary of Goodwill by segment: December 31, (In millions) 2023 2022 Steelmaking $ 956 $ 956 Other Businesses 49 174 Total goodwill $ 1,005 $ 1,130 Our 2023 annual goodwill impairment analysis resulted in a full impairment charge of $125 million for goodwill related to our Tooling and Stamping reporting unit. The fair value of our Tooling and Stamping reporting unit was estimated using the discounted cash flow methodology (level 3 within the fair value hierarchy), which considers forecasted cash flows discounted at an estimated weighted average cost of capital. The decline in the fair value of our Tooling and Stamping reporting unit below its carrying value during 2023 resulted from forgoing previous investment and capital plans in favor of other opportunities and an increase in the discount rate. INTANGIBLE ASSETS AND LIABILITIES The following is a summary of our intangible assets and liabilities: December 31, 2023 December 31, 2022 (In millions) Gross Amount Accumulated Amortization Net Amount Gross Amount Accumulated Amortization Net Amount Intangible assets 1 : Customer relationships $ 90 $ (18) $ 72 $ 90 $ (13) $ 77 Developed technology 60 (14) 46 60 (10) 50 Trade names and trademarks 18 (5) 13 18 (4) 14 Mining permits 72 (28) 44 72 (27) 45 Supplier relationships 29 (3) 26 29 (1) 28 Total intangible assets $ 269 $ (68) $ 201 $ 269 $ (55) $ 214 Intangible liabilities 2 : Above-market supply contracts $ (71) $ 24 $ (47) $ (71) $ 19 $ (52) 1 Intangible assets are classified as Other non-current assets . Amortization related to mining permits is recognized in Cost of goods sold . Amortization of all other intangible assets is recognized in Selling, general and administrative expenses . 2 Intangible liabilities are classified as Other non-current liabilities . Amortization of all intangible liabilities is recognized in Cost of goods sold . Amortization expense related to intangible assets was $13 million for both the years ended December 31, 2023 and 2022. Estimated future amortization expense related to intangible assets is $13 million annually for the years 2024 through 2028.

DEBT AND CREDIT FACILITIES

DEBT AND CREDIT FACILITIES	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Debt and Credit Facilities	NOTE 8 - DEBT AND CREDIT FACILITIES The following represents a summary of our long-term debt: (In Millions) Debt Instrument Issuer 1 Annual Effective Interest Rate December 31, 2023 December 31, 2022 Senior Secured Notes: 6.750% 2026 Senior Secured Notes Cliffs 6.990% 829 829 Senior Unsecured Notes: 7.000% 2027 Senior Notes Cliffs 9.240% 73 73 7.000% 2027 AK Senior Notes AK Steel 9.240% 56 56 5.875% 2027 Senior Notes Cliffs 6.490% 556 556 4.625% 2029 Senior Notes Cliffs 4.625% 368 368 6.750% 2030 Senior Notes Cliffs 6.750% 750 — 4.875% 2031 Senior Notes Cliffs 4.875% 325 325 6.250% 2040 Senior Notes Cliffs 6.340% 235 235 ABL Facility Cliffs 2 Variable 3 — 1,864 Total debt 3,192 4,306 Unamortized discounts and issuance costs (55) (57) Total long-term debt $ 3,137 $ 4,249 1 Unless otherwise noted, references in this column and throughout this NOTE 8 - DEBT AND CREDIT FACILITIES to "Cliffs" are to Cleveland-Cliffs Inc., and references to "AK Steel" are to AK Steel Corporation (n/k/a Cleveland-Cliffs Steel Corporation). 2 Refers to Cleveland-Cliffs Inc. as borrower under our ABL Facility. 3 Our ABL Facility annual effective interest rate was 5.60% as of December 31, 2022. OUTSTANDING SENIOR SECURED NOTES The 6.750% 2026 Senior Secured Notes bear interest at a rate of 6.750% per annum, payable semi-annually in arrears on March 15 and September 15 of each year. The 6.750% 2026 Senior Secured Notes will mature on March 15, 2026. The 6.750% 2026 Senior Secured Notes are jointly and severally and fully and unconditionally guaranteed on a senior secured basis by substantially all of our material domestic subsidiaries and are secured (subject in each case to certain exceptions and permitted liens) by (i) a first-priority lien, on substantially all of our assets and the assets of the guarantors, other than the ABL Collateral (as defined below), and (ii) a second-priority lien on the ABL Collateral, which is junior to a first-priority lien for the benefit of the lenders under our ABL Facility. We may redeem the 6.750% 2026 Senior Secured Notes in whole or in part, at any time at our option upon not less than 30, and not more than 60, days' prior notice sent to the holders of the 6.750% 2026 Senior Secured Notes. The 6.750% 2026 Senior Secured Notes are redeemable at a price equal to 103.375% of the principal amount thereof, decreasing to 101.688% on March 15, 2024 and are redeemable at par beginning on March 15, 2025. In each case, we pay the redemption premiums plus accrued and unpaid interest, if any, to, but not including, the date of redemption. In addition, if a change in control triggering event, as defined in the indenture, occurs with respect to the 6.750% 2026 Senior Secured Notes, we will be required to offer to purchase the notes at a purchase price equal to 101% of their principal amount, plus accrued and unpaid interest, if any, to, but not including, the date of purchase. The terms of the 6.750% 2026 Senior Secured Notes contain certain customary covenants; however, there are no financial covenants. OUTSTANDING SENIOR UNSECURED NOTES CLEVELAND-CLIFFS INC. 6.750% 2030 SENIOR NOTES - 2023 OFFERING On April 14, 2023, we entered into an indenture among Cliffs, the guarantors party thereto and U.S. Bank Trust Company, National Association, as trustee, relating to the issuance of $750 million aggregate principal amount of our 6.750% 2030 Senior Notes, which were issued at par. The 6.750% 2030 Senior Notes were issued in a private placement transaction exempt from the registration requirements of the Securities Act. The 6.750% 2030 Senior Notes bear interest at a rate of 6.750% per annum, payable semi-annually in arrears on April 15 and October 15 of each year, which commenced on October 15, 2023. The 6.750% 2030 Senior Notes mature on April 15, 2030. The 6.750% 2030 Senior Notes are unsecured senior obligations and rank equally in right of payment with all of our existing and future unsecured and unsubordinated indebtedness. The 6.750% 2030 Senior Notes are guaranteed on a senior unsecured basis by our material direct and indirect wholly owned domestic subsidiaries. The 6.750% 2030 Senior Notes are structurally subordinated to all existing and future indebtedness and other liabilities of our subsidiaries that do not guarantee the 6.750% 2030 Senior Notes. The 6.750% 2030 Senior Notes may be redeemed, in whole or in part, at any time at our option not less than 10 days nor more than 60 days after prior notice is sent to the holders of the 6.750% 2030 Senior Notes. The 6.750% 2030 Senior Notes are redeemable prior to April 15, 2026, at a redemption price equal to 100% of the principal amount thereof plus a "make-whole" premium set forth in the indenture. We may also redeem up to 35% of the aggregate principal amount of the 6.750% 2030 Senior Notes prior to April 15, 2026 at a redemption price equal to 106.750% of the principal amount thereof with the net cash proceeds of one or more equity offerings. The 6.750% 2030 Senior Notes are redeemable beginning on April 15, 2026, at a redemption price equal to 103.375% of the principal amount thereof, decreasing to 101.688% on April 15, 2027, and are redeemable at par beginning on April 15, 2028. In each case, we pay the applicable redemption and "make-whole" premiums plus accrued and unpaid interest, if any, to, but not including, the date of redemption. In addition, if a change in control triggering event, as defined in the indenture, occurs with respect to the 6.750% 2030 Senior Notes, we will be required to offer to repurchase the notes at a purchase price equal to 101% of their principal amount, plus accrued and unpaid interest, if any, to, but not including, the date of repurchase. The terms of the 6.750% 2030 Senior Notes contain certain customary covenants; however, there are no financial covenants. CLEVELAND-CLIFFS INC. OTHER OUTSTANDING UNSECURED SENIOR NOTES The following represents a summary of our other unsecured senior notes' maturity and interest payable due dates: Debt Instrument Maturity Interest Payable 7.000% 2027 Senior Notes March 15, 2027 March 15 and September 15 5.875% 2027 Senior Notes June 1, 2027 June 1 and December 1 4.625% 2029 Senior Notes March 1, 2029 March 1 and September 1 4.875% 2031 Senior Notes March 1, 2031 March 1 and September 1 6.250% 2040 Senior Notes October 1, 2040 April 1 and October 1 The senior notes are unsecured obligations and rank equally in right of payment with all our other existing and future unsecured and unsubordinated indebtedness. The 7.000% 2027 Senior Notes, 5.875% 2027 Senior Notes, 4.625% 2029 Senior Notes and 4.875% 2031 Senior Notes are guaranteed on a senior unsecured basis by our material direct and indirect wholly owned domestic subsidiaries and, therefore, are structurally senior to any of our existing and future indebtedness that is not guaranteed by such guarantors and are structurally subordinated to all existing and future indebtedness and other liabilities of our subsidiaries that do not guarantee the notes. There are no subsidiary guarantees of the interest and principal amounts for the 6.250% 2040 Senior Notes. The 7.000% 2027 Senior Notes may be redeemed, in whole or in part, at any time at our option upon not less than 30, and not more than 60, days' prior notice sent to the holders. The 7.000% 2027 Senior Notes are redeemable at a price equal to 102.333% of the principal amount thereof, decreasing to 101.167% on March 15, 2024 and are redeemable at par beginning on March 15, 2025. In each case, we pay the redemption premiums plus accrued and unpaid interest, if any, to, but not including, the date of redemption. The 5.875% 2027 Senior Notes may be redeemed, in whole or in part, at any time at our option upon not less than 30, and not more than 60, days' prior notice sent to the holders. The 5.875% 2027 Senior Notes are redeemable at a price equal to 101.958% of the principal amount thereof, decreasing to 100.979% on June 1, 2024 and are redeemable at par beginning on June 1, 2025. In each case, we pay the redemption premiums plus accrued and unpaid interest, if any, to, but not including, the date of redemption. The 4.625% 2029 Senior Notes may be redeemed, in whole or in part, on not less than 10, nor more than 60, days’ prior notice sent to the holders of the notes. The 4.625% 2029 Senior Notes are redeemable prior to March 1, 2024, at a redemption price equal to 100% of the principal amount thereof plus a "make-whole" premium set forth in the indenture. We may also redeem up to 35% of the aggregate principal amount of the 4.625% 2029 Senior Notes prior to March 1, 2024 at a redemption price equal to 104.625% of the principal amount thereof with the net cash proceeds of one or more equity offerings. The 4.625% 2029 Senior Notes are redeemable beginning on March 1, 2024, at a redemption price equal to 102.313% of the principal amount thereof, decreasing to 101.156% on March 1, 2025 and are redeemable at par beginning on March 1, 2026. In each case, we pay the redemption and "make-whole" premiums plus accrued and unpaid interest, if any, to, but not including, the date of redemption. The 4.875% 2031 Senior Notes may be redeemed, in whole or in part, on not less than 10, nor more than 60, days’ prior notice sent to the holders of the notes. The 4.875% 2031 Senior Notes are redeemable prior to March 1, 2026, at a redemption price equal to 100% of the principal amount thereof plus a "make-whole" premium set forth in the indenture. We may also redeem up to 35% of the aggregate principal amount of the 4.875% 2031 Senior Notes prior to March 1, 2026 at a redemption price equal to 104.875% of the principal amount thereof with the net cash proceeds of one or more equity offerings. The 4.875% 2031 Senior Notes are redeemable beginning on March 1, 2026, at a redemption price equal to 102.438% of the principal amount thereof, decreasing to 101.625% on March 1, 2027, 100.813% on March 1, 2028 and are redeemable at par beginning on March 1, 2029. In each case, we pay the redemption and "make-whole" premiums plus accrued and unpaid interest, if any, to, but not including, the date of redemption. The 6.250% 2040 Senior Notes may be redeemed any time at our option upon not less than 30, nor more than 60, days' prior notice is sent to the holders. The 6.250% 2040 Senior Notes are redeemable at a redemption price equal to the greater of (1) 100% of the principal amount of the notes to be redeemed or (2) the sum of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed, discounted to the redemption date on a semi-annual basis at the treasury rate plus 40 basis points, plus accrued and unpaid interest, if any, to, but not including, the date of redemption. In addition, if a change of control triggering event, as defined in the applicable indenture, occurs with respect to the unsecured notes, we will be required to offer to purchase the notes of the applicable series at a purchase price equal to 101% of the principal amount, plus accrued and unpaid interest, if any, to, but not including, the date of purchase. The terms of the unsecured notes contain certain customary covenants; however, there are no financial covenants. AK STEEL CORPORATION UNSECURED SENIOR NOTES As of December 31, 2023, AK Steel had outstanding a total of $56 million aggregate principal amount of 7.000% 2027 AK Senior Notes. These senior notes are unsecured obligations and rank equally in right of payment with AK Steel's guarantees of Cliffs' unsecured and unsubordinated indebtedness. These notes contain no financial covenants. The 7.000% 2027 AK Senior Notes may be redeemed, in whole or in part, at any time at our option upon not less than 30, and not more than 60, days' prior notice sent to the holders. The 7.000% 2027 AK Senior Notes are redeemable at a price equal to 102.333% of the principal amount thereof, decreasing to 101.167% on March 15, 2024 and are redeemable at par beginning on March 15, 2025. In each case, we pay the redemption premiums plus accrued and unpaid interest, if any, to, but not including, the date of redemption. ABL FACILITY On June 9, 2023, we entered into the Fourth ABL Amendment to our ABL Facility. The Fourth ABL Amendment increased the amount of tranche A revolver commitments thereunder by an additional $250 million to an aggregate principal amount of $4.75 billion. As of December 31, 2023, the ABL Facility provides for up to $4.75 billion in borrowings, including a $555 million sublimit for the issuance of letters of credit and a $200 million sublimit for swingline loans. The Fourth ABL Amendment also extended the maturity date of all commitments under the ABL Facility from March 13, 2025 to June 9, 2028 or 91 days prior to the maturity of certain other material debt. Availability under the ABL Facility is limited to an eligible borrowing base, as applicable, determined by applying customary advance rates to eligible accounts receivable, inventory and certain mobile equipment. The Fourth ABL Amendment removed the LIBOR option for variable loans due to its cessation and replaced it with a SOFR option. Borrowings under the ABL Facility bear interest, at our option, at a base rate, or if certain conditions are met, a SOFR rate, in each case, plus an applicable tiered margin. The base rate is equal to the greater of the federal funds rate plus 0.5% or the term SOFR plus 1.25%. In addition, there is an unused commitment fee of between 0.25% and 0.35%, which is applied to the unused portion of the ABL Facility. The ABL Facility and certain bank products and hedge obligations are guaranteed by certain of our existing wholly owned U.S. subsidiaries and are required to be guaranteed by certain of our future U.S. subsidiaries. Amounts outstanding under the ABL Facility are secured by (i) a first-priority security interest in the accounts receivable and other rights to payment, inventory, as-extracted collateral, certain investment property, deposit accounts, securities accounts, certain general intangibles and commercial tort claims, certain mobile equipment, commodities accounts and other related assets of ours, the other borrowers and the guarantors, and proceeds and products of each of the foregoing (collectively, the “ABL Collateral”) and (ii) a second-priority security interest in substantially all of our assets and the assets of the other borrowers and the guarantors other than the ABL Collateral. The ABL Facility contains customary representations and warranties and affirmative and negative covenants including, among others, covenants regarding the maintenance of certain financial ratios if certain conditions are triggered, covenants relating to financial reporting, covenants relating to the payment of dividends on, or purchase or redemption of, our capital stock, covenants relating to the incurrence or prepayment of certain debt, covenants relating to the incurrence of liens or encumbrances, covenants relating to compliance with laws, covenants relating to transactions with affiliates, covenants relating to mergers and sales of all or substantially all of our assets and limitations on changes in the nature of our business. As of December 31, 2023 and 2022, we were in compliance with the ABL Facility liquidity requirements and, therefore, the springing financial covenant requiring a minimum fixed charge coverage ratio of 1.0 to 1.0 was not applicable. The ABL Facility provides for customary events of default, including, among other things, the event of nonpayment of principal, interest, fees or other amounts, a representation or warranty proving to have been materially incorrect when made, failure to perform or observe certain covenants within a specified period of time, a cross-default to certain material indebtedness, the bankruptcy or insolvency of the Company and certain of its subsidiaries, monetary judgment defaults of a specified amount, invalidity of any loan documentation, a change of control of the Company, and ERISA defaults resulting in liability of a specified amount. If an event of default exists (beyond any applicable grace or cure period), the administrative agent may, and at the direction of the requisite number of lenders shall, declare all amounts owing under the ABL Facility immediately due and payable, terminate such lenders’ commitments to make loans under the ABL Facility and/or exercise any and all remedies and other rights under the ABL Facility. For certain events of default related to insolvency and receivership, the commitments of the lenders will be automatically terminated and all outstanding loans and other amounts will become immediately due and payable. The following represents a summary of our borrowing capacity under the ABL Facility: December 31, (In millions) 2023 Available borrowing base on ABL Facility 1 $ 4,397 Borrowings — Letter of credit obligations 2 (56) Borrowing capacity available $ 4,341 1 As of December 31, 2023, the ABL Facility has a maximum borrowing base of $4.75 billion. The available borrowing base is determined by applying customary advance rates to eligible accounts receivable, inventory and certain mobile equipment. 2 We issued standby letters of credit with certain financial institutions in order to support business obligations, including, but not limited to, operating agreements, employee severance, environmental obligations, workers' compensation, and insurance obligations. DEBT MATURITIES The following represents a summary of our debt instrument maturities based on the principal amounts outstanding at December 31, 2023 (in millions): 2024 2025 2026 2027 2028 Thereafter Total $ — $ — $ 829 $ 685 $ — $ 1,678 $ 3,192

PENSIONS AND OTHER POSTRETIREME

PENSIONS AND OTHER POSTRETIREMENT BENEFITS	12 Months Ended
	Dec. 31, 2023
Postemployment Benefits [Abstract]
Pension and Other Post Retirement Benefits	NOTE 9 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS We offer benefits through defined benefit pension plans, defined contribution pension plans and OPEB plans to a significant portion of our employees and retirees. Benefits are also provided through multiemployer plans for certain union members. DEFINED BENEFIT PENSION PLANS The defined benefit pension plans are largely noncontributory and limited in participation. Most plans are closed to new participants with only the legacy iron ore hourly and salaried plans still open. The pension benefit calculations vary by plan but are generally based on employees' years of service and compensation or a fixed rate and years of service. Certain salaried plans calculate benefits using a cash balance formula, which earns interest credits and allocations based on a percent of pay. OPEB PLANS We offer postretirement health care and life insurance benefits to retirees through various funded and unfunded plans. The vast majority of our plans are closed to new participants. In lieu of retiree medical coverage, many union-represented employees receive a 401(k) contribution per hour worked to a restricted Retiree Health Care Account. Cost sharing features between the employer and retiree vary by plan and several plans include employer caps. Retiree healthcare coverage is provided through programs administered by insurance companies whose charges are based on benefits paid. Certain labor agreements require the funding of VEBAs, which, depending on funding levels, may be used to reimburse the employer for paid benefits. OBLIGATIONS AND FUNDED STATUS The following tables and information provide additional disclosures: (In millions) Pension Benefits OPEB Change in benefit obligations: 2023 2022 2023 2022 Benefit obligations — beginning of year $ 4,646 $ 6,036 $ 1,233 $ 3,254 Service cost 31 45 10 35 Interest cost 235 144 64 72 Plan amendments 3 122 8 (163) Actuarial loss (gain) 116 (1,236) (158) (1,781) Benefits paid (436) (431) (163) (232) Participant contributions — — 42 47 Effect of settlement (24) (34) — — Other — — — 1 Benefit obligations — end of year $ 4,571 $ 4,646 $ 1,036 $ 1,233 Change in plan assets: Fair value of plan assets — beginning of year $ 4,338 $ 5,606 $ 728 $ 812 Actual return on plan assets 375 (809) 67 (97) Participant contributions — — 42 47 Employer contributions 29 6 65 198 Benefits paid (436) (431) (163) (232) Effect of settlement (24) (34) — — Fair value of plan assets — end of year $ 4,282 $ 4,338 $ 739 $ 728 Funded status $ (289) $ (308) $ (297) $ (505) Amounts recognized in Statements of Financial Position: Non-current assets $ 137 $ 195 $ 192 $ 161 Current liabilities 1 (18) (30) (76) (81) Non-current liabilities (408) (473) (413) (585) Total amount recognized $ (289) $ (308) $ (297) $ (505) Amounts recognized in accumulated other comprehensive loss (income): Net actuarial gain $ (304) $ (361) $ (2,033) $ (1,996) Prior service cost (credit) 106 121 (131) (156) Net amount recognized $ (198) $ (240) $ (2,164) $ (2,152) 1 Current liabilities are classified within Other current liabilities on the Statements of Consolidated Financial Position. The accumulated benefit obligation for all defined benefit pension plans was $4,557 million and $4,628 million at December 31, 2023 and 2022, respectively. COMPONENTS OF NET PERIODIC BENEFIT COST (CREDIT) Pension Benefits OPEB (In millions) 2023 2022 2021 2023 2022 2021 Service cost $ 31 $ 45 $ 56 $ 10 $ 35 $ 51 Interest cost 235 144 103 64 72 74 Expected return on plan assets (315) (355) (359) (43) (37) (40) Amortization: Net actuarial loss (gain) 3 13 32 (145) (43) 3 Prior service costs (credits) 18 5 1 (17) (3) (2) Settlements (4) (8) (22) — — — Net periodic benefit cost (credit) $ (32) $ (156) $ (189) $ (131) $ 24 $ 86 For 2024, we estimate net periodic benefit cost (credit) as follows: (In millions) Defined benefit pension plans $ (58) OPEB plans (154) Total $ (212) COMPONENTS OF OTHER COMPREHENSIVE LOSS (INCOME) The following includes details on the significant actuarial losses (gains) impacting the benefit obligation and other components of other comprehensive loss (income): Pension Benefits OPEB (In millions) 2023 2022 2023 2022 Discount rates $ 124 $ (1,143) $ 28 $ (441) Demographic updates 1 (5) (102) (208) (7) Mortality (2) 17 (11) — Per capita healthcare costs and healthcare trend 2 — — 33 (1,333) Other (1) (8) — — Actuarial loss (gain) on benefit obligation 116 (1,236) (158) (1,781) Actual returns on assets under (over) expected (60) 1,165 (24) 134 Amortization of net actuarial gain (loss) (3) (13) 145 43 Amortization of prior service credits (costs) (18) (5) 17 3 Settlements 4 8 — — Plan amendments 3 3 122 8 (163) Total recognized in other comprehensive loss (income) $ 42 $ 41 $ (12) $ (1,764) 1 In 2023, the OPEB plans generated an actuarial gain relating to updates for demographic experience. We had adjustments relating to retirements, participation, persistency and census data updates. 2 The gain in per capita healthcare costs in 2022 relating to our OPEB plans is primarily due to the negotiation of favorable Medicare Advantage Prescription Drug healthcare rates, which went into effect on January 1, 2023. Additionally, we expanded the Medicare Advantage program to retirees on some of our other plans during the 2022 USW labor negotiations which added additional savings. The negotiated rates extend through 2025. 3 In 2022, the plan amendment gains and losses were generated from the ratification of the 2022 USW labor agreements. The plan amendment loss related to our pension plans is attributable to the increase to the pre-2023 service multiplier to $115 and the service multiplier applicable to service beginning in 2023 to $126 for retirements after January 1, 2023. The plan amendment gain related to our OPEB plans is attributable to the implementation of a cap on healthcare costs for employees retiring after January 1, 2026 on one of our Cleveland-Cliffs Steel LLC plans as well as the extension of the Medicare Advantage program to plans that previously did not have the offering. CONTRIBUTIONS We make both required and discretionary pension contributions. Required contributions are based on minimum funding requirements pursuant to ERISA regulations. Funded OPEB plans are not subject to minimum regulatory funding requirements, but rather amounts are contributed pursuant to bargaining agreements. Contributions toward unfunded OPEB plans are payments made directly from corporate assets and are displayed net of participant contributions and other reimbursements. Company contributions and payments we expect to make in 2024, and made in 2023 and 2022 are as follows: Pension Benefits OPEB (In millions) VEBA 1 Direct Payments Total 2022 $ 6 $ 85 $ 113 $ 198 2023 29 — 65 65 2024 (Expected) 122 — 66 66 1 Pursuant to the applicable bargaining agreements, benefits can be paid from certain VEBAs that are at least 70% funded (all VEBAs were over 70% funded at December 31, 2023). Certain agreements with plans holding VEBA assets have capped healthcare costs. For the Cleveland-Cliffs Steel LLC VEBA, we are required to make contributions based on earnings, and we may withdraw money from the VEBA plan to the extent funds are available for costs in excess of the cap. VEBA withdrawals are represented net of direct payments. There will be no further contributions to the Cleveland-Cliffs Steel LLC VEBA based on earnings for the remainder of the labor agreement with the USW, which expires in September of 2026. ESTIMATED FUTURE BENEFIT PAYMENTS (In millions) Pension Benefits OPEB 1 2024 $ 503 $ 107 2025 442 98 2026 433 95 2027 415 89 2028 400 86 2029-2033 1,728 380 1 OPEB benefit payments are displayed net of participant contributions. ASSUMPTIONS The discount rates used to measure plan liabilities as of the December 31 measurement date are determined individually for each plan. The discount rates are determined by matching the projected cash flows used to determine the plan liabilities to a projected yield curve of high-quality corporate bonds available at the measurement date. Discount rates for expense are calculated using the granular approach for each plan. We use company-specific base mortality tables for healthy annuitants in qualified pension plans. We use tables issued by the Society of Actuaries for non-annuitants in qualified pension plans, all nonqualified pension participants and OPEB participants. For tables issued by the Society of Actuaries, we use Pri-2012 mortality tables with adjustments for blue collar, white collar or no collar depending on the plan. Mortality is projected for all plans using Scale MP-2021 with generational projection for both years. In 2023, we switched two OPEB plans from company-specific base mortality tables to the Pri-2012 mortality tables to align with our other OPEB plans. In 2022, we switched one pension plan from the Pri-2012 mortality tables to company-specific base mortality tables. The following represents weighted-average assumptions used to determine benefit obligations: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 Discount rate 5.12 % 5.47 % 5.15 % 5.52 % Interest crediting rate 5.46 5.39 N/A N/A Compensation rate increase 3.00 3.00 3.00 3.00 The following represents weighted-average assumptions used to determine net benefit cost: Pension Benefits OPEB December 31, December 31, 2023 2022 2021 2023 2022 2021 Obligation discount rate 5.47 % 3.21 % 2.32 % 5.52 % 3.33 % 2.46 % Service cost discount rate 5.61 3.49 2.78 5.65 3.91 3.28 Interest cost discount rate 5.34 2.75 1.64 5.38 3.01 2.04 Interest crediting rate 5.46 5.39 5.35 N/A N/A N/A Expected return on plan assets 7.66 6.87 6.84 5.87 4.86 5.20 Compensation rate increase 3.00 2.74 2.54 3.00 3.00 3.00 The following represents assumed weighted-average health care cost trend rates: December 31, 2023 2022 Health care cost trend rate assumed for next year 1 5.49 % 5.44 % Ultimate health care cost trend rate 4.50 % 4.50 % Year that the ultimate rate is reached 2032 2030 1 The health care trend rate for the next year is weighted for all of our OPEB plans and factors in our Medicare Advantage Prescription Drug pricing arrangements. In 2023, we increased our assumed health care cost trend rate for self insured plans to 6.50% from 6.00% for 2024, which grades down on a linear basis to 4.50% by 2032. The health care trend rate for the Medicare Advantage Prescription Drug plans is set to match the negotiated rates through 2025 and then converts to the same trend rate as our self insured plan. In 2023, we layered in a one time increase to the healthcare trend rate for the Medicare Advantage Prescription Drug plans for 2026. These increases align with our expectation of higher health care costs due to increased popularity of specialty medication, current carrier and provider negotiations and impacts from third party funding associated with the Inflation Reduction Act. PLAN ASSETS Our investment objectives with respect to our pension and OPEB assets are to maximize investment returns within reasonable and prudent levels of risk and maintain sufficient liquidity to meet benefit obligations over the life of each plan. The asset allocations are tailored to each individual plan and are determined by analyzing each plan's duration of benefit obligations, funded status and risk profile. Our investment strategy utilizes a broad mix of equity, fixed income and alternative investments to generate returns and manage risk. Equity investments are diversified across large-cap, mid-cap and small-cap companies located in the U.S. and worldwide, with a bias towards U.S. companies. Fixed income investments primarily include corporate bonds and government debt securities, which are generally customized based on a plan's obligation duration. To enhance our diversification, we also invest in hedge funds, private equity, structured credit and real estate. We review investment performance, asset allocations and policy compliance on a quarterly basis. In the fourth quarter of 2022, we increased our fixed income allocation for one of our more mature pension plans, which totaled $1.2 billion on December 31, 2022. In the fourth quarter of 2022, we also transitioned $2.9 billion of pension and OPEB assets to be managed by an external investment advisor in a delegated manner, which resulted in a shift to treasury based hedging, a higher alternative investment allocation and reduction to equity risk exposure. These changes resulted in a shift in underlying investments and increased our weighted-average expected return on plan assets in 2023 compared to 2022. The expected return on plan assets are calculated on a plan-by-plan basis and take into account each plan's strategic asset allocation. The calculation of rates by asset class are based primarily on our future expected returns and take into consideration the duration of the cash flows, active management and fees. Assets for OPEB plans include VEBA trusts pursuant to bargaining agreements that are available to fund retired employees’ life insurance obligations and medical benefits. The following table reflects the actual asset allocations for pension and VEBA assets as of December 31, 2023 and 2022, as well as the 2024 weighted average target asset allocations: Pension Assets VEBA Assets Asset Category 2024 Actual Asset Allocation at December 31, 2024 Actual Asset Allocation at December 31, 2023 2022 2023 2022 Equity securities 33.8 % 32.1 % 36.1 % 16.6 % 18.4 % 22.0 % Fixed income 41.1 38.8 40.9 78.5 74.5 67.4 Hedge funds 9.4 9.4 2.7 1.4 1.5 1.9 Private equity 3.3 3.4 3.3 — — — Structured credit 2.4 5.1 6.9 0.2 0.9 1.2 Real estate 10.0 11.2 8.2 3.3 4.7 1.7 Absolute return fixed income — — 1.9 — — 5.8 Total 100.0 % 100.0 % 100.0 % 100.0 % 100.0 % 100.0 % FAIR VALUE MEASUREMENTS Investments classified as Level 1 primarily include equity investments and fixed income mutual funds that are based on observable quoted market prices on an active exchange. Fixed income investments classified as Level 2 include U.S. Treasury STRIPS which are priced daily through a bond pricing vendor as well as corporate bonds, mortgage-backed securities and non-US bonds which have valuations based on their bid-ask spreads or quoted prices of securities with similar characteristics. Certain investments in hedge funds, private equity, structured credit and real estate are classified as Level 3 due to the absence of quoted market prices and inherent lack of liquidity. These investments are generally valued at estimated fair value based on financial inputs from our investment advisors, investment managers or third party appraisers. Certain Level 3 investments may be lagged up to three months if there are no financial inputs available. Investment commitments are made in private equity funds and capital calls are made over the life of the funds to fund the commitments. As of December 31, 2023, remaining commitments for our private equity investments total $70 million for our pension and OPEB plans. Committed amounts are funded from plan assets when capital calls are made. As a practical expedient, in accordance with ASC 820-10, certain investments that are measured at fair value using the NAV per share have not been classified in the fair value hierarchy below. NAV is based on the value of the underlying assets owned by the fund, minus its liabilities, and then divided by its number of shares outstanding. The fair value of our pension assets by asset category is as follows: (In millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs Significant Investments Measured at Net Asset Value Total Asset Category 2023 2022 2023 2022 2023 2022 2023 2022 2023 2022 Equity securities: U.S. equities $ 809 $ 564 $ — $ — $ — $ — $ — $ 569 $ 809 $ 1,133 Global equities 502 328 — — — — 65 106 567 434 Fixed income: U.S. government securities 1 22 87 657 380 — — 142 63 821 530 U.S. corporate bonds 587 574 — 266 — — 94 373 681 1,213 Non U.S. and other bonds — — — 32 — — 160 — 160 32 Hedge funds — — — — 118 115 285 — 403 115 Private equity — — — — 146 143 — — 146 143 Structured credit — — — — 220 298 — — 220 298 Real estate — — — — 286 356 189 — 475 356 Absolute return fixed income — — — — — — — 84 — 84 Total $ 1,920 $ 1,553 $ 657 $ 678 $ 770 $ 912 $ 935 $ 1,195 $ 4,282 $ 4,338 1 Includes cash equivalents. The fair value of our VEBA assets by asset category is as follows: (In millions) Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Investments Measured at Net Asset Value Total Asset Category 2023 2022 2023 2022 2023 2022 2023 2022 2023 2022 Equity securities: U.S. equities $ 102 $ 24 $ — $ — $ — $ — $ — $ 89 $ 102 $ 113 Global equities 3 5 — — — — 30 42 33 47 Fixed income: U.S. government securities 1 119 149 27 79 — — 47 — 193 228 U.S. corporate bonds 214 146 94 117 — — 49 — 357 263 Non U.S. and other bonds 3 — — — — — — — 3 — Hedge funds — — — — 10 14 — — 10 14 Private equity — — — — — — — — — — Structured credit — — — — 7 9 — — 7 9 Real estate — — — — 10 12 24 — 34 12 Absolute return fixed income — — — — — — — 42 — 42 Total $ 441 $ 324 $ 121 $ 196 $ 27 $ 35 $ 150 $ 173 $ 739 $ 728 1 Includes cash equivalents. The following represents the fair value measurements of changes in plan assets using significant unobservable inputs (Level 3): Pension Assets VEBA Assets (In millions) 2023 2022 2023 2022 Beginning balance — January 1 $ 912 $ 904 $ 35 $ 42 Actual return on plan assets: Relating to assets still held at the reporting date (16) (6) 2 1 Relating to assets sold during the period 10 15 1 1 Purchases 24 28 — — Sales (160) (29) (11) (9) Ending balance — December 31 $ 770 $ 912 $ 27 $ 35 DEFINED CONTRIBUTION PLANS Most employees are eligible to participate in various defined contribution plans. Certain of these plans have features with matching contributions or other Company contributions based on our financial results. Company contributions to these plans are expensed as incurred. Total expense from these plans was $59 million, $52 million and $55 million in 2023, 2022 and 2021, respectively. MULTlEMPLOYER PLANS We contribute to multiemployer pension plans according to collective bargaining agreements that cover certain union-represented employees. The risks of participating in these multiemployer plans are different from the risks of participating in single-employer pension plans in the following respects: • Assets contributed to a multiemployer plan by one employer may be used to provide benefits to employees of other participating employers. • If a participating employer stops contributing to a multiemployer plan, the unfunded obligations of the plan may be borne by the remaining participating employers. • If the multiemployer plan becomes significantly underfunded or is unable to pay its benefits, we may be required to contribute additional amounts in excess of the rate required by the collective bargaining agreements. • If we choose to stop participating in a multiemployer plan, we may be required to pay that plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability. Information with respect to multiemployer plans in which we participate follows: Pension Fund EIN/Pension Plan Number Pension Protection Act Zone Status 1 FIP/RP Status Pending/Implemented 2 Contributions Surcharge Imposed 3 Expiration Date of Collective Bargaining Agreement 4 2023 2022 2023 2022 2021 Steelworkers Pension Trust 23-6648508/499 Green Green No $ 119 $ 93 $ 88 No 4/1/2025 to 9/1/2026 IAM National Pension Fund’s National Pension Plan 51-6031295/002 Red Red Yes 23 22 16 Yes 5/31/2025 to 5/15/2027 Other Plans 5 1 — — Total $ 143 $ 115 $ 104 1 The most recent Pension Protection Act zone status available in 2023 and 2022 is for each plan's year-end at December 31, 2022 and 2021. The plan's actuary certifies the zone status. Generally, plans in the red zone are less than 65% funded, plans in the yellow zone are between 65% and 80% funded, and plans in the green zone are at least 80% funded. The IAM National Pension Fund's National Pension Plan voluntarily elected to place itself in the "Red Zone" in April 2019 and has implemented a rehabilitation plan to address its underfunded status. Additional contributions will be required as part of the rehabilitation plan until the plan exits the "Red Zone". 2 The "FIP/RP Status Pending/Implemented" column indicates plans for which a financial improvement plan or a rehabilitation plan is either pending or has been implemented, as defined by ERISA. 3 The surcharge represents an additional required contribution due as a result of the critical funding status of the plan. 4 We are a party to six collective bargaining agreements that require contributions to the Steelworkers Pension Trust and three collective bargaining agreements that require contributions to the IAM National Pension Fund's National Pension Plan. 5 Plans that are not individually significant to our Company are presented in aggregate. With the ratification of the 2022 USW labor agreements, we increased our contribution rate to the Steelworkers Pension Trust by $0.50 to $4.00 per eligible hour. The increase was effective November 1, 2022. We are one of the largest contributors to the Steelworkers Pension Trust. Our contributions exceeded 5% of total combined contributions in 2023 and 2022. As of January 1, 2023 (the last date for which we have information), the Steelworkers Pension Trust had a total actuarial liability of $6,378 million and assets with a market value of $5,827 million, for a funded ratio of about 91%.

STOCK COMPENSATION PLANS

STOCK COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Stock Compensation Plans	NOTE 10 - STOCK COMPENSATION PLANS At December 31, 2023, we had outstanding awards under three share-based compensation plans: the 2021 Equity Plan, the A&R 2015 Equity Plan and the 2012 Amended Equity Plan. As of December 31, 2023, there were 23.0 million remaining shares available for grant under the 2021 Equity Plan. No additional grants were issued from the 2012 Amended Equity Plan or the A&R 2015 Equity Plan after the date of approval of the 2021 Equity Plan; however, all awards previously granted under the predecessor plans will continue in accordance with the terms of the outstanding awards. Upon vesting of share-based compensation awards, we issue shares from treasury shares before issuing new shares. Forfeitures are recognized when they occur. STOCK-BASED COMPENSATION EXPENSE The following table summarizes the total compensation expense recognized for stock-based compensation awards: Year Ended December 31, (In millions, except per share amounts) 2023 2022 2021 Cost of goods sold $ (9) $ (5) $ (2) Selling, general and administrative expenses (32) (23) (16) Stock based compensation expense (41) (28) (18) Income tax benefit 10 7 4 Stock based compensation expense, net of tax $ (31) $ (21) $ (14) Decrease in basic earnings per common share $ (0.06) $ (0.04) $ (0.03) Decrease in diluted earnings per common share $ (0.06) $ (0.04) $ (0.03) The total compensation cost related to outstanding awards not yet recognized is $53 million at December 31, 2023. This expense is expected to be recognized over the remaining weighted-average period of 1.7 years. PERFORMANCE SHARES The following table summarizes the performance award activity: 2023 2022 2021 (Shares in millions) Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Outstanding at beginning of year 2.7 $ 18.53 2.4 $ 14.04 2.5 $ 10.34 Granted 1.1 31.88 1.0 28.46 0.7 25.12 Distributed (1.8) 6.50 (1.1) 17.04 (1.3) 11.74 Performance adjustment 0.7 6.43 0.5 17.84 0.6 11.93 Forfeited/canceled (0.2) 28.65 (0.1) 23.74 (0.1) 11.27 Outstanding at end of year 2.5 $ 29.09 2.7 $ 18.53 2.4 $ 14.04 The outstanding performance shares vest over a period of three years and are intended to be paid out in common shares. Performance is measured on the basis of relative TSR for the period and measured against the constituents of the S&P Metals and Mining ETF Index. The number of shares actually earned at the end of the three-year period will vary, based on performance, from 0% to 200% of the number of performance shares granted. We value our performance shares using a Monte Carlo simulation on the grant date. A correlation matrix of historical and projected stock prices was developed for both the Company and its predetermined peer group of metals and mining companies. The fair value assumes that the performance objective will be achieved. The expected term of the grant represents the time from the grant date to the end of the service period. We estimate the volatility of our common shares and that of the peer group of metals and mining companies using daily price intervals for all companies. The risk-free interest rate is the rate at the grant date on zero-coupon government bonds, with a term commensurate with the remaining performance period. RESTRICTED STOCK UNITS The following table summarizes the restricted stock units activity: 2023 2022 2021 (Shares in millions) Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Outstanding at beginning of year 2.4 $ 13.66 2.1 $ 10.31 2.1 $ 7.12 Granted 1.2 19.30 1.0 19.41 0.7 17.45 Distributed (0.9) 5.99 (0.6) 10.47 (0.6) 7.31 Forfeited/canceled (0.2) 19.84 (0.1) 17.82 (0.1) 9.50 Outstanding at end of year 2.5 $ 18.87 2.4 $ 13.66 2.1 $ 10.31 We value our restricted stock units using the closing price of our common shares on the grant date. All of the outstanding restricted stock units are subject to continued employment, are retention based, and are payable in common shares or cash in certain circumstances at a time determined by the Compensation Committee at its discretion. Most restricted stock units were granted under three-year cliff vesting terms. STOCK OPTIONS The following table summarizes the stock option activity: 2023 2022 2021 (Shares in millions) Number of Shares Weighted Average Exercise Price Number of Shares Weighted Average Exercise Price Number of Shares Weighted Average Exercise Price Outstanding at beginning of year 0.6 $ 10.39 1.0 $ 12.75 2.5 $ 11.60 Exercised (0.1) 10.22 (0.3) 16.55 (1.5) 10.36 Forfeited/canceled — 21.05 (0.1) 22.78 — 36.48 Outstanding at end of year 0.5 $ 9.59 0.6 $ 10.39 1.0 $ 12.75 Exercisable at end of year 0.5 $ 9.59 0.6 $ 10.52 0.9 $ 13.35 Stock options granted to date generally vest over a period from one The fair value of stock options is estimated on the date of grant using a Black-Scholes model using the grant date price of our common shares, the option exercise price, the option’s expected term, the volatility of our common shares, the risk-free interest rate and the dividend yield over the option’s expected term. NONEMPLOYEE DIRECTORS Our nonemployee directors are entitled to receive restricted share awards under the Directors’ Plan. For 2023, 2022 and 2021, nonemployee directors were granted a specified number of restricted shares, with a value equal to $140,000, $140,000 and $120,000, respectively. The number of shares is based on the closing price of our common shares on the date of the Annual Meeting. The restricted share awards issued under the Directors' Plan generally vest 12 months from the grant date. The awards are subject to any deferral election and the terms of the Directors’ Plan and an award agreement.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 11 - INCOME TAXES Income from continuing operations before income taxes includes the following components: Year Ended December 31, (In millions) 2023 2022 2021 United States $ 600 $ 1,803 $ 3,827 Foreign (3) (7) (24) Total $ 597 $ 1,796 $ 3,803 The components of the income tax expense from continuing operations consist of the following: Year Ended December 31, (In millions) 2023 2022 2021 Current provision: United States federal $ 4 $ 201 $ 14 United States state & local 26 131 55 Foreign 4 1 — 34 333 69 Deferred provision (benefit): United States federal 97 117 683 United States state & local 7 (22) 31 Foreign 10 (5) (10) Total income tax expense from continuing operations $ 148 $ 423 $ 773 Reconciliation of our income tax attributable to continuing operations computed at the U.S. federal statutory rate is as follows: (In millions) 2023 2022 2021 Tax at U.S. statutory rate $ 125 21 % $ 377 21 % $ 799 21 % Increase (decrease) due to: Percentage depletion in excess of cost depletion (32) (5) (49) (3) (99) (3) Valuation allowance 14 2 — — — — Unrecognized tax benefits 7 1 2 — 9 — State taxes, net 28 5 71 4 86 2 Federal & state provision to return (20) (3) 27 1 (2) — Income not subject to tax (11) (2) (9) — (9) — Goodwill impairment 26 4 — — — — Other items, net 11 2 4 — (11) — Provision for income tax expense and effective income tax rate including discrete items $ 148 25 % $ 423 23 % $ 773 20 % The decreases in income tax expense in 2023, as compared to 2022, as well as 2022 compared to 2021 are predominately related to the decrease in the pre-tax book income year-over-year. The components of income taxes for other than continuing operations consisted of the following: (In millions) 2023 2022 2021 Other comprehensive income (loss): Pension and OPEB $ 10 $ (425) $ (206) Derivative financial instruments 47 26 (21) Total $ 57 $ (399) $ (227) Significant components of our deferred tax assets and liabilities are as follows: (In millions) 2023 2022 Deferred tax assets: Operating loss and other carryforwards $ 390 $ 389 Pension and OPEB liabilities 155 244 Environmental 67 96 Product inventories 92 54 State and local 9 14 Lease liabilities 79 62 Other liabilities 180 135 Total deferred tax assets before valuation allowance 972 994 Deferred tax asset valuation allowance (396) (390) Net deferred tax assets 576 604 Deferred tax liabilities: Investment in ventures (192) (195) Lease assets (79) (38) Property, plant and equipment and mineral rights (837) (827) Other assets (103) (122) Total deferred tax liabilities (1,211) (1,182) Net deferred tax assets (liabilities) $ (635) $ (578) We had gross domestic (including states) and foreign NOLs of $1,704 million and $1,452 million, respectively, at December 31, 2023. We had gross domestic (including states) and foreign NOLs of $2,278 million and $1,444 million, respectively, at December 31, 2022. The U.S. federal NOLs will begin to expire in 2034 and state NOLs begin to expire in 2024. The foreign NOLs begin to expire in 2035. For the year ended December 31, 2023, we had no gross interest expense limitation carryforwards. For the year ended December 31, 2022, we had $77 million gross interest expense limitation carryforwards. The changes in the valuation allowance are presented below: (In millions) 2023 2022 2021 Balance at beginning of year $ 390 $ 409 $ 836 Change in valuation allowance: Included in income tax expense 6 (19) (82) Decrease from acquisitions — — (345) Balance at end of year $ 396 $ 390 $ 409 At December 31, 2023 and 2022, we have a valuation allowance recorded of $356 million and $342 million, respectively, related to foreign deferred tax assets, and an additional $40 million and $48 million, respectively, against certain state NOLs, which are expected to expire before utilization. During 2023, we recorded a $14 million valuation allowance against a portion of our Canadian deferred tax assets due to losses in recent years. We intend to maintain a valuation allowance against these deferred tax assets, unless and until sufficient positive evidence exists to support the realization of such assets. During 2021, we recorded a decrease to the valuation allowance of $345 million related to the election filed with our 2020 federal tax return to waive the pre-acquisition NOLs that are limited under Section 382 of the IRC. An offsetting decrease was recorded in the NOL deferred tax asset in the same period. Our losses in Luxembourg in recent periods represent sufficient negative evidence to require a full valuation allowance against the deferred tax assets in that jurisdiction. We intend to maintain a valuation allowance against the deferred tax assets related to these operating losses, unless and until sufficient positive evidence exists to support the realization of such assets. At December 31, 2023 and 2022, we had no cumulative undistributed earnings of foreign subsidiaries included in retained earnings. Accordingly, no provision has been made for U.S. deferred taxes related to future repatriation of earnings. A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: (In millions) 2023 2022 2021 Unrecognized tax benefits balance as of January 1 $ 58 $ 35 $ 107 Increases for tax positions in current year 18 24 4 Decrease due to tax positions in prior year — (1) (66) Lapses in statutes of limitations — — (10) Unrecognized tax benefits balance as of December 31 $ 76 $ 58 $ 35 At December 31, 2023 and 2022, we had unrecognized tax benefits of $76 million and $58 million, respectively, included in Other non-current liabilities on the Statements of Consolidated Financial Position. If the unrecognized tax benefits were recognized, the full $76 million would impact the effective tax rate. Interest and penalties related to unrecognized tax benefits are $8 million for the year ended December 31, 2023. We do not expect that the amount of unrecognized benefits will change significantly within the next 12 months. Tax years 2016 and forward remain subject to examination for the U.S., and tax years 2018 and forward remain subject to examination for Canada.

LEASE OBLIGATIONS

LEASE OBLIGATIONS	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Lease Obligations	NOTE 12 - LEASE OBLIGATIONS Our operating leases consist primarily of leases for land, office space, rail cars and storage tanks. Our finance leases consist primarily of mining equipment and rail cars. When an implicit discount rate is not readily determinable under our leases, we use our incremental borrowing rate as the discount rate to determine the present value of the lease payments. Our incremental borrowing rate is the rate of interest that we would have to borrow on a collateralized basis over a similar term and amount in a similar economic environment to pay our lease obligations. We determine the incremental borrowing rates for our leases by adjusting the local risk-free interest rate with a credit risk premium corresponding to our credit rating. From time to time, we may enter into arrangements for the construction or purchase of an asset and then enter into a financing arrangement to lease the asset. We recognize leased assets and liabilities under these arrangements when we obtain control of the asset. Lease costs are presented below: Year Ended December 31, (In millions) 2023 2022 Operating leases $ 59 $ 64 Finance leases: Amortization of right-of-use assets 92 103 Interest on lease liabilities 11 8 Short-term leases 171 160 Total $ 333 $ 335 Lease terms and discount rates are shown below: December 31, (In millions) 2023 Weighted average lease term (in years): Operating leases 8 Finance leases 7 Weighted average discount rate: Operating leases 8 % Finance leases 6 % Other information related to leases was as follows: Year Ended December 31, (In millions) 2023 2022 2021 Cash paid for amounts included in measurement of lease liabilities: Operating leases within cash flows from operating activities $ 57 $ 62 $ 70 Finance leases within cash flows from operating activities 11 8 9 Finance leases within cash flows from financing activities 92 96 94 Right-of-use assets obtained in exchange for new finance lease liabilities 93 55 50 Future minimum lease payments under noncancellable finance and operating leases as of December 31, 2023 were as follows: (In millions) Finance Leases Operating Leases 2024 $ 53 $ 56 2025 49 49 2026 39 42 2027 27 38 2028 25 29 Thereafter 74 117 Total future minimum lease payments 267 331 Less: imputed interest 52 93 Total lease payments 215 238 Less: current portion of lease liabilities 49 41 Long-term lease liabilities $ 166 $ 197 The current and long-term portions of our finance and operating lease liabilities are included in Other current liabilities and Other non-current liabilities

ASSET RETIREMENT OBLIGATIONS

ASSET RETIREMENT OBLIGATIONS	12 Months Ended
	Dec. 31, 2023
Environmental Remediation Obligations [Abstract]
Asset Retirement Obligations	NOTE 13 - ASSET RETIREMENT OBLIGATIONS The accrued closure obligation provides for contractual and legal obligations related to our indefinitely idled and closed operations and for the eventual closure of our active operations. The closure date for each of our active mine sites was determined based on the exhaustion date of the remaining mineral reserves, and the amortization of the related asset and accretion of the liability is recognized over the estimated mine lives. The closure date and expected timing of the capital requirements to meet our obligations for our indefinitely idled or closed mines is determined based on the unique circumstances of each property. For indefinitely idled or closed mines, the accretion of the liability is recognized over the anticipated timing of remediation. Asset retirement obligations at our steelmaking operations primarily include the closure and post-closure care for on-site landfills and other waste containment facilities. Asset retirement obligations have been recorded at present values using settlement dates based on when we expect these facilities to reach capacity and close. We performed a detailed assessment of our asset retirement obligations related to our active mining operations most recently in 2023 in accordance with our accounting policy, which requires us to perform an in-depth evaluation of the liability every three years in addition to routine annual assessments. In 2023, we employed third-party specialists to assist in the evaluation. The following is a summary of our asset retirement obligations: December 31, (In millions) 2023 2022 Asset retirement obligations 1 $ 459 $ 520 Less: current portion 15 21 Long-term asset retirement obligations $ 444 $ 499 1 Includes $259 million and $277 million related to our active operations as of December 31, 2023 and 2022, respectively. The following is a roll-forward of our asset retirement obligation: (In millions) 2023 2022 Asset retirement obligation as of January 1 $ 520 $ 449 Decrease from sale of business (76) — Reclassification from environmental obligations — 63 Accretion expense 26 26 Remediation payments (21) (40) Revision in estimated cash flows 10 22 Asset retirement obligation as of December 31 $ 459 $ 520 During 2023, we entered into a membership interest purchase agreement for the sale of the legal entities owning, among other things, our closed coal mines in Pennsylvania, resulting in a decrease to our asset retirement obligation.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	NOTE 14 - FAIR VALUE OF FINANCIAL INSTRUMENTS The carrying values of certain financial instruments (e.g. Accounts receivable, net , Accounts payable and Other current liabilities ) approximate fair value and, therefore, have been excluded from the table below. See NOTE 15 - DERIVATIVE INSTRUMENTS AND HEDGING for information on our derivative instruments, which are accounted for at fair value on a recurring basis. A summary of the carrying value and fair value of other financial instruments were as follows: December 31, 2023 December 31, 2022 (In millions) Classification Carrying Fair Value Carrying Fair Value Senior notes Level 1 $ 3,137 $ 3,118 $ 2,385 $ 2,311 ABL Facility - outstanding balance Level 2 — — 1,864 1,864 Total $ 3,137 $ 3,118 $ 4,249 $ 4,175 The valuation of financial assets classified in Level 2 was determined using a market approach based upon quoted prices for similar assets in active markets or other inputs that were observable.

DERIVATIVE INSTRUMENTS AND HEDG

DERIVATIVE INSTRUMENTS AND HEDGING	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging	NOTE 15 - DERIVATIVE INSTRUMENTS AND HEDGING We are exposed to fluctuations in market prices of raw materials and energy sources. We may use cash-settled commodity swaps to hedge the market risk associated with the purchase of certain of our raw materials and energy requirements. Our hedging strategy is to reduce the effect on earnings from the price volatility of these various commodity exposures, including timing differences between when we incur raw material commodity costs and when we receive sales surcharges from our customers based on those raw materials. Independent of any hedging activities, price changes in any of these commodity markets could negatively affect operating costs. Our commodity contracts are designated as cash flow hedges for accounting purposes, and we record the gains and losses for the derivatives in Accumulated other comprehensive income until we reclassify them into Cost of goods sold when we recognize the associated underlying operating costs. Refer to NOTE 17 - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) for further information. Our commodity contracts are classified as Level 2 as values were determined using a market approach based upon quoted prices for similar assets in active markets or other inputs that were observable. The following table presents the notional amount of our outstanding hedge contracts: Notional Amount December 31, Commodity Contracts Unit of Measure Maturity Dates 2023 2022 Natural Gas MMBtu January 2024 - August 2026 168,590,000 127,790,000 Electricity Megawatt hours January 2024 - October 2026 3,501,898 432,043 At December 31, 2023, we expect to reclassify $155 million of net losses related to our hedge contracts from Accumulated other comprehensive income into Cost of goods sold during the next 12 months. The following table presents the fair value of our cash flow hedges and the classification on the Statements of Consolidated Financial Position: December 31, Balance Sheet Location (In millions) 2023 2022 Other current assets $ — $ 15 Other non-current assets 1 30 Other current liabilities (105) (87) Other non-current liabilities (52) (10)

CAPITAL STOCK

CAPITAL STOCK	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Capital Stock	NOTE 16 - CAPITAL STOCK SHARE REPURCHASE PROGRAM On February 10, 2022, our Board of Directors authorized a program to repurchase outstanding common shares in the open market or in privately negotiated transactions, which may include purchases pursuant to Rule 10b5-1 plans or accelerated share repurchases, up to a maximum of $1 billion. We are not obligated to make any purchases and the program may be suspended or discontinued at any time. The share repurchase program does not have a specific expiration date. For the years ended December 31, 2023 and 2022, we repurchased 10.4 million and 12.5 million common shares, respectively, at a cost of $152 million and $240 million in the aggregate, respectively. The cost of our share repurchases excludes the excise tax due under the Inflation Reduction Act. As of December 31, 2023, there was $608 million remaining under the authorization. 1.500% 2025 CONVERTIBLE SENIOR NOTES REDEMPTION On December 1, 2021, we issued a notice of redemption for all $294 million in aggregate principal amount outstanding of our 1.500% 2025 Convertible Senior Notes. Our 1.500% 2025 Convertible Senior Notes were redeemed on January 18, 2022, through a combination settlement, with the aggregate principal amount of $294 million paid in cash, and 24 million common shares, with a fair value of $499 million, delivered to noteholders in settlement of the premium due per the terms of the indenture, plus cash in respect of the accrued and unpaid interest on the 1.500% 2025 Convertible Senior Notes to, but not including, the redemption date per the terms of the indenture. UNDERWRITTEN PUBLIC OFFERING On February 11, 2021, we sold 20 million of our common shares and 40 million common shares were sold by an affiliate of ArcelorMittal in an underwritten public offering. In each case, shares were sold at a price per share of $16.12. Prior to this sale, ArcelorMittal held approximately 78 million of our common shares, which were issued as a part of the consideration in connection with the AM USA Transaction. We did not receive any proceeds from the sale of the 40 million common shares sold on behalf of ArcelorMittal. We used the net proceeds from the offering, plus cash on hand, to redeem $322 million aggregate principal amount of our outstanding 9.875% 2025 Senior Secured Notes. SERIES B PARTICIPATING REDEEMABLE PREFERRED STOCK REDEMPTION We had 583,273 shares of our Series B Participating Redeemable Preferred Stock issued and outstanding as of December 31, 2020. During the third quarter of 2021, we redeemed all 583,273 shares of our Series B Participating Redeemable Preferred Stock at a redemption price of $1.3 billion using borrowings under our ABL Facility. AMENDMENT TO ARTICLES OF INCORPORATION On April 29, 2021, we filed a Certificate of Amendment to our Fourth Amended Articles of Incorporation, as amended, to increase the total number of authorized common shares from 600,000,000 to 1,200,000,000. PREFERRED STOCK We have 3,000,000 shares of Serial Preferred Stock, Class A, without par value, authorized, and 4,000,000 shares of Serial Preferred Stock, Class B, without par value, authorized; no preferred shares were issued or outstanding as of December 31, 2023.

ACCUMULATED OTHER COMPREHENSIVE

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	NOTE 17 - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) The components of Accumulated other comprehensive income within Cliffs shareholders’ equity and related tax effects allocated to each are shown below: December 31, (In millions) 2023 2022 2021 Foreign Currency Translation Beginning balance $ (1) $ 1 $ 3 Other comprehensive income (loss) before reclassifications 1 (2) (2) Ending balance $ — $ (1) $ 1 Derivative Instruments Beginning balance $ (16) $ 68 $ (1) Other comprehensive income (loss) before reclassifications (345) 146 151 Income tax 81 (33) (34) Other comprehensive income (loss) before reclassifications, net of tax (264) 113 117 Losses (gains) reclassified from AOCI to net income 1 144 (256) (61) Income tax expense (benefit) 2 (34) 59 13 Net losses (gains) reclassified from AOCI to net income 110 (197) (48) Ending balance $ (170) $ (16) $ 68 Pension and OPEB Beginning balance $ 1,847 $ 549 $ (135) Other comprehensive income before reclassifications 4 115 1,759 878 Income tax (39) (434) (203) Other comprehensive income before reclassifications, net of tax 76 1,325 675 Losses (gains) reclassified from AOCI to net income 3 (145) (36) 12 Income tax expense (benefit) 2 49 9 (3) Net losses (gains) reclassified from AOCI to net income (96) (27) 9 Ending balance $ 1,827 $ 1,847 $ 549 Total AOCI Ending Balance $ 1,657 $ 1,830 $ 618 1 Amounts recognized in Cost of goods sold in the Statements of Consolidated Operations. 2 Amounts recognized in Income tax expense in the Statements of Consolidated Operations. 3 Amounts recognized in Net periodic benefit credits other than service cost component in the Statements of Consolidated Operations. 4 Refer to NOTE 9 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	NOTE 18 - VARIABLE INTEREST ENTITIES SUNCOKE MIDDLETOWN We purchase all the coke and electrical power generated from SunCoke Middletown’s plant under long-term supply agreements and have committed to purchase all the expected production from the facility through 2032. We consolidate SunCoke Middletown as a VIE because we are the primary beneficiary despite having no ownership interest in SunCoke Middletown. SunCoke Middletown had income before income taxes of $52 million and $47 million for the years ended December 31, 2023 and 2022, respectively, which was included in our consolidated Income from continuing operations before income taxes . Additionally, SunCoke Middletown had cash used for capital expenditures of $25 million for the year ended December 31, 2023, compared to $12 million for the year ended December 31, 2022, that are included in our consolidated Purchase of property, plant and equipment on the Statements of Consolidated Cash Flows. The assets of the consolidated VIE can only be used to settle the obligations of the consolidated VIE and not obligations of the Company. The creditors of SunCoke Middletown do not have recourse to the assets or general credit of the Company to satisfy liabilities of the VIE. The Statements of Consolidated Financial Position includes the following amounts for SunCoke Middletown: December 31, (In millions) 2023 2022 Inventories $ 29 $ 28 Property, plant and equipment, net 288 288 Accounts payable (26) (19) Other assets (liabilities), net (39) (27) Noncontrolling interests (252) (270)

EARNINGS PER SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Earnings Per Share	NOTE 19 - EARNINGS PER SHARE The following table summarizes the computation of basic and diluted EPS: Year Ended December 31, (In millions, except per share amounts) 2023 2022 2021 Income from continuing operations $ 449 $ 1,373 $ 3,030 Income from continuing operations attributable to noncontrolling interest (51) (41) (45) Net income from continuing operations attributable to Cliffs shareholders 398 1,332 2,985 Income from discontinued operations, net of tax 1 3 3 Net income attributable to Cliffs shareholders $ 399 $ 1,335 $ 2,988 Weighted average number of shares: Basic 510 519 498 Redeemable preferred shares — — 33 Convertible senior notes 1 — 2 22 Employee stock plans 1 3 5 Diluted 511 524 558 Earnings per common share attributable to Cliffs common shareholders - basic 2 : Continuing operations $ 0.78 $ 2.57 $ 5.62 Discontinued operations — — 0.01 $ 0.78 $ 2.57 $ 5.63 Earnings per common share attributable to Cliffs common shareholders - diluted: Continuing operations $ 0.78 $ 2.55 $ 5.35 Discontinued operations — — 0.01 $ 0.78 $ 2.55 $ 5.36 1 On January 1, 2022, we adopted ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40). We utilized the modified retrospective method of adoption; using this approach, the guidance was applied to transactions outstanding as of the beginning of the fiscal year. 2 For the year ended December 31, 2021, basic earnings per share was calculated by dividing Net income attributable to Cliffs shareholders , less $187 million of earnings attributed to Series B Participating Redeemable Preferred Stock, by the weighted average number of basic common shares outstanding during the period presented. The following table summarizes the potentially dilutive shares that were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive: Year Ended December 31, (In millions) 2023 2022 2021 Employee stock plans 2 — —

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	NOTE 20 - COMMITMENTS AND CONTINGENCIES PURCHASE COMMITMENTS We purchase portions of the principal raw materials required for our steel manufacturing operations under annual and multi-year agreements, some of which have minimum quantity requirements. We also use large volumes of natural gas, electricity and industrial gases in our steel manufacturing operations. We negotiate most of our purchases of chrome, industrial gases and a portion of our electricity under multi-year agreements. Our purchases of coke are made under annual or multi-year agreements with periodic price adjustments. We typically purchase coal under annual fixed price agreements. We also purchase certain transportation services under multi-year contracts with minimum quantity requirements. Unconditional purchase obligations, including take-or-pay agreements, are as follows (in millions): 2024 2025 2026 2027 2028 Thereafter $ 2,984 $ 1,707 $ 1,133 $ 1,025 $ 929 $ 5,365 OTHER COMMERCIAL COMMITMENTS We use surety bonds and letters of credit to provide financial assurance for certain obligations and statutory requirements. As of December 31, 2023, we had $260 million of surety-backed letters of credit and surety bonds outstanding. Additionally, as of December 31, 2023, we had $56 million of outstanding letters of credit issued under our ABL Facility. CONTINGENCIES We are currently the subject of, or party to, various claims and legal proceedings incidental to our current and historical operations. These claims and legal proceedings are subject to inherent uncertainties and unfavorable rulings could occur. An unfavorable ruling could include monetary damages, additional funding requirements or an injunction. If an unfavorable ruling were to occur, there exists the possibility of a material adverse effect on our financial position and results of operations for the period in which the ruling occurs or future periods. However, based on currently available information we do not believe that any pending claims or legal proceedings will result in a material adverse effect in relation to our consolidated financial statements. ENVIRONMENTAL CONTINGENCIES Although we believe our operating practices have been consistent with prevailing industry standards, hazardous materials may have been released at operating sites or third-party sites in the past, including operating sites that we no longer own. If we reasonably can, we estimate potential remediation expenditures for those sites where future remediation efforts are probable based on identified conditions, regulatory requirements, or contractual obligations arising from the sale of a business or facility. For sites involving government required investigations, we typically make an estimate of potential remediation expenditures only after the investigation is complete and when we better understand the nature and scope of the remediation. In general, the material factors in these estimates include the costs associated with investigations, delineations, risk assessments, remedial work, governmental response and oversight, site monitoring, and preparation of reports to the appropriate environmental agencies. The following is a summary of our environmental obligations: December 31, (In millions) 2023 2022 Environmental obligations $ 134 $ 141 Less: current portion 21 23 Long-term environmental obligations $ 113 $ 118 We cannot predict the ultimate costs for each site with certainty because of the evolving nature of the investigation and remediation process. Rather, to estimate the probable costs, we must make certain assumptions. The most significant of these assumptions is for the nature and scope of the work that will be necessary to investigate and remediate a particular site and the cost of that work. Other significant assumptions include the cleanup technology that will be used, whether and to what extent any other parties will participate in paying the investigation and remediation costs, reimbursement of past response costs and future oversight costs by governmental agencies, and the reaction of the governing environmental agencies to the proposed work plans. Costs for future investigation and remediation are not discounted to their present value, unless the amount and timing of the cash disbursements are readily known. To the extent that we have been able to reasonably estimate future liabilities, we do not believe that there is a reasonable possibility that we will incur a loss or losses that exceed the amounts we accrued for the environmental matters discussed below that would, either individually or in the aggregate, have a material adverse effect on our consolidated financial condition, results of operations or cash flows. However, since we recognize amounts in the consolidated financial statements in accordance with GAAP that exclude potential losses that are not probable or that may not be currently estimable, the ultimate costs of these environmental matters may be higher than the liabilities we currently have recorded in our consolidated financial statements. Pursuant to RCRA (Resource Conservation and Recovery Act), which governs the treatment, handling and disposal of hazardous waste, the EPA and authorized state environmental agencies may conduct inspections of RCRA-regulated facilities to identify areas where there have been releases of hazardous waste or hazardous constituents into the environment and may order the facilities to take corrective action to remediate such releases. Likewise, the EPA or the states may require closure or post-closure care of residual, industrial and hazardous waste management units. Environmental regulators have the authority to inspect all of our facilities. While we cannot predict the future actions of these regulators, it is possible that they may identify conditions in future inspections of these facilities that they believe require corrective action. Pursuant to CERCLA, the EPA and state environmental authorities have conducted site investigations at some of our facilities and other third-party facilities, portions of which previously may have been used for disposal of materials that are currently regulated. The results of these investigations are still pending, and we could be directed to spend funds for remedial activities at the former disposal areas. Because of the uncertain status of these investigations, however, we cannot reasonably predict whether or when such spending might be required or its magnitude. In addition to the foregoing matters, we are or may be involved in proceedings with various regulatory authorities that may require us to pay fines, comply with more rigorous standards or other requirements or incur capital and operating expenses for environmental compliance. We believe that the ultimate disposition of any such proceedings will not have, individually or in the aggregate, a material adverse effect on our consolidated financial condition, results of operations or cash flows. TAX MATTERS The calculation of our tax liabilities involves dealing with uncertainties in the application of complex tax regulations. We recognize liabilities for anticipated tax audit issues based on our estimate of whether, and the extent to which, additional taxes will be due. If we ultimately determine that payment of these amounts is unnecessary, we reverse the liability and recognize a tax benefit during the period in which we determine that the liability is no longer necessary. We also recognize tax benefits to the extent that it is more likely than not that our positions will be sustained when challenged by the taxing authorities. To the extent we prevail in matters for which liabilities have been established, or are required to pay amounts in excess of our liabilities, our effective tax rate in a given period could be materially affected. An unfavorable tax settlement would require use of our cash and result in an increase in our effective tax rate in the year of resolution. A favorable tax settlement would be recognized as a reduction in our effective tax rate in the year of resolution. Refer to NOTE 11 - INCOME TAXES for further information. OTHER CONTINGENCIES In addition to the matters discussed above, there are various pending and potential claims against us and our subsidiaries involving product liability, personal injury, commercial, employee benefits and other matters arising in the ordinary course of business. Because of the considerable uncertainties that exist for any claim, it is difficult to reliably or accurately estimate what the amount of a loss would be if a claimant prevails. If material assumptions or factual understandings we rely on to evaluate exposure for these contingencies prove to be inaccurate or otherwise change, we may be required to record a liability for an adverse outcome. If, however, we have reasonably evaluated potential future liabilities for all of these contingencies, including those described more specifically above, it is our opinion, unless we otherwise noted, that the ultimate liability from these contingencies, individually or in the aggregate, should not have a material adverse effect on our consolidated financial position, results of operations or cash flows.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	NOTE 21 - SUBSEQUENT EVENTS We have evaluated subsequent events through the date of financial statement issuance.

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)	$ 399	$ 1,335	$ 2,988

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Dec. 31, 2023
Trading Arrangements, by Individual
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

BASIS OF PRESENTATION AND SIG_2

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Consolidation	BASIS OF CONSOLIDATION The consolidated financial statements consolidate our accounts and the accounts of our wholly owned subsidiaries, all subsidiaries in which we have a controlling interest and VIEs for which we are the primary beneficiary. All intercompany transactions and balances are eliminated upon consolidation.
Investments in Affiliates	INVESTMENTS IN AFFILIATES We have investments in several businesses accounted for using the equity method of accounting. These investments are included within our Steelmaking segment. We review an investment for impairment when circumstances indicate that a loss in value below its carrying amount is other than temporary. Our investment in affiliates of $123 million and $133 million as of December 31, 2023 and 2022, respectively, was classified in Other non-current assets.
Use of Estimates	USE OF ESTIMATES The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Our mineral reserves; future realizable cash flow; environmental, reclamation and closure obligations; valuation of business combinations, goodwill, long-lived assets, inventory, tax assets and post-employment, post-retirement and other employee benefit liabilities; reserves for contingencies and litigation require the use of various management estimates and assumptions. Actual results could differ from estimates. Management reviews its estimates on an ongoing basis. Changes in facts and circumstances may alter such estimates and affect the results of operations and financial position in future periods.
Business Combinations	BUSINESS COMBINATIONS Assets acquired and liabilities assumed in a business combination are recognized and measured based on their estimated fair values at the acquisition date, while the acquisition-related costs are expensed as incurred. Any excess of the purchase consideration when compared to the fair value of the net tangible and intangible assets acquired is recorded as goodwill. We engaged independent valuation specialists to assist with the determination of the fair value of assets acquired, liabilities assumed, noncontrolling interest, and goodwill, for the acquisitions. If the initial accounting for the business combination is incomplete by the end of the reporting period in which the acquisition occurs, an estimate will be recorded. Subsequent to the acquisition date, and not later than one year from the acquisition date, we will record any material adjustments to the initial estimate based on new information obtained that would have existed as of the date of the acquisition. Any adjustment that arises from information obtained that did not exist as of the date of the acquisition will be recorded in the period the adjustment arises.
Cash and Cash Equivalents	CASH AND CASH EQUIVALENTS Cash and cash equivalents include cash on hand and on deposit as well as all short-term securities held for the primary purpose of general liquidity. We routinely monitor and evaluate counterparty credit risk related to the financial institutions in which our short-term investment securities are held. Where right of offset exists, we report cash balances net.
Trade Accounts Receivable and Allowance for Credit Loss	TRADE ACCOUNTS RECEIVABLE AND ALLOWANCE FOR CREDIT LOSS Trade accounts receivable are recorded at the point control transfers and represent the amount of consideration we expect to receive in exchange for transferred goods and do not bear interest. We establish provisions for expected lifetime losses on accounts receivable at the time a receivable is recorded based on historical experience, customer credit quality and forecasted economic conditions. We regularly review our accounts receivable balances and the allowance for credit loss and establish or adjust the allowance as necessary using the specific identification method. We evaluate the aggregation and risk characteristics of receivable pools and develop loss rates that reflect historical collections, current forecasts of future economic conditions over the time horizon we are exposed to credit risk, and payment terms or conditions that may materially affect future forecasts.
Inventories	INVENTORIES Inventories are generally stated at the lower of cost or net realizable value using average cost, excluding depreciation and amortization. Certain iron ore inventories are stated at the lower of cost or market using the LIFO method.
Derivative Financial Instruments and Hedging Activities	DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES We are exposed to certain risks related to the ongoing operations of our business, including those caused by changes in commodity prices and energy rates. We have established policies and procedures, including the use of certain derivative instruments, to manage such risks. Derivative financial instruments are recognized as either assets or liabilities on the Statements of Consolidated Financial Position and measured at fair value. On the date a qualifying hedging instrument is executed, we designate the hedging instrument as a hedge of the variability of cash flows to be received or paid related to a forecasted transaction (cash flow hedge). We formally document all relationships between hedging instruments and hedged items, as well as our risk-management objective and strategy for undertaking various hedge transactions. This process includes linking all derivatives that are designated as cash flow hedges to specific firm commitments or forecasted transactions. We also formally assess, both at the hedge's inception and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows of the related hedged items. When it is determined that a derivative is not highly effective as a hedge, we discontinue hedge accounting prospectively and record all future changes in fair value in the period of the instrument's earnings or losses. For derivative instruments that have been designated as cash flow hedges, the changes in fair value are recorded in Accumulated other comprehensive income . Amounts recorded in Accumulated other comprehensive income are reclassified to earnings or losses in the period the underlying hedged transaction affects earnings or when the underlying hedged transaction is no longer reasonably possible of occurring. The cash flows resulting from these derivative instruments are classified in Other, net in operating activities on the Statements of Consolidated Cash Flows. For derivative instruments that have not been designated as cash flow hedges, changes in fair value are recorded in the period of the instrument's earnings or losses.
Property, Plant and Equipment	PROPERTY, PLANT AND EQUIPMENT Our properties are stated at cost less accumulated depreciation. Depreciation of plant and equipment is computed principally by the straight-line method based on estimated useful lives. Depreciation continues to be recognized when operations are idled temporarily. Depreciation and depletion are recorded over the following estimated useful lives: Asset Class Basis Life Land, land improvements and mineral rights Land and mineral rights Units of production Life of mine Land improvements Straight line 20 to 45 years Buildings Straight line 20 to 45 years Equipment Straight line/Double declining balance 3 to 45 years
Goodwill and Other Intangible Assets and Liabilities	GOODWILL Goodwill represents the excess purchase price paid over the fair value of the net assets from an acquisition. Goodwill is not amortized for financial statement purposes. Goodwill is tested on a qualitative or quantitative basis for impairment at the reporting unit level on an annual basis on October 1 and between annual tests if an event occurs or circumstances change that would more likely than not reduce the fair value of a reporting unit below its carrying value. We have an unconditional option to bypass the qualitative test for any reporting unit in any period and proceed directly to performing the quantitative test. Should our qualitative test indicate that it is more likely than not that the fair value of a reporting unit is less than its carrying value, we perform a quantitative test to determine the amount of impairment, if any, to the carrying value of the reporting unit and its associated goodwill. OTHER INTANGIBLE ASSETS AND LIABILITIES
Leases	LEASES We determine if an arrangement contains a lease at inception. We recognize right-of-use assets and lease liabilities associated with leases based on the present value of the future minimum lease payments over the lease term at the commencement date. Lease terms reflect options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Short-term leases (leases with an initial lease term of 12 months or less) are not recognized on the Statements of Consolidated Financial Position. Operating lease expense is recognized on a straight-line basis over the lease term.
Asset Impairment	ASSET IMPAIRMENT We monitor conditions that may affect the carrying value of our long-lived tangible and intangible assets when events and circumstances indicate that the carrying value of the asset groups may not be recoverable. In order to determine if assets have been impaired, assets are grouped and tested at the lowest level for which identifiable, independent cash flows are available ("asset group"). The measurement of the impairment loss to be recognized is based on the difference between the fair value and the carrying value of the asset group. Fair value can be determined using a market approach, income approach or cost approach.
Fair Value Measurements	FAIR VALUE MEASUREMENTS ASC Topic 820, Fair Value Measurements and Disclosures , establishes a three-level valuation hierarchy for classification of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. Inputs refer broadly to the assumptions that market participants would use in pricing an asset or liability. Inputs may be observable or unobservable. Observable inputs are inputs that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our own views about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. The three-tier hierarchy of inputs is summarized below: • Level 1 — Valuation is based upon quoted prices (unadjusted) for identical assets or liabilities in active markets. • Level 2 — Valuation is based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument. • Level 3 — Valuation is based upon other unobservable inputs that are significant to the fair value measurement. The classification of assets and liabilities within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement in its entirety.
Pension and Other Postretirement Plans	PENSION AND OTHER POSTRETIREMENT BENEFITS We offer defined benefit pension plans, defined contribution pension plans and OPEB plans, primarily consisting of retiree healthcare benefits as part of our total compensation and benefits programs. We recognize the funded or unfunded status of our pension and OPEB obligations on the Statements of Consolidated Financial Position based on the difference between the market value of plan assets and the actuarial present value of our retirement obligations on that date, on a plan-by-plan basis. If the plan assets exceed the pension and OPEB obligations, the amount of the surplus is recorded as an asset; if the pension and OPEB obligations exceed the plan assets, the amount of the underfunded obligations is recorded as a liability. Year-end balance sheet adjustments to pension and OPEB assets and obligations are recorded as Accumulated other comprehensive income on the Statements of Consolidated Financial Position. The actuarial estimates of the PBO (Projected benefit obligation) and APBO (Accumulated postretirement benefit obligation) incorporate various assumptions including the discount rates, the rates of increases in compensation, healthcare cost trend rates, mortality, retirement timing, employee turnover and other demographic assumptions. The discount rate is determined based on the prevailing year-end rates for high-grade corporate bonds with a duration matching the expected cash flow timing of the benefit payments from the various plans. The remaining assumptions are based on our estimates of future events by incorporating historical trends and future expectations. The amount of net periodic cost that is recorded in the Statements of Consolidated Operations consists of several components including service cost, interest cost, expected return on plan assets, and amortization of previously unrecognized amounts. Service cost represents the value of the benefits earned in the current year by the participants. Interest cost represents the cost associated with the passage of time. Certain items, such as plan amendments, gains and/or losses resulting from differences between actual and assumed results for demographic and economic factors affecting the obligations and assets of the plans, and changes in other assumptions are subject to deferred recognition for income and expense purposes. The expected return on plan assets is calculated on a plan-by-plan basis using each plan's strategic asset allocation and our expected long-term capital market return assumptions. Service costs are classified within Cost of goods sold, Selling, general and administrative expenses and Miscellaneous – net while the interest cost, expected return on assets, amortization of prior service costs/credits, net actuarial gain/loss, and other costs are classified within Net periodic benefit credits other than service cost component. Cumulative actuarial gains and losses will be amortized to expense using the corridor method, where gains and losses are recognized if they exceed 10% of the greater of the fair value of plan assets or the plans' benefit obligations. The amortization period varies by plan.
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS An asset retirement obligation is recognized when incurred if a reasonable estimate of fair value can be made, and is initially measured at fair value. The fair value of the liability is determined as the discounted value of the expected future cash flows. The asset retirement obligation is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized and amortized over the life of the related asset. Reclamation costs are adjusted periodically to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation costs. We review, on an annual basis, unless otherwise deemed necessary, the asset retirement obligation for each applicable operation in accordance with the provisions of ASC Topic 410, Asset Retirement and Environmental Obligations . We perform an in-depth evaluation of the liability every three years in addition to our routine annual assessments. Future reclamation costs for inactive operations are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at a site. Such cost estimates include, where applicable, ongoing maintenance and monitoring costs. Changes in estimates at inactive operations are reflected in Miscellaneous – net on the Statements of Consolidated Operations in the period an estimate is revised.
Environmental Remediation Costs	ENVIRONMENTAL REMEDIATION COSTS Our operating activities are subject to various laws and regulations governing protection of the environment. We conduct our operations to protect the public health and environment and believe our operations are in compliance with applicable laws and regulations in all material respects. Our environmental liabilities, including obligations for known environmental remediation exposures, have been recognized based on the estimated cost of investigation and remediation at each site. If the cost can only be estimated as a range of possible amounts with no point in the range being more likely, the minimum of the range is accrued. Future expenditures are discounted unless the amount and timing of the cash disbursements cannot be reasonably estimated. It is possible that additional environmental obligations could be incurred, the extent of which cannot be assessed. Potential insurance recoveries have not been reflected in the determination of the liabilities.
Revenue Recognition	REVENUE RECOGNITION
Repairs And Maintenance	REPAIRS AND MAINTENANCE Repairs, maintenance and replacement of components are expensed as incurred. The cost of major equipment overhauls is capitalized and depreciated over the estimated useful life, which is the period until the next scheduled overhauls. All other planned and unplanned repairs and maintenance costs are expensed when incurred.
Income Taxes	INCOME TAXES Income taxes are based on income for financial reporting purposes, calculated using tax rates by jurisdiction, and reflect a current tax liability or asset for the estimated taxes payable or recoverable on the current year tax return and expected annual changes in deferred taxes. Any interest or penalties on income tax are recognized as a component of Income tax expense . We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized within Net income in the period that includes the enactment date. We record net deferred tax assets to the extent we believe these assets will more likely than not be realized. In making such determination, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies and recent financial results of operations. Accounting for uncertainty in income taxes recognized in the financial statements requires that a tax benefit from an uncertain tax position be recognized when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on technical merits.
Foreign Currency	FOREIGN CURRENCY Our financial statements are prepared with the U.S. dollar as the reporting currency, and the functional currency of all subsidiaries is the U.S. dollar, except for our European Operations for which the functional currency is the Euro.
Earnings Per Share	EARNINGS PER SHARE We present both basic and diluted EPS amounts for continuing operations and discontinued operations. Total basic EPS amounts are calculated by dividing Net income attributable to Cliffs shareholders , less the earnings allocated to any of our outstanding Series B Participating Redeemable Preferred Stock, by the weighted average number of common shares outstanding during the period presented. Total diluted EPS amounts are calculated by dividing Net income attributable to Cliffs shareholders by the weighted average number of common shares, common share equivalents under stock plans using the treasury-stock method, common share equivalents of the Series B Participating Redeemable Preferred Stock using the if-converted method and the calculated common share equivalents in excess of the conversion rate related to our 1.500% 2025 Convertible Senior Notes using the treasury-stock method. Common share equivalents are excluded from EPS computations in the periods in which they have an anti-dilutive effect.
Variable Interest Entities	VARIABLE INTEREST ENTITIES We assess whether we have a variable interest in legal entities in which we have a financial relationship and, if so, whether or not those entities are VIEs. A VIE is an entity with insufficient equity at risk for the entity to finance its activities without additional
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS AND LEGISLATION ACCOUNTING PRONOUNCEMENTS In September 2022, the FASB issued ASU No. 2022-04, Liabilities - Supplier Finance Programs (Subtopic 405-50): Disclosure of Supplier Finance Program Obligations . This guidance requires annual and interim disclosure of the key terms of outstanding supplier finance programs and a roll-forward of the related obligations. The new standard does not affect the recognition, measurement or financial statement presentation of the supplier finance program obligations. We have adopted this standard, except for the roll-forward information, which is effective for fiscal years beginning after December 31, 2023. Refer to NOTE 2 - SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION for further information. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures . This guidance requires additional annual and interim disclosures for reportable segments. This new standard does not affect the recognition, measurement or financial statement presentation. The amendments are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures . This guidance requires additional annual and interim disclosures for income taxes. This new standard does not affect the recognition, measurement or financial statement presentation. The amendments are effective for fiscal years beginning after December 15, 2024.

BASIS OF PRESENTATION AND SIG_3

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Estimated Useful Lives	Depreciation and depletion are recorded over the following estimated useful lives: Asset Class Basis Life Land, land improvements and mineral rights Land and mineral rights Units of production Life of mine Land improvements Straight line 20 to 45 years Buildings Straight line 20 to 45 years Equipment Straight line/Double declining balance 3 to 45 years The following table indicates the carrying value of each of the major classes of our depreciable assets: December 31, (In millions) 2023 2022 Land, land improvements and mineral rights $ 1,389 $ 1,388 Buildings 946 921 Equipment 9,680 9,289 Other 302 238 Construction in progress 590 552 Total property, plant and equipment 1 12,907 12,388 Allowance for depreciation and depletion (4,012) (3,318) Property, plant and equipment, net $ 8,895 $ 9,070 1 Includes right-of-use assets related to finance leases of $306 million and $408 million as of December 31, 2023 and 2022, respectively. The net book value of the mineral and land rights are as follows: December 31, (In millions) 2023 2022 Mineral rights: Cost $ 783 $ 780 Depletion (258) (225) Net mineral rights $ 525 $ 555 Land rights $ 427 $ 434

SUPPLEMENTARY FINANCIAL STATE_2

SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2023
Disclosure Text Block [Abstract]
Roll-forward of Allowance for Credit Losses	The following is a roll-forward of our allowance for credit losses associated with Accounts receivable, net : (In millions) 2023 2022 Allowance for credit losses as of January 1 $ (4) $ (4) Increase in allowance (1) — Allowance for credit losses as of December 31 $ (5) $ (4)
Schedule of Inventories	The following table presents the detail of our Inventories on the Statements of Consolidated Financial Position: December 31, (In millions) 2023 2022 Product inventories Finished and semi-finished goods $ 2,573 $ 2,971 Raw materials 1,476 1,794 Total product inventories 4,049 4,765 Manufacturing supplies and critical spares 411 365 Inventories $ 4,460 $ 5,130
Schedule of Cash Flow, Supplemental Disclosures	A reconciliation of capital additions to cash paid for capital expenditures is as follows: Year Ended December 31, (In millions) 2023 2022 2021 Capital additions $ 785 $ 1,033 $ 857 Less: Non-cash accruals (13) 35 102 Equipment financed with seller 59 — — Right-of-use assets - finance leases 93 55 50 Cash paid for capital expenditures including deposits $ 646 $ 943 $ 705 Additionally, included within Other investing activities on the Statements of Consolidated Cash Flows are grant reimbursements related to governmental funded capital projects. For the years ended December 31, 2023, 2022 and 2021, grant reimbursements were $13 million, $27 million and $2 million, respectively. Cash payments (receipts) for interest and income taxes are as follows: Year Ended December 31, (In millions) 2023 2022 2021 Income taxes paid $ 94 $ 334 $ 166 Income tax refunds (205) (3) (16) Interest paid on debt obligations net of capitalized interest 1 256 249 299 1 Capitalized interest was $12 million, $9 million and $6 million for the years ended December 31, 2023, 2022 and 2021, respectively.
Schedule of Noncash or Part Noncash Acquisitions	Other non-cash investing and financing activities are as follows: Year Ended December 31, (In millions) 2023 2022 2021 1.500% 2025 Convertible Senior Notes redemption $ — $ 25 $ — Fair value of settlement of a pre-existing relationship as part of consideration in connection with FPT Acquisition — — (20)

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Business Combinations [Abstract]
Schedule of Fair Value of Purchase Consideration	The fair value of the total purchase consideration was determined as follows: (In millions) Cash consideration: Cash consideration pursuant to the FPT Acquisition Agreement $ 778 Cash consideration paid related to IRC Section 338(h)(10) 23 Total cash consideration 801 Fair value of settlement of a pre-existing relationship (20) Total purchase consideration $ 781
Summary of the Purchase Price Allocation to Assets Acquired and Liabilities Assumed	The following is a summary of the purchase price allocation to assets acquired and liabilities assumed in the FPT Acquisition: (In millions) Initial Allocation of Consideration Measurement Final Allocation of Consideration as of December 31, 2022 Cash and cash equivalents $ 9 $ — $ 9 Accounts receivable, net 233 2 235 Inventories 137 (2) 135 Other current assets 4 (1) 3 Property, plant and equipment 179 12 191 Other non-current assets 74 (2) 72 Accounts payable (122) — (122) Accrued employment costs (8) — (8) Other current liabilities (9) 3 (6) Other non-current liabilities (21) — (21) Net identifiable assets acquired 476 12 488 Goodwill 279 14 293 Total net assets acquired $ 755 $ 26 $ 781
Summary of Purchase Price Allocated to Identifiable Intangible Assets and Liabilities Acquired	The purchase price allocated to identifiable intangible assets acquired was: (In millions) Weighted Average Life (In years) Customer relationships $ 13 15 Supplier relationships 29 18 Trade names and trademarks 7 15 Total identifiable intangible assets $ 49 17
Summary of Unaudited Pro Forma Financial Information	The following table provides unaudited pro forma financial information, prepared in accordance with Topic 805, as if FPT had been acquired as of January 1, 2020: Year Ended (In millions) December 31, 2021 Revenues $ 21,701 Net income attributable to Cliffs shareholders 3,074

REVENUES (Tables)

REVENUES (Tables)	12 Months Ended
	Dec. 31, 2023
Revenue from Contract with Customer [Abstract]
Summary of Revenue by market and product line	The following table represents our Revenues by market: Year Ended December 31, (In millions) 2023 2022 2021 Steelmaking: Automotive $ 7,440 $ 6,661 $ 4,726 Infrastructure and manufacturing 5,612 5,869 5,380 Distributors and converters 5,330 6,388 7,671 Steel producers 2,949 3,465 2,124 Total Steelmaking 21,331 22,383 19,901 Other Businesses: Automotive 545 478 426 Infrastructure and manufacturing 38 52 47 Distributors and converters 82 76 70 Total Other Businesses 665 606 543 Total revenues $ 21,996 $ 22,989 $ 20,444 The following table represents our Revenues by product line: Year Ended December 31, (In millions) 2023 2022 2021 Steelmaking: Hot-rolled steel $ 4,864 $ 4,529 $ 5,615 Cold-rolled steel 2,658 3,193 3,186 Coated steel 6,661 6,905 5,864 Stainless and electrical steel 2,281 2,284 1,622 Plate 1,444 1,651 1,316 Slab and other steel products 1,329 1,492 1,247 Other 2,094 2,329 1,051 Total Steelmaking 21,331 22,383 19,901 Other Businesses: Other 665 606 543 Total revenues $ 21,996 $ 22,989 $ 20,444

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	12 Months Ended
	Dec. 31, 2023
Segment Reporting [Abstract]
Summary of Results by Segment	Our results by segment are as follows: Year Ended December 31, (In millions) 2023 2022 2021 Revenues: Steelmaking $ 21,331 $ 22,383 $ 19,901 Other Businesses 665 606 543 Total revenues $ 21,996 $ 22,989 $ 20,444 Adjusted EBITDA: Steelmaking $ 1,873 $ 3,089 $ 5,280 Other Businesses 43 69 9 Eliminations (5) 11 (12) Total Adjusted EBITDA $ 1,911 $ 3,169 $ 5,277 The following table provides a reconciliation of our consolidated Net income to total Adjusted EBITDA: Year Ended December 31, (In millions) 2023 2022 2021 Net income $ 450 $ 1,376 $ 3,033 Less: Interest expense, net (289) (276) (337) Income tax expense (148) (423) (773) Depreciation, depletion and amortization (973) (1,034) (897) 1,860 3,109 5,040 Less: EBITDA from noncontrolling interests 1 83 74 75 Acquisition-related expenses and adjustments (12) (1) (197) Goodwill impairment (125) — — Non-cash gain on sale of business 28 — — Loss on extinguishment of debt — (75) (88) Asset impairment — (29) — Other, net (25) (29) (27) Total Adjusted EBITDA $ 1,911 $ 3,169 $ 5,277 1 EBITDA of noncontrolling interests includes the following: Net income attributable to noncontrolling interests $ 51 $ 41 $ 45 Depreciation, depletion and amortization 32 33 30 EBITDA of noncontrolling interests $ 83 $ 74 $ 75 The following table summarizes our depreciation, depletion and amortization and capital additions by segment: Year Ended December 31, (In millions) 2023 2022 2021 Depreciation, depletion and amortization: Steelmaking $ (938) $ (994) $ (860) Other Businesses (35) (40) (37) Total depreciation, depletion and amortization $ (973) $ (1,034) $ (897) Capital additions 1: Steelmaking $ 778 $ 997 $ 787 Other Businesses 3 30 52 Corporate 4 6 18 Total capital additions $ 785 $ 1,033 $ 857 1 Refer to NOTE 2 - SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION for additional information.
Summary of Assets by Segment	The following summarizes our assets by segment: December 31, (In millions) 2023 2022 Assets: Steelmaking $ 16,880 $ 18,070 Other Businesses 657 836 Intersegment eliminations (507) (521) Total segment assets 17,030 18,385 Corporate/Eliminations 507 370 Total assets $ 17,537 $ 18,755
Summary of Amounts Relating to Geographic Location	Included in the consolidated financial statements are the following amounts relating to geographic location based on product destination: (In millions) 2023 2022 2021 Revenues: United States $ 20,000 $ 20,991 $ 18,881 Canada 1,046 963 803 Other countries 950 1,035 760 Total revenues $ 21,996 $ 22,989 $ 20,444 Property, plant and equipment, net: United States $ 8,816 $ 8,981 $ 9,092 Canada 78 88 93 Other countries 1 1 1 Total property, plant and equipment, net $ 8,895 $ 9,070 $ 9,186

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2023
Property, Plant and Equipment [Abstract]
Summary of Carrying Value of Each Major Class of Depreciable Assets	Depreciation and depletion are recorded over the following estimated useful lives: Asset Class Basis Life Land, land improvements and mineral rights Land and mineral rights Units of production Life of mine Land improvements Straight line 20 to 45 years Buildings Straight line 20 to 45 years Equipment Straight line/Double declining balance 3 to 45 years The following table indicates the carrying value of each of the major classes of our depreciable assets: December 31, (In millions) 2023 2022 Land, land improvements and mineral rights $ 1,389 $ 1,388 Buildings 946 921 Equipment 9,680 9,289 Other 302 238 Construction in progress 590 552 Total property, plant and equipment 1 12,907 12,388 Allowance for depreciation and depletion (4,012) (3,318) Property, plant and equipment, net $ 8,895 $ 9,070 1 Includes right-of-use assets related to finance leases of $306 million and $408 million as of December 31, 2023 and 2022, respectively. The net book value of the mineral and land rights are as follows: December 31, (In millions) 2023 2022 Mineral rights: Cost $ 783 $ 780 Depletion (258) (225) Net mineral rights $ 525 $ 555 Land rights $ 427 $ 434

GOODWILL AND INTANGIBLE ASSET_2

GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2023
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill by Segment	The following is a summary of Goodwill by segment: December 31, (In millions) 2023 2022 Steelmaking $ 956 $ 956 Other Businesses 49 174 Total goodwill $ 1,005 $ 1,130
Summary of Intangible Assets and Liabilities	The following is a summary of our intangible assets and liabilities: December 31, 2023 December 31, 2022 (In millions) Gross Amount Accumulated Amortization Net Amount Gross Amount Accumulated Amortization Net Amount Intangible assets 1 : Customer relationships $ 90 $ (18) $ 72 $ 90 $ (13) $ 77 Developed technology 60 (14) 46 60 (10) 50 Trade names and trademarks 18 (5) 13 18 (4) 14 Mining permits 72 (28) 44 72 (27) 45 Supplier relationships 29 (3) 26 29 (1) 28 Total intangible assets $ 269 $ (68) $ 201 $ 269 $ (55) $ 214 Intangible liabilities 2 : Above-market supply contracts $ (71) $ 24 $ (47) $ (71) $ 19 $ (52) 1 Intangible assets are classified as Other non-current assets . Amortization related to mining permits is recognized in Cost of goods sold . Amortization of all other intangible assets is recognized in Selling, general and administrative expenses . 2 Intangible liabilities are classified as Other non-current liabilities . Amortization of all intangible liabilities is recognized in Cost of goods sold .

DEBT AND CREDIT FACILITIES (Tab

DEBT AND CREDIT FACILITIES (Tables)	12 Months Ended
	Dec. 31, 2023
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	The following represents a summary of our long-term debt: (In Millions) Debt Instrument Issuer 1 Annual Effective Interest Rate December 31, 2023 December 31, 2022 Senior Secured Notes: 6.750% 2026 Senior Secured Notes Cliffs 6.990% 829 829 Senior Unsecured Notes: 7.000% 2027 Senior Notes Cliffs 9.240% 73 73 7.000% 2027 AK Senior Notes AK Steel 9.240% 56 56 5.875% 2027 Senior Notes Cliffs 6.490% 556 556 4.625% 2029 Senior Notes Cliffs 4.625% 368 368 6.750% 2030 Senior Notes Cliffs 6.750% 750 — 4.875% 2031 Senior Notes Cliffs 4.875% 325 325 6.250% 2040 Senior Notes Cliffs 6.340% 235 235 ABL Facility Cliffs 2 Variable 3 — 1,864 Total debt 3,192 4,306 Unamortized discounts and issuance costs (55) (57) Total long-term debt $ 3,137 $ 4,249 1 Unless otherwise noted, references in this column and throughout this NOTE 8 - DEBT AND CREDIT FACILITIES to "Cliffs" are to Cleveland-Cliffs Inc., and references to "AK Steel" are to AK Steel Corporation (n/k/a Cleveland-Cliffs Steel Corporation). 2 Refers to Cleveland-Cliffs Inc. as borrower under our ABL Facility. 3 Our ABL Facility annual effective interest rate was 5.60% as of December 31, 2022. The following represents a summary of our other unsecured senior notes' maturity and interest payable due dates: Debt Instrument Maturity Interest Payable 7.000% 2027 Senior Notes March 15, 2027 March 15 and September 15 5.875% 2027 Senior Notes June 1, 2027 June 1 and December 1 4.625% 2029 Senior Notes March 1, 2029 March 1 and September 1 4.875% 2031 Senior Notes March 1, 2031 March 1 and September 1 6.250% 2040 Senior Notes October 1, 2040 April 1 and October 1
Summary of Borrowing Capacity Under the ABL Facility	The following represents a summary of our borrowing capacity under the ABL Facility: December 31, (In millions) 2023 Available borrowing base on ABL Facility 1 $ 4,397 Borrowings — Letter of credit obligations 2 (56) Borrowing capacity available $ 4,341 1 As of December 31, 2023, the ABL Facility has a maximum borrowing base of $4.75 billion. The available borrowing base is determined by applying customary advance rates to eligible accounts receivable, inventory and certain mobile equipment. 2 We issued standby letters of credit with certain financial institutions in order to support business obligations, including, but not limited to, operating agreements, employee severance, environmental obligations, workers' compensation, and insurance obligations.
Summary of Debt Instrument Maturities	The following represents a summary of our debt instrument maturities based on the principal amounts outstanding at December 31, 2023 (in millions): 2024 2025 2026 2027 2028 Thereafter Total $ — $ — $ 829 $ 685 $ — $ 1,678 $ 3,192

PENSIONS AND OTHER POSTRETIRE_2

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2023
Postemployment Benefits [Abstract]
Schedule of Defined Benefit Plans Disclosures	The following tables and information provide additional disclosures: (In millions) Pension Benefits OPEB Change in benefit obligations: 2023 2022 2023 2022 Benefit obligations — beginning of year $ 4,646 $ 6,036 $ 1,233 $ 3,254 Service cost 31 45 10 35 Interest cost 235 144 64 72 Plan amendments 3 122 8 (163) Actuarial loss (gain) 116 (1,236) (158) (1,781) Benefits paid (436) (431) (163) (232) Participant contributions — — 42 47 Effect of settlement (24) (34) — — Other — — — 1 Benefit obligations — end of year $ 4,571 $ 4,646 $ 1,036 $ 1,233 Change in plan assets: Fair value of plan assets — beginning of year $ 4,338 $ 5,606 $ 728 $ 812 Actual return on plan assets 375 (809) 67 (97) Participant contributions — — 42 47 Employer contributions 29 6 65 198 Benefits paid (436) (431) (163) (232) Effect of settlement (24) (34) — — Fair value of plan assets — end of year $ 4,282 $ 4,338 $ 739 $ 728 Funded status $ (289) $ (308) $ (297) $ (505) Amounts recognized in Statements of Financial Position: Non-current assets $ 137 $ 195 $ 192 $ 161 Current liabilities 1 (18) (30) (76) (81) Non-current liabilities (408) (473) (413) (585) Total amount recognized $ (289) $ (308) $ (297) $ (505) Amounts recognized in accumulated other comprehensive loss (income): Net actuarial gain $ (304) $ (361) $ (2,033) $ (1,996) Prior service cost (credit) 106 121 (131) (156) Net amount recognized $ (198) $ (240) $ (2,164) $ (2,152) 1 Current liabilities are classified within Other current liabilities on the Statements of Consolidated Financial Position. Pension Benefits OPEB (In millions) VEBA 1 Direct Payments Total 2022 $ 6 $ 85 $ 113 $ 198 2023 29 — 65 65 2024 (Expected) 122 — 66 66 1 Pursuant to the applicable bargaining agreements, benefits can be paid from certain VEBAs that are at least 70% funded (all VEBAs were over 70% funded at December 31, 2023). Certain agreements with plans holding VEBA assets have capped healthcare costs. For the Cleveland-Cliffs Steel LLC VEBA, we are required to make contributions based on earnings, and we may withdraw money from the VEBA plan to the extent funds are available for costs in excess of the cap. VEBA withdrawals are represented net of direct payments. There will be no further contributions to the Cleveland-Cliffs Steel LLC VEBA based on earnings for the remainder of the labor agreement with the USW, which expires in September of 2026.
Components Of Net Periodic Benefit Cost	COMPONENTS OF NET PERIODIC BENEFIT COST (CREDIT) Pension Benefits OPEB (In millions) 2023 2022 2021 2023 2022 2021 Service cost $ 31 $ 45 $ 56 $ 10 $ 35 $ 51 Interest cost 235 144 103 64 72 74 Expected return on plan assets (315) (355) (359) (43) (37) (40) Amortization: Net actuarial loss (gain) 3 13 32 (145) (43) 3 Prior service costs (credits) 18 5 1 (17) (3) (2) Settlements (4) (8) (22) — — — Net periodic benefit cost (credit) $ (32) $ (156) $ (189) $ (131) $ 24 $ 86 For 2024, we estimate net periodic benefit cost (credit) as follows: (In millions) Defined benefit pension plans $ (58) OPEB plans (154) Total $ (212)
Components of Accumulated Other Comprehensive Income (Loss)	The following includes details on the significant actuarial losses (gains) impacting the benefit obligation and other components of other comprehensive loss (income): Pension Benefits OPEB (In millions) 2023 2022 2023 2022 Discount rates $ 124 $ (1,143) $ 28 $ (441) Demographic updates 1 (5) (102) (208) (7) Mortality (2) 17 (11) — Per capita healthcare costs and healthcare trend 2 — — 33 (1,333) Other (1) (8) — — Actuarial loss (gain) on benefit obligation 116 (1,236) (158) (1,781) Actual returns on assets under (over) expected (60) 1,165 (24) 134 Amortization of net actuarial gain (loss) (3) (13) 145 43 Amortization of prior service credits (costs) (18) (5) 17 3 Settlements 4 8 — — Plan amendments 3 3 122 8 (163) Total recognized in other comprehensive loss (income) $ 42 $ 41 $ (12) $ (1,764) 1 In 2023, the OPEB plans generated an actuarial gain relating to updates for demographic experience. We had adjustments relating to retirements, participation, persistency and census data updates. 2 The gain in per capita healthcare costs in 2022 relating to our OPEB plans is primarily due to the negotiation of favorable Medicare Advantage Prescription Drug healthcare rates, which went into effect on January 1, 2023. Additionally, we expanded the Medicare Advantage program to retirees on some of our other plans during the 2022 USW labor negotiations which added additional savings. The negotiated rates extend through 2025. 3 In 2022, the plan amendment gains and losses were generated from the ratification of the 2022 USW labor agreements. The plan amendment loss related to our pension plans is attributable to the increase to the pre-2023 service multiplier to $115 and the service multiplier applicable to service beginning in 2023 to $126 for retirements after January 1, 2023. The plan amendment gain related to our OPEB plans is attributable to the implementation of a cap on healthcare costs for employees retiring after January 1, 2026 on one of our Cleveland-Cliffs Steel LLC plans as well as the extension of the Medicare Advantage program to plans that previously did not have the offering.
Estimated Future Benefit Payments	(In millions) Pension Benefits OPEB 1 2024 $ 503 $ 107 2025 442 98 2026 433 95 2027 415 89 2028 400 86 2029-2033 1,728 380 1 OPEB benefit payments are displayed net of participant contributions.
Defined Benefit Plan, Assumptions	The following represents weighted-average assumptions used to determine benefit obligations: Pension Benefits OPEB December 31, December 31, 2023 2022 2023 2022 Discount rate 5.12 % 5.47 % 5.15 % 5.52 % Interest crediting rate 5.46 5.39 N/A N/A Compensation rate increase 3.00 3.00 3.00 3.00 The following represents weighted-average assumptions used to determine net benefit cost: Pension Benefits OPEB December 31, December 31, 2023 2022 2021 2023 2022 2021 Obligation discount rate 5.47 % 3.21 % 2.32 % 5.52 % 3.33 % 2.46 % Service cost discount rate 5.61 3.49 2.78 5.65 3.91 3.28 Interest cost discount rate 5.34 2.75 1.64 5.38 3.01 2.04 Interest crediting rate 5.46 5.39 5.35 N/A N/A N/A Expected return on plan assets 7.66 6.87 6.84 5.87 4.86 5.20 Compensation rate increase 3.00 2.74 2.54 3.00 3.00 3.00
Assumed Health Care Cost Trend Rates	The following represents assumed weighted-average health care cost trend rates: December 31, 2023 2022 Health care cost trend rate assumed for next year 1 5.49 % 5.44 % Ultimate health care cost trend rate 4.50 % 4.50 % Year that the ultimate rate is reached 2032 2030 1 The health care trend rate for the next year is weighted for all of our OPEB plans and factors in our Medicare Advantage Prescription Drug pricing arrangements. In 2023, we increased our assumed health care cost trend rate for self insured plans to 6.50% from 6.00% for 2024, which grades down on a linear basis to 4.50% by 2032. The health care trend rate for the Medicare Advantage Prescription Drug plans is set to match the negotiated rates through 2025 and then converts to the same trend rate as our self insured plan. In 2023, we layered in a one time increase to the healthcare trend rate for the Medicare Advantage Prescription Drug plans for 2026. These increases align with our expectation of higher health care costs due to increased popularity of specialty medication, current carrier and provider negotiations and impacts from third party funding associated with the Inflation Reduction Act.
Plan Assets and Asset Allocation	The following table reflects the actual asset allocations for pension and VEBA assets as of December 31, 2023 and 2022, as well as the 2024 weighted average target asset allocations: Pension Assets VEBA Assets Asset Category 2024 Actual Asset Allocation at December 31, 2024 Actual Asset Allocation at December 31, 2023 2022 2023 2022 Equity securities 33.8 % 32.1 % 36.1 % 16.6 % 18.4 % 22.0 % Fixed income 41.1 38.8 40.9 78.5 74.5 67.4 Hedge funds 9.4 9.4 2.7 1.4 1.5 1.9 Private equity 3.3 3.4 3.3 — — — Structured credit 2.4 5.1 6.9 0.2 0.9 1.2 Real estate 10.0 11.2 8.2 3.3 4.7 1.7 Absolute return fixed income — — 1.9 — — 5.8 Total 100.0 % 100.0 % 100.0 % 100.0 % 100.0 % 100.0 %
Fair Value of Pension Assets by Asset Category	The fair value of our pension assets by asset category is as follows: (In millions) Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs Significant Investments Measured at Net Asset Value Total Asset Category 2023 2022 2023 2022 2023 2022 2023 2022 2023 2022 Equity securities: U.S. equities $ 809 $ 564 $ — $ — $ — $ — $ — $ 569 $ 809 $ 1,133 Global equities 502 328 — — — — 65 106 567 434 Fixed income: U.S. government securities 1 22 87 657 380 — — 142 63 821 530 U.S. corporate bonds 587 574 — 266 — — 94 373 681 1,213 Non U.S. and other bonds — — — 32 — — 160 — 160 32 Hedge funds — — — — 118 115 285 — 403 115 Private equity — — — — 146 143 — — 146 143 Structured credit — — — — 220 298 — — 220 298 Real estate — — — — 286 356 189 — 475 356 Absolute return fixed income — — — — — — — 84 — 84 Total $ 1,920 $ 1,553 $ 657 $ 678 $ 770 $ 912 $ 935 $ 1,195 $ 4,282 $ 4,338 1 Includes cash equivalents. The fair value of our VEBA assets by asset category is as follows: (In millions) Quoted Prices in Active Markets for Identical Assets Significant Other Observable Inputs Significant Investments Measured at Net Asset Value Total Asset Category 2023 2022 2023 2022 2023 2022 2023 2022 2023 2022 Equity securities: U.S. equities $ 102 $ 24 $ — $ — $ — $ — $ — $ 89 $ 102 $ 113 Global equities 3 5 — — — — 30 42 33 47 Fixed income: U.S. government securities 1 119 149 27 79 — — 47 — 193 228 U.S. corporate bonds 214 146 94 117 — — 49 — 357 263 Non U.S. and other bonds 3 — — — — — — — 3 — Hedge funds — — — — 10 14 — — 10 14 Private equity — — — — — — — — — — Structured credit — — — — 7 9 — — 7 9 Real estate — — — — 10 12 24 — 34 12 Absolute return fixed income — — — — — — — 42 — 42 Total $ 441 $ 324 $ 121 $ 196 $ 27 $ 35 $ 150 $ 173 $ 739 $ 728 1 Includes cash equivalents.
Effect of Fair Value Measurements Using Significant Unobservable Inputs on Changes in Plan Assets	The following represents the fair value measurements of changes in plan assets using significant unobservable inputs (Level 3): Pension Assets VEBA Assets (In millions) 2023 2022 2023 2022 Beginning balance — January 1 $ 912 $ 904 $ 35 $ 42 Actual return on plan assets: Relating to assets still held at the reporting date (16) (6) 2 1 Relating to assets sold during the period 10 15 1 1 Purchases 24 28 — — Sales (160) (29) (11) (9) Ending balance — December 31 $ 770 $ 912 $ 27 $ 35
Multiemployer Plan	Information with respect to multiemployer plans in which we participate follows: Pension Fund EIN/Pension Plan Number Pension Protection Act Zone Status 1 FIP/RP Status Pending/Implemented 2 Contributions Surcharge Imposed 3 Expiration Date of Collective Bargaining Agreement 4 2023 2022 2023 2022 2021 Steelworkers Pension Trust 23-6648508/499 Green Green No $ 119 $ 93 $ 88 No 4/1/2025 to 9/1/2026 IAM National Pension Fund’s National Pension Plan 51-6031295/002 Red Red Yes 23 22 16 Yes 5/31/2025 to 5/15/2027 Other Plans 5 1 — — Total $ 143 $ 115 $ 104 1 The most recent Pension Protection Act zone status available in 2023 and 2022 is for each plan's year-end at December 31, 2022 and 2021. The plan's actuary certifies the zone status. Generally, plans in the red zone are less than 65% funded, plans in the yellow zone are between 65% and 80% funded, and plans in the green zone are at least 80% funded. The IAM National Pension Fund's National Pension Plan voluntarily elected to place itself in the "Red Zone" in April 2019 and has implemented a rehabilitation plan to address its underfunded status. Additional contributions will be required as part of the rehabilitation plan until the plan exits the "Red Zone". 2 The "FIP/RP Status Pending/Implemented" column indicates plans for which a financial improvement plan or a rehabilitation plan is either pending or has been implemented, as defined by ERISA. 3 The surcharge represents an additional required contribution due as a result of the critical funding status of the plan. 4 We are a party to six collective bargaining agreements that require contributions to the Steelworkers Pension Trust and three collective bargaining agreements that require contributions to the IAM National Pension Fund's National Pension Plan. 5 Plans that are not individually significant to our Company are presented in aggregate.

STOCK COMPENSATION PLANS (Table

STOCK COMPENSATION PLANS (Tables)	12 Months Ended
	Dec. 31, 2023
Share-Based Payment Arrangement [Abstract]
Summary of Total Compensation Expense Recognized for Stock-Based Compensation Awards	The following table summarizes the total compensation expense recognized for stock-based compensation awards: Year Ended December 31, (In millions, except per share amounts) 2023 2022 2021 Cost of goods sold $ (9) $ (5) $ (2) Selling, general and administrative expenses (32) (23) (16) Stock based compensation expense (41) (28) (18) Income tax benefit 10 7 4 Stock based compensation expense, net of tax $ (31) $ (21) $ (14) Decrease in basic earnings per common share $ (0.06) $ (0.04) $ (0.03) Decrease in diluted earnings per common share $ (0.06) $ (0.04) $ (0.03)
Summary of Performance Award Activity	The following table summarizes the performance award activity: 2023 2022 2021 (Shares in millions) Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Outstanding at beginning of year 2.7 $ 18.53 2.4 $ 14.04 2.5 $ 10.34 Granted 1.1 31.88 1.0 28.46 0.7 25.12 Distributed (1.8) 6.50 (1.1) 17.04 (1.3) 11.74 Performance adjustment 0.7 6.43 0.5 17.84 0.6 11.93 Forfeited/canceled (0.2) 28.65 (0.1) 23.74 (0.1) 11.27 Outstanding at end of year 2.5 $ 29.09 2.7 $ 18.53 2.4 $ 14.04
Summary of Restricted Stock Unit Activity	The following table summarizes the restricted stock units activity: 2023 2022 2021 (Shares in millions) Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Number of Shares Weighted Average Grant Date Fair Value Outstanding at beginning of year 2.4 $ 13.66 2.1 $ 10.31 2.1 $ 7.12 Granted 1.2 19.30 1.0 19.41 0.7 17.45 Distributed (0.9) 5.99 (0.6) 10.47 (0.6) 7.31 Forfeited/canceled (0.2) 19.84 (0.1) 17.82 (0.1) 9.50 Outstanding at end of year 2.5 $ 18.87 2.4 $ 13.66 2.1 $ 10.31
Summary of Stock Option Activity	The following table summarizes the stock option activity: 2023 2022 2021 (Shares in millions) Number of Shares Weighted Average Exercise Price Number of Shares Weighted Average Exercise Price Number of Shares Weighted Average Exercise Price Outstanding at beginning of year 0.6 $ 10.39 1.0 $ 12.75 2.5 $ 11.60 Exercised (0.1) 10.22 (0.3) 16.55 (1.5) 10.36 Forfeited/canceled — 21.05 (0.1) 22.78 — 36.48 Outstanding at end of year 0.5 $ 9.59 0.6 $ 10.39 1.0 $ 12.75 Exercisable at end of year 0.5 $ 9.59 0.6 $ 10.52 0.9 $ 13.35

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2023
Income Tax Disclosure [Abstract]
Schedule of Income (Loss) From Continuing Operations Before Income Taxes, Domestic and Foreign	Income from continuing operations before income taxes includes the following components: Year Ended December 31, (In millions) 2023 2022 2021 United States $ 600 $ 1,803 $ 3,827 Foreign (3) (7) (24) Total $ 597 $ 1,796 $ 3,803
Components of the Income Tax Provision (Benefit) on Continuing Operations	The components of the income tax expense from continuing operations consist of the following: Year Ended December 31, (In millions) 2023 2022 2021 Current provision: United States federal $ 4 $ 201 $ 14 United States state & local 26 131 55 Foreign 4 1 — 34 333 69 Deferred provision (benefit): United States federal 97 117 683 United States state & local 7 (22) 31 Foreign 10 (5) (10) Total income tax expense from continuing operations $ 148 $ 423 $ 773 The components of income taxes for other than continuing operations consisted of the following: (In millions) 2023 2022 2021 Other comprehensive income (loss): Pension and OPEB $ 10 $ (425) $ (206) Derivative financial instruments 47 26 (21) Total $ 57 $ (399) $ (227)
Reconciliation of Income Tax Attributable to Continuing Operations Computed at Statutory Rate	Reconciliation of our income tax attributable to continuing operations computed at the U.S. federal statutory rate is as follows: (In millions) 2023 2022 2021 Tax at U.S. statutory rate $ 125 21 % $ 377 21 % $ 799 21 % Increase (decrease) due to: Percentage depletion in excess of cost depletion (32) (5) (49) (3) (99) (3) Valuation allowance 14 2 — — — — Unrecognized tax benefits 7 1 2 — 9 — State taxes, net 28 5 71 4 86 2 Federal & state provision to return (20) (3) 27 1 (2) — Income not subject to tax (11) (2) (9) — (9) — Goodwill impairment 26 4 — — — — Other items, net 11 2 4 — (11) — Provision for income tax expense and effective income tax rate including discrete items $ 148 25 % $ 423 23 % $ 773 20 %
Significant Components of Deferred Tax Assets and Liabilities	Significant components of our deferred tax assets and liabilities are as follows: (In millions) 2023 2022 Deferred tax assets: Operating loss and other carryforwards $ 390 $ 389 Pension and OPEB liabilities 155 244 Environmental 67 96 Product inventories 92 54 State and local 9 14 Lease liabilities 79 62 Other liabilities 180 135 Total deferred tax assets before valuation allowance 972 994 Deferred tax asset valuation allowance (396) (390) Net deferred tax assets 576 604 Deferred tax liabilities: Investment in ventures (192) (195) Lease assets (79) (38) Property, plant and equipment and mineral rights (837) (827) Other assets (103) (122) Total deferred tax liabilities (1,211) (1,182) Net deferred tax assets (liabilities) $ (635) $ (578)
Summary of Changes in the Valuation Allowance	The changes in the valuation allowance are presented below: (In millions) 2023 2022 2021 Balance at beginning of year $ 390 $ 409 $ 836 Change in valuation allowance: Included in income tax expense 6 (19) (82) Decrease from acquisitions — — (345) Balance at end of year $ 396 $ 390 $ 409
Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows: (In millions) 2023 2022 2021 Unrecognized tax benefits balance as of January 1 $ 58 $ 35 $ 107 Increases for tax positions in current year 18 24 4 Decrease due to tax positions in prior year — (1) (66) Lapses in statutes of limitations — — (10) Unrecognized tax benefits balance as of December 31 $ 76 $ 58 $ 35

LEASE OBLIGATIONS (Tables)

LEASE OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Leases [Abstract]
Summary of Lease Costs	Lease costs are presented below: Year Ended December 31, (In millions) 2023 2022 Operating leases $ 59 $ 64 Finance leases: Amortization of right-of-use assets 92 103 Interest on lease liabilities 11 8 Short-term leases 171 160 Total $ 333 $ 335 Lease terms and discount rates are shown below: December 31, (In millions) 2023 Weighted average lease term (in years): Operating leases 8 Finance leases 7 Weighted average discount rate: Operating leases 8 % Finance leases 6 % Other information related to leases was as follows: Year Ended December 31, (In millions) 2023 2022 2021 Cash paid for amounts included in measurement of lease liabilities: Operating leases within cash flows from operating activities $ 57 $ 62 $ 70 Finance leases within cash flows from operating activities 11 8 9 Finance leases within cash flows from financing activities 92 96 94 Right-of-use assets obtained in exchange for new finance lease liabilities 93 55 50
Summary of Future Minimum Lease Payments under Noncancelable Finance and Operating Leases	Future minimum lease payments under noncancellable finance and operating leases as of December 31, 2023 were as follows: (In millions) Finance Leases Operating Leases 2024 $ 53 $ 56 2025 49 49 2026 39 42 2027 27 38 2028 25 29 Thereafter 74 117 Total future minimum lease payments 267 331 Less: imputed interest 52 93 Total lease payments 215 238 Less: current portion of lease liabilities 49 41 Long-term lease liabilities $ 166 $ 197

ASSET RETIREMENT OBLIGATIONS (T

ASSET RETIREMENT OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2023
Environmental Remediation Obligations [Abstract]
Schedule of Asset Retirement Obligations	The following is a summary of our asset retirement obligations: December 31, (In millions) 2023 2022 Asset retirement obligations 1 $ 459 $ 520 Less: current portion 15 21 Long-term asset retirement obligations $ 444 $ 499 1 Includes $259 million and $277 million related to our active operations as of December 31, 2023 and 2022, respectively.
Roll-forward of Asset Retirement Obligation Liability	The following is a roll-forward of our asset retirement obligation: (In millions) 2023 2022 Asset retirement obligation as of January 1 $ 520 $ 449 Decrease from sale of business (76) — Reclassification from environmental obligations — 63 Accretion expense 26 26 Remediation payments (21) (40) Revision in estimated cash flows 10 22 Asset retirement obligation as of December 31 $ 459 $ 520

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Summary of Carrying Value and Fair Value of Other Financial Instruments	A summary of the carrying value and fair value of other financial instruments were as follows: December 31, 2023 December 31, 2022 (In millions) Classification Carrying Fair Value Carrying Fair Value Senior notes Level 1 $ 3,137 $ 3,118 $ 2,385 $ 2,311 ABL Facility - outstanding balance Level 2 — — 1,864 1,864 Total $ 3,137 $ 3,118 $ 4,249 $ 4,175

DERIVATIVE INSTRUMENTS AND HE_2

DERIVATIVE INSTRUMENTS AND HEDGING (Tables)	12 Months Ended
	Dec. 31, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summary of Notional Amount of Outstanding Hedge Contracts	The following table presents the notional amount of our outstanding hedge contracts: Notional Amount December 31, Commodity Contracts Unit of Measure Maturity Dates 2023 2022 Natural Gas MMBtu January 2024 - August 2026 168,590,000 127,790,000 Electricity Megawatt hours January 2024 - October 2026 3,501,898 432,043
Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value	The following table presents the fair value of our cash flow hedges and the classification on the Statements of Consolidated Financial Position: December 31, Balance Sheet Location (In millions) 2023 2022 Other current assets $ — $ 15 Other non-current assets 1 30 Other current liabilities (105) (87) Other non-current liabilities (52) (10)

ACCUMULATED OTHERCOMPREHENSIVE

ACCUMULATED OTHERCOMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2023
Equity [Abstract]
Components of Accumulated Other Comprehensive Income (Loss)	The components of Accumulated other comprehensive income within Cliffs shareholders’ equity and related tax effects allocated to each are shown below: December 31, (In millions) 2023 2022 2021 Foreign Currency Translation Beginning balance $ (1) $ 1 $ 3 Other comprehensive income (loss) before reclassifications 1 (2) (2) Ending balance $ — $ (1) $ 1 Derivative Instruments Beginning balance $ (16) $ 68 $ (1) Other comprehensive income (loss) before reclassifications (345) 146 151 Income tax 81 (33) (34) Other comprehensive income (loss) before reclassifications, net of tax (264) 113 117 Losses (gains) reclassified from AOCI to net income 1 144 (256) (61) Income tax expense (benefit) 2 (34) 59 13 Net losses (gains) reclassified from AOCI to net income 110 (197) (48) Ending balance $ (170) $ (16) $ 68 Pension and OPEB Beginning balance $ 1,847 $ 549 $ (135) Other comprehensive income before reclassifications 4 115 1,759 878 Income tax (39) (434) (203) Other comprehensive income before reclassifications, net of tax 76 1,325 675 Losses (gains) reclassified from AOCI to net income 3 (145) (36) 12 Income tax expense (benefit) 2 49 9 (3) Net losses (gains) reclassified from AOCI to net income (96) (27) 9 Ending balance $ 1,827 $ 1,847 $ 549 Total AOCI Ending Balance $ 1,657 $ 1,830 $ 618 1 Amounts recognized in Cost of goods sold in the Statements of Consolidated Operations. 2 Amounts recognized in Income tax expense in the Statements of Consolidated Operations. 3 Amounts recognized in Net periodic benefit credits other than service cost component in the Statements of Consolidated Operations. 4 Refer to NOTE 9 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

VARIABLE INTEREST ENTITIES (Tab

VARIABLE INTEREST ENTITIES (Tables)	12 Months Ended
	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Variable Interest Entities	The Statements of Consolidated Financial Position includes the following amounts for SunCoke Middletown: December 31, (In millions) 2023 2022 Inventories $ 29 $ 28 Property, plant and equipment, net 288 288 Accounts payable (26) (19) Other assets (liabilities), net (39) (27) Noncontrolling interests (252) (270)

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2023
Earnings Per Share [Abstract]
Earnings Per Share Computation	The following table summarizes the computation of basic and diluted EPS: Year Ended December 31, (In millions, except per share amounts) 2023 2022 2021 Income from continuing operations $ 449 $ 1,373 $ 3,030 Income from continuing operations attributable to noncontrolling interest (51) (41) (45) Net income from continuing operations attributable to Cliffs shareholders 398 1,332 2,985 Income from discontinued operations, net of tax 1 3 3 Net income attributable to Cliffs shareholders $ 399 $ 1,335 $ 2,988 Weighted average number of shares: Basic 510 519 498 Redeemable preferred shares — — 33 Convertible senior notes 1 — 2 22 Employee stock plans 1 3 5 Diluted 511 524 558 Earnings per common share attributable to Cliffs common shareholders - basic 2 : Continuing operations $ 0.78 $ 2.57 $ 5.62 Discontinued operations — — 0.01 $ 0.78 $ 2.57 $ 5.63 Earnings per common share attributable to Cliffs common shareholders - diluted: Continuing operations $ 0.78 $ 2.55 $ 5.35 Discontinued operations — — 0.01 $ 0.78 $ 2.55 $ 5.36 1 On January 1, 2022, we adopted ASU 2020-06, Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (Subtopic 815-40). We utilized the modified retrospective method of adoption; using this approach, the guidance was applied to transactions outstanding as of the beginning of the fiscal year. 2 For the year ended December 31, 2021, basic earnings per share was calculated by dividing Net income attributable to Cliffs shareholders , less $187 million of earnings attributed to Series B Participating Redeemable Preferred Stock, by the weighted average number of basic common shares outstanding during the period presented.
Schedule of Potentially Dilutive Shares Excluded from the Computation of Diluted Earnings Per Share	The following table summarizes the potentially dilutive shares that were excluded from the computation of diluted earnings per share because their effect would have been anti-dilutive: Year Ended December 31, (In millions) 2023 2022 2021 Employee stock plans 2 — —

COMMITMENT AND CONTINGENCIES (T

COMMITMENT AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Unrecorded Unconditional Purchase Obligations Disclosure	Unconditional purchase obligations, including take-or-pay agreements, are as follows (in millions): 2024 2025 2026 2027 2028 Thereafter $ 2,984 $ 1,707 $ 1,133 $ 1,025 $ 929 $ 5,365
Schedule of Environmental Obligations	The following is a summary of our environmental obligations: December 31, (In millions) 2023 2022 Environmental obligations $ 134 $ 141 Less: current portion 21 23 Long-term environmental obligations $ 113 $ 118

BASIS OF PRESENTATION AND SIG_4

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) employee segment	Dec. 31, 2022 USD ($)
Basis of Presentation and Significant Accounting Policies [Line Items]
Number of employees | employee	28,000
Number of operating segments | segment	4
Number of reportable segments | segment	1
Other non-current assets
Basis of Presentation and Significant Accounting Policies [Line Items]
Investment in affiliates | $	$ 123	$ 133
Workforce represented by labor unions
Basis of Presentation and Significant Accounting Policies [Line Items]
Number of employees | employee	20,000

BASIS OF PRESENTATION AND SIG_5

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Depreciation Methods and Useful Lives (Details)	Dec. 31, 2023
Land improvements | Minimum
Property, Plant and Equipment [Line Items]
Useful life	20 years
Land improvements | Maximum
Property, Plant and Equipment [Line Items]
Useful life	45 years
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Useful life	20 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Useful life	45 years
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life	45 years

SUPPLEMENTARY FINANCIAL STATE_3

SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION - Allowance for Credit Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses as of January 1	$ (4)	$ (4)
Increase in allowance	(1)	0
Allowance for credit losses as of December 31	$ (5)	$ (4)

SUPPLEMENTARY FINANCIAL STATE_4

SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION - Inventory (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023
Disclosure Text Block [Abstract]
Finished and semi-finished goods	$ 2,971	$ 2,573
Raw materials	1,794	1,476
Total product inventories	4,765	4,049
Manufacturing supplies and critical spares	365	411
Inventories	5,130	4,460
Excess of current cost over LIFO cost of iron ore inventories	169	131
Effect of inventory build		$ 21
Effect of inventory reduction	$ 36

SUPPLEMENTARY FINANCIAL STATE_5

SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION - Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Noncash or Part Noncash Acquisitions [Line Items]
Proceeds related to sale of business	$ 35
Capital additions	785	$ 1,033	$ 857
Non-cash accruals	(13)	35	102
Equipment financed with seller	59	0	0
Right-of-use assets - finance leases	93	55	50
Cash paid for capital expenditures including deposits	646	943	705
Proceeds from government grant reimbursements	13	27	2
Income taxes paid	94	334	166
Income tax refunds	(205)	(3)	(16)
Interest paid on debt obligations net of capitalized interest	256	249	299
Interest capitalized	12	9	$ 6
Other Operating Income (Expense)
Noncash or Part Noncash Acquisitions [Line Items]
Gain on sale of business	63
Other current liabilities
Noncash or Part Noncash Acquisitions [Line Items]
Supplier finance program, current	$ 21	$ 19
Supplier Finance Program, Obligation, Current, Statement of Financial Position [Extensible Enumeration]	Other current liabilities	Other current liabilities
Accounts Payable
Noncash or Part Noncash Acquisitions [Line Items]
Supplier finance program, current	$ 91	$ 112
Supplier Finance Program, Obligation, Current, Statement of Financial Position [Extensible Enumeration]	Accounts payable	Accounts payable

SUPPLEMENTARY FINANCIAL STATE_6

SUPPLEMENTARY FINANCIAL STATEMENT INFORMATION - Non-cash Investing and Financing Activities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Noncash or Part Noncash Acquisitions [Line Items]
1.500% 2025 Convertible Senior Notes redemption	$ 0	$ 25	$ 0
Ferrous Processing and Trading
Noncash or Part Noncash Acquisitions [Line Items]
Fair value of settlement of a pre-existing relationship as part of consideration in connection with transaction	$ 0	$ 0	$ (20)

ACQUISITIONS - Consideration (D

ACQUISITIONS - Consideration (Details) - Ferrous Processing and Trading $ in Millions	Nov. 18, 2021 USD ($)
Business Acquisition [Line Items]
Cash consideration pursuant to the FPT Acquisition Agreement	$ 778
Cash consideration paid related to IRC Section 338(h)(10)	23
Total cash consideration	801
Fair value of settlement of a pre-existing relationship	(20)
Total purchase consideration	$ 781

ACQUISITIONS - Preliminary Purc

ACQUISITIONS - Preliminary Purchase Price Allocation (Details) - USD ($) $ in Millions	13 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Nov. 18, 2021
Business Acquisition [Line Items]
Goodwill	$ 1,130	$ 1,005
Ferrous Processing and Trading
Business Acquisition [Line Items]
Cash and cash equivalents	9		$ 9
Accounts receivable, net	235		233
Inventories	135		137
Other current assets	3		4
Property, plant and equipment	191		179
Other non-current assets	72		74
Accounts payable	(122)		(122)
Accrued employment costs	(8)		(8)
Other current liabilities	(6)		(9)
Other non-current liabilities	(21)		(21)
Net identifiable assets acquired	488		476
Goodwill	293		279
Total net assets acquired	781		$ 755
Measurement Period Adjustments, Cash and cash equivalents	0
Measurement Period Adjustments, Accounts receivable, net	2
Measurement Period Adjustments, Inventories	(2)
Measurement Period Adjustments, Other current assets	(1)
Measurement Period Adjustments, Property, plant and equipment	12
Measurement Period Adjustments, Other non-current assets	(2)
Measurement Period Adjustments, Accounts payable	0
Measurement Period Adjustments, Accrued employment costs	0
Measurement Period Adjustments, Other current liabilities	3
Measurement Period Adjustments, Other non-current liabilities	0
Measurement Period Adjustments, Net identifiable assets acquired	12
Measurement Period Adjustments, Goodwill	14
Measurement Period Adjustments, Total net assets acquired	$ 26

ACQUISITIONS - Narrative (Detai

ACQUISITIONS - Narrative (Details) $ in Millions	Dec. 31, 2022 USD ($)
Ferrous Processing and Trading
Business Acquisition [Line Items]
Goodwill that is deductible for tax purposes	$ 296

ACQUISITIONS - Intangible Asset

ACQUISITIONS - Intangible Assets and Liabilities (Details) - Ferrous Processing and Trading $ in Millions	Nov. 18, 2021 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 49
Weighted average life, finite-lived intangible assets	17 years
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 13
Weighted average life, finite-lived intangible assets	15 years
Supplier relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 29
Weighted average life, finite-lived intangible assets	18 years
Trade names and trademarks
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets acquired	$ 7
Weighted average life, finite-lived intangible assets	15 years

ACQUISITIONS - Pro Forma (Detai

ACQUISITIONS - Pro Forma (Details) - Ferrous Processing and Trading $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenues	$ 21,701
Net income attributable to Cliffs shareholders	$ 3,074

REVENUES - By Market and Produc

REVENUES - By Market and Product Line (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Revenues	$ 21,996	$ 22,989	$ 20,444
Steelmaking
Disaggregation of Revenue [Line Items]
Revenues	21,331	22,383	19,901
Steelmaking | Hot-rolled steel
Disaggregation of Revenue [Line Items]
Revenues	4,864	4,529	5,615
Steelmaking | Cold-rolled steel
Disaggregation of Revenue [Line Items]
Revenues	2,658	3,193	3,186
Steelmaking | Coated steel
Disaggregation of Revenue [Line Items]
Revenues	6,661	6,905	5,864
Steelmaking | Stainless and electrical steel
Disaggregation of Revenue [Line Items]
Revenues	2,281	2,284	1,622
Steelmaking | Plate
Disaggregation of Revenue [Line Items]
Revenues	1,444	1,651	1,316
Steelmaking | Slab and other steel products
Disaggregation of Revenue [Line Items]
Revenues	1,329	1,492	1,247
Steelmaking | Other
Disaggregation of Revenue [Line Items]
Revenues	2,094	2,329	1,051
Other Businesses
Disaggregation of Revenue [Line Items]
Revenues	665	606	543
Other Businesses | Other
Disaggregation of Revenue [Line Items]
Revenues	665	606	543
Automotive | Steelmaking
Disaggregation of Revenue [Line Items]
Revenues	7,440	6,661	4,726
Automotive | Other Businesses
Disaggregation of Revenue [Line Items]
Revenues	545	478	426
Infrastructure and manufacturing | Steelmaking
Disaggregation of Revenue [Line Items]
Revenues	5,612	5,869	5,380
Infrastructure and manufacturing | Other Businesses
Disaggregation of Revenue [Line Items]
Revenues	38	52	47
Distributors and converters | Steelmaking
Disaggregation of Revenue [Line Items]
Revenues	5,330	6,388	7,671
Distributors and converters | Other Businesses
Disaggregation of Revenue [Line Items]
Revenues	82	76	70
Steel producers | Steelmaking
Disaggregation of Revenue [Line Items]
Revenues	$ 2,949	$ 3,465	$ 2,124

SEGMENT REPORTING - Schedule Of

SEGMENT REPORTING - Schedule Of Segment Reporting Information, By Segment (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	4
Number of reportable segments | segment	1
Revenues	$ 21,996	$ 22,989	$ 20,444
Adjusted EBITDA	1,911	3,169	5,277
Steelmaking
Segment Reporting Information [Line Items]
Revenues	21,331	22,383	19,901
Adjusted EBITDA	1,873	3,089	5,280
Other Businesses
Segment Reporting Information [Line Items]
Revenues	665	606	543
Adjusted EBITDA	43	69	9
Eliminations
Segment Reporting Information [Line Items]
Adjusted EBITDA	$ (5)	$ 11	$ (12)

SEGMENT REPORTING - Reconciliat

SEGMENT REPORTING - Reconciliation of Net Income (Loss) to Adjusted EBITDA (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Net income	$ 450	$ 1,376	$ 3,033
Interest expense, net	(289)	(276)	(337)
Income tax expense	(148)	(423)	(773)
Depreciation, depletion and amortization	(973)	(1,034)	(897)
Goodwill impairment	(125)	0	0
Loss on extinguishment of debt	0	(75)	(88)
Asset impairment		(29)
Total Adjusted EBITDA	1,911	3,169	5,277
Income from continuing operations attributable to noncontrolling interest	51	41	45
EBITDA Calculation
Segment Reporting Information [Line Items]
Net income	450	1,376	3,033
Interest expense, net	(289)	(276)	(337)
Income tax expense	(148)	(423)	(773)
Depreciation, depletion and amortization	(973)	(1,034)	(897)
EBITDA	1,860	3,109	5,040
Adjusted EBITDA Calculation
Segment Reporting Information [Line Items]
EBITDA of noncontrolling interests	83	74	75
Acquisition-related expenses and adjustments	(12)	(1)	(197)
Goodwill impairment	(125)	0	0
Non-cash gain on sale of business	28	0	0
Loss on extinguishment of debt	0	(75)	(88)
Asset impairment	0	(29)	0
Other, net	(25)	(29)	(27)
Total Adjusted EBITDA	1,911	3,169	5,277
Income from continuing operations attributable to noncontrolling interest	51	41	45
Depreciation, depletion and amortization	$ 32	$ 33	$ 30

SEGMENT REPORTING - Depreciatio

SEGMENT REPORTING - Depreciation, Depletion and Amortization and Capital Additions By Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	$ (973)	$ (1,034)	$ (897)
Capital additions	785	1,033	857
Steelmaking
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	(938)	(994)	(860)
Capital additions	778	997	787
Other Businesses
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	(35)	(40)	(37)
Capital additions	3	30	52
Corporate/Eliminations
Segment Reporting Information [Line Items]
Capital additions	$ 4	$ 6	$ 18

SEGMENT REPORTING - Summary of

SEGMENT REPORTING - Summary of Assets by Segment (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Total assets	$ 17,537	$ 18,755
Operating Segments
Segment Reporting Information [Line Items]
Total assets	17,030	18,385
Intersegment Eliminations
Segment Reporting Information [Line Items]
Total assets	(507)	(521)
Steelmaking | Operating Segments
Segment Reporting Information [Line Items]
Total assets	16,880	18,070
Other Businesses | Operating Segments
Segment Reporting Information [Line Items]
Total assets	657	836
Corporate/Eliminations
Segment Reporting Information [Line Items]
Total assets	$ 507	$ 370

SEGMENTS REPORTING - Revenues a

SEGMENTS REPORTING - Revenues and Property, Plant and Equipment, Net by Geographical Location (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 21,996	$ 22,989	$ 20,444
Property, plant and equipment, net	8,895	9,070	9,186
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	20,000	20,991	18,881
Property, plant and equipment, net	8,816	8,981	9,092
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	1,046	963	803
Property, plant and equipment, net	78	88	93
Other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	950	1,035	760
Property, plant and equipment, net	$ 1	$ 1	$ 1

PROPERTY, PLANT AND EQUIPMENT -

PROPERTY, PLANT AND EQUIPMENT - Value Of Each Of The Major Classes Of Consolidated Depreciable Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 12,907	$ 12,388
Allowance for depreciation and depletion	(4,012)	(3,318)
Property, plant and equipment, net	8,895	9,070	$ 9,186
Right-of-use assets related to finance leases	$ 306	$ 408
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Property, plant and equipment, net	Property, plant and equipment, net
Land, land improvements and mineral rights
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 1,389	$ 1,388
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	946	921
Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,680	9,289
Other
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	302	238
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 590	$ 552

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Depreciation	$ 932	$ 988	$ 848
Impairment of long-lived assets		29
Depletion	$ 33	38	$ 46
Middletown
Property, Plant and Equipment [Line Items]
Accelerated depreciation		23
Indiana Harbor
Property, Plant and Equipment [Line Items]
Accelerated depreciation		$ 68

PROPERTY, PLANT AND EQUIPMENT_3

PROPERTY, PLANT AND EQUIPMENT - Book Value of Land and Mineral Rights Disclosure (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Mineral rights:
Cost	$ 783	$ 780
Depletion	(258)	(225)
Net mineral rights	525	555
Land rights	$ 427	$ 434

GOODWILL AND INTANGIBLE ASSET_3

GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES - Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Goodwill	$ 1,005	$ 1,130
Goodwill impairment	125	0	$ 0
Steelmaking
Goodwill [Line Items]
Goodwill	956	956
Other Businesses
Goodwill [Line Items]
Goodwill	$ 49	$ 174

GOODWILL AND INTANGIBLE ASSET_4

GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES - Intangibles (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	$ 269	$ 269
Finite-Lived Intangible Assets, Accumulated Amortization	(68)	(55)
Finite-Lived Intangible Assets, Net	201	214
Finite-Lived Intangible Liability, Gross	(71)	(71)
Finite-Lived Intangible Liability, Accumulated Amortization	24	19
Finite-Lived Intangible Liability, Net	(47)	(52)
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	90	90
Finite-Lived Intangible Assets, Accumulated Amortization	(18)	(13)
Finite-Lived Intangible Assets, Net	72	77
Developed technology
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	60	60
Finite-Lived Intangible Assets, Accumulated Amortization	(14)	(10)
Finite-Lived Intangible Assets, Net	46	50
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	18	18
Finite-Lived Intangible Assets, Accumulated Amortization	(5)	(4)
Finite-Lived Intangible Assets, Net	13	14
Mining permits
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	72	72
Finite-Lived Intangible Assets, Accumulated Amortization	(28)	(27)
Finite-Lived Intangible Assets, Net	44	45
Supplier relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	29	29
Finite-Lived Intangible Assets, Accumulated Amortization	(3)	(1)
Finite-Lived Intangible Assets, Net	$ 26	$ 28

GOODWILL AND INTANGIBLE ASSET_5

GOODWILL AND INTANGIBLE ASSETS AND LIABILITIES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 13	$ 13
Expected asset amortization, year one	13
Expected asset amortization, year two	13
Expected asset amortization, year three	13
Expected asset amortization, year four	13
Expected asset amortization, year five	13
Amortization of intangible liability	(5)	$ (5)
Expected liability amortization, year one	(5)
Expected liability amortization, year two	(5)
Expected liability amortization, year three	(5)
Expected liability amortization, year four	(5)
Expected liability amortization, year five	$ (5)

DEBT AND CREDIT FACILITIES - Sc

DEBT AND CREDIT FACILITIES - Schedule Of Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2023	Apr. 14, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Total debt	$ 3,192		$ 4,306
Unamortized discounts and issuance costs	(55)		(57)
Total long-term debt	$ 3,137		4,249
6.750% 2026 Senior Secured Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	6.75%
Annual Effective Interest Rate	6.99%
Total debt	$ 829		829
7.000% 2027 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	7%
Annual Effective Interest Rate	9.24%
Total debt	$ 73		73
7.000% 2027 AK Senior Notes | AK Steel
Debt Instrument [Line Items]
Stated interest rate	7%
Annual Effective Interest Rate	9.24%
Total debt	$ 56		56
5.875% 2027 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	5.875%
Annual Effective Interest Rate	6.49%
Total debt	$ 556		556
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	4.625%
Annual Effective Interest Rate	4.625%
Total debt	$ 368		368
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	6.75%
Annual Effective Interest Rate	6.75%
Total debt	$ 750	$ 750	0
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	4.875%
Annual Effective Interest Rate	4.875%
Total debt	$ 325		325
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	6.25%
Annual Effective Interest Rate	6.34%
Total debt	$ 235		$ 235
ABL Facility
Debt Instrument [Line Items]
Credit facility, amount outstanding	0
ABL Facility | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Annual Effective Interest Rate			5.60%
Credit facility, amount outstanding	$ 0		$ 1,864

DEBT AND CREDIT FACILITIES - De

DEBT AND CREDIT FACILITIES - Debt Issuances and Terms (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) day	Apr. 14, 2023 USD ($)	Dec. 31, 2022 USD ($)
Debt Instrument [Line Items]
Total debt	$ 3,192		$ 4,306
6.750% 2026 Senior Secured Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	6.75%
Repurchase price if triggering event occurs	101%
Total debt	$ 829		829
6.750% 2026 Senior Secured Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	103.375%
6.750% 2026 Senior Secured Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage	101.688%
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	6.75%
Repurchase price if triggering event occurs	101%
Total debt	$ 750	$ 750	0
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Minimum
Debt Instrument [Line Items]
Redemption notice period | day	10
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Maximum
Debt Instrument [Line Items]
Redemption notice period | day	60
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	100%
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage	103.375%
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance
Debt Instrument [Line Items]
Redemption price, percentage	106.75%
Restricted Amount (percent of original aggregate principal)	35%
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Redemption price, percentage	101.688%
7.000% 2027 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	7%
Total debt	$ 73		73
7.000% 2027 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	102.333%
7.000% 2027 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage	101.167%
5.875% 2027 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	5.875%
Total debt	$ 556		556
5.875% 2027 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	101.958%
5.875% 2027 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage	100.979%
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	4.625%
Total debt	$ 368		368
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage	102.313%
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance
Debt Instrument [Line Items]
Redemption price, percentage	104.625%
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Redemption price, percentage	101.156%
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	4.875%
Total debt	$ 325		325
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage	102.438%
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance
Debt Instrument [Line Items]
Redemption price, percentage	104.875%
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Three
Debt Instrument [Line Items]
Redemption price, percentage	101.625%
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Four
Debt Instrument [Line Items]
Redemption price, percentage	100.813%
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Stated interest rate	6.25%
Total debt	$ 235		235
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Minimum
Debt Instrument [Line Items]
Redemption notice period | day	30
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Maximum
Debt Instrument [Line Items]
Redemption notice period | day	60
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	100%
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two | US Treasury (UST) Interest Rate
Debt Instrument [Line Items]
Redemption price, percentage	0.40%
Unsecured Debt | Cleveland-Cliffs Inc.
Debt Instrument [Line Items]
Repurchase price if triggering event occurs	101%
7.000% 2027 AK Senior Notes | AK Steel
Debt Instrument [Line Items]
Stated interest rate	7%
Total debt	$ 56		$ 56
7.000% 2027 AK Senior Notes | AK Steel | Debt Instrument, Redemption, Period One
Debt Instrument [Line Items]
Redemption price, percentage	102.333%
7.000% 2027 AK Senior Notes | AK Steel | Debt Instrument, Redemption, Period Two
Debt Instrument [Line Items]
Redemption price, percentage	101.167%

DEBT AND CREDIT FACILITIES - AB

DEBT AND CREDIT FACILITIES - ABL Facility (Details) - USD ($) $ in Millions		12 Months Ended
	Jun. 09, 2023	Dec. 31, 2023
ABL Facility | Line of Credit
Line of Credit Facility [Line Items]
Credit facility, sublimit for swingline loans		$ 200
Letter of Credit | Line of Credit
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity		555
ABL Facility
Line of Credit Facility [Line Items]
Credit facility, maximum borrowing capacity		4,750
Available borrowing base on ABL Facility		4,397
Borrowings and Letter of credit obligations		0
Borrowing capacity available		$ 4,341
ABL Facility | Line of Credit
Line of Credit Facility [Line Items]
Increase in maximum borrowing capacity, tranche A	$ 250
Minimum fixed charge coverage ratio		1
ABL Facility | Line of Credit | Minimum
Line of Credit Facility [Line Items]
Commitment fee percentage		0.25%
ABL Facility | Line of Credit | Maximum
Line of Credit Facility [Line Items]
Commitment fee percentage		0.35%
ABL Facility | Line of Credit | Fed Funds Effective Rate Overnight Index Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
ABL Facility | Line of Credit | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
Letter of Credit
Line of Credit Facility [Line Items]
Borrowings and Letter of credit obligations		$ (56)

DEBT AND CREDIT FACILITIES - _2

DEBT AND CREDIT FACILITIES - Schedule of Debt Instrument Maturities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Debt Disclosure [Abstract]
2024	$ 0
2025	0
2026	829
2027	685
2028	0
Thereafter	1,678
Long-term Debt	$ 3,192	$ 4,306

PENSION AND OTHER POSTRETIREMEN

PENSION AND OTHER POSTRETIREMENT BENEFITS - Obligations and Funded Status (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Amounts recognized in Statements of Financial Position:
Pension and OPEB assets	$ 329	$ 356
Non-current liabilities	(821)	(1,058)
Amounts recognized in accumulated other comprehensive loss (income):
Accumulated benefit obligation	4,557	4,628
Pension Benefits
Change in benefit obligations:
Benefit obligations — beginning of year	4,646	6,036
Service cost	31	45	$ 56
Interest cost	235	144	103
Plan amendments	3	122
Actuarial loss (gain)	116	(1,236)
Benefits paid	(436)	(431)
Participant contributions	0	0
Effect of settlement	(24)	(34)
Other	0	0
Benefit obligations — end of year	4,571	4,646	6,036
Change in plan assets:
Fair value of plan assets — beginning of year	4,338	5,606
Actual return on plan assets	375	(809)
Participant contributions	0	0
Employer contributions	29	6
Benefits paid	(436)	(431)
Effect of settlement	(24)	(34)
Fair value of plan assets — end of year	4,282	4,338	5,606
Funded status	(289)	(308)
Amounts recognized in Statements of Financial Position:
Pension and OPEB assets	137	195
Current liabilities	(18)	(30)
Non-current liabilities	(408)	(473)
Total amount recognized	(289)	(308)
Amounts recognized in accumulated other comprehensive loss (income):
Net actuarial gain	(304)	(361)
Prior service cost (credit)	106	121
Net amount recognized	(198)	(240)
OPEB
Change in benefit obligations:
Benefit obligations — beginning of year	1,233	3,254
Service cost	10	35	51
Interest cost	64	72	74
Plan amendments	8	(163)
Actuarial loss (gain)	(158)	(1,781)
Benefits paid	(163)	(232)
Participant contributions	42	47
Effect of settlement	0	0
Other	0	1
Benefit obligations — end of year	1,036	1,233	3,254
Change in plan assets:
Fair value of plan assets — beginning of year	728	812
Actual return on plan assets	67	(97)
Participant contributions	42	47
Employer contributions	65	198
Benefits paid	(163)	(232)
Effect of settlement	0	0
Fair value of plan assets — end of year	739	728	$ 812
Funded status	(297)	(505)
Amounts recognized in Statements of Financial Position:
Pension and OPEB assets	192	161
Current liabilities	(76)	(81)
Non-current liabilities	(413)	(585)
Total amount recognized	(297)	(505)
Amounts recognized in accumulated other comprehensive loss (income):
Net actuarial gain	(2,033)	(1,996)
Prior service cost (credit)	(131)	(156)
Net amount recognized	$ (2,164)	$ (2,152)

PENSIONS AND OTHER POSTRETIRE_3

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Components Of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Amortization:
Net periodic benefit cost (credit)	$ (204)	$ (212)	$ (210)
Defined Benefit Plan, Expected Amounts [Abstract]
Estimated net periodic benefit cost	(212)
Pension Benefits
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	31	45	56
Interest cost	235	144	103
Expected return on plan assets	(315)	(355)	(359)
Amortization:
Net actuarial loss (gain)	3	13	32
Prior service costs (credits)	18	5	1
Settlements	(4)	(8)	(22)
Net periodic benefit cost (credit)	(32)	(156)	(189)
Defined Benefit Plan, Expected Amounts [Abstract]
Estimated net periodic benefit cost	(58)
OPEB
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	10	35	51
Interest cost	64	72	74
Expected return on plan assets	(43)	(37)	(40)
Amortization:
Net actuarial loss (gain)	(145)	(43)	3
Prior service costs (credits)	(17)	(3)	(2)
Settlements	0	0	0
Net periodic benefit cost (credit)	(131)	$ 24	$ 86
Defined Benefit Plan, Expected Amounts [Abstract]
Estimated net periodic benefit cost	$ (154)

PENSION AND POST RETIREMENT BEN

PENSION AND POST RETIREMENT BENEFITS - Components of Accumulated Other Comprehensive Loss (Income) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Jan. 01, 2023
Defined Benefit Plan Disclosure [Line Items]
Service multiplier		$ 115	$ 126
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	$ 42,000,000	41,000,000
Actual returns on assets under (over) expected	(60,000,000)	1,165,000,000
Amortization of net actuarial gain (loss)	(3,000,000)	(13,000,000)
Amortization of prior service credits (costs)	(18,000,000)	(5,000,000)
Settlements	4,000,000	8,000,000
Plan amendments	3,000,000	122,000,000
OPEB
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	(12,000,000)	(1,764,000,000)
Actual returns on assets under (over) expected	(24,000,000)	134,000,000
Amortization of net actuarial gain (loss)	145,000,000	43,000,000
Amortization of prior service credits (costs)	17,000,000	3,000,000
Settlements	0	0
Plan amendments	8,000,000	(163,000,000)
Discount rates | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	124,000,000	(1,143,000,000)
Discount rates | OPEB
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	28,000,000	(441,000,000)
Demographic updates | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	(5,000,000)	(102,000,000)
Demographic updates | OPEB
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	(208,000,000)	(7,000,000)
Mortality | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	(2,000,000)	17,000,000
Mortality | OPEB
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	(11,000,000)	0
Per capita healthcare costs | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	0	0
Per capita healthcare costs | OPEB
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	33,000,000	(1,333,000,000)
Other | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	(1,000,000)	(8,000,000)
Other | OPEB
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	0	0
Actuarial loss (gain) on benefit obligation | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	116,000,000	(1,236,000,000)
Actuarial loss (gain) on benefit obligation | OPEB
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain) on benefit obligation	$ (158,000,000)	$ (1,781,000,000)

PENSIONS AND OTHER POSTRETIRE_4

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Contributions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	$ 29	$ 6
Pension benefits, employer contributions and payments	29
Expected employer contributions, next fiscal year	122
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	65	198
Employer contributions	65	198
Expected employer contributions, next fiscal year	66
OPEB | VEBA
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	0	85
Expected employer contributions, next fiscal year	0
OPEB | Direct Payments
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer contributions	65	$ 113
Expected employer contributions, next fiscal year	$ 66

PENSION AND OTHER POSTRETIREM_2

PENSION AND OTHER POSTRETIREMENT BENEFITS - Estimated Future Benefit Payments (Details) $ in Millions	Dec. 31, 2023 USD ($)
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024	$ 503
2025	442
2026	433
2027	415
2028	400
2029-2033	1,728
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024	107
2025	98
2026	95
2027	89
2028	86
2029-2033	$ 380

PENSIONS AND OTHER POSTRETIRE_5

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Weighted-Average Assumptions Used to Determine Benefit Obligations (Details)	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	5.12%	5.47%
Interest crediting rate	5.46%	5.39%
Rate of compensation increase	3%	3%
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	5.15%	5.52%
Rate of compensation increase	3%	3%

PENSIONS AND OTHER POSTRETIRE_6

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Weighted-Average Assumptions Used to Determine Net Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Obligation discount rate	5.47%	3.21%	2.32%
Service cost discount rate	5.61%	3.49%	2.78%
Interest cost discount rate	5.34%	2.75%	1.64%
Interest crediting rate	5.46%	5.39%	5.35%
Expected return on plan assets	7.66%	6.87%	6.84%
Compensation rate increase	3%	2.74%	2.54%
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Obligation discount rate	5.52%	3.33%	2.46%
Service cost discount rate	5.65%	3.91%	3.28%
Interest cost discount rate	5.38%	3.01%	2.04%
Expected return on plan assets	5.87%	4.86%	5.20%
Compensation rate increase	3%	3%	3%

PENSIONS AND OTHER POSTRETIRE_7

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Assumed Health Care Cost Trend Rates (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Postemployment Benefits [Abstract]
Health care cost trend rate assumed for next year	5.49%	5.44%
Ultimate health care cost trend rate	4.50%	4.50%
Year that the ultimate rate is reached	2032	2030

PENSIONS AND OTHER POSTRETIRE_8

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Narrative (Details) - Pension Benefits - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fixed income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan asset investment		$ 1,200
Externally Managed Assets
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Plan asset investment		$ 2,900
Private equity
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Reserve for investment commitments	$ 70

PENSIONS AND OTHER POSTRETIRE_9

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Target Allocation and Actual Asset Allocations for Pension and VEBA Plan Assets (Details)	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	100%
Percentage of Plan Assets	100%	100%
Pension Benefits | Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	33.80%
Percentage of Plan Assets	32.10%	36.10%
Pension Benefits | Fixed income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	41.10%
Percentage of Plan Assets	38.80%	40.90%
Pension Benefits | Hedge funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	9.40%
Percentage of Plan Assets	9.40%	2.70%
Pension Benefits | Private equity
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	3.30%
Percentage of Plan Assets	3.40%	3.30%
Pension Benefits | Structured credit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	2.40%
Percentage of Plan Assets	5.10%	6.90%
Pension Benefits | Real estate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	10%
Percentage of Plan Assets	11.20%	8.20%
Pension Benefits | Absolute return fixed income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	0%
Percentage of Plan Assets	0%	1.90%
OPEB
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	100%
Percentage of Plan Assets	100%	100%
OPEB | Equity securities
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	16.60%
Percentage of Plan Assets	18.40%	22%
OPEB | Fixed income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	78.50%
Percentage of Plan Assets	74.50%	67.40%
OPEB | Hedge funds
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	1.40%
Percentage of Plan Assets	1.50%	1.90%
OPEB | Private equity
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	0%
Percentage of Plan Assets	0%	0%
OPEB | Structured credit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	0.20%
Percentage of Plan Assets	0.90%	1.20%
OPEB | Real estate
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	3.30%
Percentage of Plan Assets	4.70%	1.70%
OPEB | Absolute return fixed income
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2024 Target Allocation	0%
Percentage of Plan Assets	0%	5.80%

PENSIONS AND OTHER POSTRETIR_10

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Fair Value of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	$ 4,282	$ 4,338	$ 5,606
OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	739	728	812
Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	1,920	1,553
Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	441	324
Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	657	678
Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	121	196
Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	770	912	$ 904
Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	27	35
Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	935	1,195
Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	150	173
U.S. equities | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	809	1,133
U.S. equities | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	102	113
U.S. equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	809	564
U.S. equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	102	24
U.S. equities | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. equities | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. equities | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. equities | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. equities | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	569
U.S. equities | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	89
Global equities | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	567	434
Global equities | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	33	47
Global equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	502	328
Global equities | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	3	5
Global equities | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Global equities | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Global equities | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Global equities | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Global equities | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	65	106
Global equities | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	30	42
U.S. government securities | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	821	530
U.S. government securities | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	193	228
U.S. government securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	22	87
U.S. government securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	119	149
U.S. government securities | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	657	380
U.S. government securities | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	27	79
U.S. government securities | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. government securities | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. government securities | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	142	63
U.S. government securities | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	47	0
U.S. corporate bonds | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	681	1,213
U.S. corporate bonds | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	357	263
U.S. corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	587	574
U.S. corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	214	146
U.S. corporate bonds | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	266
U.S. corporate bonds | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	94	117
U.S. corporate bonds | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. corporate bonds | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
U.S. corporate bonds | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	94	373
U.S. corporate bonds | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	49	0
Non U.S. and other bonds | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	160	32
Non U.S. and other bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Non U.S. and other bonds | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	32
Non U.S. and other bonds | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Non U.S. and other bonds | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	160	0
Hedge funds | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	403	115
Hedge funds | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	10	14
Hedge funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Hedge funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Hedge funds | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Hedge funds | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Hedge funds | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	118	115
Hedge funds | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	10	14
Hedge funds | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	285	0
Hedge funds | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	146	143
Private equity | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	146	143
Private equity | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Private equity | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Structured credit | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	220	298
Structured credit | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	7	9
Structured credit | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Structured credit | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Structured credit | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Structured credit | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Structured credit | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	220	298
Structured credit | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	7	9
Structured credit | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Structured credit | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Real estate | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	475	356
Real estate | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	34	12
Real estate | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Real estate | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Real estate | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Real estate | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Real estate | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	286	356
Real estate | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	10	12
Real estate | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	189	0
Real estate | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	24	0
Absolute return fixed income | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	84
Absolute return fixed income | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	42
Absolute return fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Absolute return fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Absolute return fixed income | Significant  Other Observable Inputs (Level 2) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Absolute return fixed income | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Absolute return fixed income | Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Absolute return fixed income | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Absolute return fixed income | Investments Measured at Net Asset Value | Pension Benefits
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	84
Absolute return fixed income | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	42
Debt Security, Corporate, Non-US | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	3	0
Debt Security, Corporate, Non-US | Quoted Prices in Active Markets for Identical Assets (Level 1) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	3	0
Debt Security, Corporate, Non-US | Significant  Other Observable Inputs (Level 2) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Debt Security, Corporate, Non-US | Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	0	0
Debt Security, Corporate, Non-US | Investments Measured at Net Asset Value | OPEB
Defined Benefit Plan, Information about Plan Assets [Abstract]
Fair value of pension assets by asset category	$ 0	$ 0

PENSIONS AND POSTRETIREMENT BEN

PENSIONS AND POSTRETIREMENT BENEFITS - Fair Value Measurements Using Significant Unobservable Inputs (Level 3) on Changes in Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	$ 4,338	$ 5,606
Actual return on plan assets:
Fair value of plan assets — end of year	4,282	4,338
Pension Benefits | Private equity
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	143
Actual return on plan assets:
Fair value of plan assets — end of year	146	143
OPEB
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	728	812
Actual return on plan assets:
Fair value of plan assets — end of year	739	728
OPEB | Private equity
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	0
Actual return on plan assets:
Fair value of plan assets — end of year	0	0
Significant Unobservable Inputs (Level 3) | Pension Benefits
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	912	904
Actual return on plan assets:
Relating to assets still held at the reporting date	(16)	(6)
Relating to assets sold during the period	10	15
Purchases	24	28
Sales	(160)	(29)
Fair value of plan assets — end of year	770	912
Significant Unobservable Inputs (Level 3) | Pension Benefits | Private equity
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	143
Actual return on plan assets:
Fair value of plan assets — end of year	146	143
Significant Unobservable Inputs (Level 3) | OPEB
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	35
Actual return on plan assets:
Fair value of plan assets — end of year	27	35
Significant Unobservable Inputs (Level 3) | OPEB | Private equity
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	0
Actual return on plan assets:
Fair value of plan assets — end of year	0	0
Significant Unobservable Inputs (Level 3) | OPEB | VEBA Assets
Defined Benefit Plan, Change in Fair Value of Plan Assets, Level 3 Reconciliation [Roll Forward]
Fair value of plan assets — beginning of year	35	42
Actual return on plan assets:
Relating to assets still held at the reporting date	2	1
Relating to assets sold during the period	1	1
Purchases	0	0
Sales	(11)	(9)
Fair value of plan assets — end of year	$ 27	$ 35

PENSIONS AND OTHER POSTRETIR_11

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Defined Contribution Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Postemployment Benefits [Abstract]
Defined contribution pension plans	$ 59	$ 52	$ 55

PENSIONS AND OTHER POSTRETIR_12

PENSIONS AND OTHER POSTRETIREMENT BENEFITS - Multiemployer Plan (Details)	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Nov. 01, 2022 USD ($)	Oct. 31, 2022 USD ($)
Multiemployer Plan [Line Items]
Contributions	$ 143,000,000	$ 115,000,000	$ 104,000,000
Contribution per eligible hour				$ 4	$ 0.50
Steelworkers Pension Trust
Multiemployer Plan [Line Items]
Pension Plan EIN	236648508
Pension Plan Number	499
Pension Protection Act Zone Status	Green	Green
FIP/RP Status Pending/Implemented	No
Contributions	$ 119,000,000	$ 93,000,000	88,000,000
Surcharge Imposed	No
Total actuarial liability		6,378,000,000
Market value of assets		$ 5,827,000,000
Funded ratio		0.91
IAM National Pension Fund's National Pension Plan
Multiemployer Plan [Line Items]
Pension Plan EIN	516031295
Pension Plan Number	002
Pension Protection Act Zone Status	Red	Red
FIP/RP Status Pending/Implemented	Implemented
Contributions	$ 23,000,000	$ 22,000,000	16,000,000
Surcharge Imposed	Yes
Other Plans
Multiemployer Plan [Line Items]
Contributions	$ 1,000,000	$ 0	$ 0

STOCK COMPENSATION PLANS - Narr

STOCK COMPENSATION PLANS - Narrative (Details) shares in Millions	Dec. 31, 2023 shares
2021 Equity Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	23

STOCK COMPENSATION PLANS - Stoc

STOCK COMPENSATION PLANS - Stock-Based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Costs and Expenses	$ (41)	$ (28)	$ (18)
Income tax benefit	10	7	4
Stock based compensation expense, net of tax	$ (31)	$ (21)	$ (14)
Decrease in basic earnings per common share (in dollars per share)	$ 0.78	$ 2.57	$ 5.63
Decrease in diluted earnings per common share (in dollars per share)	$ 0.78	2.55	5.36
Compensation cost related to outstanding awards not yet recognized	$ 53
Expected period of recognition for outstanding awards not yet recognized	1 year 8 months 12 days
Share-based Payment Arrangement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Decrease in basic earnings per common share (in dollars per share)	$ (0.06)	(0.04)	(0.03)
Decrease in diluted earnings per common share (in dollars per share)	$ (0.06)	$ (0.04)	$ (0.03)
Cost of goods sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Costs and Expenses	$ (9)	$ (5)	$ (2)
Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Costs and Expenses	$ (32)	$ (23)	$ (16)

STOCK COMPENSATION PLANS - Perf

STOCK COMPENSATION PLANS - Performance Shares (Details) - Performance Shares - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of year (in shares)	2.7	2.4	2.5
Outstanding at beginning of year, weighted average grant date fair value (in dollars per share)	$ 18.53	$ 14.04	$ 10.34
Granted (in shares)	1.1	1	0.7
Granted, weighted average grant date fair value (in dollars per share)	$ 31.88	$ 28.46	$ 25.12
Distributed (in shares)	(1.8)	(1.1)	(1.3)
Distributed, weighted average grant date fair value (in dollars per share)	$ 6.50	$ 17.04	$ 11.74
Performance adjustment (in shares)	0.7	0.5	0.6
Performance adjustment, weighted average grant date fair value (in dollars per share)	$ 6.43	$ 17.84	$ 11.93
Forfeited/canceled (in shares)	(0.2)	(0.1)	(0.1)
Forfeited/canceled, weighted average grant date fair value (in dollars per share)	$ 28.65	$ 23.74	$ 11.27
Outstanding at end of year (in shares)	2.5	2.7	2.4
Outstanding at end of year, weighted average grant date fair value (in dollars per share)	$ 29.09	$ 18.53	$ 14.04
Performance/vesting period	3 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Percent of shares actually earned based on performance	0%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Percent of shares actually earned based on performance	200%

STOCK COMPENSATION PLANS - Rest

STOCK COMPENSATION PLANS - Restricted Stock (Details) - Restricted Stock Units (RSUs) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of year (in shares)	2.4	2.1	2.1
Outstanding at beginning of year, weighted average grant date fair value (in dollars per share)	$ 13.66	$ 10.31	$ 7.12
Granted (in shares)	1.2	1	0.7
Granted, weighted average grant date fair value (in dollars per share)	$ 19.30	$ 19.41	$ 17.45
Distributed (in shares)	(0.9)	(0.6)	(0.6)
Distributed, weighted average grant date fair value (in dollars per share)	$ 5.99	$ 10.47	$ 7.31
Forfeited/canceled (in shares)	(0.2)	(0.1)	(0.1)
Forfeited/canceled, weighted average grant date fair value (in dollars per share)	$ 19.84	$ 17.82	$ 9.50
Outstanding at end of year (in shares)	2.5	2.4	2.1
Outstanding at end of year, weighted average grant date fair value (in dollars per share)	$ 18.87	$ 13.66	$ 10.31
Performance/vesting period	3 years

STOCK COMPENSATION PLANS - St_2

STOCK COMPENSATION PLANS - Stock Options (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of year (in shares)	0.6	1	2.5
Outstanding at beginning of year, weighted average exercise price (in dollars per share)	$ 10.39	$ 12.75	$ 11.60
Exercised (in shares)	(0.1)	(0.3)	(1.5)
Exercised, weighted average exercise price (in dollars per share)	$ 10.22	$ 16.55	$ 10.36
Forfeited/canceled (in shares)	0	(0.1)	0
Forfeitured/canceled, weighted average exercise price (in dollars per share)	$ 21.05	$ 22.78	$ 36.48
Outstanding at end of year (in shares)	0.5	0.6	1
Outstanding at end of year, weighted average exercise price (in dollars per share)	$ 9.59	$ 10.39	$ 12.75
Exercisable (in shares)	0.5	0.6	0.9
Exercisable, weighted average exercise price (in dollars per share)	$ 9.59	$ 10.52	$ 13.35
Intrinsic value of options exercised	$ 1	$ 3
Weighted-average remaining contractual life of options outstanding	2 years 1 month 6 days
Aggregate intrinsic value of options outstanding	$ 5
Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Performance/vesting period	1 year
Expiration period	10 years
Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Number of Shares [Roll Forward]
Performance/vesting period	3 years

STOCK COMPENSATION PLANS - None

STOCK COMPENSATION PLANS - Nonemployee Directors (Details) - USD ($)	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost related to outstanding awards not yet recognized	$ 53,000,000
Share-based Payment Arrangement, Nonemployee | Director | Directors Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost related to outstanding awards not yet recognized	$ 140,000	$ 140,000	$ 120,000

INCOME TAXES - Schedule of Inco

INCOME TAXES - Schedule of Income Before Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
United States	$ 600	$ 1,803	$ 3,827
Foreign	(3)	(7)	(24)
Income from continuing operations before income taxes	$ 597	$ 1,796	$ 3,803

INCOME TAXES - Schedule of Comp

INCOME TAXES - Schedule of Components of Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Current Federal Tax Expense (Benefit)	$ 4	$ 201	$ 14
Current State and Local Tax Expense (Benefit)	26	131	55
Current Foreign Tax Expense (Benefit)	4	1	0
Current Income Tax Expense (Benefit)	34	333	69
Deferred Federal Income Tax Expense (Benefit)	97	117	683
Deferred State and Local Income Tax Expense (Benefit)	7	(22)	31
Deferred Foreign Income Tax Expense (Benefit)	10	(5)	(10)
Income Tax Expense (Benefit)	$ 148	$ 423	$ 773

INCOME TAXES - Schedule of Effe

INCOME TAXES - Schedule of Effective Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax at U.S. statutory rate	$ 125	$ 377	$ 799
Percentage depletion in excess of cost depletion	(32)	(49)	(99)
Valuation allowance	14	0	0
Unrecognized tax benefits	7	2	9
State taxes, net	28	71	86
Federal & state provision to return	(20)	27	(2)
Income not subject to tax	(11)	(9)	(9)
Goodwill impairment	26	0	0
Other items, net	11	4	(11)
Income Tax Expense (Benefit)	$ 148	$ 423	$ 773
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Tax at U.S. statutory rate, percent	21%	21%	21%
Percentage depletion in excess of depletion, percent	(5.00%)	(3.00%)	(3.00%)
Valuation Allowance, percent	2%	0%	0%
Unrecognized Tax Benefits, Percent	1%	0%	0%
State taxes, net, percent	5%	4%	2%
Federal & state provision to return, percent	(3.00%)	1%	0%
Income not subject to tax, Percent	(2.00%)	0%	0%
Goodwill impairment, percent	4%	0%	0%
Other items, net, percent	2%	0%	0%
Provision for income tax expense (benefit) and effective income tax rate including discrete items (percent)	25%	23%	20%

INCOME TAXES - Components of In

INCOME TAXES - Components of Income Taxes for Other than Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Other comprehensive income (loss), Pension and OPEB	$ 10	$ (425)	$ (206)
Other comprehensive income (loss), Derivative financial instruments	47	26	(21)
Other comprehensive income (loss), Total	$ 57	$ (399)	$ (227)

INCOME TAXES - Schedule of Defe

INCOME TAXES - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Operating loss and other carryforwards	$ 390	$ 389
Pension and OPEB liabilities	155	244
Environmental	67	96
Product inventories	92	54
State and local	9	14
Lease liabilities	79	62
Other liabilities	180	135
Total deferred tax assets before valuation allowance	972	994
Deferred tax asset valuation allowance	(396)	(390)	$ (409)	$ (836)
Net deferred tax assets	576	604
Deferred tax liabilities:
Investment in ventures	(192)	(195)
Lease assets	(79)	(38)
Property, plant and equipment and mineral rights	(837)	(827)
Other assets	(103)	(122)
Total deferred tax liabilities	(1,211)	(1,182)
Net deferred tax assets (liabilities)	$ (635)	$ (578)

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Valuation Allowance [Line Items]
Domestic operating loss carryforward	$ 1,704,000,000	$ 2,278,000,000
Foreign operating loss carryforward	1,452,000,000	1,444,000,000
Interest expense limitation carryforward	0	77,000,000
Deferred tax asset valuation allowance	396,000,000	390,000,000	$ 409,000,000	$ 836,000,000
Change in valuation allowance	14,000,000
Undistributed earnings of foreign subsidiaries	0	0
Foreign Tax Authority
Valuation Allowance [Line Items]
Deferred tax asset valuation allowance	356,000,000	342,000,000
State and Local Jurisdiction
Valuation Allowance [Line Items]
Deferred tax asset valuation allowance	40,000,000	48,000,000
Increase (decrease) from acquisitions
Valuation Allowance [Line Items]
Change in valuation allowance	$ 0	$ 0	$ (345,000,000)

INCOME TAXES Income Taxes - Sch

INCOME TAXES Income Taxes - Schedule of Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Valuation Allowance [Line Items]
Balance at beginning of year	$ 390	$ 409	$ 836
Change in valuation allowance	14
Balance at end of year	396	390	409
Included in income tax expense (benefit)
Valuation Allowance [Line Items]
Change in valuation allowance	6	(19)	(82)
Increase (decrease) from acquisitions
Valuation Allowance [Line Items]
Change in valuation allowance	$ 0	$ 0	$ (345)

INCOME TAXES - Schedule of Unre

INCOME TAXES - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, Beginning Balance	$ 58	$ 35	$ 107
Increases for tax positions in current year	18	24	4
Decrease due to tax positions in prior year	0	(1)	(66)
Lapses in statutes of limitations	0	0	(10)
Unrecognized Tax Benefits, Ending Balance	76	58	$ 35
Interest and penalties related to unrecognized tax benefits	8
Other non-current liabilities
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, Beginning Balance	58
Unrecognized Tax Benefits, Ending Balance	76	$ 58
Other Liabilities
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits that would impact effective tax rate	$ 76

LEASE OBLIGATIONS - Lease Costs

LEASE OBLIGATIONS - Lease Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
Operating leases	$ 59	$ 64
Finance leases, Amortization of lease cost	92	103
Finance leases, Interest on lease liabilities	11	8
Short-term leases	171	160
Total	$ 333	$ 335

LEASE OBLIGATIONS - Other Infor

LEASE OBLIGATIONS - Other Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating Lease, Weighted Average Remaining Lease Term	8 years
Finance Lease, Weighted Average Remaining Lease Term	7 years
Operating Lease, Weighted Average Discount Rate, Percent	8%
Finance Lease, Weighted Average Discount Rate, Percent	6%
Operating leases within cash flows from operating activities	$ 57	$ 62	$ 70
Finance leases within cash flows from operating activities	11	8	9
Finance leases within cash flows from financing activities	92	96	94
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 93	$ 55	$ 50

LEASE OBLIGATIONS - Future Mini

LEASE OBLIGATIONS - Future Minimum Lease Payments (Details) $ in Millions	Dec. 31, 2023 USD ($)
Leases [Abstract]
Finance Lease, Liability, Payments, Due in Next Rolling Twelve Months	$ 53
Lessee, Operating Lease, Liability, Payments, Due Next Rolling Twelve Months	56
Finance Lease, Liability, Payments, Due in Rolling Year Two	49
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Two	49
Finance Lease, Liability, Payments, Due in Rolling Year Three	39
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Three	42
Finance Lease, Liability, Payments, Due in Rolling Year Four	27
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Four	38
Finance Lease, Liability, Payments, Due in Rolling Year Five	25
Lessee, Operating Lease, Liability, Payments, Due in Rolling Year Five	29
Finance Lease, Liability, Payments, Due in Rolling after Year Five	74
Lessee, Operating Lease, Liability, Payments, Due after Rolling Year Five	117
Finance Lease, Liability, Payment, Due	267
Lessee, Operating Lease, Liability, to be Paid	331
Finance Lease, Liability, Undiscounted Excess Amount	52
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	93
Finance Lease, Liability	215
Operating Lease, Liability	238
Finance Lease, Liability, Current	49
Finance Lease, Liability, Noncurrent	166
Operating Lease, Liability, Current	41
Operating Lease, Liability, Noncurrent	$ 197
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Other Liabilities
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other non-current liabilities
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other non-current liabilities

ASSET RETIREMENT OBLIGATIONS -

ASSET RETIREMENT OBLIGATIONS - Summary Of Asset Retirement Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Environmental Remediation Obligations [Abstract]
Asset Retirement Obligation	$ 459	$ 520	$ 449
Less: current portion	15	21
Long-term asset retirement obligations	444	499
Total Segment Assets
Environmental Exit Cost [Line Items]
Asset retirement obligations related to active operations	$ 259	$ 277

ASSET RETIREMENT OBLIGATIONS _2

ASSET RETIREMENT OBLIGATIONS - Asset Retirement Obligation Roll-forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset Retirement Obligation [Roll Forward]
Asset Retirement Obligation at Beginning of Year	$ 520	$ 449
Decrease from sale of business	(76)	0
Reclassification from environmental obligations	0	63
Accretion expense	26	26
Remediation payments	(21)	(40)
Revision in estimated cash flows	10	22
Asset Retirement Obligation at End of Year	$ 459	$ 520

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS - Carrying Value And Fair Value Of Financial Instruments Disclosure (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of long-term debt	$ 3,137	$ 4,249
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of long-term debt	3,118	4,175
Senior notes | Carrying Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of long-term debt	3,137	2,385
Senior notes | Fair Value | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of long-term debt	3,118	2,311
Line of Credit | Carrying Value | Significant  Other Observable Inputs (Level 2) | ABL Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of long-term debt	0	1,864
Line of Credit | Fair Value | Significant  Other Observable Inputs (Level 2) | ABL Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of long-term debt	$ 0	$ 1,864

DERIVATIVE INSTRUMENTS AND HE_3

DERIVATIVE INSTRUMENTS AND HEDGING - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) MMBtu MWh	Dec. 31, 2022 MMBtu MWh
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Expected reclassification of net losses related to hedge contracts | $	$ 155
Commodity Contract | Natural Gas
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount | MMBtu	168,590,000	127,790,000
Commodity Contract | Electricity
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional Amount | MWh	3,501,898	432,043

DERIVATIVE INSTRUMENTS AND HE_4

DERIVATIVE INSTRUMENTS AND HEDGING - Balance Sheet Location (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Other current assets
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	$ 0	$ 15
Other non-current assets
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets	1	30
Other current liabilities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liabilities	(105)	(87)
Other non-current liabilities
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative liabilities	$ (52)	$ (10)

CAPITAL STOCK - Narrative (Deta

CAPITAL STOCK - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions

3 Months Ended

12 Months Ended

Dec. 01, 2021

Mar. 11, 2021

Dec. 09, 2020

Sep. 30, 2021

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Feb. 10, 2022

Apr. 29, 2021

Mar. 31, 2021

Feb. 11, 2021

Dec. 31, 2020

Class of Stock [Line Items]

Authorized amount of stock repurchase

$ 1,000

Repurchase of common shares

$ 152

$ 240

$ 0

Remaining authorized purchase amount

$ 608

1.500% 2025 Convertible Senior Notes redemption

$ (25)

$ (5)

Common shares, issued (in shares)

531,051,530

531,051,530

20,000,000

Common shares, sold (in shares)

40,000,000

Common stock, shares issued, price per share (in usd per share)

$ 16.12

Redeemable preferred stock, issued (in shares)

583,273

Redeemable preferred stock, outstanding (in shares)

583,273

Common shares, authorized (in shares)

1,200,000,000

1,200,000,000

1,200,000,000

600,000,000

Common Stock

Class of Stock [Line Items]

Common stock repurchases (in shares)

10,400,000

12,500,000

1.500% 2025 Convertible Senior Notes redemption (in shares)

24,200,000

Common Shares in Treasury

Class of Stock [Line Items]

Repurchase of common shares

$ 152

1.500% 2025 Convertible Senior Notes

Class of Stock [Line Items]

Redemption of debt

$ 294

Repayments of debt

294

1.500% 2025 Convertible Senior Notes redemption

$ 499

9.875% 2025 Senior Secured Notes

Class of Stock [Line Items]

Redemption of debt

$ 322

ArcelorMittal

Class of Stock [Line Items]

Common shares, sold (in shares)

40,000,000

Common Stock

Class of Stock [Line Items]

1.500% 2025 Convertible Senior Notes redemption (in shares)

24,000,000

Common Stock | ArcelorMittal USA

Class of Stock [Line Items]

Acquisition (in shares)

78,000,000

Series B Preferred Stock

Class of Stock [Line Items]

Stock redeemed during period (in shares)

583,273

Stock redeemed during period

$ 1,300

Preferred stock authorized (in shares)

4,000,000

Preferred stock issued (in shares)

0

Preferred stock outstanding (in shares)

0

Series A Preferred Stock

Class of Stock [Line Items]

Preferred stock authorized (in shares)

3,000,000

Preferred stock issued (in shares)

0

Preferred stock outstanding (in shares)

0

ACCUMULATED OTHER COMPREHENSI_2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Changes in AOCI (loss) related to shareholders' equity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 1,830	$ 618
Ending balance	1,657	1,830	$ 618
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(1)	1	3
Other comprehensive income (loss) before reclassifications, net of tax	1	(2)	(2)
Ending balance	0	(1)	1
Derivative Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(16)	68	(1)
Other comprehensive income (loss) before reclassifications	(345)	146	151
Income tax	81	(33)	(34)
Other comprehensive income (loss) before reclassifications, net of tax	(264)	113	117
Losses (gains) reclassified from AOCI to net income	144	(256)	(61)
Income tax expense (benefit)	(34)	59	13
Net losses (gains) reclassified from AOCI to net income	110	(197)	(48)
Ending balance	(170)	(16)	68
Pension and OPEB
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	1,847	549	(135)
Other comprehensive income (loss) before reclassifications	115	1,759	878
Income tax	(39)	(434)	(203)
Other comprehensive income (loss) before reclassifications, net of tax	76	1,325	675
Losses (gains) reclassified from AOCI to net income	(145)	(36)	12
Income tax expense (benefit)	49	9	(3)
Net losses (gains) reclassified from AOCI to net income	(96)	(27)	9
Ending balance	$ 1,827	$ 1,847	$ 549

VARIABLE INTEREST ENTITIES (Det

VARIABLE INTEREST ENTITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Income from continuing operations attributable to noncontrolling interest	$ 51	$ 41	$ 45
Cash paid for capital expenditures including deposits	646	943	705
Inventories	4,460	5,130
Property, plant and equipment, net	8,895	9,070	$ 9,186
Accounts payable	(2,099)	(2,186)
Noncontrolling interests	(235)	(251)
Variable Interest Entity, Primary Beneficiary | SunCoke Middletown
Variable Interest Entity [Line Items]
Income from continuing operations attributable to noncontrolling interest	52	47
Cash paid for capital expenditures including deposits	25	12
Inventories	29	28
Property, plant and equipment, net	288	288
Accounts payable	(26)	(19)
Other assets (liabilities), net	(39)	(27)
Noncontrolling interests	$ (252)	$ (270)

EARNINGS PER SHARE - Earnings P

EARNINGS PER SHARE - Earnings Per Share Computation (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Earnings Per Share [Abstract]
Income from continuing operations	$ 449	$ 1,373	$ 3,030
Income from continuing operations attributable to noncontrolling interest	51	41	45
Net income from continuing operations attributable to Cliffs shareholders	398	1,332	2,985
Income from discontinued operations, net of tax	1	3	3
Net income attributable to Cliffs shareholders	$ 399	$ 1,335	$ 2,988
Weighted average number of shares:
Basic (in shares)	510	519	498
Redeemable preferred shares (in shares)	0	0	33
Convertible senior notes (in shares)	0	2	22
Employee stock plans (in shares)	1	3	5
Diluted (in shares)	511	524	558
Earnings per common share attributable to Cliffs common shareholders - basic
Continuing operations (in dollars per share)	$ 0.78	$ 2.57	$ 5.62
Discontinued operations (in dollars per share)	0	0	0.01
Earnings (loss) per common share attributable to Cliffs common shareholders - basic (in dollars per share)	0.78	2.57	5.63
Earnings per common share attributable to Cliffs common shareholders - diluted:
Continuing operations (in dollars per share)	0.78	2.55	5.35
Discontinued operations (in dollars per share)	0	0	0.01
Earnings (loss) per common share attributable to Cliffs common shareholders - diluted (in dollars per share)	$ 0.78	$ 2.55	$ 5.36
Earnings attributed to Series B Participating Redeemable Preferred Stock			$ 187

EARNINGS PER SHARE - Anti-Dilut

EARNINGS PER SHARE - Anti-Dilutive Securities (Details) - shares shares in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Payment Arrangement
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from diluted earnings per share (in shares)	2	0	0

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Commitments Under Take-Or-Pay Obligations (Details) $ in Millions	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
2024	$ 2,984
2025	1,707
2026	1,133
2027	1,025
2028	929
Thereafter	$ 5,365

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Narrative (Details) $ in Millions	Dec. 31, 2023 USD ($)
Letter of Credit
Other Commitments [Line Items]
Credit facility, amount outstanding	$ 56
Surety Bond
Other Commitments [Line Items]
Surety-backed letters of credit and surety bonds outstanding	$ 260

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Environmental Obligations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Environmental obligations	$ 134	$ 141
Less: current portion	21	23
Long-term environmental obligations	$ 113	$ 118
Environmental Loss Contingency Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	Environmental obligations
Environmental Loss Contingency Current Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	Less: current portion
Environmental Loss Contingency Noncurrent Statement Of Financial Position Extensible Enumeration Not Disclosed Flag	Long-term environmental obligations