Cleveland-Cliffs (CLF) 10-Q 6 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	4-May-15
Document and Entity Information [Abstract]
Entity Registrant Name	CLIFFS NATURAL RESOURCES INC.
Entity Central Index Key	764065
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		153,279,552
Trading Symbol	clf

Statements_Of_Condensed_Consol

Statements Of Condensed Consolidated Operations (USD $)	3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
REVENUES FROM PRODUCT SALES AND SERVICES
Product	$399.50	$559.20
Freight and venture partners' cost reimbursements	46.5	56.3
TOTAL REVENUES	446	615.5
COST OF GOODS SOLD AND OPERATING EXPENSES	-365.2	-425.5
SALES MARGIN	80.8	190
OTHER OPERATING INCOME (EXPENSE)
Selling, general and administrative expenses	-29.1	-37.5
Miscellaneous - net	20.2	-13.3
Other operating expense	-8.9	-50.8
OPERATING INCOME	71.9	139.2
OTHER INCOME (EXPENSE)
Interest expense, net	-42.9	-40.4
Gain on extinguishment of debt	313.7	0
Other non-operating income (expense)	-0.8	0.8
TOTAL OTHER EXPENSE	270	-39.6
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND EQUITY LOSS FROM VENTURES	341.9	99.6
INCOME TAX EXPENSE	-175.1	-29.6
EQUITY LOSS FROM VENTURES, net of tax	0	-0.3
INCOME FROM CONTINUING OPERATIONS	166.8	69.7
LOSS FROM DISCONTINUED OPERATIONS, net of tax	-928.5	-140.4
NET LOSS	-761.7	-70.7
LOSS ATTRIBUTABLE TO NONCONTROLLING INTEREST (2015 - Loss of $7.7 million related to Discontinued Operations, 2014 - Loss of $7.3 million related to Discontinued Operations)	1.9	0.4
NET LOSS ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	-759.8	-70.3
PREFERRED STOCK DIVIDENDS	-12.8	-12.8
NET LOSS ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	($772.60)	($83.10)
Earnings (Loss) Per Common Share Attributable to Cliffs Shareholders - Basic
Continuing operations	$1.02	$0.37
Discontinued operations	($6.06)	($0.92)
Earnings (Loss) per Common Share Attributable to Cliffs Common Shareholders - Basic:	($5.04)	($0.55)
Earnings (Loss) Per Common Share Attributable to Cliffs Shareholders - Diluted
Continuing operations	$0.94	$0.37
Discontinued operations	($5.20)	($0.91)
Earnings (Loss) per Common Share Attributable to Cliffs Common Shareholders - Diluted:	($4.26)	($0.54)
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Basic	153,185	153,040
Diluted	178,696	153,653

Statements_Of_Condensed_Consol1

Statements Of Condensed Consolidated Comprehensive Income (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
NET LOSS ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	($759.80)	($70.30)
OTHER COMPREHENSIVE INCOME (LOSS)
Changes in pension and other post-retirement benefits, net of tax	28.8	3.4
Unrealized net gain on marketable securities, net of tax	0.8	3.9
Unrealized net gain on foreign currency translation	168	40.5
Unrealized net gain (loss) on derivative financial instruments, net of tax	-0.8	10.5
OTHER COMPREHENSIVE INCOME	196.8	58.3
OTHER COMPREHENSIVE LOSS (INCOME) ATTRIBUTABLE TO THE NONCONTROLLING INTEREST	10.8	-0.5
TOTAL COMPREHENSIVE LOSS ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	($552.20)	($12.50)

Statements_Of_Condensed_Consol2

Statements Of Condensed Consolidated Financial Position (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
CURRENT ASSETS
Cash and cash equivalents	$355.70	$271.30
Accounts receivable, net	87.1	122.7
Inventories	408.5	260.1
Supplies and other inventories	120.4	118.6
Income tax receivable	165.5	217.6
Short-term assets of discontinued operations	197.2	330.6
Other current assets	190	128
TOTAL CURRENT ASSETS	1,524.40	1,448.90
PROPERTY, PLANT AND EQUIPMENT, NET	1,047.20	1,070.50
OTHER ASSETS
Long-term assets of discontinued operations	0	400.1
Other Non-Current Assets	131	244.5
TOTAL OTHER ASSETS	131	644.6
TOTAL ASSETS	2,702.60	3,164
CURRENT LIABILITIES
Accounts payable	114.3	166.1
Accrued expenses	167.1	201.7
Short-term liabilities of discontinued operations	265	400.6
Other current liabilities	300.1	190.2
TOTAL CURRENT LIABILITIES	846.5	958.6
PENSION AND POSTEMPLOYMENT BENEFIT LIABILITIES	250.2	259.7
ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS	165.6	165.6
LONG-TERM DEBT	2,880.90	2,843.30
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS	125.2	436.1
OTHER LIABILITIES	216.3	235
TOTAL LIABILITIES	4,484.70	4,898.30
COMMITMENTS AND CONTINGENCIES (SEE NOTE 20)
CLIFFS SHAREHOLDERS' DEFICIT
Preferred Stock - no par value, Class A - 3,000,000 shares authorized, 7 % Series A Mandatory Convertible, Class A, no par value and $1,000 per share liquidation preference, Issued and Outstanding - 731,223 shares (2014 - 731,223)	731.3	731.3
Common Shares - par value $0.125 per share, Authorized - 400,000,000 shares (2014 - 400,000,000 shares); Issued - 159,546,224 shares (2014 - 159,546,224 shares); Outstanding - 153,184,519 shares (2014 - 153,246,754 shares)	19.8	19.8
Capital in excess of par value of shares	2,308.10	2,309.80
Retained deficit	-4,733.20	-3,960.70
Cost of 6,266,672 common shares in treasury (2014 - 6,299,470 shares)	-283.5	-285.7
Accumulated other comprehensive loss	-38.2	-245.8
TOTAL CLIFFS SHAREHOLDERS' DEFICIT	-1,995.70	-1,431.30
NONCONTROLLING INTEREST (DEFICIT)	213.6	-303
TOTAL DEFICIT	-1,782.10	-1,734.30
TOTAL LIABILITIES AND DEFICIT	$2,702.60	$3,164

Statements_Of_Condensed_Consol3

Statements Of Condensed Consolidated Financial Position (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Preferred stock, par value	$0	$0
Common shares, par value	$0.13	$0.13
Common shares, authorized (in shares)	400,000,000	400,000,000
Common shares, issued (in shares)	159,546,224	159,546,224
Common shares, outstanding	153,279,552	153,246,754
Common shares in treasury	6,266,672	6,299,470
Preferred Class A [Member]
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share	$1,000	$1,000
Cumulative Mandatory Convertible	7.00%	7.00%
Preferred stock, shares authorized (in shares)	3,000,000	3,000,000
Preferred Shares, Issued and Outstanding, Shares	731,223	731,223
Preferred Class B [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	4,000,000	4,000,000

Statements_Of_Condensed_Consol4

Statements Of Condensed Consolidated Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
OPERATING ACTIVITIES
NET LOSS	($761.70)	($70.70)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Depreciation, depletion and amortization	33	141.1
Impairment of long-lived assets	76.6	0
Deferred income taxes	165.8	15.1
Gain on extinguishment of debt	-313.7	0
Loss on deconsolidation, net of cash deconsolidated	776.1	0
Other	31.6	3.2
Changes in operating assets and liabilities:
Receivables and other assets	71.7	161.5
Product inventories	-154.9	-214.5
Payables and accrued expenses	-152.7	-117.7
Net cash used by operating activities	-228.2	-82
INVESTING ACTIVITIES
Purchase of property, plant and equipment	-15.9	-103.3
Other investing activities	0.2	12.6
Net cash used by investing activities	-15.7	-90.7
FINANCING ACTIVITIES
Proceeds from first lien notes offering	503.5	0
Debt issuance costs	-33.1	0
Repurchase of debt	-133.3	0
Borrowings under credit facilities	295	225
Repayment under credit facilities	-295	0
Common stock dividends	0	-23
Preferred stock dividends	-12.8	-12.8
Other financing activities	-14.3	8.7
Net cash provided by financing activities	310	197.9
EFFECT OF EXCHANGE RATE CHANGES ON CASH	-1.3	3.3
INCREASE IN CASH AND CASH EQUIVALENTS	64.8	28.5
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	290.9	335.5
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$355.70	$364

BASIS_OF_PRESENTATION_AND_SIGN

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BUSINESS SUMMARY AND SIGNIFICANT ACCOUNTING POLICIES	NOTE 1 - BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES
	The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with SEC rules and regulations and, in the opinion of management, include all adjustments (consisting of normal recurring adjustments) necessary to present fairly, the financial position, results of operations, comprehensive income and cash flows for the periods presented. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Management bases its estimates on various assumptions and historical experience, which are believed to be reasonable; however, due to the inherent nature of estimates, actual results may differ significantly due to changed conditions or assumptions. The results of operations for the three months ended March 31, 2015 are not necessarily indicative of results to be expected for the year ending December 31, 2015 or any other future period. These unaudited condensed consolidated financial statements should be read in conjunction with the financial statements and notes included in our Annual Report on Form 10-K for the year ended December 31, 2014.
	As more fully described in NOTE 14 - DISCONTINUED OPERATIONS, in January 2015, we announced that the Bloom Lake Group commenced restructuring proceedings in Montreal, Quebec, under the CCAA. Bloom Lake had recently suspended operations and for several months had been exploring options to sell certain of its Canadian assets, among other initiatives. Effective January 27, 2015, following the CCAA filing of the Bloom Lake Group, we deconsolidated the Bloom Lake Group and certain other wholly-owned subsidiaries comprising substantially all of our Canadian operations (collectively, the "Canadian Entities"). Our pre-filing financial results in Canada and subsequent expenses directly associated with the Canadian Entities are included in our financial statements and classified within discontinued operations.
	Additionally, as we continue to re-focus our strategy on strengthening our U.S. Iron Ore operations, management has determined that our North American Coal operating segment as of March 31, 2015 met the criteria to be classified as held for sale under ASC 205 - Presentation of Financial Statements. As such, all current and historical North American Coal operating segment results are included in our financial statements and classified within discontinued operations.
	We will now report our results from continuing operations in two reportable segments: U.S. Iron Ore and Asia Pacific Iron Ore.
	Basis of Consolidation
	The unaudited condensed consolidated financial statements include our accounts and the accounts of our wholly-owned and majority-owned subsidiaries, including the following operations:
	Name	Location	Ownership Interest	Operation	Status of Operations
	Northshore	Minnesota	100.00%	Iron Ore	Active
	United Taconite	Minnesota	100.00%	Iron Ore	Active
	Tilden	Michigan	85.00%	Iron Ore	Active
	Empire	Michigan	79.00%	Iron Ore	Active
	Koolyanobbing	Western Australia	100.00%	Iron Ore	Active
	Pinnacle	West Virginia	100.00%	Coal	Active - Held for Sale
	Oak Grove	Alabama	100.00%	Coal	Active - Held for Sale
	Wabush1	Newfoundland and Labrador/ Quebec, Canada	100.00%	Iron Ore	Permanent closure
	Bloom Lake1	Quebec, Canada	82.80%	Iron Ore	Care-and-maintenance
	Cliffs Chromite Ontario - Black Label Deposit1	Ontario, Canada	100.00%	Chromite	Suspended
	Cliffs Chromite Ontario - Black Thor Deposit1	Ontario, Canada	100.00%	Chromite	Suspended
	Cliffs Chromite Ontario & Cliffs Chromite Far North - Big Daddy Deposit1	Ontario, Canada	70.00%	Chromite	Suspended
	1 As of January 27, 2015, we deconsolidated substantially all of our Canadian operations following the CCAA filing. See NOTE 14 - DISCONTINUED OPERATIONS for further information.
	Intercompany transactions and balances are eliminated upon consolidation.
	Equity Method Investments
	Investments in unconsolidated ventures that we have the ability to exercise significant influence over, but not control, are accounted for under the equity method. The following table presents the detail of our investments in unconsolidated ventures and where those investments are classified in the Statements of Unaudited Condensed Consolidated Financial Position as of March 31, 2015 and December 31, 2014. Parentheses indicate a net liability.
					(In Millions)
	Investment	Classification	Accounting	Interest	March 31,		December 31,
			Method	Percentage	2015		2014
	Hibbing	Other non-current assets	Equity Method	23%	$	2.5	$	3.1
	Other	Other non-current assets	Equity Method	Various	0.9		1
					$	3.4	$	4.1
	Foreign Currency
	Our financial statements are prepared with the U.S. dollar as the reporting currency. The functional currency of the Company’s Australian subsidiaries is the Australian dollar. The functional currency of all other international subsidiaries is the U.S. dollar. The financial statements of international subsidiaries are translated into U.S. dollars using the exchange rate at each balance sheet date for assets and liabilities and a weighted average exchange rate for each period for revenues, expenses, gains and losses. Where the local currency is the functional currency, translation adjustments are recorded as Accumulated other comprehensive loss. Income taxes generally are not provided for foreign currency translation adjustments. To the extent that monetary assets and liabilities, inclusive of intercompany notes, are recorded in a currency other than the functional currency, these amounts are remeasured each reporting period, with the resulting gain or loss being recorded in the Statements of Unaudited Condensed Consolidated Operations. Transaction gains and losses resulting from remeasurement of short-term intercompany loans are included in Miscellaneous - net in our Statements of Unaudited Condensed Consolidated Operations. For the three months ended March 31, 2015, net gains of $13.5 million related to the impact of transaction gains and losses resulting from remeasurement. Of these transaction gains and losses, for the three months ended March 31, 2015, gains of $12.4 million and gains of $1.5 million, respectively, resulted from remeasurement of short-term intercompany loans and cash and cash equivalents. For the three months ended March 31, 2014, losses of $11.4 million related to the impact of transaction gains and losses resulting from remeasurement, of which included losses of $8.8 million and losses of $3.1 million, respectively, resulted from remeasurement of short-term intercompany loans and cash and cash equivalents.
	Significant Accounting Policies
	A detailed description of our significant accounting policies can be found in the audited financial statements for the fiscal year ended December 31, 2014 included in our Annual Report on Form 10-K filed with the SEC. The significant accounting policies requiring updates have been included within the disclosures below.
	Derivative Financial Instruments and Hedging Activities
	According to our global hedge policy, the policy allows for hedging not more than 75 percent, but not less than 40 percent for up to 12 months and not less than 10 percent for up to 15 months, of forecasted net currency exposures that are probable to occur. Full hedge compliance under the policy has been waived through December 31, 2015. The waiver was a result of the evaluation of the potential risk of being over hedged and the uncertainty of the 2015 currency exposures. During 2015, we have not entered into any new foreign currency exchange contracts to hedge our foreign currency exposure and we do not expect to enter into any during the remainder of 2015. In the future, we may enter into additional hedging instruments as needed in order to further hedge our exposure to changes in foreign currency exchange rates.
	Recent Accounting Pronouncements
	Issued and Not Effective
	In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This ASU requires retrospective adoption and will be effective for us beginning in our first quarter of 2016. Early adoption is permitted. We do not expect this adoption to have an impact on our Statements of Unaudited Condensed Consolidated Operations or Statements of Unaudited Condensed Consolidated Cash Flows.  The impact of the adoption of the guidance will result in reclassification of the unamortized debt issuance costs on the Statements of Unaudited Condensed Consolidated Financial Position, which were $46.2 million and $25.6 million at March 31, 2015 and December, 31, 2014, respectively.

SEGMENT_REPORTING

SEGMENT REPORTING	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
SEGMENT REPORTING	NOTE 2 - SEGMENT REPORTING
	Our continuing operations are organized and managed according to product category and geographic location: U.S. Iron Ore and Asia Pacific Iron Ore. The U.S. Iron Ore segment is comprised of our interests in five U.S. mines that provide iron ore to the integrated steel industry. The Asia Pacific Iron Ore segment is located in Western Australia and provides iron ore to the seaborne market for Asian steel producers. There were no intersegment product revenues in the first quarters of 2015 or 2014.
	We have historically evaluated segment performance based on sales margin, defined as revenues less cost of goods sold, and operating expenses identifiable to each segment. Additionally, beginning in the third quarter of 2014, concurrent with the change in control on July 29, 2014, management began to evaluate segment performance based on EBITDA, defined as Net Loss before interest, income taxes, depreciation, depletion and amortization, and Adjusted EBITDA, defined as EBITDA excluding certain items such as impacts of discontinued operations, foreign currency remeasurement, severance recorded in Selling, general and administrative expenses, or SG&A, extinguishment of debt and intersegment corporate allocations of SG&A costs. Management uses and believes that investors benefit from referring to these measures in evaluating operating and financial results, as well as in planning, forecasting and analyzing future periods as these financial measures approximate the cash flows associated with the operational earnings.
	The following tables present a summary of our reportable segments for the three months ended March 31, 2015 and 2014, including a reconciliation of segment sales margin to Income from Continuing Operations Before Income Taxes and Equity Loss from Ventures and a reconciliation of Net Loss to EBITDA and Adjusted EBITDA:
		(In Millions)
		Three Months Ended
		March 31,
		2015						2014
	Revenues from product sales and services:
	U.S. Iron Ore	$	311.8		70	%		$	361.3		59	%
	Asia Pacific Iron Ore	134.2			30	%		254.2			41	%
	Total revenues from product sales and services	$	446		100	%		$	615.5		100	%
	Sales margin:
	U.S. Iron Ore	$	80					$	95
	Asia Pacific Iron Ore	0.8						66.3
	Eliminations with Discontinued Operations	—						28.7
	Sales margin	80.8						190
	Other operating income	(8.9		)				(50.8		)
	Other income (expense)	270						(39.6		)
	Income from continuing operations before income taxes and equity loss from ventures	$	341.9					$	99.6
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Net Loss	$	(761.7	)	$	(70.7	)
	Less:
	Interest expense, net	(44.2		)	(42.7		)
	Income tax benefit (expense)	(175.0		)	21.8
	Depreciation, depletion and amortization	(33.0		)	(141.1		)
	EBITDA	$	(509.5	)	$	91.3
	Less:
	Impact of discontinued operations	$	(924.1	)	$	(118.1	)
	North American Coal operations impact	(5.5		)	18.2
	Gain on extinguishment of debt	313.7			—
	Severance in SG&A	(1.5		)	(6.0		)
	Foreign exchange remeasurement	13.5			(11.4		)
	Adjusted EBITDA	$	94.4		$	208.6
	EBITDA:
	U.S. Iron Ore	$	101.6		$	123.6
	Asia Pacific Iron Ore	18			85.3
	Other	(629.1		)	(117.6		)
	Total EBITDA	$	(509.5	)	$	91.3
	Adjusted EBITDA:
	U.S. Iron Ore	$	105.1		$	128.7
	Asia Pacific Iron Ore	5.7			99.1
	Other	(16.4		)	(19.2		)
	Total Adjusted EBITDA	$	94.4		$	208.6
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Depreciation, depletion and amortization:
	U.S. Iron Ore	$	21.7		$	28.7
	Asia Pacific Iron Ore	6.3			39.1
	Other	1.8			1.9
	Total depreciation, depletion and amortization	$	29.8		$	69.7
	Capital additions1:
	U.S. Iron Ore	$	9.5		$	14.9
	Asia Pacific Iron Ore	3.4			3.2
	Other	0.4			0.9
	Total capital additions	$	13.3		$	19
	1    Includes capital lease additions and non-cash accruals. Refer to NOTE 17 - CASH FLOW INFORMATION.
	A summary of assets by segment is as follows:
		(In Millions)
	March 31,			December 31,
	2015			2014
Assets:
U.S. Iron Ore	$	1,550.10		$	1,464.90
Asia Pacific Iron Ore	250.6			274.6
Other	31.2			147
Total segment assets	1,831.90			1,886.50
Corporate	673.5			546.8
Assets of Discontinued Operations	197.2			730.7
Total assets	$	2,702.60		$	3,164.00

INVENTORIES

INVENTORIES	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Inventories	NOTE 3 - INVENTORIES
	The following table presents the detail of our Inventories in the Statements of Unaudited Condensed Consolidated Financial Position as of March 31, 2015 and December 31, 2014:
		(In Millions)
		31-Mar-15						31-Dec-14
	Segment	Finished Goods		Work-in Process		Total Inventory		Finished Goods		Work-in		Total
										Process		Inventory
	U.S. Iron Ore	$	294.5	$	13.9	$	308.4	$	132.1	$	13.5	$	145.6
	Asia Pacific Iron Ore	15.1		85		100.1		26.4		88.1		114.5
	Total	$	309.6	$	98.9	$	408.5	$	158.5	$	101.6	$	260.1

PROPERTY_PLANT_AND_EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPMENT	NOTE 4 - PROPERTY, PLANT AND EQUIPMENT
	The following table indicates the value of each of the major classes of our consolidated depreciable assets as of March 31, 2015 and December 31, 2014:
		(In Millions)
		March 31,			December 31,
		2015			2014
	Land rights and mineral rights	$	500.5		$	500.5
	Office and information technology	69.7			73.7
	Buildings	59.8			59.8
	Mining equipment	584.9			585.1
	Processing equipment	512.7			510.2
	Electric power facilities	44.2			46.8
	Land improvements	24.8			24.7
	Other	54.7			55
	Construction in-progress	20.7			14.4
		1,872.00			1,870.20
	Allowance for depreciation and depletion	(824.8		)	(799.7		)
		$	1,047.20		$	1,070.50
	We recorded depreciation and depletion expense of $28.7 million and $67.7 million in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 and March 31, 2014, respectively.

DEBT_AND_CREDIT_FACILITIES

DEBT AND CREDIT FACILITIES	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
DEBT AND CREDIT FACILITIES	NOTE 5 - DEBT AND CREDIT FACILITIES
	The following represents a summary of our long-term debt as of March 31, 2015 and December 31, 2014:
	($ in Millions)
	March 31, 2015
	Debt Instrument		Type	Annual Effective Interest Rate	Final Maturity	Total Face Amount		Total Debt
	$700 Million 4.875% 2021 Senior Notes		Fixed	4.89%	2021	$	423.2	$	422.9	-1
	$1.3 Billion Senior Notes:
	$500 Million 4.80% 2020 Senior Notes		Fixed	4.83%	2020	308.5		308.1		-2
	$800 Million 6.25% 2040 Senior Notes		Fixed	6.34%	2040	492.8		487		-3
	$400 Million 5.90% 2020 Senior Notes		Fixed	5.98%	2020	326.8		325.7		-4
	$500 Million 3.95% 2018 Senior Notes		Fixed	6.32%	2018	436		433.8		-5
	$540 Million 8.25% 2020 First Lien Notes		Fixed	9.97%	2020	540		503.5		-6
	$544.2 Million 7.75% 2020 Second Lien Notes		Fixed	15.55%	2020	544.2		397.2		-7
	$550 Million ABL Facility:
	Asset-Based Revolving Credit Facility		Variable	—%	2020	550		—		-8
	Fair Value Adjustment to Interest Rate Hedge							2.7
	Total debt					$	3,621.50	$	2,880.90
	Less: Short-term and current portion of long-term debt							—
	Long-term debt							$	2,880.90
	($ in Millions)
	31-Dec-14
	Debt Instrument		Type	Annual Effective Interest Rate	Final Maturity	Total Face Amount		Total Debt
	$700 Million 4.875% 2021 Senior Notes		Fixed	4.88%	2021	$	690	$	689.5	-1
	$1.3 Billion Senior Notes:
	$500 Million 4.80% 2020 Senior Notes		Fixed	4.83%	2020	490		489.4		-2
	$800 Million 6.25% 2040 Senior Notes		Fixed	6.34%	2040	800		790.5		-3
	$400 Million 5.90% 2020 Senior Notes		Fixed	5.98%	2020	395		393.7		-4
	$500 Million 3.95% 2018 Senior Notes		Fixed	5.17%	2018	480		477.4		-5
	$1.125 Billion Credit Facility:
	Revolving Credit Agreement		Variable	2.94%	2017	1,125.00		—		-9
	Fair Value Adjustment to Interest Rate Hedge							2.8
	Total debt					$	3,980.00	$	2,843.30
	Less: Short-term and current portion of long-term debt							—
	Long-term debt							$	2,843.30
	-1	During the first quarter of 2015, we purchased $58.3 million of outstanding 4.875 percent senior notes that were trading at a discount of 52.0 percent which resulted in a gain on extinguishment of $20.0 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $208.5 million of the 4.875 percent senior notes for $170.3 million of the 7.75 percent second lien notes at a discount of $46.0 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $83.1 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $700.0 million 4.875 percent senior notes were recorded at a par value of $423.2 million less unamortized discounts of $0.3 million, based on an imputed interest rate of 4.89 percent. As of December 31, 2014, the $700.0 million 4.875 percent senior notes were recorded at a par value of $690.0 million less unamortized discounts of $0.5 million based on an imputed interest rate of 4.88 percent.
	-2	During the first quarter of 2015, we purchased $43.8 million of outstanding 4.80 percent senior notes that were trading at a discount of 54.3 percent, which resulted in a gain on extinguishment of $15.6 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $137.8 million of the 4.80 percent senior notes for $112.9 million of the 7.75 percent second lien notes at a discount of $30.5 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $54.6 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $500.0 million 4.80 percent senior notes were recorded at a par value of $308.5 million less unamortized discounts of $0.4 million, based on an imputed interest rate of 4.83 percent. As of December 31, 2014, the $500.0 million 4.80 percent senior notes were recorded at a par value of $490.0 million less unamortized discounts of $0.6 million based on an imputed interest rate of 4.83 percent.
	-3	During the first quarter of 2015, we purchased $45.9 million of outstanding 6.25 percent senior notes that were trading at a discount of 52.5 percent, which resulted in a gain on extinguishment of $15.0 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $261.3 million of the 6.25 percent senior notes for $203.5 million of the 7.75 percent second lien notes at a discount of $55.0 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $107.3 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $800 million 6.25 percent senior notes were recorded at a par value of $492.8 million less unamortized discounts of $5.8 million, based on an imputed interest rate of 6.34 percent. As of December 31, 2014, the $800 million 6.25 percent senior notes were recorded at a par value of $800.0 million less unamortized discounts of $9.5 million based on an imputed interest rate of 6.34 percent.
	-4	During the first quarter of 2015, we purchased $1.3 million of outstanding 5.90 percent senior notes that were trading at a discount of 58.0 percent, which resulted in a gain on extinguishment of $0.3 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $67.0 million of the 5.90 percent senior notes for $57.5 million of the 7.75 percent second lien notes at a discount of $15.5 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $24.5 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $400.0 million 5.90 percent senior notes were recorded at a par value of $326.8 million less unamortized discounts of $1.1 million, based on an imputed interest rate of 5.98 percent. As of December 31, 2014, the $400.0 million 5.90 percent senior notes were recorded at a par value of $395.0 million less unamortized discounts of $1.3 million based on an imputed interest rate of 5.98 percent.
	-5	During the first quarter of 2015, we purchased $44.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 77.5 percent, which resulted in a gain on the extinguishment of debt of $7.1 million. As of March 31, 2015, the $500.0 million 3.95 percent senior notes were recorded at a par value of $436.0 million less unamortized discounts of $2.2 million, based on an imputed interest rate of 6.32 percent. As of December 31, 2014, the $500.0 million 3.95 percent senior notes were recorded at a par value of $480.0 million less unamortized discounts of $2.6 million based on an imputed interest rate of 5.17 percent.
	-6	As of March 31, 2015, the $540.0 million 8.25 percent first lien notes were recorded at a par value of $540.0 million less unamortized discounts of $36.5 million, based on an imputed interest rate of 9.97 percent.
	-7	As of March 31, 2015, the $544.2 million 7.75 percent second lien notes were recorded at a par value of $544.2 million less unamortized discounts of $147.0 million, based on an imputed interest rate of 15.55 percent. See NOTE 6 - FAIR VALUE MEASUREMENTS for further discussion of unamortized discount as a result of the exchange offers.
	-8	As of March 31, 2015, no loans were drawn under the ABL Facility and we had total availability of $441.1 million as a result of borrowing base limitations. As of March 31, 2015, the principal amount of letter of credit obligations totaled $136.2 million and foreign exchange hedge obligations totaled $5.5 million, thereby further reducing available borrowing capacity on our ABL Facility to $299.4 million.
	-9	As of December 31, 2014, we had no revolving loans drawn under the revolving credit agreement of which had $1.125 billion availability. As of December 31, 2014, the principal amount of letter of credit obligations totaled $149.5 million, thereby further reducing available borrowing capacity on the revolving credit agreement to $975.5 million.
	Revolving Credit Facility
	As of March 30, 2015, we eliminated the revolving credit agreement which was last amended on January 22, 2015 (Amendment No. 6). The amended terms waived the potential event of default related to a CCAA filing for Canadian entities. The CCAA filing for our Bloom Lake Group was made subsequent to the effectiveness of this amendment. The amendment also reduced the size of the existing facility from $1.125 billion to $900 million. The revolving credit agreement was replaced with our ABL Facility.
	As of December 31, 2014, we were in compliance with all applicable financial covenants related to the revolving credit agreement.
	ABL Facility
	On March 30, 2015, we entered into a new senior secured asset-based revolving credit facility with various financial institutions. The ABL Facility will mature upon the earlier of March 30, 2020 or 60 days prior to the maturity of the New First Lien Notes (as defined below) and certain other material debt, and provides for up to $550.0 million in borrowings, comprised of (i) a $450.0 million U.S. tranche, including a $250.0 million sublimit for the issuance of letters of credit and a $100.0 million sublimit for U.S. swingline loans, and (ii) a $100.0 million Australian tranche, including a $50.0 million sublimit for the issuance of letters of credit and a $20.0 million sublimit for Australian swingline loans. Availability under both the U.S. tranche and Australian tranche of the ABL Facility is limited to an eligible U.S. borrowing base and Australian borrowing base, as applicable, determined by applying customary advance rates to eligible accounts receivable, inventory and certain mobile equipment. As of March 31, 2015, no loans were drawn under the ABL Facility and we had total availability of $441.1 million on our ABL Facility, as a result of borrowing base limitations. As of March 31, 2015, the principal amount of letter of credit obligations totaled $136.2 million and foreign exchange hedge obligations totaled $5.5 million, thereby reducing available borrowing capacity on our ABL Facility to $299.4 million.
	The ABL Facility and certain bank products and hedge obligations are guaranteed by us and certain of our existing wholly-owned U.S. and Australian subsidiaries and are required to be guaranteed by certain of our future U.S. and Australian subsidiaries; provided, however, that the obligations of any U.S. entity will not be guaranteed by any Australian entity. Amounts outstanding under the ABL Facility will be secured by (i) a first-priority security interest in the ABL Collateral (as defined herein), including, in the case of the Australian tranche only, ABL Collateral owned by a borrower or guarantor that is organized under laws of Australia, and (ii) a third-priority security interest in the Notes Collateral. The priority of the security interests in the ABL Collateral and the Notes Collateral of the lenders under the ABL Facility and the holders of the First Lien Notes are set forth in intercreditor provisions contained in and ABL intercreditor agreement.
	The ABL Collateral generally consists of the following assets of our direct and indirect wholly-owned U.S. subsidiaries (other than certain excluded subsidiaries): accounts receivable and other rights to payment, inventory, as-extracted collateral, investment property, certain general intangibles and commercial tort claims, certain mobile equipment, commodities accounts, deposit accounts, securities accounts and other related assets and proceeds and products of each of the foregoing.
	Borrowings under the ABL Facility bear interest, at our option, at a base rate, an Australian base rate or, if certain conditions are met, a LIBOR rate, in each case plus an applicable margin. The base rate is equal to the greater of the federal funds rate plus ½ of 1 percent, the LIBOR rate based on a one-month interest period plus 1 percent and the floating rate announced by BAML as its “prime rate.” The Australian base rate is equal to the LIBOR rate as of 11:00 a.m. on the first business day of each month for a one-month period. The LIBOR rate is a per annum fixed rate equal to LIBOR with respect to the applicable interest period and amount of LIBOR rate loan requested.
	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, compliance with laws, transactions with affiliates, mergers and sales of all or substantially all of our assets and limitations on changes in the nature of our business.
	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. In the event of a default by us (beyond any applicable grace or cure period, if any), 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 defaults 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.
	As of March 31, 2015, 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.
	$540 Million 8.25% 2020 Senior Secured First Lien Notes - 2015 Offering
	On March 30, 2015, we entered into an indenture among the Company, the guarantors party thereto and U.S. Bank National Association, as trustee and notes collateral agent, relating to our issuance of $540 million aggregate principal amount of 8.25 percent Senior First Lien Notes due 2020 (the "First Lien Notes"). The First Lien Notes were sold on March 30, 2015 in a private transaction exempt from the registration requirements of the Securities Act.
	The First Lien Notes bear interest at a rate of 8.25 percent per annum. Interest on the Notes is payable semi-annually in arrears on March 31 and September 30 of each year, commencing on September 30, 2015. The First Lien Notes mature on March 31, 2020 and are secured senior obligations of the Company.
	The First Lien 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, other than the ABL Collateral (the "Notes Collateral"), 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 the ABL Facility. The First Lien Notes and guarantees are general senior obligations of the Company and the applicable guarantor; are effectively senior to all of our unsecured indebtedness, to the extent of the value of the collateral; together with other obligations secured equally and ratably with the First Lien Notes, are effectively (i) senior to our existing and future ABL obligations, to the extent and value of the Notes Collateral and (ii) senior to our obligations under the Second Lien Notes, to the extent and value of the collateral; are effectively subordinated to (i) our existing and future ABL obligations, to the extent and value of the ABL Collateral, and (ii) any existing or future indebtedness that is secured by liens on assets that do not constitute a part of the collateral, to the extent of the value of such assets; will rank equally in right of payment with all existing and future senior indebtedness, and any guarantees thereof; will rank equally in priority as to the Notes Collateral with any future debt secured equally and ratably with the First Lien Notes incurred after March 30, 2015; rank senior in right of payment to all existing and future subordinated indebtedness; and structurally subordinated to all existing and future indebtedness and other liabilities of our subsidiaries that do not guarantee the First Lien Notes. The relative priority of the liens securing our First Lien Notes obligations and Second Lien Notes obligations compared to the liens securing our obligations under the ABL Facility and certain other matters relating to the administration of security interests are set forth in intercreditor agreements.
	The terms of the First Lien Notes are governed by the First Lien Notes indenture. The First Lien Notes indenture contains customary covenants that, among other things, limit our ability to incur secured indebtedness, create liens on principal property and the capital stock or debt of a subsidiary that owns a principal property, use proceeds of dispositions of collateral, enter into sale and leaseback transactions, merge or consolidate with another company, and transfer or sell all or substantially all of our assets. Upon the occurrence of a “change of control triggering event,” as defined in the indenture, we are required to offer to repurchase the First Lien Notes at 101 percent of the aggregate principal amount thereof, plus any accrued and unpaid interest, if any, to, but excluding, the repurchase date.
	We may redeem any of the First Lien Notes beginning on March 31, 2018. The initial redemption price is 108.25 percent of their principal amount, plus accrued and unpaid interest, if any, to, but excluding, the redemption date. The redemption price will decline after 2018 and will be 100 percent of their principal amount, plus accrued interest, beginning on June 30, 2019. We may also redeem some or all of the First Lien Notes at any time and from time to time prior to March 31, 2018 at a price equal to 100 percent of the principal amount thereof plus a “make-whole” premium, plus accrued and unpaid interest, if any, to, but excluding, the redemption date. In addition, at any time and from time to time on or prior to March 31, 2018, we may redeem in the aggregate up to 35 percent of the original aggregate principal amount of the First Lien Notes (calculated after giving effect to any issuance of additional First Lien Notes) with the net cash proceeds of certain equity offerings, at a redemption price of 108.25 percent, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, so long as at least 65 percent of the original aggregate principal amount of the First Lien Notes (calculated after giving effect to any issuance of additional First Lien Notes) issued under the First Lien Notes indenture remain outstanding after each such redemption.
	The First Lien Notes indenture contains customary events of default, including failure to make required payments, failure to comply with certain agreements or covenants, failure to pay or acceleration of certain other indebtedness, certain events of bankruptcy and insolvency, and failure to pay certain judgments. An event of default under the First Lien indenture will allow either the trustee or the holders of at least 25 percent in aggregate principal amount of the then-outstanding First Lien Notes issued under such indenture to accelerate, or in certain cases, will automatically cause the acceleration of, the amounts due under the First Lien Notes.
	$544 Million Senior Secured Second Lien Notes - 2015 Offering
	On March 30, 2015, we also entered into an indenture among the Company, the guarantors and U.S. Bank National Association, as trustee and notes collateral agent, relating to our issuance of $544.2 million aggregate principal amount of 7.75 percent second lien senior secured notes due 2020 (the "Second Lien Notes"). The Second Lien Notes were issued on March 30, 2015 in exchange offers for certain of our existing senior notes.
	The Second Lien Notes bear interest at a rate of 7.75 percent per annum. Interest on the Second Lien Notes is payable semi-annually in arrears on March 31 and September 30 of each year, commencing on September 30, 2015. The Second Lien Notes mature on March 31, 2020 and are secured senior obligations of the Company.
The Second Lien Notes have substantially similar terms to those of the First Lien Notes except with respect to their priority security interest in the collateral. The Second Lien 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 second-priority lien (junior to the First Lien Notes) on substantially all of our assets, other than the ABL Collateral, and (ii) a third-priority lien (junior to the ABL Facility and the First Lien Notes) on the ABL Collateral.
The Company may redeem any of the Second Lien Notes beginning on March 31, 2017. The initial redemption price is 103.875 percent of their principal amount, plus accrued and unpaid interest, if any, to, but excluding, the redemption date. The redemption price will decline each year after March 31, 2017 and will be 100 percent of their principal amount, plus accrued interest, beginning on March 31, 2019. The Company may also redeem some or all of the Second Lien Notes at any time and from time to time prior to March 31, 2017 at a price equal to 100 percent of the principal amount thereof plus a “make-whole” premium, plus accrued and unpaid interest, if any, to, but excluding, the redemption date. In addition, at any time and from time to time on or prior to March 31, 2017, the Company may redeem in the aggregate up to 35 percent of the original aggregate principal amount of the Second Lien Notes (calculated after giving effect to any issuance of additional Second Lien Notes) with the net cash proceeds of certain equity offerings, at a redemption price of 107.75 percent, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, so long as at least 65 percent of the original aggregate principal amount of the Second Lien Notes (calculated after giving effect to any issuance of additional Second Lien Notes) issued under the Second Lien Notes Indenture remain outstanding after each such redemption.
Letters of Credit
We issued standby letters of credit with certain financial institutions in order to support general business obligations including, but not limited to, workers compensation and environmental obligations. As of March 31, 2015 and December 31, 2014, these letter of credit obligations totaled $136.2 million and $149.5 million, respectively.
Debt Maturities
The following represents a summary of our maturities of debt instruments, excluding borrowings on the ABL Facility, based on the principal amounts outstanding at March 31, 2015:
	(In Millions)
	Maturities of Debt
2015 (April 1 - December 31)	$	—
2016	—
2017	—
2018	436
2019	—
2020	1,719.50
2021 and thereafter	916
Total maturities of debt	$	3,071.50

FAIR_VALUE_OF_FINANCIAL_INSTRU

FAIR VALUE OF FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	NOTE 6 - FAIR VALUE MEASUREMENTS
	The following represents the assets and liabilities of the Company measured at fair value at March 31, 2015 and December 31, 2014:
		(In Millions)
		March 31, 2015
	Description	Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total
		Markets for Identical Assets/Liabilities				(Level 2)				(Level 3)
		(Level 1)
	Assets:
	Cash equivalents	$	120			$	—			$	—			$	120
	Derivative assets	—				—				34.5				34.5
	Available-for-sale marketable securities	2.8				—				—				2.8
	Total	$	122.8			$	—			$	34.5			$	157.3
	Liabilities:
	Derivative liabilities	$	—			$	1.6			$	16.2			$	17.8
	Foreign exchange contracts	—				8.7				—				8.7
	Total	$	—			$	10.3			$	16.2			$	26.5
		(In Millions)
		December 31, 2014
	Description	Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total
		Markets for Identical				(Level 2)				(Level 3)
		Assets/Liabilities (Level 1)
	Assets:
	Derivative assets	$	—			$	—			$	63.2			$	63.2
	Available-for-sale marketable securities	4.3				—				—				4.3
	Total	$	4.3			$	—			$	63.2			$	67.5
	Liabilities:
	Derivative liabilities	$	—			$	—			$	9.5			$	9.5
	Foreign exchange contracts	—				31.5				—				31.5
	Total	$	—			$	31.5			$	9.5			$	41
	Financial assets classified in Level 1 at March 31, 2015 include money market funds and available-for-sale marketable securities. Financial assets classified in Level 1 at December 31, 2014 include available-for-sale marketable securities. The valuation of these instruments is based upon unadjusted quoted prices for identical assets in active markets.
	The valuation of financial assets and liabilities classified in Level 2 is determined using a market approach based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable. Level 2 securities primarily include derivative financial instruments valued using financial models that use as their basis readily observable market parameters. At March 31, 2015 and December 31, 2014, such derivative financial instruments included our existing foreign currency exchange contracts. The fair value of the foreign currency exchange contracts is based on forward market prices and represents the estimated amount we would receive or pay to terminate these agreements at the reporting date, taking into account creditworthiness, nonperformance risk and liquidity risks associated with current market conditions.
	The derivative financial assets classified within Level 3 at March 31, 2015 and December 31, 2014 included a freestanding derivative instrument related to certain supply agreements with one of our U.S. Iron Ore customers. The agreements include provisions for supplemental revenue or refunds based on the customer’s annual steel pricing at the time the product is consumed in the customer’s blast furnaces. We account for this provision as a derivative instrument at the time of sale and adjust this provision to fair value as an adjustment to Product revenues each reporting period until the product is consumed and the amounts are settled. The fair value of the instrument is determined using a market approach based on an estimate of the annual realized price of hot-rolled steel at the steelmaker’s facilities, and takes into consideration current market conditions and nonperformance risk.
	The Level 3 derivative assets and liabilities also consisted of derivatives related to certain provisional pricing arrangements with our U.S. Iron Ore and Asia Pacific Iron Ore customers at March 31, 2015 and December 31, 2014. These provisional pricing arrangements specify provisional price calculations, where the pricing mechanisms generally are based on market pricing, with the final revenue rate to be based on market inputs at a specified point in time in the future, per the terms of the supply agreements. The difference between the provisionally agreed-upon price and the estimated final revenue rate is characterized as a derivative and is required to be accounted for separately once the revenue has been recognized. The derivative instrument is adjusted to fair value through Product revenues each reporting period based upon current market data and forward-looking estimates provided by management until the final revenue rate is determined.
	The following table illustrates information about quantitative inputs and assumptions for the derivative assets and derivative liabilities categorized in Level 3 of the fair value hierarchy:
	Qualitative/Quantitative Information About Level 3 Fair Value Measurements
			(In Millions)				Balance Sheet Location		Valuation Technique		Unobservable Input		Range or Point Estimate per ton
			Fair Value at March 31, 2015										(Weighted Average)
	Provisional Pricing Arrangements		$	16.2			Other current liabilities		Market Approach		Management's		$51
											Estimate of 62% Fe
	Customer Supply Agreement		$	34.5			Other current assets		Market Approach		Hot-Rolled Steel Estimate		$540 - $575 ($563)
	The significant unobservable input used in the fair value measurement of the reporting entity’s provisional pricing arrangements is management’s estimate of 62 percent Fe fines spot price based upon current market data, including historical seasonality and forward-looking estimates determined by management. Significant increases or decreases in this input would result in a significantly higher or lower fair value measurement, respectively.
	The significant unobservable input used in the fair value measurement of the reporting entity’s customer supply agreement is the future hot-rolled steel price that is estimated based on projections provided by the customer, current market data, analysts' projections and forward-looking estimates determined by management. Significant increases or decreases in this input would result in a significantly higher or lower fair value measurement, respectively.
	We recognize any transfers between levels as of the beginning of the reporting period. There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the three months ended March 31, 2015 or 2014. The following tables represent a reconciliation of the changes in fair value of financial instruments measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three months ended March 31, 2015 and 2014.
		(In Millions)
		Derivative Assets (Level 3)
		Three Months Ended
		March 31,
		2015				2014
	Beginning balance	$	63.2			$	57.7
	Total gains (losses)
	Included in earnings	10.1				29
	Settlements	(38.8		)		(43.4		)
	Transfers into Level 3	—				—
	Transfers out of Level 3	—				—
	Ending balance - March 31	$	34.5			$	43.3
	Total gains for the period included in earnings attributable to the change in unrealized gains on assets still held at the reporting date	$	10.1			$	29
		(In Millions)
		Derivative Liabilities (Level 3)
		Three Months Ended
		March 31,
		2015				2014
	Beginning balance	$	(9.5	)		$	(1.0	)
	Total gains (losses)
	Included in earnings	(16.2		)		(4.0		)
Settlements	9.5				1
Transfers into Level 3	—				—
Transfers out of Level 3	—				—
Ending balance - March 31	$	(16.2	)		$	(4.0	)
Total losses for the period included in earnings attributable to the change in unrealized losses on liabilities still held at the reporting date	$	(16.2	)		$	(4.0	)
Gains and losses included in earnings are reported in Product revenues in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 and 2014.
The carrying amount for certain financial instruments (e.g., Accounts receivable, net, Accounts payable and Accrued expenses) approximates fair value and, therefore, has been excluded from the table below. A summary of the carrying amount and fair value of other financial instruments at March 31, 2015 and December 31, 2014 were as follows:
			(In Millions)
			March 31, 2015								December 31, 2014
	Classification		Carrying				Fair Value				Carrying				Fair Value
			Value								Value
Long-term debt:
Senior notes—$700 million	Level 1		$	422.9			$	220			$	689.5			$	367.3
Senior notes—$1.3 billion	Level 1		795.1				425.8				1,279.90				704
Senior notes—$400 million	Level 1		325.7				190.5				393.7				228.1
Senior notes—$500 million	Level 1		433.8				337.9				477.4				312
Senior First Lien Notes —$540 million	Level 1		503.5				507.6				—				—
Senior Second Lien Notes —$544.2 million	Level 2		397.2				397.2				—				—
Asset-Based Revolving Credit Facility	Level 2		—				—				—				—
Fair value adjustment to interest rate hedge	Level 2		2.7				2.7				2.8				2.8
Total long-term debt			$	2,880.90			$	2,081.70			$	2,843.30			$	1,614.20
The fair value of long-term debt was determined using quoted market prices based upon current borrowing rates. The asset based lending credit facility is variable rate interest and approximates fair value. See NOTE 5 - DEBT AND CREDIT FACILITIES for further information.
Items Measured at Fair Value on a Non-Recurring Basis
The following tables present information about the financial and non-financial assets and liabilities that were measured on a fair value basis at March 31, 2015 and December 31, 2014. The tables also indicate the fair value hierarchy of the valuation techniques used to determine such fair value.
		(In Millions)
		31-Mar-15
Description		Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total			Total Gains
		Markets for Identical Assets/				(Level 2)				(Level 3)
		Liabilities
		(Level 1)
Liabilities:
$544.2 Million 7.75% 2020 Second Lien Notes		$	—			$	397.2			$	—			$	397.2		$	269.5
		$	—			$	397.2			$	—			$	397.2		$	269.5
The $544.2 million 7.75 percent Second Lien Notes issued in the exchange offers were recorded as an extinguishment of debt as the change in debt terms was considered substantial. As such, the newly issued Second Lien Senior Notes were recorded at fair value at the issuance date. In order to determine the fair value of the Second Lien Senior Notes on the date of the exchange, we utilized the median bid ask spread obtained from various investment banks for the exchange date. The bid ask spread is indicative of the fair value of the notes on the exchange date. The 27.0 percent discount equated to a discount of $147.0 million on the issue value of $544.2 million, or an estimated fair value of $397.2 million.
		(In Millions)
		31-Dec-14
Description		Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total			Total Losses
		Markets for Identical Assets/				(Level 2)				(Level 3)
		Liabilities
		(Level 1)
Assets:
Goodwill impairment -		$	—			$	—			$	—			$	—		$	73.5
Asia Pacific Iron Ore reporting unit
Other long-lived assets -
Property, plant and equipment
and Mineral rights:
Asia Pacific Iron Ore reporting unit		—				—				72.4				72.4			526.5
Other reporting units		—				—				—				—			11.3
Other long-lived assets -
Intangibles and other long-term assets:
Asia Pacific Iron Ore reporting unit		—				—				7				7			24.2
Investment in ventures		—				—				—				—			9.2
impairment - Global Exploration
		$	—			$	—			$	79.4			$	79.4		$	644.7
Financial Assets
During the third quarter of 2014, an impairment charge of $9.2 million to investment in ventures was recorded within our Global Exploration operating segment as a decision was made to abandon the investment during the period.
Non-Financial Assets
During the third and fourth quarter of 2014, we identified factors that indicated the carrying values of the asset groups in the chart above may not be recoverable primarily due to long-term price forecasts as part of management’s long-range planning process. Updated estimates of long-term prices for all products, specifically the Platts 62 percent Fe fines spot price were lower than prior estimates. This especially affects the Asia Pacific Iron Ore business segment because their contracts correlate heavily to world market spot pricing. These estimates were updated based upon current market conditions, macro-economic factors influencing the balance of supply and demand for our products and expectations for future cost and capital expenditure requirements. Additionally, our CEO, Lourenco Goncalves, was appointed by the Board of Directors in early August 2014 and was subsequently identified as the CODM in accordance with ASC 280, Segment Reporting. Our CODM views Asia Pacific Iron Ore as a non-core asset and has communicated plans to evaluate the business unit for a change in strategy including possible divestiture. These factors, among other considerations utilized in the individual impairment assessments, indicate that the carrying value of the respective asset groups in the chart above and Asia Pacific Iron Ore goodwill may not be recoverable.
During the third quarter of 2014, a goodwill impairment charge of $73.5 million was recorded for our Asia Pacific Iron Ore reporting units within our Asia Pacific Iron Ore operating segment. Based on our review of the fair value hierarchy, the inputs used in these fair value measurements were considered Level 3 inputs.
We also recorded impairment charges to property, plant and equipment, mineral rights, intangible assets and other long-term assets during the second half of 2014 related to our Asia Pacific Iron Ore operating segment, along with impairments charged to reporting units within our Other reportable segments. A detailed break out of the impairment charges is shown in the chart above. The recorded impairment charges reduce the related assets to their estimated fair value as we determined that the future cash flows associated with these operations were not sufficient to support the recoverability of the carrying value of these assets. Fair value was determined based on management's best estimate within a range of fair values, which is considered a Level 3 input, and resulted in an asset impairment charge of $562.0 million. The Level 3 inputs used to determine fair value included models developed and market inputs obtained by management which provided a range of fair value estimates of property, plant and equipment. Management’s models include internally developed long-term future cash flow estimates, capital expenditure and cost estimates, market inputs to determine long-term pricing assumptions, discount rates, and foreign exchange rates.

PENSIONS_AND_OTHER_POSTRETIREM

PENSIONS AND OTHER POSTRETIREMENT BENEFITS	3 Months Ended
	Mar. 31, 2015
Postemployment Benefits [Abstract]
PENSIONS AND OTHER POSTRETIREMENT BENEFITS	NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS
	The following are the components of defined benefit pension and OPEB expense for the three months ended March 31, 2015 and 2014:
	Defined Benefit Pension Expense
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Service cost	$	6.3		$	6.7
	Interest cost	9.4			10.1
	Expected return on plan assets	(14.9		)	(14.5		)
	Amortization:
	Prior service costs	0.6			0.6
	Net actuarial loss	5.4			3.5
	Curtailments/settlements	0.3			0.3
	Net periodic benefit cost to continuing operations	$	7.1		$	6.7
	Other Postretirement Benefits Expense
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Service cost	$	1.5		$	1.7
	Interest cost	3.3			3.4
	Expected return on plan assets	(4.6		)	(4.3		)
	Amortization:
	Prior service costs	(0.9		)	(0.9		)
	Net actuarial loss	3.1			1.3
	Net periodic benefit cost to continuing operations	$	2.4		$	1.2
	We made pension contributions of $3.9 million for the three months ended March 31, 2015, compared to pension contributions of $4.0 million for the three months ended March 31, 2014. OPEB contributions are typically made on an annual basis in the first quarter of each year, but due to plan funding requirements being met, no OPEB contributions were required or made for the three months ended March 31, 2015 and March 31, 2014.

STOCK_COMPENSATION_PLANS

STOCK COMPENSATION PLANS	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK COMPENSATION PLANS	NOTE 8 - STOCK COMPENSATION PLANS
	Employees’ Plans
	The Compensation and Organization Committee of the Board of Directors approved grants under the 2012 Amended Equity Plan to certain officers and employees for the 2015 to 2017 performance period. Shares granted under the awards during 2015 consisted of 0.9 million performance shares based on TSR, 0.9 million restricted share units and 0.4 million stock options, each of which may or may not convert into shares based on our shares achieving and maintaining certain milestones above an absolute threshold during the performance period.
	For the outstanding 2012 Equity Plan awards that were issued subsequent to October 2013 and the 2012 Amended Equity Plan awards, each performance share, if earned, entitles the holder to receive common shares or cash within a range between a threshold and maximum number of our common shares, with the actual number of common shares earned dependent upon whether the Company achieves certain objectives and performance goals as established by the Compensation and Organization Committee. The performance share or unit grants vest over a period of three years and are intended to be paid out in common shares or cash in certain circumstances. Performance for the 2015 to 2017 performance period 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 on the last day of trading of the performance period. The final payouts for the 2015 to 2017 performance period grants will vary from zero to 200 percent of the original grant.
	The restricted share units are subject to continued employment, are retention based, will vest in equal thirds on each of December 31, 2015, December 31, 2016 and December 31, 2017, and are payable in common shares or cash in certain circumstances at a time determined by the Committee at its discretion.
	The stock options vest on December 31, 2017, subject to continued employment through the vesting date, are exercisable at a strike price of $7.70 after the vesting date and expire on January 12, 2025.
	Determination of Fair Value
	The fair value of each performance share grant is estimated on the date of grant using a Monte Carlo simulation to forecast relative TSR performance. A correlation matrix of historic and projected stock prices was developed for both the Company and our predetermined peer group of mining and metals companies. The fair value assumes that performance goals will be achieved.
	The expected term of the grant represents the time from the grant date to the end of the service period for each of the three plan-year agreements. We estimate the volatility of our common shares and that of the peer group of mining and metals 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 life of the performance period.
	The following assumptions were utilized to estimate the fair value for the first quarter of 2015 performance share grants:
	Grant Date	Grant Date Market Price		Average Expected Term (Years)	Expected Volatility	Risk-Free Interest Rate	Dividend Yield	Fair Value		Fair Value (Percent of Grant Date Market Price)
	January 12, 2015	$	7.7	2.97	58.30%	0.91%	—%	$	11.56	150.13%
	February 9, 2015	$	6.57	2.89	58.30%	0.87%	—%	$	9.86	150.13%
	The fair value of each stock option grant is estimated on the date of grant using a Black-Scholes valuation model. The expected term of the option grant is determined using the simplified method. We estimate the volatility of our common shares using historical stock prices with consistent frequency over the most recent historical period equal to the option’s expected term. The risk-free interest rate is the rate at the grant date on zero-coupon government bonds, with a term commensurate with the expected term.
	The following assumptions were utilized to estimate the fair value for the first quarter of 2015 stock option grants:
	Grant Date	Grant Date Market Price		Average Expected Term (Years)	Expected Volatility	Risk-Free Interest Rate	Dividend Yield	Fair Value
	January 12, 2015	$	7.7	6.47	75.30%	1.60%	—%	$	5.23
	The fair value of the restricted share units is determined based on the closing price of our common shares on the grant date. The restricted share units granted under either the 2012 Equity Plan or the 2012 Amended Equity Plan generally vest over a period of three years.

INCOME_TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 9 - INCOME TAXES
	For the three months ended March 31, 2015, we recorded an income tax expense in continuing operations of $175.1 million compared with an expense of $29.6 million for the comparable prior-year period. The increase of income tax expense was primarily driven by the placement of a valuation allowance against U.S. deferred tax assets that were recognized in prior years.
	We determined our interim tax provision using a methodology required by ASC 740, Income Taxes, as it is the Company’s position that the use of an estimated annual effective tax rate would not be reliable. The year-to-date expense was calculated using the year-to-date income, considering non-taxable and non-deductible items expected to be incurred for the full year unless those items are expected to be ratably incurred based on operating activity or profitability, (e.g. depletion), in which case we only considered year-to-date actual amounts, multiplied by the statutory rate and offset by the computed valuation allowance.
	There were discrete items recorded in the first quarter of 2015 which resulted in a $167.5 million expense. These adjustments relate primarily to the placement of a valuation allowance against US deferred tax assets that were recognized in prior years.

LEASE_OBLIGATIONS

LEASE OBLIGATIONS	3 Months Ended
	Mar. 31, 2015
Leases [Abstract]
LEASE OBLIGATIONS	NOTE 10 - LEASE OBLIGATIONS
	We lease certain mining, production and other equipment under operating and capital leases. The leases are for varying lengths, generally at market interest rates and contain purchase and/or renewal options at the end of the terms. Our operating lease expense was $4.3 million for the three months ended March 31, 2015, respectively, compared with $6.2 million for the same respective period in 2014.
	Future minimum payments under capital leases and non-cancellable operating leases at March 31, 2015 are as follows:
		(In Millions)
		Capital Leases			Operating Leases
	2015 (April 1 - December 31)	$	20.5		$	7.5
	2016	25.8			7.9
	2017	22.8			7.3
	2018	18.4			6.6
	2019	10			4.8
	2020 and thereafter	18.8			9.9
	Total minimum lease payments	$	116.3		$	44
	Amounts representing interest	25.1
	Present value of net minimum lease payments	$	91.2	(1)
	(1)	The total is comprised of $19.5 million and $71.7 million classified as Other current liabilities and Other liabilities, respectively, in the Statements of Unaudited Condensed Consolidated Financial Position at March 31, 2015.

ENVIRONMENTAL_AND_MINE_CLOSURE

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS	3 Months Ended
	Mar. 31, 2015
Environmental Remediation Obligations [Abstract]
ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS	NOTE 11 - ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS
	We had environmental and mine closure liabilities of $169.0 million and $170.8 million at March 31, 2015 and December 31, 2014, respectively. The following is a summary of the obligations as of March 31, 2015 and December 31, 2014:
		(In Millions)
		March 31,			December 31,
		2015			2014
	Environmental	$	3.7		$	5.5
	Mine closure
	LTVSMC	23.2			22.9
	Operating mines:
	U.S. Iron Ore	121.8			120.9
	Asia Pacific Iron Ore	20.3			21.5
	Total mine closure	165.3			165.3
	Total environmental and mine closure obligations	169			170.8
	Less current portion	3.4			5.2
	Long term environmental and mine closure obligations	$	165.6		$	165.6
	Mine Closure
	The accrued closure obligation for our active mining operations provides for contractual and legal obligations associated with the eventual closure of the mining operations. The accretion of the liability and amortization of the related asset is recognized over the estimated mine lives for each location.
	The following represents a rollforward of our asset retirement obligation liability related to our active mining locations for the three months ended March 31, 2015 and for the year ended December 31, 2014:
		(In Millions)
		March 31,			December 31,
		2015			2014 (1)
	Asset retirement obligation at beginning of period	$	142.4		$	177.6
	Accretion expense	1.2			5.7
	Exchange rate changes	(1.5		)	(2.4		)
	Revision in estimated cash flows	—			(38.5		)
	Asset retirement obligation at end of period	$	142.1		$	142.4
	(1) Represents a 12-month rollforward of our asset retirement obligation at December 31, 2014.

GOODWILL_AND_OTHER_INTANGIBLE_

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES	NOTE 12 - GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES
	Goodwill
	The following table summarizes changes in the carrying amount of goodwill allocated by operating segment for the three months ended March 31, 2015 and the year ended December 31, 2014:
		(In Millions)
		31-Mar-15												December 31, 2014
		U.S. Iron Ore				Asia Pacific				Total				U.S. Iron Ore				Asia Pacific Iron Ore				Total
						Iron Ore
	Beginning Balance	$	2			$	—			$	2			$	2			$	72.5			$	74.5
	Arising in business combinations	—				—				—				—				—				—
	Impairment	—				—				—				—				(73.5		)		(73.5		)
	Impact of foreign currency translation	—				—				—				—				1				1
	Ending Balance	$	2			$	—			$	2			$	2			$	—			$	2
	Accumulated goodwill impairment loss	$	—			$	(73.5	)		$	(73.5	)		$	—			$	(73.5	)		$	(73.5	)
	Other Intangible Assets and Liabilities
	The following table is a summary of intangible assets and liabilities as of March 31, 2015 and December 31, 2014:
				(In Millions)
				31-Mar-15												31-Dec-14
		Classification		Gross				Accumulated				Net				Gross				Accumulated				Net
				Carrying				Amortization				Carrying				Carrying				Amortization				Carrying
				Amount								Amount				Amount								Amount
	Definite-lived intangible assets:
	Permits	Other non-current assets		$	78.7			$	(17.5	)		$	61.2			$	79.2			$	(16.5	)		$	62.7
	Total intangible assets			$	78.7			$	(17.5	)		$	61.2			$	79.2			$	(16.5	)		$	62.7
	Below-market sales contracts	Other current liabilities		$	(23.0	)		$	—			$	(23.0	)		$	(23.0	)		$	—			$	(23.0	)
	Below-market sales contracts	Other liabilities		(205.9		)		182.8				(23.1		)		(205.9		)		182.8				(23.1		)
	Total below-market sales contracts			$	(228.9	)		$	182.8			$	(46.1	)		$	(228.9	)		$	182.8			$	(46.1	)
	Amortization expense relating to intangible assets was $1.1 million for the three months ended March 31, 2015 and is recognized in Cost of goods sold and operating expenses in the Statements of Unaudited Condensed Consolidated Operations. Amortization expense relating to intangible assets was $2.3 million for the comparable period in 2014. The estimated amortization expense relating to intangible assets for the remainder of this year and each of the five succeeding years is as follows:
		(In Millions)
		Amount
	Year Ending December 31,
	2015 (remaining nine months)	$	3
	2016	4
	2017	4
	2018	4.2
	2019	3.1
	2020	2.5
	Total	$	20.8
	The below-market sales contract is classified as a liability and recognized over the term of the underlying contract, which has a remaining life of approximately two years and expires December 31, 2016. For the three months ended March 31, 2015 and 2014, there were no Product revenues related to the below-market sales contract due to the timing of the Great Lakes shipping season. The following amounts are estimated to be recognized in Product revenues for the remainder of this year and the succeeding fiscal year:
		(In Millions)
		Amount
	Year Ending December 31,
	2015 (remaining nine months)	$	23
	2016	23.1
	Total	$	46.1

DERIVATIVE_INSTRUMENTS_AND_HED

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES
	The following table presents the fair value of our derivative instruments and the classification of each in the Statements of Unaudited Condensed Consolidated Financial Position as of March 31, 2015 and December 31, 2014:
		(In Millions)
		Derivative Assets												Derivative Liabilities
		March 31, 2015						December 31, 2014						March 31, 2015				31-Dec-14
	Derivative Instrument	Balance Sheet Location		Fair				Balance		Fair				Balance Sheet	Fair			Balance Sheet	Fair
				Value				Sheet		Value				Location	Value			Location	Value
								Location
	Derivatives designated as hedging instruments under ASC 815:
	Foreign Exchange Contracts			$	—					$	—				$	—		Other current liabilities	$	21.6
	Total derivatives designated as hedging instruments under ASC 815			$	—					$	—				$	—			$	21.6
	Derivatives not designated as hedging instruments under ASC 815:
	Foreign Exchange Contracts			$	—					$	—			Other current liabilities	$	8.7		Other current liabilities	$	9.9
	Commodity Contracts			—						—				Other current liabilities	1.6				—
	Customer Supply Agreement	Other current assets		34.5				Other current assets		63.2					—				—
	Provisional Pricing Arrangements			—						—				Other current liabilities	16.2			Other current liabilities	9.5
	Total derivatives not designated as hedging instruments under ASC 815			$	34.5					$	63.2				$	26.5			$	19.4
	Total derivatives			$	34.5					$	63.2				$	26.5			$	41
	Derivatives Designated as Hedging Instruments
	Cash Flow Hedges
	Australian Dollar Foreign Exchange Contracts
	We are subject to changes in foreign currency exchange rates as a result of our operations in Australia and Canada. With respect to Australia, foreign exchange risk arises from our exposure to fluctuations in foreign currency exchange rates because the functional currency of our Asia Pacific operations is the Australian dollar. Our Asia Pacific operations receive funds in U.S. currency for their iron ore sales.
	We use foreign currency exchange contracts to hedge our foreign currency exposure for a portion of our U.S. dollar sales receipts in our Australian functional currency entities and our entities with Canadian dollar operating costs. For our Australian operations, U.S. dollars are converted to Australian dollars at the currency exchange rate in effect during the period the transaction occurred. The primary objective for the use of these instruments is to reduce exposure to changes in currency exchange rates and to protect against undue adverse movement in these exchange rates. These instruments qualify for hedge accounting treatment and are tested for effectiveness at inception and at least once each reporting period. If and when any of our hedge contracts are determined not to be highly effective as hedges, the underlying hedged transaction is no longer likely to occur, or the derivative is terminated, hedge accounting is discontinued. Due to the uncertainty of 2015 hedge exposures, we have suspended entering into new foreign exchange rate contracts. As discussed in NOTE 1 - BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES, we have waived compliance with our current derivative financial instruments and hedging activities policy through December 31, 2015.
	As of March 31, 2015, we had outstanding Australian foreign currency exchange contracts with notional amounts of $20.0 million in the form of forward contracts for which we elected hedge accounting. One outstanding Australian foreign exchange rate contract matures in May 2015 and the other matures in September 2015. This compares with outstanding Australian foreign currency exchange contracts with a notional amount of $220.0 million as of December 31, 2014.
	Changes in fair value of highly effective hedges are recorded as a component of Accumulated other comprehensive loss in the Statements of Unaudited Condensed Consolidated Financial Position. Any ineffectiveness is recognized immediately in income. As of March 31, 2015 and 2014, there was no material ineffectiveness recorded for foreign exchange contracts that were classified as cash flow hedges. However, certain Australian hedge contracts were deemed ineffective during the first quarter of 2015 and no longer qualified for hedge accounting treatment. All of these de-designated hedges were settled and were no longer outstanding by March 31, 2015. The de-designated hedges are discussed within the Derivatives Not Designated as Hedging Instruments section of this footnote. Amounts recorded as a component of Accumulated other comprehensive loss are reclassified into earnings in the same period the forecasted transactions affect earnings. Of the amounts remaining in Accumulated other comprehensive loss related to the designated Australian hedge contracts, we estimate that losses of $2.2 million (net of tax), respectively, will be reclassified into earnings within the next 12 months.
	The following summarizes the effect of our derivatives designated as cash flow hedging instruments, net of tax in Accumulated other comprehensive loss in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 and 2014:
		(In Millions)
	Derivatives in Cash Flow Hedging Relationships	Amount of Gain (Loss)								Location of Gain (Loss)		Amount of Gain (Loss)
		Recognized in OCI on Derivatives								Reclassified		Reclassified
										from Accumulated OCI into Earnings		from Accumulated
												OCI into Earnings
		(Effective Portion)								(Effective Portion)		(Effective Portion)
		Three Months Ended										Three Months Ended
		March 31,										March 31,
		2015				2014						2015			2014
	Australian Dollar Foreign	$	(2.6	)		$	5.5			Product revenues		$	(6.3	)	$	(9.1	)
	Exchange Contracts
	(hedge designation)
	Australian Dollar Foreign	(4.5		)		—				Product revenues		—			—
	Exchange Contracts
	(prior to de-designation)
	Canadian Dollar Foreign Exchange Contracts	—				(7.8		)		Cost of goods sold and operating expenses		—			(3.4		)
	(hedge designation)
	Canadian Dollar Foreign Exchange Contracts	—				—				Cost of goods sold and operating expenses		—			(0.3		)
	(prior to de-designation)
		$	(7.1	)		$	(2.3	)				$	(6.3	)	$	(12.8	)
	Derivatives Not Designated as Hedging Instruments
	Foreign Exchange Contracts
	During the first quarter of 2015, in connection with our refinancing initiatives, we discontinued hedge accounting and early-settled certain of our Australian foreign currency exchange contracts associated with Asia Pacific Iron Ore operations. Subsequent to de-designation, no further foreign currency exchange rate contracts were entered into for the Asia Pacific Iron Ore operations. The amounts that were previously recorded as a component of Accumulated other comprehensive loss prior to de-designation and remaining in Accumulated other comprehensive loss as of March 31, 2015 will be reclassified to earnings and a corresponding realized gain or loss will be recognized when the forecasted cash flow occurs. The hedges were de-designated at the end of the first quarter of 2015. No forecasted cash flows have occurred related to the de-designated contracts between the de-designation date and March 31, 2015. For the three months ended March 31, 2015, prior to the de-designation of the Asia Pacific Iron Ore hedges, we reclassified losses of $6.3 million from Accumulated other comprehensive loss related to contracts that matured during the year, and recorded the amounts as Product revenues on the Statements of Unaudited Condensed Consolidated Operations. As of March 31, 2015, losses of $12.5 million (net of tax) remain in Accumulated other comprehensive loss related to the effective cash flow hedge contracts prior to de-designation and early-settlement. We estimate the remaining losses of $12.5 million (net of tax) will be reclassified to Product revenues during the remainder of 2015 upon the occurrence of the related forecasted cash flows.
	During the fourth quarter of 2014, we discontinued hedge accounting for Canadian foreign currency exchange contracts for all outstanding contracts associated with Bloom Lake operations as projected future cash flows were no longer considered probable or reasonably possible, but we continued to hold these instruments as economic hedges to manage currency risk. Our parent company holds the Canadian foreign currency exchange contracts and the contracts were unaffected by Bloom Lake General Partner Limited and certain of its affiliates filing under the CCAA on January 27, 2015. Subsequent to de-designation, no further foreign currency exchange contracts were entered into for the Bloom Lake operations. As of March 31, 2015 and December 31, 2014, the de-designated outstanding foreign exchange rate contracts had notional amounts of $41.4 million and $183.0 million in the form of forward contracts, respectively. The outstanding contracts as of March 31, 2015 have varying maturity dates ranging from May 2015 to September 2015.
	The amounts that were previously recorded as a component of Accumulated other comprehensive loss prior to de-designation and remaining in Accumulated other comprehensive loss as of December 31, 2014 were reclassified to earnings upon the de-designation of the hedges as the hedges would not be effective prospectively due to the projected future cash flows associated with the hedges no longer being considered probable or reasonably possible. We reclassified losses of $7.3 million from Accumulated other comprehensive loss related to contracts that had not matured during the year, and recorded the amounts as Cost of goods sold and operating expenses on the Statements of Unaudited Condensed Consolidated Operations. A corresponding realized gain or loss is recognized in each period until settlement of the related economic hedge during 2015.
	We previously discontinued hedge accounting for Canadian foreign currency exchange contracts for all outstanding contracts associated with the Wabush operation and the Ferroalloys operating segment as projected future cash flows were no longer considered probable, but we continued to hold these instruments as economic hedges to manage currency risk. Subsequent to de-designation, no further foreign currency exchange contracts were entered into for the Wabush operation or the Ferroalloys operating segment. As of March 31, 2015 and December 31, 2014, there were no outstanding de-designated foreign currency exchange rate contracts as all remaining de-designated foreign exchange contracts matured during the second quarter of 2014.
	Prior to the maturation of the contracts and as a result of discontinued hedge accounting, the instruments were prospectively adjusted to fair value each reporting period through Cost of goods sold and operating expenses on the Statements of Unaudited Condensed Consolidated Operations. For the three months ended March 31, 2014, the change in fair value of our de-designated foreign currency exchange contracts resulted in net losses of $0.9 million. The amounts that were previously recorded as a component of Accumulated other comprehensive loss prior to de-designation were reclassified to earnings and a corresponding realized gain or loss was recognized when the forecasted cash flow occurred. For the three months ended March 31, 2014, we reclassified losses of $0.3 million from Accumulated other comprehensive loss related to contracts that matured during the period, and recorded the amounts as Cost of goods sold and operating expenses on the Statements of Unaudited Condensed Consolidated Operations.
	Fair Value Hedges
	Interest Rate Hedges
	Our fixed-to-variable interest rate swap derivative instruments, with a notional amount of $250.0 million, were de-designated and settled during August 2014. Prior to settlement, the derivatives were designated and qualified as fair value hedges. The objective of the hedges was to offset changes in the fair value of our debt instruments associated with fluctuations in the benchmark LIBOR interest rate as part of our risk management strategy.
	Prior to de-designation and settlement, when the interest rate swap derivative instruments were designated and qualified as fair-value hedges, the gain or loss on the hedge instrument as well as the offsetting loss or gain on the hedged item attributable to the hedged risk were recognized in net income. We included the gain or loss on the derivative instrument and the offsetting loss or gain on the hedged item in Other non-operating income (expense). The net gain recognized in Other non-operating income (expense) for the three months ended March 31, 2014 was $0.2 million.
	Customer Supply Agreements
	Most of our U.S. Iron Ore long-term supply agreements are comprised of a base price with annual price adjustment factors. The base price is the primary component of the purchase price for each contract. The indexed price adjustment factors are integral to the iron ore supply contracts and vary based on the agreement, but typically include adjustments based upon changes in the Platts 62 percent Fe fines spot price and/or international pellet prices and changes in specified Producer Price Indices, including those for industrial commodities, energy and steel. The pricing adjustments generally operate in the same manner, with each factor typically comprising a portion of the price adjustment, although the weighting of each factor varies based upon the specific terms of each agreement. In most cases, these adjustment factors have not been finalized at the time our product is sold. In these cases, we historically have estimated the adjustment factors at each reporting period based upon the best third-party information available. The estimates are then adjusted to actual when the information has been finalized. The price adjustment factors have been evaluated to determine if they contain embedded derivatives. The price adjustment factors share the same economic characteristics and risks as the host contract and are integral to the host contract as inflation adjustments; accordingly, they have not been separately valued as derivative instruments. Certain of our term supply agreements contain price collars, which typically limit the percentage increase or decrease in prices for our products during any given year.
	A certain supply agreement with one U.S. Iron Ore customer provides for supplemental revenue or refunds to the customer based on the customer’s average annual steel pricing at the time the product is consumed in the customer’s blast furnace. The supplemental pricing is characterized as a freestanding derivative and is required to be accounted for separately once the product is shipped. The derivative instrument, which is finalized based on a future price, is adjusted to fair value as a revenue adjustment each reporting period until the pellets are consumed and the amounts are settled.
	We recognized $10.1 million as Product revenues in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 related to the supplemental payments. This compares with Product revenues of $27.7 million for the comparable period in 2014. Derivative assets, representing the fair value of the pricing factors, were $34.5 million and $63.2 million in the March 31, 2015 and December 31, 2014 Statements of Unaudited Condensed Consolidated Financial Position, respectively.
	Provisional Pricing Arrangements
	Certain of our U.S. Iron Ore and Asia Pacific Iron Ore customer supply agreements specify provisional price calculations, where the pricing mechanisms generally are based on market pricing, with the final revenue rate to be based on market inputs at a specified period in time in the future, per the terms of the supply agreements. The difference between the provisionally agreed-upon price and the estimated final revenue rate is characterized as a freestanding derivative and is required to be accounted for separately once the provisional revenue has been recognized. The derivative instrument is adjusted to fair value through Product revenues each reporting period based upon current market data and forward-looking estimates provided by management until the final revenue rate is determined. At March 31, 2015 and December 31, 2014, we recorded no Other current assets related to our estimate of the final revenue rate with any of our customers. At March 31, 2015 and December 31, 2014, we recorded $16.2 million and $9.5 million, respectively, as Other current liabilities in the Statements of Unaudited Condensed Consolidated Financial Position related to our estimate of the final revenue rate with our U.S. Iron Ore and Asia Pacific Iron Ore customers. These amounts represent the difference between the provisional price agreed upon with our customers based on the supply agreement terms and our estimate of the final revenue rate based on the price calculations established in the supply agreements. As a result, we recognized a net $16.2 million decrease in Product revenues in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 related to these arrangements. This compares with a net $2.7 million decrease in Product revenues for the comparable period in 2014.
	The following summarizes the effect of our derivatives that are not designated as hedging instruments in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 and 2014:
(In Millions)
Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized in	Amount of Gain (Loss) Recognized in Income on Derivative
	Income on Derivative
		Three Months Ended
		March 31,
		2015				2014
Foreign Exchange Contracts	Other non-operating income (expense) (1)	$	(5.9	)		$	(0.9	)
Commodity Contracts	Cost of goods sold and operating expenses	(3.6		)		—
Customer Supply Agreement	Product revenues	10.1				27.7
Provisional Pricing Arrangements	Product revenues	(16.2		)		(2.7		)
		$	(15.6	)		$	24.1
(1)	At March 31, 2014, the location of the Gain (Loss) Recognized in Income on Derivative for Foreign Exchange Contracts was Cost of goods sold and operating expenses.
Refer to NOTE 6 - FAIR VALUE MEASUREMENTS for additional information.

DISCONTINUED_OPERATIONS_DISCON

DISCONTINUED OPERATIONS DISCONTINUED OPERATIONS	3 Months Ended
	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	NOTE 14 - DISCONTINUED OPERATIONS
	The information below sets forth selected financial information related to operating results of our businesses classified as discontinued operations. While the reclassification of revenues and expenses related to discontinued operations from prior periods have no impact upon previously reported net income, the Statements of Unaudited Condensed Consolidated Operations present the revenues and expenses that were reclassified from the specified line items to discontinued operations and the Statements of Unaudited Condensed Consolidated Financial Position present the assets and liabilities that were reclassified from the specified line items to assets and liabilities of discontinued operations.
	The chart below provides an asset group breakout for each financial statement line impacted by discontinued operations.
						Canadian Operations
			North American Coal			Eastern Canadian Iron Ore			Other			Total Canadian Operations				Total of Discontinued Operations
	Statements of Unaudited Condensed Consolidated Operations
	Loss from Discontinued Operations, net of tax	YTD	$	(75.7	)	$	(852.7	)	$	(0.1	)	$	(852.8	)		$	(928.5	)
		31-Mar-15
	Loss from Discontinued Operations, net of tax	YTD	$	(46.3	)	$	(91.2	)	$	(2.9	)	$	(94.1	)		$	(140.4	)
		31-Mar-14
	Statements of Unaudited Condensed Consolidated Financial Position
	Short-term assets of discontinued operations	As of	$	188.6		$	8.6		$	—		$	8.6			$	197.2
		31-Mar-15
	Long-term assets of discontinued operations	As of	$	—		$	—		$	—		$	—			$	—
		31-Mar-15
	Short-term liabilities of discontinued operations	As of	$	197.7		$	67.3		$	—		$	67.3			$	265
		31-Mar-15
	Long-term liabilities of discontinued operations	As of	$	—		$	125.2		$	—		$	125.2			$	125.2
		31-Mar-15
	Short-term assets of discontinued operations	As of	$	143.8		$	183.5		$	3.3		$	186.8			$	330.6
		31-Dec-14
	Long-term assets of discontinued operations	As of	$	130.4		$	256		$	13.7		$	269.7			$	400.1
		31-Dec-14
	Short-term liabilities of discontinued operations	As of	$	81.3		$	316.3		$	3		$	319.3			$	400.6
		31-Dec-14
	Long-term liabilities of discontinued operations	As of	$	125.9		$	304.6		$	5.6		$	310.2			$	436.1
		31-Dec-14
	Non-Cash Operating and Investing Activities
	Depreciation, depletion and amortization:	YTD	$	3.2		$	—		$	—		$	—			$	3.2
		31-Mar-15
	Purchase of property, plant and equipment	YTD	$	2.5		$	—		$	—		$	—			$	2.5
		31-Mar-15
	Impairment of long-lived assets	YTD	$	73.4		$	—		$	—		$	—			$	73.4
		31-Mar-15
	Depreciation, depletion and amortization:	YTD	$	29.9		$	41.2		$	0.1		$	41.3			$	71.2
		31-Mar-14
	Purchase of property, plant and equipment	YTD	$	10		$	75.6		$	—		$	75.6			$	85.6
		31-Mar-14
	Impairment of long-lived assets	YTD	$	—		$	—		$	—		$	—			$	—
		31-Mar-14
	North American Coal Operations
	Background
	As we continue to refine our strategy to one that focuses on strengthening our U.S. Iron Ore operations, management has determined that our North American Coal operating segment as of March 31, 2015 met the criteria to be classified as held for sale under ASC 205 - Presentation of Financial Statements. As such, all current and historical North American Coal operating segment results are included in our financial statement and classified within discontinued operations. Consistent with our strategy to extract maximum value from our current assets, we plan to sell the North American Coal assets within the current year. In the first quarter of 2015, as part of the held for sale classification assigned to North American Coal, an impairment of $73.4 million was recorded. The impairment charge was to reduce the assets to their estimated fair value which was determined based on potential sales scenarios.
	Loss on Discontinued Operations
	Our planned sale of the Oak Grove and Pinnacle mine assets represents a strategic shift in our business. For this reason, our previously reported North American Coal operating segment results for all periods, prior to the March 31, 2015 held for sale determination, are classified as discontinued operations. This includes our CLCC assets, which were sold during the fourth quarter of 2014.
			(In Millions)
			Three Months Ended
			March 31,
	Loss from Discontinued Operations		2015			2014
	REVENUES FROM PRODUCT SALES AND SERVICES		$	116.6		$	166.2
	COST OF GOODS SOLD AND OPERATING EXPENSES		(107.3		)	(214.6		)
	SALES MARGIN		9.3			(48.4		)
	OTHER OPERATING EXPENSE		(11.3		)	(4.5		)
	OTHER EXPENSE		(0.4		)	(0.6		)
	LOSS FROM DISCONTINUED OPERATIONS BEFORE INCOME TAXES		(2.4		)	(53.5		)
	IMPAIRMENT OF LONG-LIVED ASSETS		(73.4		)	—
	INCOME TAX BENEFIT		0.1			7.2
	LOSS FROM DISCONTINUED OPERATIONS, net of tax		$	(75.7	)	$	(46.3	)
	Items Measured at Fair Value on a Non-Recurring Basis
	The following table presents information about the impairment charge on non-financial assets that was measured on a fair value basis at March 31, 2015. The tables also indicate the fair value hierarchy of the valuation techniques used to determine such fair value.
			(In Millions)
			31-Mar-15
	Description		Quoted Prices in Active			Significant Other Observable Inputs				Significant Unobservable Inputs				Total				Total Losses
			Markets for Identical Assets/			(Level 2)				(Level 3)
Liabilities
(Level 1)
Assets:
Other long-lived assets - Property, plant and equipment and Mineral rights: North American Coal operating unit		$	—		$	—			$	20.4			$	20.4			$	(73.4	)
		$	—		$	—			$	20.4			$	20.4			$	(73.4	)
We determined the fair value and recoverability of our North American Coal operating segment by comparing the estimated fair value of the underlying assets and liabilities to the estimated sales price of the operating segment held for sale.
Recorded Assets and Liabilities
		(In Millions)
Assets and Liabilities of Discontinued Operations		March 31,			December 31,
		2015			2014
Accounts receivable, net		$	42.7		$	44.8
Inventories		59.7			50.3
Supplies and other inventories		28.4			28.2
Other current assets		29.4			20.5
Property, plant and equipment, net		20.4			94.7
Other non-current assets		8			35.7
Total assets of discontinued operations		$	188.6		$	274.2
Accounts payable		$	23.3		$	22.4
Accrued liabilities		16.7			27.9
Other current liabilities		34.7			31
Pension and postemployment benefit liabilities1		56.7			55.8
Environmental and mine closure obligations		34.4			33.9
Other liabilities		31.9			36.2
Total liabilities of discontinued operations		$	197.7		$	207.2
1 This does not include a liability of approximately $330 million, which is the most recent estimate of Pinnacle and Oak Grove’s combined share of the underfunded liability under the UMWA 1974 Pension Plan.
Income Taxes
We have recognized a tax benefit of $0.1 million in discontinued operations, which primarily relates to a loss on our North American Coal investments.
Canadian Operations
Background
On November 30, 2013, we suspended indefinitely our Chromite Project in Northern Ontario. The Chromite Project remained suspended throughout 2014. Our Wabush Scully iron ore mine in Newfoundland and Labrador was idled by the end of the first quarter of 2014 and subsequently began to commence permanent closure in the fourth quarter of 2014. During 2014, we also limited exploration spending on the Labrador Trough South property in Québec. In November 2014, we announced that we were pursuing exit options for our Eastern Canadian Iron Ore operations. In December 2014, iron ore production at the Bloom Lake mine was suspended and the Bloom Lake mine was placed in "care-and-maintenance" mode. Together, the suspension of exploration efforts, shutdown of the Wabush Scully mine and the cessation of operations at our Bloom Lake mine represent a complete curtailment of our Canadian operations.
On January 27, 2015, we announced that the Bloom Lake Group commenced restructuring proceedings (the "Filing") under the CCAA with the Québec Superior Court (Commercial Division) in Montreal (the “Court”). The Bloom Lake Group was no longer generating any revenues and was not able to meet its obligations as they came due. The Filing addressed the Bloom Lake Group's immediate liquidity issues and permits the Bloom Lake Group to preserve and protect its assets for the benefit of all stakeholders while restructuring and sale options are explored. As part of the CCAA process, the Court approved the appointment of a monitor and certain other financial advisors.
As a result of the Filing, we no longer have a controlling interest in the Bloom Lake Group. For this reason, we deconsolidated the Bloom Lake Group and certain other wholly-owned subsidiaries (collectively, the "Canadian Entities") effective January 27, 2015, which resulted in a pretax impairment loss on deconsolidation and other charges, totaling $818.7 million. The pretax loss on deconsolidation includes the derecognition of the carrying amounts of the Canadian Entities assets, liabilities and accumulated other comprehensive loss and the recording of our remaining interests at fair value.
Subsequent to deconsolidation, we utilized the cost method to account for our investment in the Canadian Entities, which has been reflected as zero in our Statements of Unaudited Condensed Consolidated Financial Position at March 31, 2015 based on the estimated fair value of the Canadian Entities' net assets. Loans to and accounts receivable from the Canadian Entities are recorded at an estimated fair value of $112.1 million classified as Other current assets in the Statements of Unaudited Condensed Consolidated Financial Position at March 31, 2015.
Loss on Discontinued Operations
Our Canadian exit represents a strategic shift in our business. For this reason, our previously reported Eastern Canadian Iron Ore and Ferroalloys operating segment results for all periods prior to the January 27, 2015 deconsolidation as well as costs to exit are classified as discontinued operations.
		(In Millions)
		Three Months Ended
		March 31,
Loss from Discontinued Operations		2015			2014
REVENUES FROM PRODUCT SALES AND SERVICES		$	11.3		$	158.3
COST OF GOODS SOLD AND OPERATING EXPENSES		(11.1		)	(208.0		)
ELIMINATIONS WITH CONTINUING OPERATIONS		—			(28.7		)
SALES MARGIN		0.2			(78.4		)
OTHER OPERATING EXPENSE		(33.3		)	(58.6		)
OTHER EXPENSE		(1.0		)	(1.4		)
LOSS FROM DISCONTINUED OPERATIONS BEFORE INCOME TAXES		(34.1		)	(138.4		)
PRETAX EXIT COSTS		(818.7		)	—
INCOME TAX BENEFIT		—			44.3
LOSS FROM DISCONTINUED OPERATIONS, net of tax		$	(852.8	)	$	(94.1	)
The first quarter Canadian Entities pretax exit costs totaled $818.7 million and included the following:
		(In Millions)
		Three Months Ended
		March 31,
Pretax Exit Costs		2015
Investment Impairment on Deconsolidation		$	(476.0	)
Contingent Liabilities		(342.7		)
Total Pretax Exit Costs		$	(818.7	)
Investments in the Canadian Entities
Cliffs continues to indirectly own a majority of the interest in the Canadian Entities but has deconsolidated those entities because Cliffs no longer has a controlling interest. At the date of deconsolidation, January 27, 2015, we adjusted our investment in the Canadian Entities to fair value with a corresponding charge to LOSS FROM DISCONTINUED OPERATIONS, net of tax. As the estimated amount of the Canadian Entities' liabilities exceeded the estimated fair value of the assets available for distribution to its creditors, the fair value of Cliffs’ equity investment is approximately zero.
Amounts Receivable from the Canadian Entities
Prior to deconsolidation, various Cliffs wholly-owned entities made loans to the Canadian Entities for the purpose of funding its operations and had accounts receivable generated in the ordinary course of business. The loans, corresponding interest and the accounts receivable were considered intercompany transactions and eliminated in our consolidated financial statements. As of the deconsolidation date, the loans, associated interest and accounts receivable are considered related party transactions and have been recognized in our consolidated financial statements at their estimated fair value of $112.1 million classified as Other current assets in the Statements of Unaudited Condensed Consolidated Financial Position at March 31, 2015.
Contingent Liabilities
Certain liabilities consisting primarily of equipment loans and capital leases of the Bloom Lake Group were secured through corporate guarantees and standby letters of credit. Upon the filing of CCAA and subsequent to the deconsolidation, we recorded liabilities of $166.1 million in our consolidated results, classified as Other current liabilities in the Statements of Unaudited Condensed Consolidated Financial Position at March 31, 2015.
Additionally, certain liabilities of subsidiaries of the Canadian Entities for which we have joint and several liability were recorded in our consolidated results to reflect obligations of deconsolidated entities which did not file in CCAA but do not have the ability to fund their share of liabilities. As such, subsequent to deconsolidation we recorded liabilities of $51.4 million and $125.2 million classified as Short-term liabilities of discontinued operations and Long-term liabilities of discontinued operations, respectively, in the Statements of Unaudited Condensed Consolidated Financial Position at March 31, 2015.
Contingencies
The recorded expenses include an accrual for the estimated probable loss related to claims that may be asserted against us, primarily under guarantees of certain debt arrangements and leases. The beneficiaries of those guarantees may seek damages or other related relief as a result of our exit from Canada. Our probable loss estimate is based on the expectation that claims will be asserted against us and negotiated settlements will be reached, and not on any determination that it is probable we would be found liable were these claims to be litigated. Given the early stage of our exit and the Filing, our estimates involve significant judgment and are based on currently available information, an assessment of the validity of certain claims and estimated payments by the Canadian Entities. We are not able to reasonably estimate a range of possible losses in excess of the accrual because there are significant factual and legal issues to be resolved. We believe that it is reasonably possible that future changes to our estimates of loss and the ultimate amount paid on these claims could be material to our results of operations in future periods. Any such losses would be reported in discontinued operations.
Items Measured at Fair Value on a Non-Recurring Basis
The following table presents information about the financial assets and liabilities that was measured on a fair value basis at March 31, 2015. The tables also indicate the fair value hierarchy of the valuation techniques used to determine such fair value.
		(In Millions)
		31-Mar-15
Description		Quoted Prices in Active			Significant Other Observable Inputs				Significant Unobservable Inputs				Total				Total Losses
		Markets for Identical Assets/			(Level 2)				(Level 3)
		Liabilities
		(Level 1)
Assets:
Loans to and accounts receivables from the Canadian Entities		$	—		$	—			$	112.1			$	112.1			$	(476.0	)
Liabilities:
Contingent liabilities and joint and several liabilities		$	—		$	—			$	342.7			$	342.7			$	(342.7	)
We determined the fair value and recoverability of our Canadian investments by comparing the estimated fair value of the underlying assets of the Canadian Entities to estimated liabilities at the time of the Filing. We recorded the contingent liabilities and joint and several liabilities at the historical book value which best approximated fair value.
Outstanding liabilities include accounts payable and other liabilities, forward commitments, unsubordinated related party payables, lease liabilities and other potential claims. Potential claims include an accrual for the estimated probable loss related to claims that may be asserted against the Bloom Lake Group under certain contracts. Claimants may seek damages or other related relief as a result of the Bloom Lake Group's exit from Canada. Based on our estimates, the fair value of liabilities exceeds the fair value of assets.
To assess the fair value and recoverability of the amounts receivable from the Canadian Entities, we estimated the fair value of the underlying net assets of the Canadian Entities available for distribution to their creditors in relation to the estimated creditor claims and the priority of those claims.
Our estimates involve significant judgment and are based on currently available information, an assessment of the validity of certain claims and estimated payments made by the Canadian Entities. Our ultimate recovery is subject to the final liquidation value of the Canadian Entities. Further, the final liquidation value and ultimate recovery of the creditors of the Canadian Entities, including Cliffs Natural Resources and various subsidiaries, may impact our estimates of contingent liability exposure described previously.
Recorded Assets and Liabilities
		(In Millions)
Assets and Liabilities of Discontinued Operations		March 31,
		2015
Accounts receivable, net		$	3
Income tax receivable		1.8
Other non-current assets		3.8
Total Assets		$	8.6
Accounts payable		$	0.5
Accrued expenses		51.1
Other liabilities		140.9
Total Liabilities		$	192.5
		(In Millions)
Assets and Liabilities of Discontinued Operations		December 31,
		2014
Cash and cash equivalents		$	19.7
Accounts receivable, net		37.9
Inventories		16.3
Supplies and other inventories		48.5
Income tax receivable		20.1
Other current assets		44.3
Property, plant and equipment, net		249.8
Other non-current assets		19.9
Total Assets		$	456.5
Accounts payable		$	83.6
Accrued expenses		200
Other current liabilities		35.7
Pension and postemployment benefit liabilities		79.8
Environmental and mine closure obligations		56.5
Other liabilities		173.9
Total Liabilities		$	629.5
Income Taxes
Canadian deferred tax assets relating to both historical and current year net operating losses were included in our equity investment in the Canada Subsidiaries that has been reduced to zero. Due to the valuation allowance position in all jurisdictions, there is no income tax benefit related to the deconsolidation charges recognized in the consolidated financials dated March 31, 2015.

CAPITAL_STOCK

CAPITAL STOCK	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
CAPITAL STOCK	NOTE 15 - CAPITAL STOCK
	Dividends
	On February 11, 2014, May 13, 2014, September 8, 2014 and November 19, 2014, our Board of Directors declared the quarterly cash dividend of $17.50 per Preferred Share, which is equivalent to approximately $0.44 per depositary share. The cash dividend was paid on May 1, 2014, August 1, 2014, November 3, 2014, and February 2, 2015 to our Preferred Shareholders of record as of the close of business on April 15, 2014, July 15, 2014, October 15, 2014 and January 15, 2015, respectively. On March 27, 2015, our Board of Directors declared the quarterly cash dividends of $17.50 per Preferred Share, which is equivalent to approximately $0.44 per depositary share. The cash dividend of $12.8 million was paid on May 1, 2015 to our shareholders of record as of the close of business on April 15, 2015.
	On January 26, 2015, we announced that our Board of Directors had decided to eliminate the quarterly dividend of $0.15 per share on our common shares. The decision is applicable to this first quarter of 2015 and all subsequent quarters. The elimination of the common share dividend provides us with additional free cash flow of approximately $92 million annually, which we intend to use for further debt reduction.
	During 2014, a cash dividend of $0.15 per share was paid on March 3, 2014, June 3, 2014, September 2, 2014 and December 1, 2014 to our common shareholders of record as of close of business on February 21, 2014, May 23, 2014, August 15, 2014 and November 15, 2014, respectively.

SHAREHOLDERS_EQUITY

SHAREHOLDERS' EQUITY	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
SHAREHOLDERS' EQUITY	NOTE 16 - SHAREHOLDERS' EQUITY (DEFICIT)
	The following table reflects the changes in shareholders' equity (deficit) attributable to both Cliffs and the noncontrolling interests primarily related to Bloom Lake, Tilden and Empire of which Cliffs owns 82.8 percent, 85 percent and 79 percent, respectively, for the three months ended March 31, 2015 and March 31, 2014:
		(In Millions)
		Cliffs				Noncontrolling				Total Equity (Deficit)
		Shareholders’				Interest (Deficit)
		Equity (Deficit)
	31-Dec-14	$	(1,431.3	)		$	(303.0	)		$	(1,734.3	)
	Comprehensive income
	Net loss	(759.8		)		(1.9		)		(761.7		)
	Other comprehensive income	207.6				(10.8		)		196.8
	Total comprehensive income	(552.2		)		(12.7		)		(564.9		)
	Effect of deconsolidation	—				528.2				528.2
	Stock and other incentive plans	0.6				—				0.6
	Preferred share dividends	(12.8		)		—				(12.8		)
	Undistributed losses to noncontrolling interest	—				1.1				1.1
	31-Mar-15	$	(1,995.7	)		$	213.6			$	(1,782.1	)
		(In Millions)
		Cliffs				Noncontrolling				Total Equity (Deficit)
		Shareholders’				Interest (Deficit)
		Equity (Deficit)
	31-Dec-13	$	6,069.50			$	814.8			$	6,884.30
	Comprehensive income
	Net income	(70.3		)		(0.4		)		(70.7		)
	Other comprehensive income	57.8				0.5				58.3
	Total comprehensive income	(12.5		)		0.1				(12.4		)
	Stock and other incentive plans	(1.4		)		—				(1.4		)
	Common and preferred share dividends	(36.1		)		—				(36.1		)
	Undistributed losses to noncontrolling interest	—				1.2				1.2
	31-Mar-14	$	6,019.50			$	816.1			$	6,835.60
	The following table reflects the changes in Accumulated other comprehensive income (loss) related to Cliffs shareholders’ equity for March 31, 2015 and March 31, 2014:
		(In Millions)
		Changes in Pension and Other Post-Retirement Benefits, net of tax				Unrealized Net Gain (Loss) on Securities, net of tax				Unrealized Net Gain (Loss) on Foreign Currency Translation			Net Unrealized Gain (Loss) on Derivative Financial Instruments, net of tax			Accumulated Other Comprehensive Income (Loss)
	Balance December 31, 2014	$	(291.1	)		$	(1.0	)		$	64.4		$	(18.1	)	$	(245.8	)
	Other comprehensive income (loss) before reclassifications	31.1				2.8				(14.7		)	(7.1		)	12.1
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	8.5				(2.0		)		182.7			6.3			195.5
	Balance March 31, 2015	$	(251.5	)		$	(0.2	)		$	232.4		$	(18.9	)	$	(38.2	)
		(In Millions)
		Changes in Pension and Other Post-Retirement Benefits, net of tax				Unrealized Net Gain (Loss) on Securities, net of tax				Unrealized Net Gain (Loss) on Foreign Currency Translation			Net Unrealized Gain (Loss) on Derivative Financial Instruments, net of tax			Accumulated Other Comprehensive Income (Loss)
	Balance December 31, 2013	$	(204.9	)		$	6.2			$	106.7		$	(20.9	)	$	(112.9	)
	Other comprehensive income (loss) before reclassifications	(0.4		)		3.8				40.5			(2.3		)	41.6
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	3.3				0.1				—			12.8			16.2
	Balance March 31, 2014	$	(202.0	)		$	10.1			$	147.2		$	(10.4	)	$	(55.1	)
	The following table reflects the details about Accumulated other comprehensive income (loss) components related to Cliffs shareholders’ equity for the three months ended March 31, 2015:
			(In Millions)
	Details about Accumulated Other Comprehensive Income (Loss) Components		Amount of (Gain)/Loss Reclassified into Income								Affected Line Item in the Statement of Unaudited Condensed Consolidated Operations
			Three Months Ended
			March 31,
			2015				2014
	Amortization of Pension and Postretirement Benefit Liability:
	Prior service costs (1)		$	(0.3	)		$	(0.3	)
	Net actuarial loss (1)		8.5				4.8
	Settlements/curtailments (1)		0.3				0.3
			8.5				4.8				Total before taxes
			—				(1.6		)		Income tax benefit (expense)
			$	8.5			$	3.2			Net of taxes
	Unrealized gain (loss) on marketable securities:
	Sale of marketable securities		$	—			$	0.1			Other non-operating income (expense)
	Impairment		(2.0		)		—				Other non-operating income (expense)
			(2.0		)		0.1				Total before taxes
			—				—				Income tax benefit (expense)
			$	(2.0	)		$	0.1			Net of taxes
	Unrealized gain (loss) on foreign currency translation:
	Effect of deconsolidation (2)		$	182.7			$	—			Loss from Discontinued Operations, net of tax
			—				—				Income tax benefit (expense)
		$	182.7			$	—			Net of taxes
Unrealized gain (loss) on derivative financial instruments:
Australian dollar foreign exchange contracts		$	9			$	13			Product revenues
Canadian dollar foreign exchange contracts		—				5.5				Cost of goods sold and operating expenses
		9				18.5				Total before taxes
		(2.7		)		(5.7		)		Income tax benefit (expense)
		$	6.3			$	12.8			Net of taxes
Total Reclassifications for the Period		$	195.5			$	16.1
(1)	These accumulated other comprehensive income components are included in the computation of net periodic benefit cost. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.
(2)	Represents Canadian accumulated currency translation adjustments deconsolidated on January 27, 2015.

CASH_FLOW_INFORMATION

CASH FLOW INFORMATION	3 Months Ended
	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Cash Flow Information	NOTE 17 - CASH FLOW INFORMATION
	A reconciliation of capital additions to cash paid for capital expenditures for the three months ended March 31, 2015 and 2014 is as follows:
		(In Millions)
		Three Months Ended
		March 31,
		2015		2014
	Capital additions	$	26.1	$	79.2
	Cash paid for capital expenditures	15.9		103.3
	Difference	$	10.2	$	(24.1	)
	Non-cash accruals	$	10.2	$	(34.0	)
	Capital leases	—		9.9
	Total	$	10.2	$	(24.1	)
	Non-Cash Financing Activities - Declared Dividends
	On March 27, 2015, our Board of Directors declared the quarterly cash dividend on our Preferred Shares of $17.50 per share, which is equivalent to approximately $0.44 per depositary share, each representing 1/40th of a share of Series A preferred stock. The cash dividend of $12.8 million was paid on May 1, 2015 to our preferred shareholders of record as of the close of business on April 15, 2015.

RELATED_PARTIES

RELATED PARTIES	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
RELATED PARTIES	NOTE 18 - RELATED PARTIES
	Three of our five U.S. iron ore mines are owned with various joint venture partners that are integrated steel producers or their subsidiaries. We are the manager of each of the mines we co-own and rely on our joint venture partners to make their required capital contributions and to pay for their share of the iron ore pellets that we produce. The joint venture partners are also our customers. The following is a summary of the mine ownership of these iron ore mines at March 31, 2015:
	Mine		Cliffs Natural Resources		ArcelorMittal			U.S. Steel Corporation
	Empire		79	%	21	%		—
	Tilden		85	%	—			15	%
	Hibbing		23	%	62.3	%		14.7	%
	ArcelorMittal has a unilateral right to put its interest in the Empire mine to us, but has not exercised this right to date.
	Product revenues from related parties were as follows:
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Product revenues from related parties	$	110.4		$	134.4
	Total product revenues	399.5			559.2
	Related party product revenue as a percent of total product revenue	27.6		%	24		%
	Amounts due from related parties recorded in Accounts receivable, net and Other current assets, including trade accounts receivable, a customer supply agreement and provisional pricing arrangements, were $61.2 million and $127.6 million at March 31, 2015 and December 31, 2014, respectively. Amounts due to related parties recorded in Accounts payable and Other current liabilities, including provisional pricing arrangements, were $0.1 million at March 31, 2015 and amounts including provisional pricing arrangements and liabilities to related parties were $11.8 million at December 31, 2014.

EARNINGS_PER_SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
EARNINGS PER SHARE	NOTE 19 - EARNINGS PER SHARE
	The following table summarizes the computation of basic and diluted earnings (loss) per share:
		(In Millions, Except Per Share Amounts)
		Three Months Ended
		March 31,
		2015			2014
	Net Income from Continuing Operations Attributable to Cliffs Shareholders	$	168.7		$	70.1
	Loss from Discontinued Operations, net of tax	(928.5		)	(140.4		)
	Net Loss Attributable to Cliffs Shareholders	$	(759.8	)	$	(70.3	)
	Preferred Stock Dividends	(12.8		)	(12.8		)
	Net Loss Attributable to Cliffs Common Shareholders	$	(772.6	)	$	(83.1	)
	Weighted Average Number of Shares:
	Basic	153.2			153
	Depositary Shares	25.2			—
	Employee Stock Plans	0.3			0.6
	Diluted	178.7			153.6
	Earnings (Loss) per Common Share Attributable to
	Cliffs Common Shareholders - Basic:
	Continuing operations	$	1.02		$	0.37
	Discontinued operations	(6.06		)	(0.92		)
		$	(5.04	)	$	(0.55	)
	Earnings (Loss) per Common Share Attributable to
	Cliffs Common Shareholders - Diluted:
	Continuing operations	$	0.94		$	0.37
	Discontinued operations	(5.20		)	(0.91		)
		$	(4.26	)	$	(0.54	)
	There was no anti-dilution for the three months ended March 31, 2015. The diluted earnings per share calculation excludes 25.2 million depositary shares that were anti-dilutive for the three months ended March 31, 2014.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 20 - COMMITMENTS AND CONTINGENCIES
	Contingencies
	Litigation
	We are currently a party to various claims and legal proceedings incidental to our operations. If management believes that a loss arising from these matters is probable and can reasonably be estimated, we record the amount of the loss, or the minimum estimated liability when the loss is estimated using a range, and no point within the range is more probable than another. As additional information becomes available, any potential liability related to these matters is assessed and the estimates are revised, if necessary. Based on currently available information, management believes that the ultimate outcome of these matters, individually and in the aggregate, will not have a material effect on our financial position, results of operations or cash flows. However, litigation is 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 impact on the financial position and results of operations of the period in which the ruling occurs, or future periods. However, we believe that any pending litigation will not result in a material liability in relation to our consolidated financial statements.

SUBSEQUENT_EVENTS

SUBSEQUENT EVENTS	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE 21 - SUBSEQUENT EVENTS
	We have evaluated subsequent events through the date of financial statement issuance.

BASIS_OF_PRESENTATION_AND_SIGN1

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis Of Consolidation	Basis of Consolidation
	The unaudited condensed consolidated financial statements include our accounts and the accounts of our wholly-owned and majority-owned subsidiaries, including the following operations:
	Name	Location	Ownership Interest	Operation	Status of Operations
	Northshore	Minnesota	100.00%	Iron Ore	Active
	United Taconite	Minnesota	100.00%	Iron Ore	Active
	Tilden	Michigan	85.00%	Iron Ore	Active
	Empire	Michigan	79.00%	Iron Ore	Active
	Koolyanobbing	Western Australia	100.00%	Iron Ore	Active
	Pinnacle	West Virginia	100.00%	Coal	Active - Held for Sale
	Oak Grove	Alabama	100.00%	Coal	Active - Held for Sale
	Wabush1	Newfoundland and Labrador/ Quebec, Canada	100.00%	Iron Ore	Permanent closure
	Bloom Lake1	Quebec, Canada	82.80%	Iron Ore	Care-and-maintenance
	Cliffs Chromite Ontario - Black Label Deposit1	Ontario, Canada	100.00%	Chromite	Suspended
	Cliffs Chromite Ontario - Black Thor Deposit1	Ontario, Canada	100.00%	Chromite	Suspended
	Cliffs Chromite Ontario & Cliffs Chromite Far North - Big Daddy Deposit1	Ontario, Canada	70.00%	Chromite	Suspended
	1 As of January 27, 2015, we deconsolidated substantially all of our Canadian operations following the CCAA filing. See NOTE 14 - DISCONTINUED OPERATIONS for further information.
	Intercompany transactions and balances are eliminated upon consolidation.
Equity Method Investments	Equity Method Investments
	Investments in unconsolidated ventures that we have the ability to exercise significant influence over, but not control, are accounted for under the equity method. The following table presents the detail of our investments in unconsolidated ventures and where those investments are classified in the Statements of Unaudited Condensed Consolidated Financial Position as of March 31, 2015 and December 31, 2014. Parentheses indicate a net liability.
					(In Millions)
	Investment	Classification	Accounting	Interest	March 31,		December 31,
			Method	Percentage	2015		2014
	Hibbing	Other non-current assets	Equity Method	23%	$	2.5	$	3.1
	Other	Other non-current assets	Equity Method	Various	0.9		1
					$	3.4	$	4.1
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign Currency
	Our financial statements are prepared with the U.S. dollar as the reporting currency. The functional currency of the Company’s Australian subsidiaries is the Australian dollar. The functional currency of all other international subsidiaries is the U.S. dollar. The financial statements of international subsidiaries are translated into U.S. dollars using the exchange rate at each balance sheet date for assets and liabilities and a weighted average exchange rate for each period for revenues, expenses, gains and losses. Where the local currency is the functional currency, translation adjustments are recorded as Accumulated other comprehensive loss. Income taxes generally are not provided for foreign currency translation adjustments. To the extent that monetary assets and liabilities, inclusive of intercompany notes, are recorded in a currency other than the functional currency, these amounts are remeasured each reporting period, with the resulting gain or loss being recorded in the Statements of Unaudited Condensed Consolidated Operations. Transaction gains and losses resulting from remeasurement of short-term intercompany loans are included in Miscellaneous - net in our Statements of Unaudited Condensed Consolidated Operations. For the three months ended March 31, 2015, net gains of $13.5 million related to the impact of transaction gains and losses resulting from remeasurement. Of these transaction gains and losses, for the three months ended March 31, 2015, gains of $12.4 million and gains of $1.5 million, respectively, resulted from remeasurement of short-term intercompany loans and cash and cash equivalents. For the three months ended March 31, 2014, losses of $11.4 million related to the impact of transaction gains and losses resulting from remeasurement, of which included losses of $8.8 million and losses of $3.1 million, respectively, resulted from remeasurement of short-term intercompany loans and cash and cash equivalents.
Derivatives, Policy [Policy Text Block]	Derivative Financial Instruments and Hedging Activities
	According to our global hedge policy, the policy allows for hedging not more than 75 percent, but not less than 40 percent for up to 12 months and not less than 10 percent for up to 15 months, of forecasted net currency exposures that are probable to occur. Full hedge compliance under the policy has been waived through December 31, 2015. The waiver was a result of the evaluation of the potential risk of being over hedged and the uncertainty of the 2015 currency exposures. During 2015, we have not entered into any new foreign currency exchange contracts to hedge our foreign currency exposure and we do not expect to enter into any during the remainder of 2015. In the future, we may enter into additional hedging instruments as needed in order to further hedge our exposure to changes in foreign currency exchange rates.
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements
	Issued and Not Effective
	In April 2015, the FASB issued ASU 2015-03, Simplifying the Presentation of Debt Issuance Costs, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This ASU requires retrospective adoption and will be effective for us beginning in our first quarter of 2016. Early adoption is permitted. We do not expect this adoption to have an impact on our Statements of Unaudited Condensed Consolidated Operations or Statements of Unaudited Condensed Consolidated Cash Flows.  The impact of the adoption of the guidance will result in reclassification of the unamortized debt issuance costs on the Statements of Unaudited Condensed Consolidated Financial Position, which were $46.2 million and $25.6 million at March 31, 2015 and December, 31, 2014, respectively.

BASIS_OF_PRESENTATION_AND_SIGN2

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule Of Subsidiaries	The unaudited condensed consolidated financial statements include our accounts and the accounts of our wholly-owned and majority-owned subsidiaries, including the following operations:
	Name	Location	Ownership Interest	Operation	Status of Operations
	Northshore	Minnesota	100.00%	Iron Ore	Active
	United Taconite	Minnesota	100.00%	Iron Ore	Active
	Tilden	Michigan	85.00%	Iron Ore	Active
	Empire	Michigan	79.00%	Iron Ore	Active
	Koolyanobbing	Western Australia	100.00%	Iron Ore	Active
	Pinnacle	West Virginia	100.00%	Coal	Active - Held for Sale
	Oak Grove	Alabama	100.00%	Coal	Active - Held for Sale
	Wabush1	Newfoundland and Labrador/ Quebec, Canada	100.00%	Iron Ore	Permanent closure
	Bloom Lake1	Quebec, Canada	82.80%	Iron Ore	Care-and-maintenance
	Cliffs Chromite Ontario - Black Label Deposit1	Ontario, Canada	100.00%	Chromite	Suspended
	Cliffs Chromite Ontario - Black Thor Deposit1	Ontario, Canada	100.00%	Chromite	Suspended
	Cliffs Chromite Ontario & Cliffs Chromite Far North - Big Daddy Deposit1	Ontario, Canada	70.00%	Chromite	Suspended
	1 As of January 27, 2015, we deconsolidated substantially all of our Canadian operations following the CCAA filing. See NOTE 14 - DISCONTINUED OPERATIONS for further information.
Schedule of Equity Method Investments	The following table presents the detail of our investments in unconsolidated ventures and where those investments are classified in the Statements of Unaudited Condensed Consolidated Financial Position as of March 31, 2015 and December 31, 2014. Parentheses indicate a net liability.
					(In Millions)
	Investment	Classification	Accounting	Interest	March 31,		December 31,
			Method	Percentage	2015		2014
	Hibbing	Other non-current assets	Equity Method	23%	$	2.5	$	3.1
	Other	Other non-current assets	Equity Method	Various	0.9		1
					$	3.4	$	4.1

SEGMENT_REPORTING_Tables

SEGMENT REPORTING (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Schedule Of Segment Reporting Information, By Segment	The following tables present a summary of our reportable segments for the three months ended March 31, 2015 and 2014, including a reconciliation of segment sales margin to Income from Continuing Operations Before Income Taxes and Equity Loss from Ventures and a reconciliation of Net Loss to EBITDA and Adjusted EBITDA:
		(In Millions)
		Three Months Ended
		March 31,
		2015						2014
	Revenues from product sales and services:
	U.S. Iron Ore	$	311.8		70	%		$	361.3		59	%
	Asia Pacific Iron Ore	134.2			30	%		254.2			41	%
	Total revenues from product sales and services	$	446		100	%		$	615.5		100	%
	Sales margin:
	U.S. Iron Ore	$	80					$	95
	Asia Pacific Iron Ore	0.8						66.3
	Eliminations with Discontinued Operations	—						28.7
	Sales margin	80.8						190
	Other operating income	(8.9		)				(50.8		)
	Other income (expense)	270						(39.6		)
	Income from continuing operations before income taxes and equity loss from ventures	$	341.9					$	99.6
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Net Loss	$	(761.7	)	$	(70.7	)
	Less:
	Interest expense, net	(44.2		)	(42.7		)
	Income tax benefit (expense)	(175.0		)	21.8
	Depreciation, depletion and amortization	(33.0		)	(141.1		)
	EBITDA	$	(509.5	)	$	91.3
	Less:
	Impact of discontinued operations	$	(924.1	)	$	(118.1	)
	North American Coal operations impact	(5.5		)	18.2
	Gain on extinguishment of debt	313.7			—
	Severance in SG&A	(1.5		)	(6.0		)
	Foreign exchange remeasurement	13.5			(11.4		)
	Adjusted EBITDA	$	94.4		$	208.6
	EBITDA:
	U.S. Iron Ore	$	101.6		$	123.6
	Asia Pacific Iron Ore	18			85.3
	Other	(629.1		)	(117.6		)
	Total EBITDA	$	(509.5	)	$	91.3
	Adjusted EBITDA:
	U.S. Iron Ore	$	105.1		$	128.7
	Asia Pacific Iron Ore	5.7			99.1
	Other	(16.4		)	(19.2		)
	Total Adjusted EBITDA	$	94.4		$	208.6
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Depreciation, depletion and amortization:
	U.S. Iron Ore	$	21.7		$	28.7
	Asia Pacific Iron Ore	6.3			39.1
	Other	1.8			1.9
	Total depreciation, depletion and amortization	$	29.8		$	69.7
	Capital additions1:
	U.S. Iron Ore	$	9.5		$	14.9
	Asia Pacific Iron Ore	3.4			3.2
	Other	0.4			0.9
	Total capital additions	$	13.3		$	19
	1    Includes capital lease additions and non-cash accruals. Refer to NOTE 17 - CASH FLOW INFORMATION.
Summary of Assets by Segment	A summary of assets by segment is as follows:
		(In Millions)
		March 31,			December 31,
		2015			2014
	Assets:
	U.S. Iron Ore	$	1,550.10		$	1,464.90
	Asia Pacific Iron Ore	250.6			274.6
	Other	31.2			147
	Total segment assets	1,831.90			1,886.50
	Corporate	673.5			546.8
	Assets of Discontinued Operations	197.2			730.7
	Total assets	$	2,702.60		$	3,164.00

INVENTORIES_Tables

INVENTORIES (Tables)	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Schedule Of Inventories	The following table presents the detail of our Inventories in the Statements of Unaudited Condensed Consolidated Financial Position as of March 31, 2015 and December 31, 2014:
		(In Millions)
		31-Mar-15						31-Dec-14
	Segment	Finished Goods		Work-in Process		Total Inventory		Finished Goods		Work-in		Total
										Process		Inventory
	U.S. Iron Ore	$	294.5	$	13.9	$	308.4	$	132.1	$	13.5	$	145.6
	Asia Pacific Iron Ore	15.1		85		100.1		26.4		88.1		114.5
	Total	$	309.6	$	98.9	$	408.5	$	158.5	$	101.6	$	260.1

PROPERTY_PLANT_AND_EQUIPMENT_T

PROPERTY, PLANT AND EQUIPMENT (Tables)	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Value Of Each Of The Major Classes Of Consolidated Depreciable Assets	The following table indicates the value of each of the major classes of our consolidated depreciable assets as of March 31, 2015 and December 31, 2014:
		(In Millions)
		March 31,			December 31,
		2015			2014
	Land rights and mineral rights	$	500.5		$	500.5
	Office and information technology	69.7			73.7
	Buildings	59.8			59.8
	Mining equipment	584.9			585.1
	Processing equipment	512.7			510.2
	Electric power facilities	44.2			46.8
	Land improvements	24.8			24.7
	Other	54.7			55
	Construction in-progress	20.7			14.4
		1,872.00			1,870.20
	Allowance for depreciation and depletion	(824.8		)	(799.7		)
		$	1,047.20		$	1,070.50

DEBT_AND_CREDIT_FACILITIES_Tab

DEBT AND CREDIT FACILITIES (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	The following represents a summary of our long-term debt as of March 31, 2015 and December 31, 2014:
	($ in Millions)
	March 31, 2015
	Debt Instrument		Type	Annual Effective Interest Rate	Final Maturity	Total Face Amount		Total Debt
	$700 Million 4.875% 2021 Senior Notes		Fixed	4.89%	2021	$	423.2	$	422.9	-1
	$1.3 Billion Senior Notes:
	$500 Million 4.80% 2020 Senior Notes		Fixed	4.83%	2020	308.5		308.1		-2
	$800 Million 6.25% 2040 Senior Notes		Fixed	6.34%	2040	492.8		487		-3
	$400 Million 5.90% 2020 Senior Notes		Fixed	5.98%	2020	326.8		325.7		-4
	$500 Million 3.95% 2018 Senior Notes		Fixed	6.32%	2018	436		433.8		-5
	$540 Million 8.25% 2020 First Lien Notes		Fixed	9.97%	2020	540		503.5		-6
	$544.2 Million 7.75% 2020 Second Lien Notes		Fixed	15.55%	2020	544.2		397.2		-7
	$550 Million ABL Facility:
	Asset-Based Revolving Credit Facility		Variable	—%	2020	550		—		-8
	Fair Value Adjustment to Interest Rate Hedge							2.7
	Total debt					$	3,621.50	$	2,880.90
	Less: Short-term and current portion of long-term debt							—
	Long-term debt							$	2,880.90
	($ in Millions)
	31-Dec-14
	Debt Instrument		Type	Annual Effective Interest Rate	Final Maturity	Total Face Amount		Total Debt
	$700 Million 4.875% 2021 Senior Notes		Fixed	4.88%	2021	$	690	$	689.5	-1
	$1.3 Billion Senior Notes:
	$500 Million 4.80% 2020 Senior Notes		Fixed	4.83%	2020	490		489.4		-2
	$800 Million 6.25% 2040 Senior Notes		Fixed	6.34%	2040	800		790.5		-3
	$400 Million 5.90% 2020 Senior Notes		Fixed	5.98%	2020	395		393.7		-4
	$500 Million 3.95% 2018 Senior Notes		Fixed	5.17%	2018	480		477.4		-5
	$1.125 Billion Credit Facility:
	Revolving Credit Agreement		Variable	2.94%	2017	1,125.00		—		-9
	Fair Value Adjustment to Interest Rate Hedge							2.8
	Total debt					$	3,980.00	$	2,843.30
	Less: Short-term and current portion of long-term debt							—
	Long-term debt							$	2,843.30
	-1	During the first quarter of 2015, we purchased $58.3 million of outstanding 4.875 percent senior notes that were trading at a discount of 52.0 percent which resulted in a gain on extinguishment of $20.0 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $208.5 million of the 4.875 percent senior notes for $170.3 million of the 7.75 percent second lien notes at a discount of $46.0 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $83.1 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $700.0 million 4.875 percent senior notes were recorded at a par value of $423.2 million less unamortized discounts of $0.3 million, based on an imputed interest rate of 4.89 percent. As of December 31, 2014, the $700.0 million 4.875 percent senior notes were recorded at a par value of $690.0 million less unamortized discounts of $0.5 million based on an imputed interest rate of 4.88 percent.
	-2	During the first quarter of 2015, we purchased $43.8 million of outstanding 4.80 percent senior notes that were trading at a discount of 54.3 percent, which resulted in a gain on extinguishment of $15.6 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $137.8 million of the 4.80 percent senior notes for $112.9 million of the 7.75 percent second lien notes at a discount of $30.5 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $54.6 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $500.0 million 4.80 percent senior notes were recorded at a par value of $308.5 million less unamortized discounts of $0.4 million, based on an imputed interest rate of 4.83 percent. As of December 31, 2014, the $500.0 million 4.80 percent senior notes were recorded at a par value of $490.0 million less unamortized discounts of $0.6 million based on an imputed interest rate of 4.83 percent.
	-3	During the first quarter of 2015, we purchased $45.9 million of outstanding 6.25 percent senior notes that were trading at a discount of 52.5 percent, which resulted in a gain on extinguishment of $15.0 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $261.3 million of the 6.25 percent senior notes for $203.5 million of the 7.75 percent second lien notes at a discount of $55.0 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $107.3 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $800 million 6.25 percent senior notes were recorded at a par value of $492.8 million less unamortized discounts of $5.8 million, based on an imputed interest rate of 6.34 percent. As of December 31, 2014, the $800 million 6.25 percent senior notes were recorded at a par value of $800.0 million less unamortized discounts of $9.5 million based on an imputed interest rate of 6.34 percent.
	-4	During the first quarter of 2015, we purchased $1.3 million of outstanding 5.90 percent senior notes that were trading at a discount of 58.0 percent, which resulted in a gain on extinguishment of $0.3 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $67.0 million of the 5.90 percent senior notes for $57.5 million of the 7.75 percent second lien notes at a discount of $15.5 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $24.5 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of March 31, 2015, the $400.0 million 5.90 percent senior notes were recorded at a par value of $326.8 million less unamortized discounts of $1.1 million, based on an imputed interest rate of 5.98 percent. As of December 31, 2014, the $400.0 million 5.90 percent senior notes were recorded at a par value of $395.0 million less unamortized discounts of $1.3 million based on an imputed interest rate of 5.98 percent.
	-5	During the first quarter of 2015, we purchased $44.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 77.5 percent, which resulted in a gain on the extinguishment of debt of $7.1 million. As of March 31, 2015, the $500.0 million 3.95 percent senior notes were recorded at a par value of $436.0 million less unamortized discounts of $2.2 million, based on an imputed interest rate of 6.32 percent. As of December 31, 2014, the $500.0 million 3.95 percent senior notes were recorded at a par value of $480.0 million less unamortized discounts of $2.6 million based on an imputed interest rate of 5.17 percent.
	-6	As of March 31, 2015, the $540.0 million 8.25 percent first lien notes were recorded at a par value of $540.0 million less unamortized discounts of $36.5 million, based on an imputed interest rate of 9.97 percent.
	-7	As of March 31, 2015, the $544.2 million 7.75 percent second lien notes were recorded at a par value of $544.2 million less unamortized discounts of $147.0 million, based on an imputed interest rate of 15.55 percent. See NOTE 6 - FAIR VALUE MEASUREMENTS for further discussion of unamortized discount as a result of the exchange offers.
	-8	As of March 31, 2015, no loans were drawn under the ABL Facility and we had total availability of $441.1 million as a result of borrowing base limitations. As of March 31, 2015, the principal amount of letter of credit obligations totaled $136.2 million and foreign exchange hedge obligations totaled $5.5 million, thereby further reducing available borrowing capacity on our ABL Facility to $299.4 million.
	-9	As of December 31, 2014, we had no revolving loans drawn under the revolving credit agreement of which had $1.125 billion availability. As of December 31, 2014, the principal amount of letter of credit obligations totaled $149.5 million, thereby further reducing available borrowing capacity on the revolving credit agreement to $975.5 million.
Schedule of Maturities of Long-term Debt [Table Text Block]	Debt Maturities
	The following represents a summary of our maturities of debt instruments, excluding borrowings on the ABL Facility, based on the principal amounts outstanding at March 31, 2015:
		(In Millions)
		Maturities of Debt
	2015 (April 1 - December 31)	$	—
	2016	—
	2017	—
	2018	436
	2019	—
	2020	1,719.50
	2021 and thereafter	916
	Total maturities of debt	$	3,071.50

FAIR_VALUE_OF_FINANCIAL_INSTRU1

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Of Assets And Liabilities	The following represents the assets and liabilities of the Company measured at fair value at March 31, 2015 and December 31, 2014:
		(In Millions)
		March 31, 2015
	Description	Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total
		Markets for Identical Assets/Liabilities				(Level 2)				(Level 3)
		(Level 1)
	Assets:
	Cash equivalents	$	120			$	—			$	—			$	120
	Derivative assets	—				—				34.5				34.5
	Available-for-sale marketable securities	2.8				—				—				2.8
	Total	$	122.8			$	—			$	34.5			$	157.3
	Liabilities:
	Derivative liabilities	$	—			$	1.6			$	16.2			$	17.8
	Foreign exchange contracts	—				8.7				—				8.7
	Total	$	—			$	10.3			$	16.2			$	26.5
		(In Millions)
		December 31, 2014
	Description	Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total
		Markets for Identical				(Level 2)				(Level 3)
		Assets/Liabilities (Level 1)
	Assets:
	Derivative assets	$	—			$	—			$	63.2			$	63.2
	Available-for-sale marketable securities	4.3				—				—				4.3
	Total	$	4.3			$	—			$	63.2			$	67.5
	Liabilities:
	Derivative liabilities	$	—			$	—			$	9.5			$	9.5
	Foreign exchange contracts	—				31.5				—				31.5
	Total	$	—			$	31.5			$	9.5			$	41
Fair Value, Recurring and Nonrecurring, Valuation Techniques	The following table illustrates information about quantitative inputs and assumptions for the derivative assets and derivative liabilities categorized in Level 3 of the fair value hierarchy:
	Qualitative/Quantitative Information About Level 3 Fair Value Measurements
			(In Millions)				Balance Sheet Location		Valuation Technique		Unobservable Input		Range or Point Estimate per ton
			Fair Value at March 31, 2015										(Weighted Average)
	Provisional Pricing Arrangements		$	16.2			Other current liabilities		Market Approach		Management's		$51
											Estimate of 62% Fe
	Customer Supply Agreement		$	34.5			Other current assets		Market Approach		Hot-Rolled Steel Estimate		$540 - $575 ($563)
Fair Value, Assets Measured On Recurring Basis, Unobservable Input Reconciliation	The following tables represent a reconciliation of the changes in fair value of financial instruments measured at fair value on a recurring basis using significant unobservable inputs (Level 3) for the three months ended March 31, 2015 and 2014.
		(In Millions)
		Derivative Assets (Level 3)
		Three Months Ended
		March 31,
		2015				2014
	Beginning balance	$	63.2			$	57.7
	Total gains (losses)
	Included in earnings	10.1				29
	Settlements	(38.8		)		(43.4		)
	Transfers into Level 3	—				—
	Transfers out of Level 3	—				—
	Ending balance - March 31	$	34.5			$	43.3
	Total gains for the period included in earnings attributable to the change in unrealized gains on assets still held at the reporting date	$	10.1			$	29
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
		(In Millions)
		Derivative Liabilities (Level 3)
		Three Months Ended
		March 31,
		2015				2014
	Beginning balance	$	(9.5	)		$	(1.0	)
	Total gains (losses)
	Included in earnings	(16.2		)		(4.0		)
	Settlements	9.5				1
	Transfers into Level 3	—				—
	Transfers out of Level 3	—				—
	Ending balance - March 31	$	(16.2	)		$	(4.0	)
	Total losses for the period included in earnings attributable to the change in unrealized losses on liabilities still held at the reporting date	$	(16.2	)		$	(4.0	)
Schedule Of Carrying Value And Fair Value Of Financial Instruments	A summary of the carrying amount and fair value of other financial instruments at March 31, 2015 and December 31, 2014 were as follows:
				(In Millions)
				March 31, 2015								December 31, 2014
		Classification		Carrying				Fair Value				Carrying				Fair Value
				Value								Value
	Long-term debt:
	Senior notes—$700 million	Level 1		$	422.9			$	220			$	689.5			$	367.3
	Senior notes—$1.3 billion	Level 1		795.1				425.8				1,279.90				704
	Senior notes—$400 million	Level 1		325.7				190.5				393.7				228.1
	Senior notes—$500 million	Level 1		433.8				337.9				477.4				312
	Senior First Lien Notes —$540 million	Level 1		503.5				507.6				—				—
	Senior Second Lien Notes —$544.2 million	Level 2		397.2				397.2				—				—
	Asset-Based Revolving Credit Facility	Level 2		—				—				—				—
	Fair value adjustment to interest rate hedge	Level 2		2.7				2.7				2.8				2.8
	Total long-term debt			$	2,880.90			$	2,081.70			$	2,843.30			$	1,614.20
Fair Value Measurements, Nonrecurring
			(In Millions)
			31-Mar-15
	Description		Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total			Total Gains
			Markets for Identical Assets/				(Level 2)				(Level 3)
			Liabilities
			(Level 1)
	Liabilities:
	$544.2 Million 7.75% 2020 Second Lien Notes		$	—			$	397.2			$	—			$	397.2		$	269.5
			$	—			$	397.2			$	—			$	397.2		$	269.5
	The $544.2 million 7.75 percent Second Lien Notes issued in the exchange offers were recorded as an extinguishment of debt as the change in debt terms was considered substantial. As such, the newly issued Second Lien Senior Notes were recorded at fair value at the issuance date. In order to determine the fair value of the Second Lien Senior Notes on the date of the exchange, we utilized the median bid ask spread obtained from various investment banks for the exchange date. The bid ask spread is indicative of the fair value of the notes on the exchange date. The 27.0 percent discount equated to a discount of $147.0 million on the issue value of $544.2 million, or an estimated fair value of $397.2 million.
			(In Millions)
			31-Dec-14
	Description		Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total			Total Losses
			Markets for Identical Assets/				(Level 2)				(Level 3)
			Liabilities
			(Level 1)
	Assets:
	Goodwill impairment -		$	—			$	—			$	—			$	—		$	73.5
	Asia Pacific Iron Ore reporting unit
	Other long-lived assets -
	Property, plant and equipment
	and Mineral rights:
	Asia Pacific Iron Ore reporting unit		—				—				72.4				72.4			526.5
	Other reporting units		—				—				—				—			11.3
	Other long-lived assets -
	Intangibles and other long-term assets:
	Asia Pacific Iron Ore reporting unit		—				—				7				7			24.2
	Investment in ventures		—				—				—				—			9.2
	impairment - Global Exploration
			$	—			$	—			$	79.4			$	79.4		$	644.7

PENSIONS_AND_OTHER_POSTRETIREM1

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Tables)	3 Months Ended
	Mar. 31, 2015
Postemployment Benefits [Abstract]
Schedule of Net Benefit Costs [Table Text Block]	The following are the components of defined benefit pension and OPEB expense for the three months ended March 31, 2015 and 2014:
	Defined Benefit Pension Expense
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Service cost	$	6.3		$	6.7
	Interest cost	9.4			10.1
	Expected return on plan assets	(14.9		)	(14.5		)
	Amortization:
	Prior service costs	0.6			0.6
	Net actuarial loss	5.4			3.5
	Curtailments/settlements	0.3			0.3
	Net periodic benefit cost to continuing operations	$	7.1		$	6.7
	Other Postretirement Benefits Expense
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Service cost	$	1.5		$	1.7
	Interest cost	3.3			3.4
	Expected return on plan assets	(4.6		)	(4.3		)
	Amortization:
	Prior service costs	(0.9		)	(0.9		)
	Net actuarial loss	3.1			1.3
	Net periodic benefit cost to continuing operations	$	2.4		$	1.2

STOCK_COMPENSATION_PLANS_Table

STOCK COMPENSATION PLANS (Tables)	3 Months Ended
	Mar. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Schedule Of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions	The following assumptions were utilized to estimate the fair value for the first quarter of 2015 performance share grants:
	Grant Date	Grant Date Market Price		Average Expected Term (Years)	Expected Volatility	Risk-Free Interest Rate	Dividend Yield	Fair Value		Fair Value (Percent of Grant Date Market Price)
	January 12, 2015	$	7.7	2.97	58.30%	0.91%	—%	$	11.56	150.13%
	February 9, 2015	$	6.57	2.89	58.30%	0.87%	—%	$	9.86	150.13%
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	The following assumptions were utilized to estimate the fair value for the first quarter of 2015 stock option grants:
	Grant Date	Grant Date Market Price		Average Expected Term (Years)	Expected Volatility	Risk-Free Interest Rate	Dividend Yield	Fair Value
	January 12, 2015	$	7.7	6.47	75.30%	1.60%	—%	$	5.23

LEASE_OBLIGATIONS_Tables

LEASE OBLIGATIONS (Tables)	3 Months Ended
	Mar. 31, 2015
Leases [Abstract]
Schedule Of Future Minimum Lease Payments For Capital Leases And Operating Leases	Future minimum payments under capital leases and non-cancellable operating leases at March 31, 2015 are as follows:
		(In Millions)
		Capital Leases			Operating Leases
	2015 (April 1 - December 31)	$	20.5		$	7.5
	2016	25.8			7.9
	2017	22.8			7.3
	2018	18.4			6.6
	2019	10			4.8
	2020 and thereafter	18.8			9.9
	Total minimum lease payments	$	116.3		$	44
	Amounts representing interest	25.1
	Present value of net minimum lease payments	$	91.2	(1)
	(1)	The total is comprised of $19.5 million and $71.7 million classified as Other current liabilities and Other liabilities, respectively, in the Statements of Unaudited Condensed Consolidated Financial Position at March 31, 2015.

ENVIRONMENTAL_AND_MINE_CLOSURE1

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Tables)	3 Months Ended
	Mar. 31, 2015
Environmental Remediation Obligations [Abstract]
Summary Of Mine Closure Obligations	The following is a summary of the obligations as of March 31, 2015 and December 31, 2014:
		(In Millions)
		March 31,			December 31,
		2015			2014
	Environmental	$	3.7		$	5.5
	Mine closure
	LTVSMC	23.2			22.9
	Operating mines:
	U.S. Iron Ore	121.8			120.9
	Asia Pacific Iron Ore	20.3			21.5
	Total mine closure	165.3			165.3
	Total environmental and mine closure obligations	169			170.8
	Less current portion	3.4			5.2
	Long term environmental and mine closure obligations	$	165.6		$	165.6
Asset Retirement Obligation Disclosure	The following represents a rollforward of our asset retirement obligation liability related to our active mining locations for the three months ended March 31, 2015 and for the year ended December 31, 2014:
		(In Millions)
		March 31,			December 31,
		2015			2014 (1)
	Asset retirement obligation at beginning of period	$	142.4		$	177.6
	Accretion expense	1.2			5.7
	Exchange rate changes	(1.5		)	(2.4		)
	Revision in estimated cash flows	—			(38.5		)
	Asset retirement obligation at end of period	$	142.1		$	142.4
	(1) Represents a 12-month rollforward of our asset retirement obligation at December 31, 2014.

GOODWILL_AND_OTHER_INTANGIBLE_1

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule Of Goodwill	The following table summarizes changes in the carrying amount of goodwill allocated by operating segment for the three months ended March 31, 2015 and the year ended December 31, 2014:
		(In Millions)
		31-Mar-15												December 31, 2014
		U.S. Iron Ore				Asia Pacific				Total				U.S. Iron Ore				Asia Pacific Iron Ore				Total
						Iron Ore
	Beginning Balance	$	2			$	—			$	2			$	2			$	72.5			$	74.5
	Arising in business combinations	—				—				—				—				—				—
	Impairment	—				—				—				—				(73.5		)		(73.5		)
	Impact of foreign currency translation	—				—				—				—				1				1
	Ending Balance	$	2			$	—			$	2			$	2			$	—			$	2
	Accumulated goodwill impairment loss	$	—			$	(73.5	)		$	(73.5	)		$	—			$	(73.5	)		$	(73.5	)
Schedule Of Finite-Lived Intangible Assets By Major Class	The following table is a summary of intangible assets and liabilities as of March 31, 2015 and December 31, 2014:
				(In Millions)
				31-Mar-15												31-Dec-14
		Classification		Gross				Accumulated				Net				Gross				Accumulated				Net
				Carrying				Amortization				Carrying				Carrying				Amortization				Carrying
				Amount								Amount				Amount								Amount
	Definite-lived intangible assets:
	Permits	Other non-current assets		$	78.7			$	(17.5	)		$	61.2			$	79.2			$	(16.5	)		$	62.7
	Total intangible assets			$	78.7			$	(17.5	)		$	61.2			$	79.2			$	(16.5	)		$	62.7
	Below-market sales contracts	Other current liabilities		$	(23.0	)		$	—			$	(23.0	)		$	(23.0	)		$	—			$	(23.0	)
	Below-market sales contracts	Other liabilities		(205.9		)		182.8				(23.1		)		(205.9		)		182.8				(23.1		)
	Total below-market sales contracts			$	(228.9	)		$	182.8			$	(46.1	)		$	(228.9	)		$	182.8			$	(46.1	)
Estimated Amortization Expense Relating To Intangible Assets	The estimated amortization expense relating to intangible assets for the remainder of this year and each of the five succeeding years is as follows:
		(In Millions)
		Amount
	Year Ending December 31,
	2015 (remaining nine months)	$	3
	2016	4
	2017	4
	2018	4.2
	2019	3.1
	2020	2.5
	Total	$	20.8
Schedule Of Earnings To Be Recognized On Below-Market Sales Contract	The following amounts are estimated to be recognized in Product revenues for the remainder of this year and the succeeding fiscal year:
		(In Millions)
		Amount
	Year Ending December 31,
	2015 (remaining nine months)	$	23
	2016	23.1
	Total	$	46.1

DERIVATIVE_INSTRUMENTS_AND_HED1

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value	The following table presents the fair value of our derivative instruments and the classification of each in the Statements of Unaudited Condensed Consolidated Financial Position as of March 31, 2015 and December 31, 2014:
		(In Millions)
		Derivative Assets												Derivative Liabilities
		March 31, 2015						December 31, 2014						March 31, 2015				31-Dec-14
	Derivative Instrument	Balance Sheet Location		Fair				Balance		Fair				Balance Sheet	Fair			Balance Sheet	Fair
				Value				Sheet		Value				Location	Value			Location	Value
								Location
	Derivatives designated as hedging instruments under ASC 815:
	Foreign Exchange Contracts			$	—					$	—				$	—		Other current liabilities	$	21.6
	Total derivatives designated as hedging instruments under ASC 815			$	—					$	—				$	—			$	21.6
	Derivatives not designated as hedging instruments under ASC 815:
	Foreign Exchange Contracts			$	—					$	—			Other current liabilities	$	8.7		Other current liabilities	$	9.9
	Commodity Contracts			—						—				Other current liabilities	1.6				—
	Customer Supply Agreement	Other current assets		34.5				Other current assets		63.2					—				—
	Provisional Pricing Arrangements			—						—				Other current liabilities	16.2			Other current liabilities	9.5
	Total derivatives not designated as hedging instruments under ASC 815			$	34.5					$	63.2				$	26.5			$	19.4
	Total derivatives			$	34.5					$	63.2				$	26.5			$	41
Schedule Of Derivative Gains (Losses) Recognized In Accumulated Other Comprehensive Income	The following summarizes the effect of our derivatives designated as cash flow hedging instruments, net of tax in Accumulated other comprehensive loss in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 and 2014:
		(In Millions)
	Derivatives in Cash Flow Hedging Relationships	Amount of Gain (Loss)								Location of Gain (Loss)		Amount of Gain (Loss)
		Recognized in OCI on Derivatives								Reclassified		Reclassified
										from Accumulated OCI into Earnings		from Accumulated
												OCI into Earnings
		(Effective Portion)								(Effective Portion)		(Effective Portion)
		Three Months Ended										Three Months Ended
		March 31,										March 31,
		2015				2014						2015			2014
	Australian Dollar Foreign	$	(2.6	)		$	5.5			Product revenues		$	(6.3	)	$	(9.1	)
	Exchange Contracts
	(hedge designation)
	Australian Dollar Foreign	(4.5		)		—				Product revenues		—			—
	Exchange Contracts
	(prior to de-designation)
	Canadian Dollar Foreign Exchange Contracts	—				(7.8		)		Cost of goods sold and operating expenses		—			(3.4		)
	(hedge designation)
	Canadian Dollar Foreign Exchange Contracts	—				—				Cost of goods sold and operating expenses		—			(0.3		)
	(prior to de-designation)
		$	(7.1	)		$	(2.3	)				$	(6.3	)	$	(12.8	)
Schedule Of Derivatives Not Designated As Hedging Instruments Statements Of Financial Performance Location Table	The following summarizes the effect of our derivatives that are not designated as hedging instruments in the Statements of Unaudited Condensed Consolidated Operations for the three months ended March 31, 2015 and 2014:
	(In Millions)
	Derivatives Not Designated as Hedging Instruments	Location of Gain (Loss) Recognized in	Amount of Gain (Loss) Recognized in Income on Derivative
		Income on Derivative
			Three Months Ended
			March 31,
			2015				2014
	Foreign Exchange Contracts	Other non-operating income (expense) (1)	$	(5.9	)		$	(0.9	)
	Commodity Contracts	Cost of goods sold and operating expenses	(3.6		)		—
	Customer Supply Agreement	Product revenues	10.1				27.7
	Provisional Pricing Arrangements	Product revenues	(16.2		)		(2.7		)
			$	(15.6	)		$	24.1
	(1)	At March 31, 2014, the location of the Gain (Loss) Recognized in Income on Derivative for Foreign Exchange Contracts was Cost of goods sold and operating expenses.

DISCONTINUED_OPERATIONS_DISCON1

DISCONTINUED OPERATIONS DISCONTINUED OPERATIONS (Tables)	3 Months Ended
	Mar. 31, 2015
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Line Items]
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]	The chart below provides an asset group breakout for each financial statement line impacted by discontinued operations.
						Canadian Operations
			North American Coal			Eastern Canadian Iron Ore			Other			Total Canadian Operations				Total of Discontinued Operations
	Statements of Unaudited Condensed Consolidated Operations
	Loss from Discontinued Operations, net of tax	YTD	$	(75.7	)	$	(852.7	)	$	(0.1	)	$	(852.8	)		$	(928.5	)
		31-Mar-15
	Loss from Discontinued Operations, net of tax	YTD	$	(46.3	)	$	(91.2	)	$	(2.9	)	$	(94.1	)		$	(140.4	)
		31-Mar-14
	Statements of Unaudited Condensed Consolidated Financial Position
	Short-term assets of discontinued operations	As of	$	188.6		$	8.6		$	—		$	8.6			$	197.2
		31-Mar-15
	Long-term assets of discontinued operations	As of	$	—		$	—		$	—		$	—			$	—
		31-Mar-15
	Short-term liabilities of discontinued operations	As of	$	197.7		$	67.3		$	—		$	67.3			$	265
		31-Mar-15
	Long-term liabilities of discontinued operations	As of	$	—		$	125.2		$	—		$	125.2			$	125.2
		31-Mar-15
	Short-term assets of discontinued operations	As of	$	143.8		$	183.5		$	3.3		$	186.8			$	330.6
		31-Dec-14
	Long-term assets of discontinued operations	As of	$	130.4		$	256		$	13.7		$	269.7			$	400.1
		31-Dec-14
	Short-term liabilities of discontinued operations	As of	$	81.3		$	316.3		$	3		$	319.3			$	400.6
		31-Dec-14
	Long-term liabilities of discontinued operations	As of	$	125.9		$	304.6		$	5.6		$	310.2			$	436.1
		31-Dec-14
	Non-Cash Operating and Investing Activities
	Depreciation, depletion and amortization:	YTD	$	3.2		$	—		$	—		$	—			$	3.2
		31-Mar-15
	Purchase of property, plant and equipment	YTD	$	2.5		$	—		$	—		$	—			$	2.5
		31-Mar-15
	Impairment of long-lived assets	YTD	$	73.4		$	—		$	—		$	—			$	73.4
		31-Mar-15
	Depreciation, depletion and amortization:	YTD	$	29.9		$	41.2		$	0.1		$	41.3			$	71.2
		31-Mar-14
	Purchase of property, plant and equipment	YTD	$	10		$	75.6		$	—		$	75.6			$	85.6
		31-Mar-14
	Impairment of long-lived assets	YTD	$	—		$	—		$	—		$	—			$	—
		31-Mar-14
North American Coal [Member]
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Line Items]
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Table Text Block]	Recorded Assets and Liabilities
			(In Millions)
	Assets and Liabilities of Discontinued Operations		March 31,			December 31,
			2015			2014
	Accounts receivable, net		$	42.7		$	44.8
	Inventories		59.7			50.3
	Supplies and other inventories		28.4			28.2
	Other current assets		29.4			20.5
	Property, plant and equipment, net		20.4			94.7
	Other non-current assets		8			35.7
	Total assets of discontinued operations		$	188.6		$	274.2
	Accounts payable		$	23.3		$	22.4
	Accrued liabilities		16.7			27.9
	Other current liabilities		34.7			31
	Pension and postemployment benefit liabilities1		56.7			55.8
	Environmental and mine closure obligations		34.4			33.9
	Other liabilities		31.9			36.2
	Total liabilities of discontinued operations		$	197.7		$	207.2
	1 This does not include a liability of approximately $330 million, which is the most recent estimate of Pinnacle and Oak Grove’s combined share of the underfunded liability under the UMWA 1974 Pension Plan.
Schedule of Disposal Groups, including Discontinued Operations, Income Statement [Table Text Block]	Loss on Discontinued Operations
	Our planned sale of the Oak Grove and Pinnacle mine assets represents a strategic shift in our business. For this reason, our previously reported North American Coal operating segment results for all periods, prior to the March 31, 2015 held for sale determination, are classified as discontinued operations. This includes our CLCC assets, which were sold during the fourth quarter of 2014.
			(In Millions)
			Three Months Ended
			March 31,
	Loss from Discontinued Operations		2015			2014
	REVENUES FROM PRODUCT SALES AND SERVICES		$	116.6		$	166.2
	COST OF GOODS SOLD AND OPERATING EXPENSES		(107.3		)	(214.6		)
	SALES MARGIN		9.3			(48.4		)
	OTHER OPERATING EXPENSE		(11.3		)	(4.5		)
	OTHER EXPENSE		(0.4		)	(0.6		)
	LOSS FROM DISCONTINUED OPERATIONS BEFORE INCOME TAXES		(2.4		)	(53.5		)
	IMPAIRMENT OF LONG-LIVED ASSETS		(73.4		)	—
	INCOME TAX BENEFIT		0.1			7.2
	LOSS FROM DISCONTINUED OPERATIONS, net of tax		$	(75.7	)	$	(46.3	)
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Table Text Block]	Items Measured at Fair Value on a Non-Recurring Basis
	The following table presents information about the impairment charge on non-financial assets that was measured on a fair value basis at March 31, 2015. The tables also indicate the fair value hierarchy of the valuation techniques used to determine such fair value.
			(In Millions)
			31-Mar-15
	Description		Quoted Prices in Active			Significant Other Observable Inputs				Significant Unobservable Inputs				Total				Total Losses
			Markets for Identical Assets/			(Level 2)				(Level 3)
			Liabilities
			(Level 1)
	Assets:
	Other long-lived assets - Property, plant and equipment and Mineral rights: North American Coal operating unit		$	—		$	—			$	20.4			$	20.4			$	(73.4	)
			$	—		$	—			$	20.4			$	20.4			$	(73.4	)
Canadian Entities [Member]
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Line Items]
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Table Text Block]	Recorded Assets and Liabilities
			(In Millions)
	Assets and Liabilities of Discontinued Operations		March 31,
			2015
	Accounts receivable, net		$	3
	Income tax receivable		1.8
	Other non-current assets		3.8
	Total Assets		$	8.6
	Accounts payable		$	0.5
	Accrued expenses		51.1
	Other liabilities		140.9
	Total Liabilities		$	192.5
			(In Millions)
	Assets and Liabilities of Discontinued Operations		December 31,
			2014
	Cash and cash equivalents		$	19.7
	Accounts receivable, net		37.9
	Inventories		16.3
	Supplies and other inventories		48.5
	Income tax receivable		20.1
	Other current assets		44.3
	Property, plant and equipment, net		249.8
	Other non-current assets		19.9
	Total Assets		$	456.5
	Accounts payable		$	83.6
	Accrued expenses		200
	Other current liabilities		35.7
	Pension and postemployment benefit liabilities		79.8
	Environmental and mine closure obligations		56.5
	Other liabilities		173.9
	Total Liabilities		$	629.5
Schedule of Disposal Groups, including Discontinued Operations, Income Statement [Table Text Block]	Loss on Discontinued Operations
	Our Canadian exit represents a strategic shift in our business. For this reason, our previously reported Eastern Canadian Iron Ore and Ferroalloys operating segment results for all periods prior to the January 27, 2015 deconsolidation as well as costs to exit are classified as discontinued operations.
			(In Millions)
			Three Months Ended
			March 31,
	Loss from Discontinued Operations		2015			2014
	REVENUES FROM PRODUCT SALES AND SERVICES		$	11.3		$	158.3
	COST OF GOODS SOLD AND OPERATING EXPENSES		(11.1		)	(208.0		)
	ELIMINATIONS WITH CONTINUING OPERATIONS		—			(28.7		)
	SALES MARGIN		0.2			(78.4		)
	OTHER OPERATING EXPENSE		(33.3		)	(58.6		)
	OTHER EXPENSE		(1.0		)	(1.4		)
	LOSS FROM DISCONTINUED OPERATIONS BEFORE INCOME TAXES		(34.1		)	(138.4		)
	PRETAX EXIT COSTS		(818.7		)	—
	INCOME TAX BENEFIT		—			44.3
	LOSS FROM DISCONTINUED OPERATIONS, net of tax		$	(852.8	)	$	(94.1	)
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Table Text Block]	Items Measured at Fair Value on a Non-Recurring Basis
	The following table presents information about the financial assets and liabilities that was measured on a fair value basis at March 31, 2015. The tables also indicate the fair value hierarchy of the valuation techniques used to determine such fair value.
			(In Millions)
			31-Mar-15
	Description		Quoted Prices in Active			Significant Other Observable Inputs				Significant Unobservable Inputs				Total				Total Losses
			Markets for Identical Assets/			(Level 2)				(Level 3)
			Liabilities
			(Level 1)
	Assets:
	Loans to and accounts receivables from the Canadian Entities		$	—		$	—			$	112.1			$	112.1			$	(476.0	)
	Liabilities:
	Contingent liabilities and joint and several liabilities		$	—		$	—			$	342.7			$	342.7			$	(342.7	)
PreTax Exit Costs [Table Text Block]	The first quarter Canadian Entities pretax exit costs totaled $818.7 million and included the following:
			(In Millions)
			Three Months Ended
			March 31,
	Pretax Exit Costs		2015
	Investment Impairment on Deconsolidation		$	(476.0	)
	Contingent Liabilities		(342.7		)
	Total Pretax Exit Costs		$	(818.7	)

SHAREHOLDERS_EQUITY_Shareholde

SHAREHOLDERS' EQUITY Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Stockholders Equity [Table Text Block]	The following table reflects the changes in shareholders' equity (deficit) attributable to both Cliffs and the noncontrolling interests primarily related to Bloom Lake, Tilden and Empire of which Cliffs owns 82.8 percent, 85 percent and 79 percent, respectively, for the three months ended March 31, 2015 and March 31, 2014:
		(In Millions)
		Cliffs				Noncontrolling				Total Equity (Deficit)
		Shareholders’				Interest (Deficit)
		Equity (Deficit)
	31-Dec-14	$	(1,431.3	)		$	(303.0	)		$	(1,734.3	)
	Comprehensive income
	Net loss	(759.8		)		(1.9		)		(761.7		)
	Other comprehensive income	207.6				(10.8		)		196.8
	Total comprehensive income	(552.2		)		(12.7		)		(564.9		)
	Effect of deconsolidation	—				528.2				528.2
	Stock and other incentive plans	0.6				—				0.6
	Preferred share dividends	(12.8		)		—				(12.8		)
	Undistributed losses to noncontrolling interest	—				1.1				1.1
	31-Mar-15	$	(1,995.7	)		$	213.6			$	(1,782.1	)
		(In Millions)
		Cliffs				Noncontrolling				Total Equity (Deficit)
		Shareholders’				Interest (Deficit)
		Equity (Deficit)
	31-Dec-13	$	6,069.50			$	814.8			$	6,884.30
	Comprehensive income
	Net income	(70.3		)		(0.4		)		(70.7		)
	Other comprehensive income	57.8				0.5				58.3
	Total comprehensive income	(12.5		)		0.1				(12.4		)
	Stock and other incentive plans	(1.4		)		—				(1.4		)
	Common and preferred share dividends	(36.1		)		—				(36.1		)
	Undistributed losses to noncontrolling interest	—				1.2				1.2
	31-Mar-14	$	6,019.50			$	816.1			$	6,835.60
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table reflects the changes in Accumulated other comprehensive income (loss) related to Cliffs shareholders’ equity for March 31, 2015 and March 31, 2014:
		(In Millions)
		Changes in Pension and Other Post-Retirement Benefits, net of tax				Unrealized Net Gain (Loss) on Securities, net of tax				Unrealized Net Gain (Loss) on Foreign Currency Translation			Net Unrealized Gain (Loss) on Derivative Financial Instruments, net of tax			Accumulated Other Comprehensive Income (Loss)
	Balance December 31, 2014	$	(291.1	)		$	(1.0	)		$	64.4		$	(18.1	)	$	(245.8	)
	Other comprehensive income (loss) before reclassifications	31.1				2.8				(14.7		)	(7.1		)	12.1
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	8.5				(2.0		)		182.7			6.3			195.5
	Balance March 31, 2015	$	(251.5	)		$	(0.2	)		$	232.4		$	(18.9	)	$	(38.2	)
		(In Millions)
		Changes in Pension and Other Post-Retirement Benefits, net of tax				Unrealized Net Gain (Loss) on Securities, net of tax				Unrealized Net Gain (Loss) on Foreign Currency Translation			Net Unrealized Gain (Loss) on Derivative Financial Instruments, net of tax			Accumulated Other Comprehensive Income (Loss)
	Balance December 31, 2013	$	(204.9	)		$	6.2			$	106.7		$	(20.9	)	$	(112.9	)
	Other comprehensive income (loss) before reclassifications	(0.4		)		3.8				40.5			(2.3		)	41.6
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	3.3				0.1				—			12.8			16.2
	Balance March 31, 2014	$	(202.0	)		$	10.1			$	147.2		$	(10.4	)	$	(55.1	)
Details of Accumulated Other Comprehensive Income (Loss) Components [Table Text Block]	The following table reflects the details about Accumulated other comprehensive income (loss) components related to Cliffs shareholders’ equity for the three months ended March 31, 2015:
			(In Millions)
	Details about Accumulated Other Comprehensive Income (Loss) Components		Amount of (Gain)/Loss Reclassified into Income								Affected Line Item in the Statement of Unaudited Condensed Consolidated Operations
			Three Months Ended
			March 31,
			2015				2014
	Amortization of Pension and Postretirement Benefit Liability:
	Prior service costs (1)		$	(0.3	)		$	(0.3	)
	Net actuarial loss (1)		8.5				4.8
	Settlements/curtailments (1)		0.3				0.3
			8.5				4.8				Total before taxes
			—				(1.6		)		Income tax benefit (expense)
			$	8.5			$	3.2			Net of taxes
	Unrealized gain (loss) on marketable securities:
	Sale of marketable securities		$	—			$	0.1			Other non-operating income (expense)
	Impairment		(2.0		)		—				Other non-operating income (expense)
			(2.0		)		0.1				Total before taxes
			—				—				Income tax benefit (expense)
			$	(2.0	)		$	0.1			Net of taxes
	Unrealized gain (loss) on foreign currency translation:
	Effect of deconsolidation (2)		$	182.7			$	—			Loss from Discontinued Operations, net of tax
			—				—				Income tax benefit (expense)
			$	182.7			$	—			Net of taxes
	Unrealized gain (loss) on derivative financial instruments:
	Australian dollar foreign exchange contracts		$	9			$	13			Product revenues
	Canadian dollar foreign exchange contracts		—				5.5				Cost of goods sold and operating expenses
			9				18.5				Total before taxes
			(2.7		)		(5.7		)		Income tax benefit (expense)
			$	6.3			$	12.8			Net of taxes
	Total Reclassifications for the Period		$	195.5			$	16.1
	(1)	These accumulated other comprehensive income components are included in the computation of net periodic benefit cost. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.
	(2)	Represents Canadian accumulated currency translation adjustments deconsolidated on January 27, 2015.

CASH_FLOW_INFORMATION_Tables

CASH FLOW INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2015
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Disclosures	A reconciliation of capital additions to cash paid for capital expenditures for the three months ended March 31, 2015 and 2014 is as follows:
		(In Millions)
		Three Months Ended
		March 31,
		2015		2014
	Capital additions	$	26.1	$	79.2
	Cash paid for capital expenditures	15.9		103.3
	Difference	$	10.2	$	(24.1	)
	Non-cash accruals	$	10.2	$	(34.0	)
	Capital leases	—		9.9
	Total	$	10.2	$	(24.1	)

RELATED_PARTIES_Tables

RELATED PARTIES (Tables)	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Summary Of Other Ownership Interests	The following is a summary of the mine ownership of these iron ore mines at March 31, 2015:
	Mine		Cliffs Natural Resources		ArcelorMittal			U.S. Steel Corporation
	Empire		79	%	21	%		—
	Tilden		85	%	—			15	%
	Hibbing		23	%	62.3	%		14.7	%
Summary Of Related Party Transactions Table Disclosure	Product revenues from related parties were as follows:
		(In Millions)
		Three Months Ended
		March 31,
		2015			2014
	Product revenues from related parties	$	110.4		$	134.4
	Total product revenues	399.5			559.2
	Related party product revenue as a percent of total product revenue	27.6		%	24		%

EARNINGS_PER_SHARE_Tables

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share Computation	The following table summarizes the computation of basic and diluted earnings (loss) per share:
		(In Millions, Except Per Share Amounts)
		Three Months Ended
		March 31,
		2015			2014
	Net Income from Continuing Operations Attributable to Cliffs Shareholders	$	168.7		$	70.1
	Loss from Discontinued Operations, net of tax	(928.5		)	(140.4		)
	Net Loss Attributable to Cliffs Shareholders	$	(759.8	)	$	(70.3	)
	Preferred Stock Dividends	(12.8		)	(12.8		)
	Net Loss Attributable to Cliffs Common Shareholders	$	(772.6	)	$	(83.1	)
	Weighted Average Number of Shares:
	Basic	153.2			153
	Depositary Shares	25.2			—
	Employee Stock Plans	0.3			0.6
	Diluted	178.7			153.6
	Earnings (Loss) per Common Share Attributable to
	Cliffs Common Shareholders - Basic:
	Continuing operations	$	1.02		$	0.37
	Discontinued operations	(6.06		)	(0.92		)
		$	(5.04	)	$	(0.55	)
	Earnings (Loss) per Common Share Attributable to
	Cliffs Common Shareholders - Diluted:
	Continuing operations	$	0.94		$	0.37
	Discontinued operations	(5.20		)	(0.91		)
		$	(4.26	)	$	(0.54	)

BASIS_OF_PRESENTATION_AND_SIGN3

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Unamortized Debt Issuance Expense	$46.20		$25.60
Derivative, Policy, Percentage of Amount Permitted to be Hedged	75.00%
Current Fiscal Year End Date	-19
Derivative, Policy, Minimum Percentage of Amount Permitted to be Hedged for Derivatives with Periods of up to Twelve Months	40.00%
Derivative, Policy, Minimum Percentage of Amount Permitted to be Hedged for Derivatives with Periods of up to Fifteen Months	10.00%
Transaction Gains and Losses Resulting from Remeasurement [Member]
Related Party Transaction [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	13.5	-11.4
Short-term intercompany loan [Member]
Related Party Transaction [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	12.4	-8.8
Cash and Cash Equivalents [Member]
Related Party Transaction [Line Items]
Foreign Currency Transaction Gain (Loss), before Tax	$1.50	($3.10)

BASIS_OF_PRESENTATION_AND_SIGN4

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Schedule Of Subsidiaries) (Details)	3 Months Ended
	Mar. 31, 2015
Northshore [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Minnesota
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Iron Ore
United Taconite [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Minnesota
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Iron Ore
Wabush [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Newfoundland and Labrador/ Quebec, Canada
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Iron Ore
Bloom Lake [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Quebec, Canada
Noncontrolling Interest, Ownership Percentage by Parent	82.80%
Segment Reporting Information, Description of Products and Services	Iron Ore
Tilden [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Michigan
Noncontrolling Interest, Ownership Percentage by Parent	85.00%
Segment Reporting Information, Description of Products and Services	Iron Ore
Empire [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Michigan
Noncontrolling Interest, Ownership Percentage by Parent	79.00%
Segment Reporting Information, Description of Products and Services	Iron Ore
Koolyanobbing [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Western Australia
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Iron Ore
Pinnacle [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	West Virginia
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Coal
Oak Grove [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Alabama
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Coal
Black Label Deposit [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Ontario, Canada
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Chromite
Black Thor Deposit [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Ontario, Canada
Noncontrolling Interest, Ownership Percentage by Parent	100.00%
Segment Reporting Information, Description of Products and Services	Chromite
Big Daddy Chromite Deposit [Member]
Related Party Transaction [Line Items]
Entity Address, State or Province	Ontario, Canada
Noncontrolling Interest, Ownership Percentage by Parent	70.00%
Segment Reporting Information, Description of Products and Services	Chromite

BASIS_OF_PRESENTATION_AND_SIGN5

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Investments In Unconsolidated Ventures) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Schedule of Equity Method Investments [Line Items]
Investment	$3.40	$4.10
Other Noncurrent Liabilities [Member] | Hibbing [Member]
Schedule of Equity Method Investments [Line Items]
Investment		3.1
Other Noncurrent Assets [Member] | Hibbing [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest, equity method investment	23.00%
Investment	2.5
Other Noncurrent Assets [Member] | Other Equity Investees [Member]
Schedule of Equity Method Investments [Line Items]
Investment	$0.90	$1

SEGMENT_REPORTING_Narrative_De

SEGMENT REPORTING (Narrative) (Details)	3 Months Ended
	Mar. 31, 2015
	Facility
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	5
Asia Pacific Iron Ore [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	1

SEGMENT_REPORTING_Schedule_Of_

SEGMENT REPORTING (Schedule Of Segment Reporting Information, By Segment) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	($761.70)		($70.70)
Revenues from producet sales and services, percent	100.00%		100.00%
Revenues from product sales and services	446		615.5
Sales Margin	80.8		190
Other operating expense	-8.9		-50.8
Other expense	270		-39.6
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND EQUITY LOSS FROM VENTURES	341.9		99.6
Depreciation, depletion and amortization	33		141.1
Depreciation, Depletion and Amortization excluding Depreciation, Amortization and Depletion expense for Discontinued Operations	29.8		69.7
EBITDA	-509.5		91.3
Capital Additions	13.3	[1]	19	[1]
Interest Income (Expense), net, including Discontinued Operations	-44.2		-42.7
Income Tax Expense (Benefit), including Discontinued Operations	-175		21.8
Gain on extinguishment of debt	313.7		0
Adjusted EBITDA	94.4		208.6
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Revenues from producet sales and services, percent	70.00%		59.00%
Revenues from product sales and services	311.8		361.3
Sales Margin	80		95
Depreciation, depletion and amortization	21.7		28.7
EBITDA	101.6		123.6
Capital Additions	9.5	[1]	14.9	[1]
Adjusted EBITDA	105.1		128.7
Asia Pacific Iron Ore [Member]
Segment Reporting Information [Line Items]
Revenues from producet sales and services, percent	30.00%		41.00%
Revenues from product sales and services	134.2		254.2
Sales Margin	0.8		66.3
Depreciation, depletion and amortization	6.3		39.1
EBITDA	18		85.3
Capital Additions	3.4	[1]	3.2	[1]
Adjusted EBITDA	5.7		99.1
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Eliminations with Discontinued Operations	0		28.7
All Other Segments [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	1.8		1.9
Capital Additions	0.4	[1]	0.9	[1]
Other Segment [Member]
Segment Reporting Information [Line Items]
EBITDA	-629.1		-117.6
Adjusted EBITDA	-16.4		-19.2
EBITDA Calculation [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization	-33		-141.1
Adjusted EBITDA Calculation [Member]
Segment Reporting Information [Line Items]
Impact of Discontinued Operations	-924.1		-118.1
North American Coal Impact	-5.5		18.2
Foreign Exchange Remeasurement	13.5		-11.4
Severance Costs in SG&A	($1.50)		($6)
[1]	Includes capital lease additions and non-cash accruals. Refer to NOTE 17 - CASH FLOW INFORMATION.

SEGMENT_REPORTING_Segment_Repo

SEGMENT REPORTING Segment Reporting (Summary of Assets by Segment) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Segment Reporting Information [Line Items]
Assets	$2,702.60	$3,164
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	1,550.10	1,464.90
Asia Pacific Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	250.6	274.6
All Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	31.2	147
Total Segment Assets [Member]
Segment Reporting Information [Line Items]
Assets	1,831.90	1,886.50
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	673.5	546.8
Discontinued Operations [Member]
Segment Reporting Information [Line Items]
Disposal Group, Including Discontinued Operation, Assets	$197.20	$730.70

INVENTORIES_Schedule_Of_Invent

INVENTORIES (Schedule Of Inventories) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Inventory, Net [Abstract]
Finished Goods	$309.60	$158.50
Work-in Process	98.9	101.6
Total Inventory	408.5	260.1
U.S. Iron Ore [Member]
Inventory, Net [Abstract]
Finished Goods	294.5	132.1
Work-in Process	13.9	13.5
Total Inventory	308.4	145.6
Asia Pacific Iron Ore [Member]
Inventory, Net [Abstract]
Finished Goods	15.1	26.4
Work-in Process	85	88.1
Total Inventory	$100.10	$114.50

PROPERTY_PLANT_AND_EQUIPMENT_N

PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Property, Plant and Equipment [Line Items]
Depreciation And Depletion	$28.70	$67.70

PROPERTY_PLANT_AND_EQUIPMENT_V

PROPERTY, PLANT AND EQUIPMENT (Value Of Each Of The Major Classes Of Consolidated Depreciable Assets) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$1,872	$1,870.20
Accumulated Depreciation and Depletion, Property, Plant and Equipment	-824.8	-799.7
Property, plant and equipment, net	1,047.20	1,070.50
Land Rights And Mineral Rights [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	500.5	500.5
Office And Information Technology [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	69.7	73.7
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	59.8	59.8
Mining Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	584.9	585.1
Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	512.7	510.2
Electric Power Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	44.2	46.8
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	24.8	24.7
Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	54.7	55
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$20.70	$14.40

DEBT_AND_CREDIT_FACILITIES_Nar

DEBT AND CREDIT FACILITIES (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 30, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Letters of credit outstanding	$136.20			$149.50
Five hundred forty million Eight point two five Twenty twenty First Lien Notes [Member]
Line of Credit Facility [Line Items]
Stated interest rate	8.25%
Repurchase Price of $540M 8.25% Notes if Triggering Event Occurs	1.01
Initial Redemption Price	1.0825
Redemption Price after 2018	1
Redemption Price from time to time and Prior to March 31, 2018	1
Amount in aggregate that can be redeemed on or prior to March 31, 2018	0.35
Redemption Price of 35 percent or less of Outstanding	1.0825
Amount to Remain Outstanding Prior to March 31, 2018	0.65
In the Event of Default Amount that will Accelerate	0.25
Debt Instrument, Par Value	540
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Line of Credit Facility [Line Items]
Stated interest rate	7.75%
Initial Redemption Price	1.03875
Redemption Price beginning March 31, 2019	1
Redemption Price from time to time and Prior to March 31, 2017	1
Amount in aggregate that can be redeemed on or prior to March 31, 2017	0.35
Redemption Price of 35 percent or less of Outstanding	1.0775
Amount to Remain Outstanding Prior to March 31, 2018	0.65
Debt Instrument, Par Value	544.2
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, borrowing capacity	441.1
Credit facility, amount outstanding	0	[1]		0	[2]
Debt Instrument, Par Value	550		900	1,125
U.S. Tranche	450
Sublimit for Issuers of Letters of Credit for U.S. Tranche	250
Sublimit for U.S. Swingline Loans	100
Australian Tranche	100
Sublimit for Issuance of Letters of Credit for Australian Tranche	50
Sublimit for Australian Swingline Loans	20
Credit facility remaining capacity	299.4			975.5
LIBOR Rate Based on a One-month interest period plus 1 percent	0.01
Fixed Charge Coverage Ratio	1
Letters of credit outstanding	136.2			149.5
Foreign Exchange Hedge Obligations	$5.50
Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Base Rate	0.005
Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Base Rate	0.01
[1]	As of MarchB 31, 2015, no loans were drawn under the ABL Facility and we had total availability of $441.1 million as a result of borrowing base limitations. As of MarchB 31, 2015, the principal amount of letter of credit obligations totaled $136.2 million and foreign exchange hedge obligations totaled $5.5 million, thereby further reducing available borrowing capacity on our ABL Facility to $299.4 million.
[2]	As of DecemberB 31, 2014, we had no revolving loans drawn under the revolving credit agreement of which had $1.125 billion availability. As of DecemberB 31, 2014, the principal amount of letter of credit obligations totaled $149.5 million, thereby further reducing available borrowing capacity on the revolving credit agreement to $975.5 million.

DEBT_AND_CREDIT_FACILITIES_Sch

DEBT AND CREDIT FACILITIES (Schedule Of Long-Term Debt) (Details) (USD $)	3 Months Ended			12 Months Ended
	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2014		Mar. 30, 2015
Debt Instrument [Line Items]
Gain on extinguishment of debt	$313,700,000		$0
Total Face Amount	3,621,500,000				3,980,000,000
Letters of credit outstanding	136,200,000				149,500,000
Long-term Debt	2,880,900,000				2,843,300,000
Current portion of long-term debt	0				0
Long-term debt noncurrent portion	2,880,900,000				2,843,300,000
$700 Million 4.875% 2021 Senior Note [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	58,300,000
Stated interest rate	4.88%				4.88%
Debt Repurchase Discount	52.00%
Debt Instrument, Face Amount Exchanged	208,500,000
Type	Fixed			Fixed
Final Maturity	2021			2021
Total Face Amount	700,000,000				700,000,000
Debt Instrument, Par Value	423,200,000				690,000,000
Long-term Debt	422,900,000	[1]			689,500,000	[1]
Debt Instrument, Unamortized Discount	300,000				500,000
Imputed interest rate	4.89%				4.88%
$500 million 4.80% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	43,800,000
Stated interest rate	4.80%				4.80%
Debt Repurchase Discount	54.30%
Debt Instrument, Face Amount Exchanged	137,800,000
Type	Fixed			Fixed
Final Maturity	2020			2020
Total Face Amount	500,000,000				500,000,000
Debt Instrument, Par Value	308,500,000				490,000,000
Long-term Debt	308,100,000	[2]			489,400,000	[2]
Debt Instrument, Unamortized Discount	400,000				600,000
Imputed interest rate	4.83%				4.83%
$800 Million 6.25% 2040 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	45,900,000
Stated interest rate	6.25%
Debt Repurchase Discount	52.50%
Debt Instrument, Face Amount Exchanged	261,300,000
Type	Fixed			Fixed
Final Maturity	2040			2040
Total Face Amount	800,000,000
Debt Instrument, Par Value	492,800,000				800,000,000
Long-term Debt	487,000,000	[3]			790,500,000	[3]
Debt Instrument, Unamortized Discount	5,800,000				9,500,000
Imputed interest rate	6.34%				6.34%
$400 Million 5.90% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	1,300,000
Stated interest rate	5.90%				5.90%
Debt Repurchase Discount	58.00%
Debt Instrument, Face Amount Exchanged	67,000,000
Type	Fixed			Fixed
Final Maturity	2020			2020
Total Face Amount	400,000,000				400,000,000
Debt Instrument, Par Value	326,800,000				395,000,000
Long-term Debt	325,700,000	[4]			393,700,000	[4]
Debt Instrument, Unamortized Discount	1,100,000				1,300,000
Imputed interest rate	5.98%				5.98%
$500 Million 3.95% 2018 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	44,000,000
Stated interest rate	3.95%				3.95%
Debt Repurchase Discount	77.50%
Type	Fixed			Fixed
Final Maturity	2018			2018
Total Face Amount	500,000,000				500,000,000
Debt Instrument, Par Value	436,000,000				480,000,000
Long-term Debt	433,800,000	[5]			477,400,000	[5]
Debt Instrument, Unamortized Discount	2,200,000				2,600,000
Imputed interest rate	6.32%				5.17%
Five hundred forty million Eight point two five Twenty twenty First Lien Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	8.25%
Type	Fixed
Final Maturity	2020
Total Face Amount	540,000,000				0
Debt Instrument, Par Value	540,000,000
Long-term Debt	503,500,000	[5]
Debt Instrument, Unamortized Discount	36,500,000
Imputed interest rate	9.97%
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	7.75%
Discount Received in Debt Exchange of $400M 5.90% Notes	15,500,000
Debt Instrument, Face Amount Received in Debt Exchange of $400M 5.90% Notes	57,500,000
Debt Instrument, Face Amount Received in Debt Exchange of $800M 6.25% Notes	203,500,000
Discount Received in Debt Exchange of $800M 6.25% Notes	55,000,000
Discount Received in Debt Exchange of $500M 4.80% Notes	30,500,000
Debt Instrument, Face Amount Received in Debt Exchange of $500M 4.80% Notes	112,900,000
Discount Received in Debt Exchange of $700M 4.875% Notes	46,000,000
Debt instrument, Face Amount Received in Debt Exchange of $700M 4.875% Notes	170,300,000
Type	Fixed
Final Maturity	2020
Total Face Amount	544,200,000				0
Debt Instrument, Par Value	544,200,000
Long-term Debt	397,200,000	[5]
Debt Instrument, Unamortized Discount	147,000,000
Imputed interest rate	15.55%				15.55%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Type	Variable			Variable
Final Maturity	2020			2017
Debt Instrument, Par Value	550,000,000				1,125,000,000		900,000,000
Credit facility, amount outstanding	0	[6]			0	[7]
Revolving credit facility, borrowing capacity	441,100,000
Letters of credit outstanding	136,200,000				149,500,000
Foreign Exchange Hedge Obligations	5,500,000
Imputed interest rate	0.00%				2.94%
Credit facility remaining capacity	299,400,000				975,500,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Fair Value Adjustment to Interest Rate Hedge	2,700,000				2,800,000
Debt Repurchase [Member] | $700 Million 4.875% 2021 Senior Note [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	20,000,000
Debt Repurchase [Member] | $500 million 4.80% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	15,600,000
Debt Repurchase [Member] | $800 Million 6.25% 2040 Senior Notes [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	15,000,000
Debt Repurchase [Member] | $400 Million 5.90% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	300,000
Debt Repurchase [Member] | $500 Million 3.95% 2018 Senior Notes [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	7,100,000
Exchange of Debt [Member] | $700 Million 4.875% 2021 Senior Note [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	83,100,000
Exchange of Debt [Member] | $500 million 4.80% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	54,600,000
Exchange of Debt [Member] | $800 Million 6.25% 2040 Senior Notes [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	107,300,000
Exchange of Debt [Member] | $400 Million 5.90% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Gain on extinguishment of debt	$24,500,000
[1]	During the first quarter of 2015, we purchased $58.3 million of outstanding 4.875 percent senior notes that were trading at a discount of 52.0 percent which resulted in a gain on extinguishment of $20.0 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $208.5 million of the 4.875 percent senior notes for $170.3 million of the 7.75 percent second lien notes at a discount of $46.0 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $83.1 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of MarchB 31, 2015, the $700.0 million 4.875 percent senior notes were recorded at a par value of $423.2 million less unamortized discounts of $0.3 million, based on an imputed interest rate of 4.89 percent. As of DecemberB 31, 2014, the $700.0 million 4.875 percent senior notes were recorded at a par value of $690.0 million less unamortized discounts of $0.5 million based on an imputed interest rate of 4.88 percent.
[2]	During the first quarter of 2015, we purchased $43.8 million of outstanding 4.80 percent senior notes that were trading at a discount of 54.3 percent, which resulted in a gain on extinguishment of $15.6 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $137.8 million of the 4.80 percent senior notes for $112.9 million of the 7.75 percent second lien notes at a discount of $30.5 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $54.6 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of MarchB 31, 2015, the $500.0 million 4.80 percent senior notes were recorded at a par value of $308.5 million less unamortized discounts of $0.4 million, based on an imputed interest rate of 4.83 percent. As of DecemberB 31, 2014, the $500.0 million 4.80 percent senior notes were recorded at a par value of $490.0 million less unamortized discounts of $0.6 million based on an imputed interest rate of 4.83 percent.
[3]	During the first quarter of 2015, we purchased $45.9 million of outstanding 6.25 percent senior notes that were trading at a discount of 52.5 percent, which resulted in a gain on extinguishment of $15.0 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $261.3 million of the 6.25 percent senior notes for $203.5 million of the 7.75 percent second lien notes at a discount of $55.0 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $107.3 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of MarchB 31, 2015, the $800 million 6.25 percent senior notes were recorded at a par value of $492.8 million less unamortized discounts of $5.8 million, based on an imputed interest rate of 6.34 percent. As of DecemberB 31, 2014, the $800 million 6.25 percent senior notes were recorded at a par value of $800.0 million less unamortized discounts of $9.5 million based on an imputed interest rate of 6.34 percent.
[4]	During the first quarter of 2015, we purchased $1.3 million of outstanding 5.90 percent senior notes that were trading at a discount of 58.0 percent, which resulted in a gain on extinguishment of $0.3 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $67.0 million of the 5.90 percent senior notes for $57.5 million of the 7.75 percent second lien notes at a discount of $15.5 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $24.5 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of MarchB 31, 2015, the $400.0 million 5.90 percent senior notes were recorded at a par value of $326.8 million less unamortized discounts of $1.1 million, based on an imputed interest rate of 5.98 percent. As of DecemberB 31, 2014, the $400.0 million 5.90 percent senior notes were recorded at a par value of $395.0 million less unamortized discounts of $1.3 million based on an imputed interest rate of 5.98 percent.
[5]	During the first quarter of 2015, we purchased $44.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 77.5 percent, which resulted in a gain on the extinguishment of debt of $7.1 million. As of MarchB 31, 2015, the $500.0 million 3.95 percent senior notes were recorded at a par value of $436.0 million less unamortized discounts of $2.2 million, based on an imputed interest rate of 6.32 percent. As of DecemberB 31, 2014, the $500.0 million 3.95 percent senior notes were recorded at a par value of $480.0 million less unamortized discounts of $2.6 million based on an imputed interest rate of 5.17 percent.
[6]	As of MarchB 31, 2015, no loans were drawn under the ABL Facility and we had total availability of $441.1 million as a result of borrowing base limitations. As of MarchB 31, 2015, the principal amount of letter of credit obligations totaled $136.2 million and foreign exchange hedge obligations totaled $5.5 million, thereby further reducing available borrowing capacity on our ABL Facility to $299.4 million.
[7]	As of DecemberB 31, 2014, we had no revolving loans drawn under the revolving credit agreement of which had $1.125 billion availability. As of DecemberB 31, 2014, the principal amount of letter of credit obligations totaled $149.5 million, thereby further reducing available borrowing capacity on the revolving credit agreement to $975.5 million.

DEBT_AND_CREDIT_FACILITIES_DEB

DEBT AND CREDIT FACILITIES DEBT AND CREDIT FACILITIES (Schedule of Debt Maturities) (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Debt Disclosure [Abstract]
Debt Maturities Remainder 2015	$0
Debt Maturities 2016	0
Debt Maturities 2017	0
Debt Maturities 2018	436
Debt Maturities 2019	0
Debt Maturities 2020	1,719.50
Debt Maturities 2021 and After	916
Long-term Debt, Maturities, Total	$3,071.50

FAIR_VALUE_OF_FINANCIAL_INSTRU2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets And Liabilities Components [Line Items]
Management Estimate of 62% Fe	62.00%
Goodwill, Impairment Loss	$0	$73,500,000
Other Asset Impairment Charges		562,000,000
Global Exploration Investment in Venture [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Equity Method Investments, Fair Value Disclosure		0
Equity Method Investment, Other than Temporary Impairment		9,200,000
Asia Pacific Iron Ore [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Goodwill, Impairment Loss		73,500,000
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Debt Instrument, Par Value	544,200,000
Debt Instrument, Fair Value Disclosure	397,200,000
Stated interest rate	7.75%
Debt discount	0.27
Debt Instrument, Unamortized Discount	147,000,000
Fair Value, Inputs, Level 2 [Member] | Global Exploration Investment in Venture [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Equity Method Investments, Fair Value Disclosure		0
Fair Value, Inputs, Level 2 [Member] | Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Debt Instrument, Fair Value Disclosure	$397,200,000	$0

FAIR_VALUE_OF_FINANCIAL_INSTRU3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value Of Assets And Liabilities) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Assets:
Cash equivalents	$120
Derivative assets	34.5	63.2
Marketable Securities	2.8	4.3
Total	157.3	67.5
Liabilities:
Derivative liabilities	17.8	9.5
Foreign exchange contracts	8.7	31.5
Total	26.5	41
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents	120
Marketable Securities	2.8	4.3
Total	122.8	4.3
Fair Value, Inputs, Level 2 [Member]
Liabilities:
Derivative liabilities	1.6
Foreign exchange contracts	8.7	31.5
Total	10.3	31.5
Fair Value, Inputs, Level 3 [Member]
Assets:
Derivative assets	34.5	63.2
Total	34.5	63.2
Liabilities:
Derivative liabilities	16.2	9.5
Total	$16.20	$9.50

FAIR_VALUE_OF_FINANCIAL_INSTRU4

FAIR VALUE OF FINANCIAL INSTRUMENTS (Schedule Of Quantitative Inputs And Assumptions For Level 3 Assets And Liabilities) (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value	$34,500,000	$63,200,000
Derivative liability, fair value	26,500,000	41,000,000
Management Estimate of 62% Fe	62.00%
Not Designated as Hedging Instrument [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value	34,500,000	63,200,000
Derivative liability, fair value	26,500,000	19,400,000
Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Managements Estimate Of 62% Fee [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Management Estimate of 62% Fe	62.00%
Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Provisional Pricing Arrangements [Member] | Managements Estimate Of 62% Fee [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement with unobservable inputs derivative asset range	51
Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Customer Supply Agreement [Member] | Hot-Rolled Steel Estimate [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement with unobservable inputs derivative asset range	563
Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Customer Supply Agreement [Member] | Hot-Rolled Steel Estimate [Member] | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement with unobservable inputs derivative asset range	540
Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Customer Supply Agreement [Member] | Hot-Rolled Steel Estimate [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement with unobservable inputs derivative asset range	575
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Provisional Pricing Arrangements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value	0	0
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Customer Supply Agreement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value	34,500,000	63,200,000
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Provisional Pricing Arrangements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, fair value	16,200,000	9,500,000
Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Market Approach Valuation Technique [Member] | Customer Supply Agreement [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, fair value	$0	$0

FAIR_VALUE_OF_FINANCIAL_INSTRU5

FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value, Assets and Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Fair Value, Assets Measured On Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance - January 1	$63.20	$57.70
Total gains
Included in earnings	10.1	29
Settlements	-38.8	-43.4
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance - March 31	34.5	43.3
Total gains for the period included in earnings attributable to the change in unrealized gains on assets still held at the reporting date	10.1	29
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance - January 1	-9.5	-1
Total gains
Included in earnings	-16.2	-4
Settlements	9.5	1
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance - March 31	-16.2	-4
Total losses for the period included in earnings attributable to the change in unrealized losses on liabilities still held at the reporting date	($16.20)	($4)

FAIR_VALUE_OF_FINANCIAL_INSTRU6

FAIR VALUE OF FINANCIAL INSTRUMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	$3,621,500,000		$3,980,000,000
Long-term debt:
Long-term Debt	2,880,900,000		2,843,300,000
Total long-term debt, carrying value	2,880,900,000		2,843,300,000
$700 Million 4.875% 2021 Senior Note [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	700,000,000		700,000,000
Long-term debt:
Long-term Debt	422,900,000	[1]	689,500,000	[1]
Senior Notes - $1.3 Billion [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	1,300,000,000		1,300,000,000
$400 Million 5.90% 2020 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	400,000,000		400,000,000
Long-term debt:
Long-term Debt	325,700,000	[2]	393,700,000	[2]
$500 Million 3.95% 2018 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	500,000,000		500,000,000
Long-term debt:
Long-term Debt	433,800,000	[3]	477,400,000	[3]
Five hundred forty million Eight point two five Twenty twenty First Lien Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	540,000,000		0
Long-term debt:
Long-term Debt	503,500,000	[3]
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	544,200,000		0
Long-term debt:
Debt Instrument, Fair Value Disclosure	397,200,000
Long-term Debt	397,200,000	[3]
Revolving Credit Facility [Member]
Long-term debt:
Revolving loan, carrying value	0	[4]	0	[5]
Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	2,700,000		2,800,000
Fair Value, Inputs, Level 2 [Member]
Long-term debt:
Total long-term debt, fair value	2,081,700,000		1,614,200,000
Fair Value, Inputs, Level 2 [Member] | $700 Million 4.875% 2021 Senior Note [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	220,000,000		367,300,000
Fair Value, Inputs, Level 2 [Member] | Senior Notes - $1.3 Billion [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	425,800,000		704,000,000
Fair Value, Inputs, Level 2 [Member] | $400 Million 5.90% 2020 Senior Notes [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	190,500,000		228,100,000
Fair Value, Inputs, Level 2 [Member] | $500 Million 3.95% 2018 Senior Notes [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	337,900,000		312,000,000
Fair Value, Inputs, Level 2 [Member] | Five hundred forty million Eight point two five Twenty twenty First Lien Notes [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	507,600,000		0
Fair Value, Inputs, Level 2 [Member] | Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	397,200,000		0
Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Long-term debt:
Revolving loan, fair value	0		0
Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	2,700,000		2,800,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Long-term debt:
Total long-term debt, carrying value	2,880,900,000		2,843,300,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | $700 Million 4.875% 2021 Senior Note [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	422,900,000		689,500,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $1.3 Billion [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	795,100,000		1,279,900,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | $400 Million 5.90% 2020 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	325,700,000		393,700,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | $500 Million 3.95% 2018 Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	433,800,000		477,400,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Five hundred forty million Eight point two five Twenty twenty First Lien Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	503,500,000		0
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	397,200,000		0
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior Notes, Noncurrent	0		0
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	$2,700,000		$2,800,000
[1]	During the first quarter of 2015, we purchased $58.3 million of outstanding 4.875 percent senior notes that were trading at a discount of 52.0 percent which resulted in a gain on extinguishment of $20.0 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $208.5 million of the 4.875 percent senior notes for $170.3 million of the 7.75 percent second lien notes at a discount of $46.0 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $83.1 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of MarchB 31, 2015, the $700.0 million 4.875 percent senior notes were recorded at a par value of $423.2 million less unamortized discounts of $0.3 million, based on an imputed interest rate of 4.89 percent. As of DecemberB 31, 2014, the $700.0 million 4.875 percent senior notes were recorded at a par value of $690.0 million less unamortized discounts of $0.5 million based on an imputed interest rate of 4.88 percent.
[2]	During the first quarter of 2015, we purchased $1.3 million of outstanding 5.90 percent senior notes that were trading at a discount of 58.0 percent, which resulted in a gain on extinguishment of $0.3 million. In addition, on March 27, 2015, we exchanged as part of a tender offer $67.0 million of the 5.90 percent senior notes for $57.5 million of the 7.75 percent second lien notes at a discount of $15.5 million based on an imputed interest rate of 15.55 percent, resulting in a gain on extinguishment of $24.5 million, net of amounts expensed for unamortized original issue discount and deferred origination fees. As of MarchB 31, 2015, the $400.0 million 5.90 percent senior notes were recorded at a par value of $326.8 million less unamortized discounts of $1.1 million, based on an imputed interest rate of 5.98 percent. As of DecemberB 31, 2014, the $400.0 million 5.90 percent senior notes were recorded at a par value of $395.0 million less unamortized discounts of $1.3 million based on an imputed interest rate of 5.98 percent.
[3]	During the first quarter of 2015, we purchased $44.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 77.5 percent, which resulted in a gain on the extinguishment of debt of $7.1 million. As of MarchB 31, 2015, the $500.0 million 3.95 percent senior notes were recorded at a par value of $436.0 million less unamortized discounts of $2.2 million, based on an imputed interest rate of 6.32 percent. As of DecemberB 31, 2014, the $500.0 million 3.95 percent senior notes were recorded at a par value of $480.0 million less unamortized discounts of $2.6 million based on an imputed interest rate of 5.17 percent.
[4]	As of MarchB 31, 2015, no loans were drawn under the ABL Facility and we had total availability of $441.1 million as a result of borrowing base limitations. As of MarchB 31, 2015, the principal amount of letter of credit obligations totaled $136.2 million and foreign exchange hedge obligations totaled $5.5 million, thereby further reducing available borrowing capacity on our ABL Facility to $299.4 million.
[5]	As of DecemberB 31, 2014, we had no revolving loans drawn under the revolving credit agreement of which had $1.125 billion availability. As of DecemberB 31, 2014, the principal amount of letter of credit obligations totaled $149.5 million, thereby further reducing available borrowing capacity on the revolving credit agreement to $975.5 million.

FAIR_VALUE_OF_FINANCIAL_INSTRU7

FAIR VALUE OF FINANCIAL INSTRUMENTS FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value Measurements, Nonrecurring) (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss	$0	$73.50
Assets, Fair Value Disclosure, Nonrecurring	397.2	79.4
Impairment of goodwill and other long-lived assets	269.5	644.7
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	397.2	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	79.4
Global Exploration Investment in Venture [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure		0
Equity Method Investment, Other than Temporary Impairment		9.2
Global Exploration Investment in Venture [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure		0
Global Exploration Investment in Venture [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure		0
Global Exploration Investment in Venture [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity Method Investments, Fair Value Disclosure		0
Asia Pacific Iron Ore [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Fair Value Disclosure		0
Goodwill, Impairment Loss		73.5
Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Fair Value Disclosure		0
Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Fair Value Disclosure		0
Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Fair Value Disclosure		0
Other Reporting Units [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0
Tangible Asset Impairment Charges		11.3
Other Reporting Units [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0
Other Reporting Units [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0
Other Reporting Units [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0
Asia Pacific [Member] | Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0
Finite-lived Intangible Assets, Fair Value Disclosure		0
Asia Pacific Iron Ore [Member] | Asia Pacific Iron Ore [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		72.4
Tangible Asset Impairment Charges		526.5
Other Asset Impairment Charges		24.2
Finite-lived Intangible Assets, Fair Value Disclosure		7
Asia Pacific Iron Ore [Member] | Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		0
Finite-lived Intangible Assets, Fair Value Disclosure		0
Asia Pacific Iron Ore [Member] | Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		72.4
Finite-lived Intangible Assets, Fair Value Disclosure		7
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Fair Value Disclosure	397.2
Gain on new debt issued	269.5
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Fair Value Disclosure	0
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Fair Value Disclosure	397.2	0
Five hundred Forty-four Million Seven Point Seven Five Twenty Twenty Second Lien Notes [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Fair Value Disclosure	$0

PENSIONS_AND_OTHER_POSTRETIREM2

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Pension Plans, Defined Benefit [Member]
Definted Benefit Plan Disclosure [Line Items]
Pension Contributions	$3.90	$4
Other Postretirement Benefit Plans, Defined Benefit [Member]
Definted Benefit Plan Disclosure [Line Items]
Other Postretirement Benefit Expense	$0	$0

PENSIONS_AND_OTHER_POSTRETIREM3

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Estimated Net Periodic Benefit Cost) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	$6.30	$6.70
Defined Benefit Plan, Interest Cost	9.4	10.1
Defined Benefit Plan, Expected Return on Plan Assets	-14.9	-14.5
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	0.6	0.6
Defined Benefit Plan, Amortization of Gains (Losses)	5.4	3.5
Defined Benefit Plan, Curtailments	0.3	0.3
Defined Benefit Plan, Net Periodic Benefit Cost	7.1	6.7
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Service Cost	1.5	1.7
Defined Benefit Plan, Interest Cost	3.3	3.4
Defined Benefit Plan, Expected Return on Plan Assets	-4.6	-4.3
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	-0.9	-0.9
Defined Benefit Plan, Amortization of Gains (Losses)	3.1	1.3
Defined Benefit Plan, Net Periodic Benefit Cost	$2.40	$1.20

STOCK_COMPENSATION_PLANS_Narra

STOCK COMPENSATION PLANS (Narrative) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option Indexed to Issuer's Equity, Strike Price	$7.70
2012 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance/vesting period	3 years
2015 to 2017 Performance Period [Member] | 2012 Equity Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout rate, as a percentage of the original grant	0.00%
2015 to 2017 Performance Period [Member] | 2012 Equity Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payout rate, as a percentage of the original grant	200.00%
Performance Shares [Member] | 2012 Amended Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance shares granted	0.9
Employee Stock Option [Member] | 2012 Amended Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance shares granted	0.4
Restricted Stock Units (RSUs) [Member] | 2012 Amended Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted shares granted	0.9

STOCK_COMPENSATION_PLANS_Assum

STOCK COMPENSATION PLANS (Assumptions Utilized To Estimate Fair Value For Performance Share Grants) (Details) (Performance Shares [Member], USD $)	3 Months Ended
	Mar. 31, 2015
January 12, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Market Price	$7.70
Average Expected Term (Years)	2 years 11 months 20 days
Expected Volatility	58.30%
Risk-Free Interest Rate	0.91%
Dividend Yield	0.00%
Fair Value	$11.56
Fair Value (Percent of Grant Date Market Price)	150.13%
February 9, 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Market Price	$6.57
Average Expected Term (Years)	2 years 10 months 20 days
Expected Volatility	58.30%
Risk-Free Interest Rate	0.87%
Dividend Yield	0.00%
Fair Value	$9.86
Fair Value (Percent of Grant Date Market Price)	150.13%

STOCK_COMPENSATION_PLANS_Stock

STOCK COMPENSATION PLANS Stock Option Activity (Details) (Employee Stock Option [Member], January 12, 2015 [Member], USD $)	3 Months Ended
	Mar. 31, 2015
Employee Stock Option [Member] | January 12, 2015 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Grant Date Price	$7.70
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term	6 years 5 months 20 days
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate	75.30%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate	1.60%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate	0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$5.23

INCOME_TAXES_Narrative_Details

INCOME TAXES (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Tax Examination [Line Items]
Income Tax Expense (Benefit)	$175.10	$29.60
Discrete tax items expense	$167.50

LEASE_OBLIGATIONS_Narrative_De

LEASE OBLIGATIONS (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Leases [Abstract]
Operating lease expense	$4.30	$6.20

LEASE_OBLIGATIONS_Future_Minim

LEASE OBLIGATIONS (Future Minimum Lease Payments) (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Capital Leases
2015 (April 1 - December 31)	$20.50
2016	25.8
2017	22.8
2018	18.4
2019	10
2020 and thereafter	18.8
Total minimum lease payments	116.3
Amounts representing interest	25.1
Present value of net minimum lease payments	91.2	[1]
Operating Leases
2015 (April 1 - December 31)	7.5
2016	7.9
2017	7.3
2018	6.6
2019	4.8
2020 and thereafter	9.9
Total minimum lease payments	44
Other Current Liabilities [Member]
Capital Leases
Present value of net minimum lease payments	19.5
Other Liabilities [Member]
Capital Leases
Present value of net minimum lease payments	$71.70
[1]	The total is comprised of $19.5 million and $71.7 million classified as Other current liabilities and Other liabilities, respectively, in the Statements of Unaudited Condensed Consolidated Financial Position at MarchB 31, 2015.

ENVIRONMENTAL_AND_MINE_CLOSURE2

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Narrative) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Environmental Remediation Obligations [Abstract]
Total environmental and mine closure obligations	$169	$170.80

ENVIRONMENTAL_AND_MINE_CLOSURE3

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Summary Of Mine Closure Obligations) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Loss Contingencies [Line Items]
Environmental	$3.70	$5.50
Mine Reclamation and Closing Liability, current and noncurrent	165.3	165.3
Total environmental and mine closure obligations	169	170.8
Less current portion	3.4	5.2
Long term environmental and mine closure obligations	165.6	165.6
U.S. Iron Ore [Member] | Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	121.8	120.9
Asia Pacific Iron Ore [Member] | Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	20.3	21.5
LTV Steel Mining Company [Member] | Previously Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	$23.20	$22.90

ENVIRONMENTAL_AND_MINE_CLOSURE4

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Asset Retirement Obligation Disclosure) (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Asset Retirement Obligation [Roll Forward]
Asset retirement obligation at beginning of period	$142.40	$177.60
Accretion expense	1.2	5.7
Exchange rate changes	-1.5	-2.4
Revision in estimated cash flows		-38.5
Asset retirement obligation at end of period	$142.10	$142.40

GOODWILL_AND_OTHER_INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Goodwill [Line Items]
Below Market Sales Contract, Remaining Life	2 years
Product	$399.50	$559.20
Cost of Sales [Member]
Goodwill [Line Items]
Amortization expense relating to intangible assets	1.1	2.3
Product Revenues [Member] | Sales Revenue, Goods, Net [Member]
Goodwill [Line Items]
Product	$0

GOODWILL_AND_OTHER_INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Goodwill) (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Beginning Balance	$2	$74.50
Arising in business combinations	0	0
Impairment	0	-73.5
Impact of foreign currency translation	0	1
Ending Balance	2	2
Accumulated goodwill impairment loss	-73.5	-73.5
U.S. Iron Ore [Member]
Goodwill [Roll Forward]
Beginning Balance	2	2
Arising in business combinations	0	0
Impairment	0	0
Impact of foreign currency translation	0	0
Ending Balance	2	2
Accumulated goodwill impairment loss	0	0
Asia Pacific Iron Ore [Member]
Goodwill [Roll Forward]
Beginning Balance	0	72.5
Arising in business combinations	0	0
Impairment	0	-73.5
Impact of foreign currency translation	0	1
Ending Balance	0	0
Accumulated goodwill impairment loss	($73.50)	($73.50)

GOODWILL_AND_OTHER_INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Finite-Lived Intangible Assets By Major Class) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount	$78.70	$79.20
Definite lived intangible assets - Accumulated Amortization	-17.5	-16.5
Definite lived intangible assets - Net Carrying Amount	61.2	62.7
Permits [Member] | Other Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount	78.7	79.2
Definite lived intangible assets - Accumulated Amortization	-17.5	-16.5
Definite lived intangible assets - Net Carrying Amount	61.2	62.7
Below Market Sales Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount	-228.9	-228.9
Definite lived intangible assets - Accumulated Amortization	182.8	182.8
Definite lived intangible assets - Net Carrying Amount	-46.1	-46.1
Below Market Sales Contracts [Member] | Other Current Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount	-23	-23
Definite lived intangible assets - Net Carrying Amount	-23	-23
Below Market Sales Contracts [Member] | Other Liabilities [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount	-205.9	-205.9
Definite lived intangible assets - Accumulated Amortization	182.8	182.8
Definite lived intangible assets - Net Carrying Amount	($23.10)	($23.10)

GOODWILL_AND_OTHER_INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Estimated Amortization Expense Relating To Intangible Assets) (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Estimated amortization expense, intangible assets [Abstract]
2015 (remaining nine months)	$3
2016	4
2017	4
2018	4.2
2019	3.1
2020	2.5
Total	$20.80

GOODWILL_AND_OTHER_INTANGIBLE_6

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Earnings To Be Recognized On Below Market Sales Contract) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Estimated recognition of product revenues, below-market sales contracts [Abstract]
2015 (remaining nine months)	$23
2016	23.1
Total	$46.10

DERIVATIVE_INSTRUMENTS_AND_HED2

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details) (USD $)	3 Months Ended				12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Dec. 31, 2014	Jun. 30, 2014
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	($15.60)		$24.10
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-6.3		-12.8
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0		-0.3
Interest Rate Swap [Member] | Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net			0.2
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount						250
Australian Dollar Foreign Exchange Contract Hedge Designation [Member] | Product Revenues [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-6.3		-9.1
Australian Dollar Foreign Exchange Contract Hedge Designation [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	20				220
Australian Dollar Foreign Exchange Contract Hedge Designation [Member] | Designated as Hedging Instrument [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Derivative [Line Items]
Amount that will be reclassified to product revenues in the next 12 months upon settlement of the related contracts	-2.2
Australian Dollar Foreign Exchange Contract Prior To De Designation [Member] | Not Designated as Hedging Instrument [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Derivative [Line Items]
Amount that will be reclassified to product revenues in the next 12 months upon settlement of the related contracts	-12.5
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0		-3.4
Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	0				0
Foreign Exchange Contract [Member] | Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-5.9	[1]	-0.9	[1]
Customer Supply Agreement [Member] | Not Designated as Hedging Instrument [Member] | Product Revenues [Member]
Derivative [Line Items]
Amount of gain/(loss) recognized in income on derivative	10.1		27.7
Customer Supply Agreement [Member] | Not Designated as Hedging Instrument [Member] | Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Derivative assets	34.5				63.2
Provisional Pricing Arrangements [Member] | Product Revenues [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-16.2		-2.7
Provisional Pricing Arrangements [Member] | Not Designated as Hedging Instrument [Member] | U S Iron Ore And Asia Pacific Iron Ore [Member] | Product Revenues [Member]
Derivative [Line Items]
Amount of gain/(loss) recognized in income on derivative	-16.2		-2.7
Provisional Pricing Arrangements [Member] | Not Designated as Hedging Instrument [Member] | U S Iron Ore And Asia Pacific Iron Ore [Member] | Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Derivative assets	0
Provisional Pricing Arrangements [Member] | Not Designated as Hedging Instrument [Member] | U S Iron Ore And Asia Pacific Iron Ore [Member] | Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	16.2				9.5
Corporate [Member] | Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net			0.3
Corporate [Member] | Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	41.4				183
Corporate [Member] | Foreign Exchange Contract [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net			$0.90		($7.30)
[1]	At March 31, 2014, the location of the Gain (Loss) Recognized in Income on Derivative for Foreign Exchange Contracts was Cost of goods sold and operating expenses.

DERIVATIVE_INSTRUMENTS_AND_HED3

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$34.50	$63.20
Derivative liability, fair value	26.5	41
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Derivative liability, fair value	0	21.6
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	34.5	63.2
Derivative liability, fair value	26.5	19.4
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Derivative Financial Instruments, Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Derivative Financial Instruments, Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	0	21.6
Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Derivative Financial Instruments, Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Derivative Financial Instruments, Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	8.7	9.9
Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Derivative Financial Instruments, Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member] | Commodity Contract [Member] | Derivative Financial Instruments, Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	1.6	0
Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Customer Supply Agreement [Member] | Derivative Financial Instruments, Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	34.5	63.2
Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Customer Supply Agreement [Member] | Derivative Financial Instruments, Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	0	0
Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Derivative Financial Instruments, Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Derivative Financial Instruments, Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	$16.20	$9.50

DERIVATIVE_INSTRUMENTS_AND_HED4

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Statements Of Financial Performance Location Table) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	($7.10)	($2.30)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-6.3	-12.8
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	-2.6	5.5
Australian Dollar Foreign Exchange Contract Hedge Designation [Member] | Product Revenues [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-6.3	-9.1
Australian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	-4.5	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	-7.8
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	-3.4
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
Derivative [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivative (Effective Portion)	0	0
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	$0	($0.30)

DERIVATIVE_INSTRUMENTS_AND_HED5

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Schedule Of Derivatives Not Designated As Hedging Instruments) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	($15.60)		$24.10
Foreign Exchange Contract [Member] | Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-5.9	[1]	-0.9	[1]
Commodity Contract [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-3.6		0
Customer Supply Agreements [Member] | Product Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	10.1		27.7
Provisional Pricing Arrangements [Member] | Product Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	($16.20)		($2.70)
[1]	At March 31, 2014, the location of the Gain (Loss) Recognized in Income on Derivative for Foreign Exchange Contracts was Cost of goods sold and operating expenses.

DISCONTINUED_OPERATIONS_DISCON2

DISCONTINUED OPERATIONS DISCONTINUED OPERATIONS (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Canadian Entities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Tax Effect of Discontinued Operation	$0	$44,300,000
Business Exit Costs	-818,700,000	0
Cost Method Investments	0
North American Coal [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Pension and Other Postretirement Defined Benefit Plans, Liabilities	330,000,000
Discontinued Operation, Tax Effect of Discontinued Operation	100,000	7,200,000
Tangible Asset Impairment Charges	-73,400,000
Asia Pacific Iron Ore [Member] | Asia Pacific Iron Ore [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Tangible Asset Impairment Charges			526,500,000
Other Current Assets [Member] | Canadian Entities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loans, Associated Interest and Accounts Receivable recognized in Consolidated Financials at Fair Value	112,100,000
Other Current Liabilities [Member] | Bloom Lake Group [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Contingent Liabilities recognized in Consolidated Financials	166,100,000
Short-term Liabilities of Discontinued Operations [Member] | Canadian Entities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities Recorded for Wholly-owned Subsidiaries of Bloom Lake Group that did not file CCAA	51,400,000
Long-term Liabilities of Discontinued Operations [Member] | Canadian Entities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Liabilities Recorded for Wholly-owned Subsidiaries of Bloom Lake Group that did not file CCAA	$125,200,000

DISCONTINUED_OPERATIONS_Schedu

DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued Operations, Income Statement, Balance Sheet and Cash Flows (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
LOSS FROM DISCONTINUED OPERATIONS, net of tax	($928.50)	($140.40)
Short-term assets of discontinued operations	197.2		330.6
Long-term assets of discontinued operations	0		400.1
Short-term liabilities of discontinued operations	265		400.6
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS	125.2		436.1
Depreciation, depletion and amortization	33	141.1
Payments to Acquire Property, Plant, and Equipment	15.9	103.3
Asset Impairment Charges, Cash Flows	76.6	0
North American Coal [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
LOSS FROM DISCONTINUED OPERATIONS, net of tax	-75.7	-46.3
Short-term assets of discontinued operations	188.6		143.8
Long-term assets of discontinued operations	0		130.4
Short-term liabilities of discontinued operations	197.7		81.3
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS	0		125.9
Depreciation, depletion and amortization	3.2	29.9
Payments to Acquire Property, Plant, and Equipment	2.5	10
Asset Impairment Charges, Cash Flows	73.4	0
Eastern Canadian Iron Ore [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
LOSS FROM DISCONTINUED OPERATIONS, net of tax	-852.7	-91.2
Short-term assets of discontinued operations	8.6		183.5
Long-term assets of discontinued operations	0		256
Short-term liabilities of discontinued operations	67.3		316.3
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS	125.2		304.6
Depreciation, depletion and amortization	0	41.2
Payments to Acquire Property, Plant, and Equipment	0	75.6
Asset Impairment Charges, Cash Flows	0	0
Other Canadian Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
LOSS FROM DISCONTINUED OPERATIONS, net of tax	-0.1	-2.9
Short-term assets of discontinued operations	0		3.3
Long-term assets of discontinued operations	0		13.7
Short-term liabilities of discontinued operations	0		3
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS	0		5.6
Depreciation, depletion and amortization	0	0.1
Payments to Acquire Property, Plant, and Equipment	0	0
Asset Impairment Charges, Cash Flows	0	0
Canadian Entities [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
LOSS FROM DISCONTINUED OPERATIONS, net of tax	-852.8	-94.1
Short-term assets of discontinued operations	8.6		186.8
Long-term assets of discontinued operations	0		269.7
Short-term liabilities of discontinued operations	67.3		319.3
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS	125.2		310.2
Depreciation, depletion and amortization	0	41.3
Payments to Acquire Property, Plant, and Equipment	0	75.6
Asset Impairment Charges, Cash Flows	0	0
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Depreciation, depletion and amortization	3.2	71.2
Payments to Acquire Property, Plant, and Equipment	2.5	85.6
Asset Impairment Charges, Cash Flows	$73.40	$0

DISCONTINUED_OPERATIONS_Schedu1

DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued Operations, Income Statement - North American Coal (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Line Items]
LOSS FROM DISCONTINUED OPERATIONS, net of tax	($928.50)	($140.40)
North American Coal [Member]
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Line Items]
Disposal Group, Including Discontinued Operation, Revenue	116.6	166.2
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	-107.3	-214.6
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)	9.3	-48.4
Disposal Group, Including Discontinued Operation, Operating Expense	-11.3	-4.5
Disposal Group, Including Discontinued Operation, Other Expense	-0.4	-0.6
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	-2.4	-53.5
Impairment of Long-Lived Assets to be Disposed of	-73.4	0
Discontinued Operation, Tax Effect of Discontinued Operation	0.1	7.2
LOSS FROM DISCONTINUED OPERATIONS, net of tax	($75.70)	($46.30)

DISCONTINUED_OPERATIONS_Schedu2

DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued Operations, Assets and Liabilities - North American Coal (Details) (North American Coal [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
North American Coal [Member]
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Line Items]
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	$42.70	$44.80
Disposal Group, Including Discontinued Operation, Inventory	59.7	50.3
Disposal group, including Discontinued Operations, Prepaid Supplies	28.4	28.2
Disposal Group, Including Discontinued Operation, Other Assets, Current	29.4	20.5
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment	20.4	94.7
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent	8	35.7
Disposal Group, Including Discontinued Operation, Assets	188.6	274.2
Disposal Group, Including Discontinued Operation, Accounts Payable	23.3	22.4
Disposal Group, Including Discontinued Operation, Accrued Liabilities	16.7	27.9
Disposal Group, Including Discontinued Operation, Other Liabilities, Current	34.7	31
Disposal group, Including Discontinued Operation, Pension and Other Postretirement Obligations	56.7	55.8
Disposal Group Including Discontinued Operations Environmental Loss Contingency And Mine Reclamation And Closing Liability CurrentAnd Noncurrent	34.4	33.9
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent	31.9	36.2
Disposal Group, Including Discontinued Operation, Liabilities	$197.70	$207.20

DISCONTINUED_OPERATIONS_Schedu3

DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued Operations, Income Statement - Canadian Entities (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
LOSS FROM DISCONTINUED OPERATIONS, net of tax	($928.50)	($140.40)
Canadian Entities [Member]
Disposal Group, Including Discontinued Operation, Revenue	11.3	158.3
Disposal Group, Including Discontinued Operation, Costs of Goods Sold	-11.1	-208
Eliminations with Continuing Operations	0	-28.7
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)	0.2	-78.4
Disposal Group, Including Discontinued Operation, Operating Expense	-33.3	-58.6
Disposal Group, Including Discontinued Operation, Other Expense	-1	-1.4
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	-34.1	-138.4
Business Exit Costs	-818.7	0
Discontinued Operation, Tax Effect of Discontinued Operation	0	44.3
LOSS FROM DISCONTINUED OPERATIONS, net of tax	($852.80)	($94.10)

DISCONTINUED_OPERATIONS_PreTax

DISCONTINUED OPERATIONS PreTax Exit Costs (Details) (Canadian Entities [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Canadian Entities [Member]
PreTax Exit Costs [Line Items]
Investment Impairment on Deconsolidation	($476)
Contingent Liabilities	-342.7
Business Exit Costs	($818.70)	$0

Recovered_Sheet1

DISCONTINUED OPERATIONS Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis - Canadian Entities (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Canadian Entities [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure	$112.10
Losses on Loans to and Accounts Receivables from the Bloom Lake Group	-476
Bloom Lake Group [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure	342.7
Losses on Contingent Liabilities and Joint and Several Liabilities	-342.7
Fair Value, Inputs, Level 1 [Member] | Canadian Entities [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure	0
Fair Value, Inputs, Level 1 [Member] | Bloom Lake Group [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member] | Canadian Entities [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member] | Bloom Lake Group [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member] | Canadian Entities [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Loans to and Accounts Receivables from Bloom Lake Group, Fair Value Disclosure	112.1
Fair Value, Inputs, Level 3 [Member] | Bloom Lake Group [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Contingent Liabilities and Joint and Several Liabilities, Fair Value Disclosure	$342.70

DISCONTINUED_OPERATIONS_Schedu4

DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued Operations, Assets and Liabilities - Canadian Entities (Details) (Canadian Entities [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Canadian Entities [Member]
Schedule of Disposal Groups, Including Discontinued Operations, Assets and Liabilities [Line Items]
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents		$19.70
Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net	3	37.9
Disposal Group, Including Discontinued Operation, Inventory		16.3
Disposal group, including Discontinued Operations, Prepaid Supplies		48.5
Disposal group, including Discontinued Operations, Income taxes receivable	1.8	20.1
Disposal Group, Including Discontinued Operation, Other Assets, Current		44.3
Disposal Group, Including Discontinued Operation, Property, Plant and Equipment		249.8
Disposal Group, Including Discontinued Operation, Other Assets, Noncurrent	3.8	19.9
Disposal Group, Including Discontinued Operation, Assets	8.6	456.5
Disposal Group, Including Discontinued Operation, Accounts Payable	0.5	83.6
Disposal Group, Including Discontinued Operation, Accrued Liabilities	51.1	200
Disposal Group, Including Discontinued Operation, Other Liabilities, Current		35.7
Disposal group, Including Discontinued Operation, Pension and Other Postretirement Obligations		79.8
Disposal Group Including Discontinued Operations Environmental Loss Contingency And Mine Reclamation And Closing Liability CurrentAnd Noncurrent		56.5
Disposal Group, Including Discontinued Operation, Other Liabilities, Noncurrent	140.9	173.9
Disposal Group, Including Discontinued Operation, Liabilities	$192.50	$629.50

Recovered_Sheet2

DISCONTINUED OPERATIONS Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis - North American Coal (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	$397.20	$79.40
Impairment Charges	269.5	644.7
North American Coal [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	20.4
Tangible Asset Impairment Charges	-73.4
Assets, Fair Value Disclosure, Nonrecurring	20.4
Impairment Charges	-73.4
Fair Value, Inputs, Level 1 [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	0
Fair Value, Inputs, Level 1 [Member] | North American Coal [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Assets, Fair Value Disclosure, Nonrecurring	0
Fair Value, Inputs, Level 2 [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	397.2	0
Fair Value, Inputs, Level 2 [Member] | North American Coal [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	0
Assets, Fair Value Disclosure, Nonrecurring	0
Fair Value, Inputs, Level 3 [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	0	79.4
Fair Value, Inputs, Level 3 [Member] | North American Coal [Member]
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	20.4
Assets, Fair Value Disclosure, Nonrecurring	$20.40

CAPITAL_STOCK_Details

CAPITAL STOCK (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	1-May-15	Feb. 02, 2015	Nov. 03, 2014	Aug. 01, 2014	1-May-14	Dec. 01, 2014	Sep. 02, 2014	Jun. 03, 2014	Mar. 03, 2014
Class of Stock [Line Items]
Dividends, Preferred Stock	$12.80	$12.80
Elimination of Dividend	$0.15
Free Cash Flow Due to Quarterly Dividend Elimination	92
Preferred Class A [Member]
Class of Stock [Line Items]
Dividends payable, per share			$17.50	$17.50	$17.50	$17.50	$17.50
Dividends, Preferred Stock	$12.80	$12.80
Common Stock [Member]
Class of Stock [Line Items]
Dividends payable, per share								$0.15	$0.15	$0.15	$0.15
Depositary Share [Member]
Class of Stock [Line Items]
Dividends payable, per share			$0.44	$0.44	$0.44	$0.44	$0.44

SHAREHOLDERS_EQUITY_Schedule_o

SHAREHOLDERS' EQUITY Schedule of Shareholders' Equity (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013
Stockholders' Equity Attributable to Parent	($1,995.70)		($1,431.30)
Stockholders' Equity Attributable to Noncontrolling Interest	213.6		-303
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	-1,782.10	6,835.60	-1,734.30	6,884.30
NET LOSS ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	-759.8	-70.3
INCOME (LOSS) ATTRIBUTABLE TO NONCONTROLLING INTEREST	-1.9	-0.4
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	-761.7	-70.7
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	-552.2	-12.5
Other Comprehensive Income (Loss), Net of Tax	196.8	58.3
OTHER COMPREHENSIVE LOSS (INCOME) ATTRIBUTABLE TO THE NONCONTROLLING INTEREST	10.8	-0.5
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	-564.9	-12.4
Deconsolidation, Gain (Loss), Amount	528.2
Stock and Other Incentive Plans	0.6	-1.4
Preferred share dividends	-12.8	-36.1
Undistributed Gains To Noncontrolling Interest	1.1	1.2
Cliffs Shareholders Equity [Member]
Stockholders' Equity Attributable to Parent	-1,995.70	6,019.50	-1,431.30	6,069.50
NET LOSS ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	-759.8	-70.3
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	207.6	57.8
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	-552.2	-12.5
Deconsolidation, Gain (Loss), Amount	0
Stock and Other Incentive Plans	0.6	-1.4
Preferred share dividends	-12.8	-36.1
Undistributed Gains To Noncontrolling Interest	0	0
Noncontrolling Interest [Member]
Stockholders' Equity Attributable to Noncontrolling Interest	213.6	816.1	-303	814.8
INCOME (LOSS) ATTRIBUTABLE TO NONCONTROLLING INTEREST	-1.9	-0.4
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	-10.8	0.5
OTHER COMPREHENSIVE LOSS (INCOME) ATTRIBUTABLE TO THE NONCONTROLLING INTEREST	-12.7	0.1
Deconsolidation, Gain (Loss), Amount	528.2
Stock and Other Incentive Plans	0	0
Preferred share dividends	0	0
Undistributed Gains To Noncontrolling Interest	$1.10	$1.20

SHAREHOLDERS_EQUITY_Accumulate

SHAREHOLDERS' EQUITY Accumulate Other Comprehensive Income (Loss) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	($251.50)		($291.10)	($204.90)	($202)
Accumulated other comprehensive loss	-38.2		-245.8	-112.9	-55.1
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	-0.2		-1	6.2	10.1
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	232.4		64.4	106.7	147.2
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	-18.9		-18.1	-20.9	-10.4
Accumulated Other Comprehensive Income (Loss) [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	12.1	41.6
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	195.5	16.2
Accumulated Defined Benefit Plans Adjustment [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	31.1	-0.4
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	2.8	3.8
Accumulated Translation Adjustment [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	-14.7	40.5
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax	-7.1	-2.3
Accumulated Defined Benefit Plans Adjustment [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	8.5	3.3
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	-2	0.1
Accumulated Translation Adjustment [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	182.7	0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	$6.30	$12.80

SHAREHOLDERS_EQUITY_Details_of

SHAREHOLDERS' EQUITY Details of Accumulated Other Comprehensive Income (Loss) Components (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	($6.30)		($12.80)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	195.5		16.1
Accumulated Defined Benefit Plans Adjustment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	-0.3	[1]	-0.3	[1]
Defined Benefit Plan, Amortization of Gains (Losses)	8.5	[1]	4.8	[1]
Defined Benefit Plan, Curtailments	0.3	[1]	0.3	[1]
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	8.5		4.8
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	0		-1.6
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	8.5		3.2
Realized Gain (Loss) on Marketable Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Marketable Securities, Realized Gain (Loss)	0		0.1
Accumulated Other-than-Temporary Impairment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, before Tax, Including Portion Attributable to Noncontrolling Interest, Available-for-sale Securities	-2		0
Realized Gain (Loss) on Marketable Securities and Other than Temporary Impairment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities and Impairment on Securities Arising During Period, before tax	-2		0.1
Other Comprehensive Income (Loss), Realized Holding Gain (Loss) on Securities and Impairment on Securities Arising During Period, Tax	0		0
Other Comprehensive Income (Loss), Realized Holding Gain (Loss) on Securities and Impairment on Securities Arising During Period, net of tax	-2		0.1
Foreign Currency Translation Adjustment [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax	182.7	[2]	0	[2]
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax	0		0
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax	182.7		0
Realized Gain Loss On Derivatives [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
(Gain) Loss on Derivative Instruments, Net, Pretax	9		18.5
Tax on Derivative Instruments Gain/Loss Reclassified from Accumulated OCI in to Earnings	-2.7		-5.7
Amount of (gain)/loss recognized in income on derivative	6.3		12.8
Australian Hedge Contracts [Member] | Realized Gain Loss On Derivatives [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	9		13
Canadian Hedge Contracts [Member] | Realized Gain Loss On Derivatives [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	$0		$5.50
[1]	These accumulated other comprehensive income components are included in the computation of net periodic benefit cost. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.
[2]	Represents Canadian accumulated currency translation adjustments deconsolidated on January 27, 2015.

SHAREHOLDERS_EQUITY_Narrative_

SHAREHOLDERS' EQUITY Narrative (Details)	Mar. 31, 2015
Empire [Member]
Noncontrolling Interest, Ownership Percentage by Parent	79.00%
Tilden [Member]
Noncontrolling Interest, Ownership Percentage by Parent	85.00%
Bloom Lake [Member]
Noncontrolling Interest, Ownership Percentage by Parent	82.80%

CASH_FLOW_INFORMATION_Narrativ

CASH FLOW INFORMATION (Narrative) (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	1-May-15	Feb. 02, 2015	Nov. 03, 2014	Aug. 01, 2014	1-May-14
Dividends Payable [Line Items]
Depositary Share Interest in a Share of 7% Series A Mandatory Convertible Preferred Stock, Class A	0.025
Preferred stock cash dividend	$12.80	$12.80
Preferred Class A [Member]
Dividends Payable [Line Items]
Dividends payable, per share			$17.50	$17.50	$17.50	$17.50	$17.50
Preferred stock cash dividend	$12.80	$12.80
Depositary Share [Member]
Dividends Payable [Line Items]
Dividends payable, per share			$0.44	$0.44	$0.44	$0.44	$0.44

CASH_FLOW_INFORMATION_Reconcil

CASH FLOW INFORMATION (Reconciliation Of Capital Additions To Cash Paid For Capital Expenditures) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Supplemental Cash Flow Information [Abstract]
Capital Additions	$26.10	$79.20
Cash Paid for Capital Expenditures	15.9	103.3
Non-cash accruals	10.2	-34
Capital leases	0	9.9
Total	$10.20	($24.10)

RELATED_PARTIES_Narrative_Deta

RELATED PARTIES (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
	Facility
Segment Reporting Information [Line Items]
Due from Related Parties, Current	61.2	$127.60
Due to Related Parties, Current	0.1	$11.80
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	5
Joint Venture Partners [Member] | U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	3

RELATED_PARTIES_Summary_Of_Oth

RELATED PARTIES (Summary Of Other Ownership Interests) (Details)	Mar. 31, 2015
Hibbing [Member] | Arcelor Mittal [Member]
Related Party Transaction [Line Items]
Ownership interest, equity method investment	62.30%
Hibbing [Member] | U. S. Steel Canada [Member]
Related Party Transaction [Line Items]
Ownership interest, equity method investment	14.70%
Empire [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	79.00%
Empire [Member] | Arcelor Mittal [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	21.00%
Empire [Member] | U. S. Steel Canada [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%
Tilden [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	85.00%
Tilden [Member] | Arcelor Mittal [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%
Tilden [Member] | U. S. Steel Canada [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	15.00%
Bloom Lake [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	82.80%
Other Noncurrent Assets [Member] | Hibbing [Member]
Related Party Transaction [Line Items]
Ownership interest, equity method investment	23.00%

RELATED_PARTIES_Summary_Of_Rel

RELATED PARTIES (Summary Of Related Party Transactions Table Disclosure) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Related Party Transactions [Abstract]
Product revenues from related parties	$110.40	$134.40
Product	$399.50	$559.20
Related party product revenue as a percent of total product revenue	27.60%	24.00%

EARNINGS_PER_SHARE_EARNINGS_PE

EARNINGS PER SHARE EARNINGS PER SHARE (Narrative) (Details)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	25.2

Recovered_Sheet3

EARNINGS PER SHARE (Earnings Per Share Computation) (Details) (USD $)	3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income (Loss) from Continuing Operations Attributable to Parent	$168.70	$70.10
LOSS FROM DISCONTINUED OPERATIONS, net of tax	-928.5	-140.4
Net Loss Attributable to Cliffs Shareholders	-759.8	-70.3
PREFERRED STOCK DIVIDENDS	-12.8	-12.8
NET INCOME ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	-772.6	-83.1
Earnings (Loss) Per Common Share Attributable to Cliffs Common Shareholders - Basic
Continuing operations	$1.02	$0.37
Discontinued operations	($6.06)	($0.92)
Earnings (Loss) per Common Share Attributable to Cliffs Common Shareholders - Basic:	($5.04)	($0.55)
Earnings (Loss) Per Common Share Attributable to Cliffs Shareholders - Diluted
Continuing operations	$0.94	$0.37
Discontinued operations	($5.20)	($0.91)
Earnings (Loss) per Common Share Attributable to Cliffs Common Shareholders - Diluted:	($4.26)	($0.54)
Weighted Average Number of Shares:
Basic	153,185	153,040
Depositary Shares	25,215	0
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	296	613
Diluted	178,696	153,653
Preferred Class A [Member]
PREFERRED STOCK DIVIDENDS	($12.80)	($12.80)