Cleveland-Cliffs (CLF) 10-K 25 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 23, 2015	Jun. 30, 2014
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-K
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		153,279,552
Trading Symbol	clf
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$2,397,182,297

Statements_Of_Condensed_Consol

Statements Of Condensed Consolidated Financial Position (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
CURRENT ASSETS
Cash and cash equivalents	$290.90	$335.50
Accounts receivable, net	205.6	270
Inventories	326.7	391.4
Supplies and other inventories	195.2	216
Income tax receivable	237.7	74.1
Other current assets	192.8	273
TOTAL CURRENT ASSETS	1,448.90	1,560
PROPERTY, PLANT AND EQUIPMENT, NET	1,414.90	11,153.40
OTHER ASSETS
Deferred income taxes	156.4	41.5
Other non-current assets	143.8	367
TOTAL OTHER ASSETS	300.2	408.5
TOTAL ASSETS	3,164	13,121.90
CURRENT LIABILITIES
Accounts payable	272.1	345.5
Accrued employment costs	99.5	129
Income taxes payable	1	55.6
State and local taxes payable	52.5	61.7
Current portion of debt	21.8	20.9
Accrued expenses	255.3	206.4
Accrued royalties	31.2	57.3
Current portion of capital leases	74.5	49
Other current liabilities	150.7	160.1
TOTAL CURRENT LIABILITIES	958.6	1,085.50
POSTEMPLOYMENT BENEFIT LIABILITIES
Pensions	275.4	197.5
Other postretirement benefits	119.8	96.5
TOTAL POSTEMPLOYMENT BENEFIT LIABILITIES	395.2	294
ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS	256	309.7
DEFERRED INCOME TAXES	51.3	1,146.50
LONG-TERM DEBT	2,962.30	3,022.60
OTHER LIABILITIES	274.9	379.3
TOTAL LIABILITIES	4,898.30	6,237.60
COMMITMENTS AND CONTINGENCIES (SEE NOTE 20)
CLIFFS SHAREHOLDERS' EQUITY
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 (See Note 15), Issued and Outstanding - 731,223 shares (2013 - 731,250)	731.3	731.3
Common Shares - par value $0.125 per share, Authorized - 400,000,000 shares (2013 - 400,000,000 shares); Issued - 159,546,224 shares (2013 - 159,546,224) shares); Outstanding - 153,246,754 shares (2013 - 153,126,291) shares)	19.8	19.8
Capital in excess of par value of shares	2,309.80	2,329.50
Retained earnings (Accumulated deficit)	-3,960.70	3,407.30
Cost of 6,299,470 common shares in treasury (2013 - 6,419,933 shares)	-285.7	-305.5
Accumulated other comprehensive loss	-245.8	-112.9
TOTAL CLIFFS SHAREHOLDERS' EQUITY (DEFICIT)	-1,431.30	6,069.50
NONCONTROLLING INTEREST (DEFICIT)	-303	814.8
TOTAL EQUITY (DEFICIT)	-1,734.30	6,884.30
TOTAL LIABILITIES AND EQUITY (DEFICIT)	$3,164	$13,121.90

Statements_Of_Condensed_Consol1

Statements Of Condensed Consolidated Financial Position (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Preferred stock, par value	$0	$0
Cumulative Mandatory Convertible	7.00%	7.00%
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	153,246,754	153,126,291
Common shares in treasury	6,299,470	6,419,133
Preferred Class A [Member]
Class of Stock [Line Items]
Preferred Stock, Liquidation Preference Per Share	$1,000	$1,000
Preferred stock, shares authorized (in shares)	3,000,000	3,000,000
Preferred Shares, Issued and Outstanding, Shares	731,223	731,250
Preferred Class B [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	4,000,000	4,000,000

Statements_Of_Condensed_Consol2

Statements Of Condensed Consolidated Operations (USD $)	12 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
REVENUES FROM PRODUCT SALES AND SERVICES
Product	$4,230.80	$5,346.60	$5,520.90
Reimbursement Revenue	392.9	344.8	351.8
TOTAL REVENUES	4,623.70	5,691.40	5,872.70
COST OF GOODS SOLD AND OPERATING EXPENSES	-4,172.30	-4,542.10	-4,700.60
SALES MARGIN	451.4	1,149.30	1,172.10
OTHER OPERATING INCOME (EXPENSE)
Selling, general and administrative expenses	-208.7	-231.6	-282.5
Exploration costs	-8.8	-59	-142.8
Impairment of goodwill and other long-lived assets	-9,029.90	-250.8	-1,049.90
Gain (loss) on disposal of other assets	-423	16.7	1.2
Miscellaneous - net	-226.3	46.4	-6.9
Other operating expense	-9,896.70	-478.3	-1,480.90
OPERATING INCOME (LOSS)	-9,445.30	671	-308.8
OTHER INCOME (EXPENSE)
Interest expense, net	-185.2	-179.1	-195.6
Other non-operating income (expense)	26.8	-2.6	2.6
TOTAL OTHER INCOME (EXPENSE)	-158.4	-181.7	-193
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND EQUITY INCOME (LOSS) FROM VENTURES	-9,603.70	489.3	-501.8
INCOME TAX BENEFIT (EXPENSE)	1,302	-55.1	-255.9
EQUITY LOSS FROM VENTURES, net of tax	-9.9	-74.4	-404.8
INCOME (LOSS) FROM CONTINUING OPERATIONS	-8,311.60	359.8	-1,162.50
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	0	2	35.9
NET INCOME (LOSS)	-8,311.60	361.8	-1,126.60
LOSS ATTRIBUTABLE TO NONCONTROLLING INTEREST	1,087.40	51.7	227.2
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	-7,224.20	413.5	-899.4
PREFERRED STOCK DIVIDENDS	-51.2	-48.7	0
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	($7,275.40)	$364.80	($899.40)
EARNINGS (LOSS) PER COMMON SHARE ATTRIBUTABLE TO CLIFFS SHAREHOLDERS - BASIC
Continuing operations	($47.52)	$2.39	($6.57)
Discontinued operations	$0	$0.01	$0.25
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Basic:	($47.52)	$2.40	($6.32)
EARNINGS (LOSS) PER COMMON SHARE ATTRIBUTABLE TO CLIFFS SHAREHOLDERS - DILUTED
Continuing operations	($47.52)	$2.36	($6.57)
Discontinued operations	$0	$0.01	$0.25
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Diluted:	($47.52)	$2.37	($6.32)
AVERAGE NUMBER OF SHARES (IN THOUSANDS)
Basic	153,098	151,726	142,351
Diluted	153,098	174,323	142,351

Statements_Of_Condensed_Consol3

Statements Of Condensed Consolidated Comprehensive Income (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	($7,224.20)	$413.50	($899.40)
OTHER COMPREHENSIVE INCOME (LOSS)
Pension and OPEB liability, net of tax	-91	208.3	33.8
Unrealized net gain (loss) on marketable securities, net of tax	-7.2	3.1	-0.5
Unrealized net gain (loss) on foreign currency translation	-42.3	-208.6	3.8
Unrealized net gain (loss) on derivative financial instruments, net of tax	2.8	-29.6	7.5
OTHER COMPREHENSIVE INCOME (LOSS)	-137.7	-26.8	44.6
OTHER COMPREHENSIVE LOSS (INCOME) ATTRIBUTABLE TO THE NONCONTROLLING INTEREST	4.8	-30.5	-7.6
TOTAL COMPREHENSIVE INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	($7,357.10)	$356.20	($862.40)

Statements_Of_Condensed_Consol4

Statements Of Condensed Consolidated Cash Flows (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
OPERATING ACTIVITIES
Net income (loss)	($8,311.60)	$361.80	($1,126.60)
Adjustments to reconcile net income (loss) to net cash provided (used) by operating activities:
Depreciation, depletion and amortization	504	593.3	525.8
Impairment of goodwill and other long-lived assets	9,029.90	250.8	1,049.90
Equity loss in ventures (net of tax)	9.9	74.4	404.8
Deferred income taxes	-1,153.90	-138.1	127
Changes in deferred revenue and below-market sales contracts	-18	-52.8	-24.5
Loss on sale of Cliffs Logan County Coal	419.6	0	0
Other	-37.7	-3.3	-40.9
Changes in operating assets and liabilities:
Receivables and other assets	-82.8	138.8	-74.8
Product inventories	37.8	30.8	39.9
Payables and accrued expenses	-38.3	-109.8	-366.1
Net cash provided by operating activities	358.9	1,145.90	514.5
INVESTING ACTIVITIES
Purchase of property, plant and equipment	-284.1	-861.6	-1,127.50
Proceeds from sale of Cliffs Logan County Coal	155	0	0
Proceeds from sale of Sonoma	0	0	152.6
Other investing activities	25.5	50.3	13.1
Net cash used in investing activities	-103.6	-811.3	-961.8
FINANCING ACTIVITIES
Net proceeds from issuance of Series A, Mandatory Convertible Preferred Stock, Class A	0	709.4	0
Net proceeds from issuance of common shares	0	285.3	0
Net proceeds from issuance of senior notes	0	0	497
Repayment of term loan	0	-847.1	-124.8
Borrowings under credit facilities	1,219.50	670.5	1,012
Repayment under credit facilities	-1,219.50	-995.5	-687
Proceeds from equipment loans	0	164.8	0
Repayments of equipment loans	-20.9	-3	0
Repayment of senior notes	0	0	-325
Repurchase of debt	-28.8	0	0
Contributions (to)/by joint ventures, net	-25.7	23.3	95.4
Common stock dividends	-92.5	-91.9	-307.2
Preferred stock dividends	-51.2	-35.7	0
Other financing activities	-69.2	-52	-40.8
Net cash (used in) provided by financing activities	-288.3	-171.9	119.6
EFFECT OF EXCHANGE RATE CHANGES ON CASH	-11.6	-22.4	1.3
INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	-44.6	140.3	-326.4
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD	335.5	195.2	521.6
CASH AND CASH EQUIVALENTS AT END OF PERIOD	$290.90	$335.50	$195.20

Statements_of_Consolidated_Cha

Statements of Consolidated Changes in Equity (USD $)	Total	Depositary Shares [Member]	Common Stock [Member]	Capital in Excess of Par Value of Shares [Member]	Retained Earnings [Member]	Common Shares in Treasury [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	Depositary Shares [Member]	Depositary Shares [Member]	Common Stock [Member]	Common Stock [Member]
In Millions, except Share data, unless otherwise specified	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	USD ($)	Capital in Excess of Par Value of Shares [Member]		Capital in Excess of Par Value of Shares [Member]
										USD ($)		USD ($)
Balance, beginning of period at Dec. 31, 2011	$7,039.70		$18.50	$1,770.80	$4,424.30	($336)	($92.60)	$1,254.70
Balance, beginning of period (in shares) at Dec. 31, 2011			142,000,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
NET INCOME (LOSS)	-1,126.60				-899.4			-227.2
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	862.4						37
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest								7.6
Other Comprehensive Income (Loss), Net of Tax	44.6
Pension and OPEB liability, net of tax	33.8
Unrealized net loss on marketable securities, net of tax	-0.5
Total comprehensive income (loss)	-1,082							-219.6
Purchase of subsidiary shares from noncontrolling interest	-2.1							-2.1
Undistributed losses to noncontrolling interest to subsidiary	0.4							0.4
Capital contribution by noncontrolling interest to subsidiary	104.4			1.6				102.8
Stock Issued During Period, Value, Acquisitions	-8							-8
Stock and other incentive plans (in shares)			500,000
Stock and other incentive plans	15.7			2.3		13.4
Common stock dividends ($0.60 per share)	-307.2				-307.2
Preferred stock dividends ($1.66 per depositary share)	0
Balance, end of period at Dec. 31, 2012	5,760.90		18.5	1,774.70	3,217.70	-322.6	-55.6	1,128.20
Balance, end of period (in shares) at Dec. 31, 2012			142,500,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
NET INCOME (LOSS)	361.8				413.5			-51.7
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	-356.2						-57.3
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest								30.5
Other Comprehensive Income (Loss), Net of Tax	-26.8
Pension and OPEB liability, net of tax	208.3
Unrealized net loss on marketable securities, net of tax	3.1
Total comprehensive income (loss)	335							-21.2
Equity offering (in shares)		29,300,000	10,400,000
Equity offering	285.3	731.3	1.3						709.4	-21.9		284
Purchase of subsidiary shares from noncontrolling interest				295.4	-82.7
Undistributed losses to noncontrolling interest to subsidiary	17							17
Capital contribution by noncontrolling interest to subsidiary	5.2			0.2	-0.6			5.6
Stock Issued During Period, Value, Acquisitions	-102.1							-314.8
Stock and other incentive plans (in shares)			300,000
Stock and other incentive plans	14.2			-2.9		17.1
Common stock dividends ($0.60 per share)	-91.9				-91.9
Preferred stock dividends ($1.66 per depositary share)	-48.7				-48.7
Preferred Stock, Shares Outstanding		29,300,000
Balance, end of period at Dec. 31, 2013	6,884.30	731.3	19.8	2,329.50	3,407.30	-305.5	-112.9	814.8
Balance, end of period (in shares) at Dec. 31, 2013	153,126,291		153,200,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
NET INCOME (LOSS)	-8,311.60				-7,224.20			-1,087.40
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	7,357.10						-132.9
Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest								-4.8
Other Comprehensive Income (Loss), Net of Tax	-137.7
Pension and OPEB liability, net of tax	-91
Unrealized net loss on marketable securities, net of tax	-7.2
Total comprehensive income (loss)	-8,449.30							-1,092.20
Undistributed losses to noncontrolling interest to subsidiary	-25.5							-25.5
Capital contribution by noncontrolling interest to subsidiary	-0.1							-0.1
Stock and other incentive plans	0.1			-19.7		19.8
Common stock dividends ($0.60 per share)	-92.5				-92.5
Preferred stock dividends ($1.66 per depositary share)	-51.2
Preferred Stock Dividends	-51.3				-51.3
Preferred Stock, Shares Outstanding		29,300,000
Balance, end of period at Dec. 31, 2014	-1,734.30	731.3	19.8	2,309.80	-3,960.70	-285.7	-245.8	-303
Balance, end of period (in shares) at Dec. 31, 2014	153,246,754		153,200,000
Balance, beginning of period at Sep. 30, 2014
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred stock dividends ($1.66 per depositary share)	-12.8
Preferred Stock, Shares Outstanding		29,300,000
Balance, end of period at Dec. 31, 2014	($1,734.30)	$731.30	$19.80
Balance, end of period (in shares) at Dec. 31, 2014	153,246,754		153,200,000

Statements_of_Consolidated_Cha1

Statements of Consolidated Changes in Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Class of Stock [Line Items]
Common stock dividends per share	$0.60	$0.60	$2.16
Preferred stock dividends per share	$1.75	$1.66

BASIS_OF_PRESENTATION_AND_SIGN

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

BUSINESS SUMMARY AND SIGNIFICANT ACCOUNTING POLICIES

NOTE 1 - BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES

Business Summary

We are an international mining and natural resources company, a major global iron ore producer and a producer of low-volatile metallurgical coal. In the U.S., we operate five iron ore mines in Michigan and Minnesota, and two low-volatile metallurgical coal operations located in Alabama and West Virginia. In the fourth quarter of 2014, we sold our CLCC assets, which consisted of two high-volatile metallurgical coal mines and one thermal coal mine. The sale was completed on December 31, 2014. As such, our results include the CLCC results through the day of the sale completion. As of December 31, 2014, our Asia Pacific operations consist solely of our Koolyanobbing iron ore mining complex in Western Australia. We also own two iron ore mines in Eastern Canada. In the first quarter of 2014, Wabush Scully mine in Newfoundland and Labrador was idled and subsequently moved to permanent closure during the fourth quarter. 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. Our operations are organized according to product category and geographic location: U.S. Iron Ore, Asia Pacific Iron Ore, North American Coal and Eastern Canadian Iron Ore.

Significant Accounting Policies

We consider the following policies to be beneficial in understanding the judgments that are involved in the preparation of our consolidated financial statements and the uncertainties that could impact our financial condition, results of operations and cash flows.

Use of Estimates

The preparation of financial statements, in conformity with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions related to mineral reserves future realizable cash flow; environmental, reclamation and closure obligations; valuation of long-lived assets and investments; valuation of inventory; valuation of post-employment, post-retirement and other employee benefit liabilities; valuation of tax assets; reserves for contingencies and litigation; and the fair value of derivative instruments. Actual results could differ from estimates. On an ongoing basis, management reviews estimates. Changes in facts and circumstances may alter such estimates and affect results of operations and financial position in future periods.

Basis of Consolidation

The consolidated financial statements include our accounts and the accounts of our wholly owned and majority-owned subsidiaries, including the following operations at December 31, 2014:

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

Oak Grove

Alabama

100.00%

Coal

Active

CLCC

West Virginia

100.00%

Coal

Assets sold as of December 31, 2014

Wabush

Newfoundland and Labrador/ Québec, Canada

100.00%

Iron Ore

Permanent closure

Bloom Lake

Québec, Canada

82.80%

Iron Ore

Care-and-maintenance

Cliffs Chromite Ontario - Black Label Deposit

Ontario, Canada

100.00%

Chromite

Suspended

Cliffs Chromite Ontario - Black Thor Deposit

Ontario, Canada

100.00%

Chromite

Suspended

Cliffs Chromite Ontario & Cliffs Chromite Far North - Big Daddy Deposit

Ontario, Canada

70.00%

Chromite

Suspended

Intercompany transactions and balances are eliminated upon consolidation.

Noncontrolling Interests

During the fourth quarter of 2013, CQIM’s interest in Bloom Lake increased by an aggregate of 7.8 percent after CQIM paid both its own and WISCO’s proportionate shares of the cash call for the first half of 2013.  As a result of our cash call payments, CQIM was issued a total of 457,556 new Bloom Lake units, increasing our interest to 82.8 percent in Bloom Lake and diluting WISCO’s interest to 17.2 percent.  The new unit issuance decreased equity attributable to WISCO by $314.8 million for the year ended December 31, 2013 by decreasing WISCO’s interest in Bloom Lake’s accumulated deficit.   We accounted for the increase in ownership as an equity transaction, which resulted in a $314.8 million increase to equity attributable to Cliffs’ shareholders.

Immaterial Error

In connection with our acquisition of Consolidated Thompson in May 2011, the Company acquired a 75 percent controlling interest in Bloom Lake. For financial reporting purposes, the Company fully consolidates Bloom Lake in the accompanying financial statements and allocates a portion of its consolidated results of operations and shareholders’ equity, which is reported as Loss attributable to noncontrolling interest in the Statements of Consolidated Operations and Noncontrolling interest in the Statements of Consolidated Financial Position.

As a result of the application of ASC 805, Business Combinations, we allocated the purchase price to the assets, liabilities and noncontrolling interest at the acquisition date of May 11, 2011 based on their fair values. These fair value adjustments were recorded in the opening balance sheet and consolidated results of operations; however, subsequent effects of the amortization of these fair value adjustments were not allocated to the noncontrolling interest.

In accordance with U.S. GAAP, management has quantitatively and qualitatively evaluated the materiality of the error and has determined that the misstatement was immaterial to the interim and annual financial statements previously filed from June 30, 2011 through December 31, 2013. Accordingly, the adjustment was recorded prospectively in the Statements of Consolidated Operations for the period ended December 31, 2013 and in the Statements of Consolidated Financial Position as of December 31, 2013. The adjustment to noncontrolling interest related to Bloom Lake was approximately $45.1 million and resulted in an increase to Net Income (Loss) Attributable to Cliffs Shareholders and a reduction of Loss attributable to noncontrolling interest and corresponding decrease to Noncontrolling interest in the Statements of Consolidated Financial Position for the year end and as of December 31, 2013. The adjustments also resulted in an increase to basic and diluted earnings per common share of $0.30 and $0.26, respectively, for the year ended December 31, 2013. No other financial statement line items were impacted by this adjustment. The prior period amounts included within the accompanying Consolidated Financial Statements have not been retrospectively adjusted for this impact due to management's materiality assessment as discussed above. The impact of the prospective adjustments in the Statements of Consolidated Operations would have resulted in an increase to basic and diluted earnings per common share of $0.25 and $0.07 for the years ended December 31, 2012 and 2011, respectively.

Cash Equivalents

Cash and cash equivalents include cash on hand and on deposit as well as all short-term securities held for the primary purpose of general liquidity. We consider investments in highly liquid debt instruments with an original maturity of three months or less from the date of acquisition to be cash equivalents. We routinely monitor and evaluate counterparty credit risk related to the financial institutions by which our short-term investment securities are held.

Trade Accounts Receivable and Allowance for Doubtful Accounts

Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is our best estimate of the amount of probable credit losses in Cliffs' existing accounts receivable. We establish provisions for losses on accounts receivable when it is probable that all or part of the outstanding balance will not be collected. We regularly review our accounts receivable balances and establish or adjust the allowance as necessary using the specific identification method. The allowance for doubtful accounts was $8.1 million at December 31, 2014 and 2013. There was $9.0 million of bad debt expense for the year ended December 31, 2012. There was no bad debt expense for the years ended December 31, 2014 and 2013.

Inventories

U.S. Iron Ore

U.S. Iron Ore product inventories are stated at the lower of cost or market. Cost of iron ore inventories is determined using the LIFO method.

We had approximately 1.4 million tons and 1.2 million tons of finished goods stored at ports and customer facilities on the lower Great Lakes to service customers at December 31, 2014 and 2013, respectively. We maintain ownership of the inventories until title has transferred to the customer, usually when payment is received. Maintaining ownership of the iron ore products at ports on the lower Great Lakes reduces risk of non-payment by customers.

Asia Pacific Iron Ore

Asia Pacific Iron Ore product inventories are stated at the lower of cost or market. Costs of inventories are being valued on a weighted average cost basis. We maintain ownership of the inventories until title has transferred to the customer, which generally is when the product is loaded into the vessel.

North American Coal

North American Coal product inventories are stated at the lower of cost or market. Cost of coal inventories is calculated using the weighted average cost. We maintain ownership until coal is loaded into rail cars at the mine for domestic sales and until loaded in the vessels at the terminal for export sales.

Eastern Canadian Iron Ore

Iron ore pellet inventories are stated at the lower of cost or market. Cost is determined using the LIFO method. We maintain ownership of the inventories until title has transferred to the customer, which is generally when the product is loaded into the vessel.

Iron ore concentrate inventories are stated at the lower of cost or market. The cost of iron ore concentrate inventories is determined using weighted average cost. We maintain ownership of the inventories until title has transferred to the customer, which generally is when the product is loaded into the vessel.

Supplies and Other Inventories

Supply inventories include replacement parts, fuel, chemicals and other general supplies, which are expected to be used or consumed in normal operations. Supply inventories also include critical spares. Critical spares are replacement parts for equipment that is critical for the continued operation of the mine or processing facilities.

Supply inventories are stated at the lower of cost or market using average cost, less an allowance for obsolete and surplus items. The allowance for obsolete and surplus items was $68.2 million and $63.4 million at December 31, 2014 and 2013, respectively.

Derivative Financial Instruments and Hedging Activities

We are exposed to certain risks related to the ongoing operations of our business, including those caused by changes in commodity prices, interest rates and foreign currency exchange rates. We have established policies and procedures, including the use of certain derivative instruments, to manage such risks.

Derivative financial instruments are recognized as either assets or liabilities in the Statements of Consolidated Financial Position and measured at fair value. On the date a derivative instrument is entered into, we generally designate a qualifying derivative instrument as a hedge of the variability of cash flows to be received or paid related to a recognized asset or liability or forecasted transaction (cash flow hedge). We formally document all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. This process includes linking all derivatives that are designated as cash flow hedges to specific firm commitments or forecasted transactions. We also formally assess both at the hedge's inception and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows of the related hedged items. When it is determined that a derivative is not highly effective as a hedge or that it has ceased to be a highly effective hedge, we discontinue hedge accounting prospectively and record all future changes in fair value in the period of the instrument's earnings or losses. The policy allows for 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.

For derivative instruments that have been designated as cash flow hedges, the effective portion of the changes in fair value are recorded in accumulated other comprehensive income (loss) and any portion that is ineffective is recorded in current period earnings or losses. Amounts recorded in accumulated other comprehensive income (loss) are reclassified to earnings or losses in the period the underlying hedged transaction affects earnings or when the underlying hedged transaction is no longer reasonably possible of occurring.

For derivative instruments that have not been designated as cash flow hedges, changes in fair value are recorded in the period of the instrument's earnings or losses.

Refer to NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES for further information.

Property, Plant and Equipment

Our properties are stated at the lower of cost less accumulated depreciation or fair value. Depreciation of plant and equipment is computed principally by the straight-line method based on estimated useful lives, not to exceed the mine lives. The Northshore, United Taconite, Empire, Tilden and Wabush operations use the double-declining balance method of depreciation for certain mining equipment. The Asia Pacific Iron Ore operation uses the production output method for certain mining equipment. Depreciation is provided over the following estimated useful lives:

Asset Class

Basis

Life

Buildings

Straight line

45 Years

Mining equipment

Straight line/Double declining balance

3 to 20 Years

Processing equipment

Straight line

10 to 45 Years

Electric power facilities

Straight line

10 to 45 years

Land improvements

Straight line

20 to 45 years

Office and information technology

Straight line

3 to 15 Years

Depreciation continues to be recognized when operations temporarily are idled.

Our Asia Pacific Iron Ore, Bloom Lake, Wabush, and United Taconite operations' interests in iron ore reserves and mineralized materials were valued when acquired using a discounted cash flow method. The fair value was estimated based upon the present value of the expected future cash flows from iron ore operations over the economic lives of the respective mines.

Our North American Coal operation leases coal mining rights from third parties through lease agreements. The lease agreements are for varying terms and extend through the earlier of their lease termination date or until all merchantable and mineable coal has been extracted. Our interest in coal reserves and non-reserve coal was valued when acquired using a discounted cash flow method. The fair value was estimated based upon the present value of the expected future cash flows from coal operations over the life of the reserves acquired.

Refer to NOTE 4 - PROPERTY, PLANT AND EQUIPMENT for further information.

Capitalized Stripping Costs

During the development phase, stripping costs are capitalized as a part of the depreciable cost of building, developing and constructing a mine. These capitalized costs are amortized over the productive life of the mine using the units of production method. The production phase does not commence until the removal of more than a de minimis amount of saleable mineral material occurs in conjunction with the removal of overburden or waste material for purposes of obtaining access to an ore body. The stripping costs incurred in the production phase of a mine are variable production costs included in the costs of the inventory produced (extracted) during the period that the stripping costs are incurred.

Stripping costs related to expansion of a mining asset of proven and probable reserves are variable production costs that are included in the costs of the inventory produced during the period that the stripping costs are incurred.

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 Consolidated Financial Position as of December 31, 2014 and December 31, 2013. Parentheses indicate a net liability.

(In Millions)

Investment

Classification

Accounting

Ownership Interest

December 31,

December 31, 2013

Method

2014

Hibbing

Other non-current assets 1

Equity Method

23%

$

3.1

(3.9

)

Other

Other non-current assets

Equity Method

Various

3.9

34.7

$

7

$

30.8

1 At December 31, 2013, the classification for Hibbing was Other liabilities.

During the year ended December 31, 2014, an impairment charge of $21.5 million was recorded related to joint ventures investments and is recognized in Impairment of goodwill and other long-lived assets in the Statements of Consolidated Operations.

Hibbing

Our share of equity income (loss) is eliminated against consolidated product inventory upon production, and against Cost of goods sold and operating expenses when sold. This effectively reduces our cost for our share of the mining ventures' production cost, reflecting the cost-based nature of our participation in unconsolidated ventures.

Amapá

On December 27, 2012, our Board of Directors authorized the sale of our 30 percent interest in Amapá. Per this original agreement, together with Anglo, we were to sell our respective interest in a 100 percent sale transaction to Zamin. The carrying value of our investment was in excess of the net proceeds expected from the sale, which approximated fair value, resulting in a $365.4 million impairment charge, which was recorded through Equity loss from ventures, net of tax in the Statements of Consolidated Operations for the year ended December 31, 2012.

On March 28, 2013, an unknown event caused the Santana port shiploader to collapse into the Amazon River, preventing further ship loading by the mine operator, Anglo. In light of the March 28, 2013 collapse of the Santana port shiploader and subsequent evaluation of the effect that this event had on the carrying value of our investment in Amapá as of June 30, 2013, we recorded an impairment charge of $67.6 million in the second quarter of 2013.

On August 28, 2013, we entered into additional agreements to sell our 30 percent interest in Amapá to Anglo for nominal cash consideration, plus the right to certain contingent deferred consideration upon the two-year anniversary of the closing.  The closing was conditional on obtaining certain regulatory approvals and the additional agreement provided Anglo with an option to request that we transfer our interest in Amapá directly to Zamin.  Anglo exercised this option and the transfer to Zamin was completed in the fourth quarter of 2013.

Cockatoo Island

On July 31, 2012, we entered into a definitive asset sale agreement with our joint venture partner, HWE Cockatoo Pty Ltd., to sell our beneficial interest in the mining tenements and certain infrastructure of Cockatoo Island to Pluton Resources, which was amended on August 31, 2012. On September 7, 2012, the closing date, Pluton Resources paid a nominal sum of AUD $4.00 and assumed ownership of the assets and responsibility for the environmental rehabilitation obligations and other assumed liabilities not inherently attached to the tenements acquired. The rehabilitation obligations and assumed liabilities that are inherently attached to the tenements were transferred to Pluton Resources upon registration by the Department of Mining and Petroleum denoting Pluton Resources as the tenement holder. Upon final settlement of the sale, which was completed during the second quarter of 2013, we extinguished approximately $18.6 million related to the estimated cost of the rehabilitation.

Goodwill

Goodwill represents the excess purchase price paid over the fair value of the net assets of acquired companies. We had goodwill of $2.0 million and $74.5 million recorded in the Statements of Consolidated Financial Position at December 31, 2014 and 2013, respectively. In accordance with the provisions of ASC 350, we compare the fair value of the respective reporting unit to its carrying value on an annual basis (or more frequently if necessary as discussed below) to determine if there is potential goodwill impairment. If the fair value of the reporting unit is less than its carrying value, an impairment loss is recorded to the extent that the implied value of the goodwill within the reporting unit is less than the carrying value of its goodwill.

During the third quarter of 2014, a goodwill impairment charge of $73.5 million was recorded for our Asia Pacific Iron Ore reporting unit within the Asia Pacific Iron Ore operating segment. The impairment charge was a result of downward long-term pricing estimates as determined through management's long-range planning process.

After performing our annual goodwill impairment test in the fourth quarter of 2013, we determined that $80.9 million of goodwill associated with our Ferroalloys operating segment was impaired. The impairment charge was primarily a result of the decision made in the fourth quarter of 2013 to indefinitely suspend the Chromite Project and to not allocate additional capital for the project given the uncertain timeline and risks associated with the development of necessary infrastructure to bring the project online.

During the fourth quarter of 2012, upon performing our annual goodwill impairment test, a goodwill impairment charge of $997.3 million was recorded for our CQIM reporting unit within the Eastern Canadian Iron Ore operating segment. The impairment charge for our CQIM reporting unit was driven by the project’s lower than anticipated long-term profitability coupled with delays in achieving full operational capacity and higher capital and operating costs. Additionally, the announced delay of the Phase II expansion of the Bloom Lake mine also contributed to the impairment.

Refer to NOTE 12 - GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES and NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS for further information.

Other Intangible Assets and Liabilities

Other intangible assets are subject to periodic amortization on a straight-line basis over their estimated useful lives as follows:

Intangible Assets

Basis

Useful Life (years)

Permits - Asia Pacific Iron Ore

Units of production

Life of mine

Permits - All Other

Straight line

15 - 40

Utility Contracts

Straight line

5

Leases - North American Coal

Units of production

Life of mine

Leases - All Other

Straight line

4.5 - 17.5

Asset Impairment

Long-Lived Tangible and Intangible Assets

We monitor conditions that may affect the carrying value of our long-lived tangible and intangible assets when events and circumstances indicate that the carrying value of the asset groups may not be recoverable. In order to determine if assets have been impaired, assets are grouped and tested at the lowest level for which identifiable, independent cash flows are available ("asset group"). An impairment loss exists when projected undiscounted cash flows are less than the carrying value of the asset group. The measurement of the impairment loss to be recognized is based on the difference between the fair value and the carrying value of the asset group. Fair value can be determined using a market approach, income approach or cost approach.

As a result of these assessments during 2014, we determined that the cash flows associated with our Eastern Canadian Iron Ore, Asia Pacific Iron Ore, North American Coal and Ferroalloys asset groups were not sufficient to support the recoverability of the carrying value of these productive assets. Accordingly, during 2014, we recorded a long-lived tangible asset impairment charge of $8,839.0 million and an intangible asset impairment charge of $15.5 million in our Statements of Consolidated Operations. At December 31, 2013, we determined there were long-lived tangible and intangible asset impairments related to the Wabush operations within our Eastern Canadian Iron Ore operating segment that resulted in impairment charges of $145.1 million and $9.5 million, respectively. At December 31, 2012, we determined there was a long-lived asset impairment related to the Wabush mine's pelletizing operations that resulted in an impairment charge of $49.9 million.

Refer to NOTE 4 - PROPERTY, PLANT AND EQUIPMENT, NOTE 12 - GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES and NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS for further information.

Fair Value Measurements

Valuation Hierarchy

ASC 820 establishes a three-level valuation hierarchy for classification of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. Inputs refer broadly to the assumptions that market participants would use in pricing an asset or liability. Inputs may be observable or unobservable. Observable inputs are inputs that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. The three-tier hierarchy of inputs is summarized below:

•

Level 1 — Valuation is based upon quoted prices (unadjusted) for identical assets or liabilities in active markets.

•

Level 2 — Valuation is based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument.

•

Level 3 — Valuation is based upon other unobservable inputs that are significant to the fair value measurement.

The classification of assets and liabilities within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement in its entirety. Valuation methodologies used for assets and liabilities measured at fair value are as follows:

Cash Equivalents

Where quoted prices are available in an active market, cash equivalents are classified within Level 1 of the valuation hierarchy. Cash equivalents classified in Level 1 at December 31, 2014 and 2013 include money market funds. Valuation of these instruments is determined using a market approach and is based upon unadjusted quoted prices for identical assets in active markets.

Marketable Securities

Where quoted prices are available in an active market, marketable securities are classified within Level 1 of the valuation hierarchy. Marketable securities classified in Level 1 at December 31, 2014 and 2013 include available-for-sale securities. The valuation of these instruments is determined using a market approach and is based upon unadjusted quoted prices for identical assets in active markets.

Derivative Financial Instruments

Derivative financial instruments valued using financial models that use as their basis readily observable market parameters are classified within Level 2 of the valuation hierarchy. Such derivative financial instruments include substantially all of our foreign currency exchange contracts and derivative financial instruments that are valued based upon published pricing settlements realized by other companies in the industry. Derivative financial instruments that are valued based upon models with significant unobservable market parameters and are normally traded less actively, are classified within Level 3 of the valuation hierarchy.

Refer to NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS and NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

Pensions and Other Postretirement Benefits

We offer defined benefit pension plans, defined contribution pension plans and other postretirement benefit plans, primarily consisting of retiree healthcare benefits, to most employees in North America as part of a total compensation and benefits program. We do not have employee pension or post-retirement benefit obligations at our Asia Pacific Iron Ore operations or our Bloom Lake mine operations within our Eastern Canadian Iron Ore segment.

We recognize the funded or unfunded status of our postretirement benefit obligations on our December 31, 2014 and 2013 Statements of Consolidated Financial Position based on the difference between the market value of plan assets and the actuarial present value of our retirement obligations on that date, on a plan-by-plan basis. If the plan assets exceed the retirement obligations, the amount of the surplus is recorded as an asset; if the retirement obligations exceed the plan assets, the amount of the underfunded obligations are recorded as a liability. Year-end balance sheet adjustments to postretirement assets and obligations are recorded as Accumulated other comprehensive loss.

The actuarial estimates of the PBO and APBO retirement obligations incorporate various assumptions including the discount rates, the rates of increases in compensation, healthcare cost trend rates, mortality, retirement timing and employee turnover. For the U.S. and Canadian plans, the discount rate is determined based on the prevailing year-end rates for high-grade corporate bonds with a duration matching the expected cash flow timing of the benefit payments from the various plans. The remaining assumptions are based on our estimates of future events by incorporating historical trends and future expectations. The amount of net periodic cost that is recorded in the Statements of Consolidated Operations consists of several components including service cost, interest cost, expected return on plan assets, and amortization of previously unrecognized amounts. Service cost represents the value of the benefits earned in the current year by the participants. Interest cost represents the cost associated with the passage of time. Certain items, such as plan amendments, gains and/or losses resulting from differences between actual and assumed results for demographic and economic factors affecting the obligations and assets of the plans, and changes in other assumptions are subject to deferred recognition for income and expense purposes. The expected return on plan assets is determined utilizing the weighted average of expected returns for plan asset investments in various asset categories based on historical performance, adjusted for current trends. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

Asset Retirement Obligations

Asset retirement obligations are recognized when incurred and recorded as liabilities at fair value. The fair value of the liability is determined as the discounted value of the expected future cash flow. The asset retirement obligation is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized as part of the asset’s carrying value and amortized over the life of the related asset. Reclamation costs are adjusted periodically to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation costs. We review, on an annual basis, unless otherwise deemed necessary, the asset retirement obligation at each mine site in accordance with the provisions of ASC 410. We perform an in-depth evaluation of the liability every three years in addition to routine annual assessments.

Future remediation costs for inactive mines are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at a site. Such cost estimates include, where applicable, ongoing maintenance and monitoring costs. Changes in estimates at inactive mines are reflected in earnings in the period an estimate is revised. See NOTE 11 - ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS for further information.

Environmental Remediation Costs

We have a formal policy for environmental protection and restoration. Our mining and exploration activities are subject to various laws and regulations governing protection of the environment. We conduct our operations to protect the public health and environment and believe our operations are in compliance with applicable laws and regulations in all material respects. Our environmental liabilities, including obligations for known environmental remediation exposures at active and closed mining operations and other sites, have been recognized based on the estimated cost of investigation and remediation at each site. If the cost only can be estimated as a range of possible amounts with no point in the range being more likely, the minimum of the range is accrued. Future expenditures are not discounted unless the amount and timing of the cash disbursements reasonably can be estimated. It is possible that additional environmental obligations could be incurred, the extent of which cannot be assessed. Potential insurance recoveries have not been reflected in the determination of the liabilities. See NOTE 11 - ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS for further information.

Revenue Recognition

U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore

We sell our products pursuant to comprehensive supply agreements negotiated and executed with our customers. Revenue is recognized from a sale when persuasive evidence of an arrangement exists, the price is fixed or determinable, the product is delivered in accordance with F.O.B. terms, title and risk of loss have transferred to the customer in accordance with the specified provisions of each supply agreement and collection of the sales price reasonably is assured. Our U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore supply agreements provide that title and risk of loss transfer to the customer either upon loading of the vessel, shipment or, as is the case with some of our U.S. Iron Ore supply agreements, when payment is received. Under certain term supply agreements, we ship the product to ports on the lower Great Lakes or to the customers’ facilities prior to the transfer of title. Our rationale for shipping iron ore products to certain customers and retaining title until payment is received for these products is to minimize credit risk exposure.

Iron ore sales are recorded at a sales price specified in the relevant supply agreements resulting in revenue and a receivable at the time of sale. Upon revenue recognition for provisionally priced sales, a freestanding derivative is created for the difference between the sales price used and expected future settlement price. The derivative, which does not qualify for hedge accounting, is adjusted to fair value through Product revenues as a revenue adjustment each reporting period based upon current market data and forward-looking estimates determined by management until the final sales price is determined. The principal risks associated with recognition of sales on a provisional basis include iron ore price fluctuations between the date initially recorded and the date of final settlement. For revenue recognition, we estimate the future settlement rate; however, if significant changes in iron ore prices occur between the provisional pricing date and the final settlement date, we might be required to either return a portion of the sales proceeds received or bill for the additional sales proceeds due based on the provisional sales price. Refer to NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES for further information.

In addition, certain supply agreements with one customer include provisions for supplemental revenue or refunds based on the customer’s annual steel pricing for the year 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 record this provision at fair value until the year the product is consumed and the amounts are settled as an adjustment to revenue. Refer to NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES for further information.

Revenue from product sales also includes reimbursement for freight charges paid on behalf of customers and freight costs to move product from the Upper Great Lakes to ports in Québec to use for exports and from the port of Esperance to ports in China, which are included in Freight and venture partners' cost reimbursements separate from Product revenues. Revenue is recognized for the expected reimbursement of services when the services are performed.

North American Coal

We sell our products pursuant to supply agreements negotiated and executed with our customers. Revenue is recognized when persuasive evidence of an arrangement exists, the price is fixed or determinable, the product is delivered in accordance with F.O.B. terms, title and risk of loss have transferred to the customer in accordance with the specified provisions of each supply agreement and collection of the sales price reasonably is assured. Delivery on our coal sales is determined to be complete for revenue recognition purposes when title and risk of loss has passed to the customer in accordance with stated contractual terms and there are no other future obligations related to the shipment. For domestic shipments, title and risk of loss generally passes as the coal is loaded into transport carriers for delivery to the customer. For international shipments, title generally passes at the time coal is loaded onto the shipping vessel. Revenue from product sales in 2014, 2013 and 2012 included reimbursement for freight charges paid to move coal from the mine to port locations of $115.0 million, $85.8 million and $101.0 million, respectively, and is recorded in Freight and venture partners' cost reimbursements on the Statements of Consolidated Operations.

Deferred Revenue

The terms of one of our U.S. Iron Ore pellet supply agreements required supplemental payments to be paid by the customer during the period 2009 through 2012, with the option to defer a portion of the 2009 monthly amount in exchange for interest payments until the deferred amount was repaid in 2013. Installment amounts received under this arrangement in excess of sales are classified as deferred revenue in the Statements of Consolidated Financial Position upon receipt of payment. Revenue is recognized over the life of the supply agreement, which extends until 2022, in equal annual installments. As of December 31, 2014 and 2013, installment amounts received in excess of sales totaled $102.8 million and $115.6 million, respectively. As of December 31, 2014, deferred revenue of $12.8 million was recorded in Other current liabilities and $90.0 million was recorded as long term in Other liabilities in the Statements of Consolidated Financial Position. As of December 31, 2013, deferred revenue of $12.8 million was recorded in Other current liabilities and $102.8 million was recorded as long term in Other liabilities in the Statements of Consolidated Financial Position.

In 2014 and 2013, due to the payment terms and the timing of cash receipts near year-end, cash receipts exceeded shipments. The shipments were completed early in the subsequent years. We considered whether revenue should be recognized on these sales under the “bill and hold” guidance provided by the SEC Staff; however, based upon the assessment performed, revenue recognition on these transactions totaling $29.3 million and $13.5 million, respectively, was deferred on the December 31, 2014 and December 31, 2013 Statements of Consolidated Financial Position.

Cost of Goods Sold

U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore

Cost of goods sold and operating expenses represents all direct and indirect costs and expenses applicable to the sales and revenues of our mining operations. Operating expenses primarily represent the portion of the Tilden mining venture costs for which we do not own; that is, the costs attributable to the share of the mine’s production owned by the other joint venture partner in the Tilden mine. The mining venture functions as a captive cost company; it supplies product only to its owners effectively for the cost of production. Accordingly, the noncontrolling interests’ revenue amounts are stated at cost of production and are offset by an equal amount included in Cost of goods sold and operating expenses resulting in no sales margin reflected for the noncontrolling partner participant. As we are responsible for product fulfillment, we act as a principal in the transaction and, accordingly, record revenue under these arrangements on a gross basis.

The following table is a summary of reimbursements in our U.S. Iron Ore operations for the years ended December 31, 2014, 2013 and 2012:

(In Millions)

Year Ended December 31,

2014

2013

2012

Reimbursements for:

Freight

$

163

$

177.3

$

142

Venture partners’ cost

108

82.2

108.8

Total reimbursements

$

271

$

259.5

$

250.8

In 2014, we began selling a portion of its Asia Pacific Iron Ore product on a CFR basis. As a result, $6.9 million of freight was included in Cost of goods sold and operating expenses. There was no freight for the year ended December 31, 2013.

Where we have joint ownership of a mine, our contracts entitle us to receive royalties and/or management fees, which we earn as the pellets are produced.

North American Coal

Cost of goods sold and operating expenses represent all direct and indirect costs and expenses applicable to the sales and revenues of our mining operations.

Repairs and Maintenance

Repairs, maintenance and replacement of components are expensed as incurred. The cost of major equipment overhauls is capitalized and depreciated over the estimated useful life, which is the period until the next scheduled overhaul, generally five years. All other planned and unplanned repairs and maintenance costs are expensed when incurred.

Share-Based Compensation

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. Consistent with the guidelines of ASC 718, a correlation matrix of historic and projected stock prices was developed for both the Company and its 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 estimated 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 plans.

The fair value of stock options is estimated on the date of grant using a Black-Scholes model using the grant date price of our common shares and option exercise price, and assumptions regarding the option’s expected term, the volatility of our common shares, the risk-free interest rate, and the dividend yield over the option’s expected term.

Refer to NOTE 8 - STOCK COMPENSATION PLANS for additional information.

Income Taxes

Income taxes are based on income for financial reporting purposes, calculated using tax rates by jurisdiction, and reflect a current tax liability or asset for the estimated taxes payable or recoverable on the current year tax return and expected annual changes in deferred taxes. Any interest or penalties on income tax are recognized as a component of income tax expense.

We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

We record net deferred tax assets to the extent we believe these assets will more likely than not be realized. In making such determination, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies and recent financial results of operations.

Accounting for uncertainty in income taxes recognized in the financial statements requires that a tax benefit from an uncertain tax position be recognized when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on technical merits.

See NOTE 9 - INCOME TAXES for further information.

Discontinued Operations

On July 10, 2012, we entered into a definitive share and asset sale agreement to sell our 45 percent economic interest in the Sonoma joint venture coal mine located in Queensland, Australia. Upon completion of the transaction on November 12, 2012, we collected approximately AUD $141.0 million in net cash proceeds. The assets sold included our interests in the Sonoma mine along with our ownership of the affiliated washplant. The Sonoma operations previously were included in Other within our reportable segments.

In April 2014, the FASB issued ASU 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which changes the criteria for reporting discontinued operations and requires additional disclosures about discontinued operations. The standard requires that an entity report as a discontinued operation only a disposal that represents a strategic shift in operations that has a major effect on its operations and financial results. ASU 2014-08 is effective prospectively for new disposals that occur within annual periods beginning on or after December 15, 2014. Early adoption is permitted and we adopted ASU 2014-08 during the three months ended December 31, 2014. Both Wabush and CLCC did not qualify as discontinued operations as determined under the new guidance. Neither the closure of Wabush nor the sale of the CLCC assets was considered a strategic shift in operations that had a major effect on our operations. Refer to NOTE 14 - DISCONTINUED OPERATIONS for further discussion of our adoption of ASU 2014-08.

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. Where the U.S. dollar is the functional currency, translation adjustments are recorded in the Statements of Consolidated Operations. Income taxes generally are not provided for foreign currency translation adjustments.

Earnings Per Share

We present both basic and diluted earnings per share amounts. Basic earnings per share amounts are calculated by dividing Net Income (Loss) Attributable to Cliffs Shareholders less any paid or declared but unpaid dividends on our depositary shares by the weighted average number of common shares outstanding during the period presented. Diluted earnings per share amounts are calculated by dividing Net Income (Loss) Attributable to Cliffs Shareholders by the weighted average number of common shares, common share equivalents under stock plans using the treasury stock method and the number of common shares that would be issued under an assumed conversion of our outstanding depositary shares, each representing a 1/40th interest in a share of our Series A Mandatory Convertible Preferred Stock, Class A, under the if-converted method. Our outstanding depositary shares are convertible into common shares based on the volume weighted average of closing prices of our common shares over the 20 consecutive trading day period ending on the third day immediately preceding the end of the reporting period. Common share equivalents are excluded from EPS computations in the periods in which they have an anti-dilutive effect. See NOTE 19 - EARNINGS PER SHARE for further information.

Recent Accounting Pronouncements

Issued and Not Effective

In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties About an Entity's Ability to Continue as a Going Concern. ASU 2014-15 will explicitly require management to assess an entity's ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. ASU 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. Specifically, ASU 2014-15 provides a definition of the term "substantial doubt" and requires an assessment for a period of one year after the date that the financial statements are issued (or available to be issued). It also requires certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans and requires an express statement and other disclosures when substantial doubt is not alleviated. The new standard will be effective for all entities in the first annual period ending after December 15, 2016 and for annual periods and interim periods thereafter. Earlier adoption is permitted. We are currently evaluating the impact the adoption of the guidance will have on the Statements of Consolidated Financial Position, Statements of Consolidated Operations or Statements of Consolidated Cash Flows.

In June 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers.  The new revenue guidance broadly replaces the revenue guidance provided throughout the Codification.  The core principle of the revenue guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.  To achieve that core principle, an entity should apply the following steps: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation.  The new revenue guidance also requires the capitalization of certain contract acquisition costs.  Reporting entities must provide new disclosures providing qualitative and quantitative information on the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers.  New disclosures also include qualitative and quantitative information on significant judgments, changes in judgments, and contract acquisition assets.  The update is effective for annual periods and interim periods within those annual periods beginning after December 15, 2016 and may be adopted either retrospectively or retrospectively with the cumulative effect.  Earlier adoption is not permitted. We are still evaluating the impact of the updated guidance on the Statements of Consolidated Financial Position, Statements of Consolidated Operations or Statements of Consolidated Cash Flows.

SEGMENT_REPORTING

SEGMENT REPORTING	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
SEGMENT REPORTING	NOTE 2 - SEGMENT REPORTING
	Our Company’s operations are organized and managed according to product category and geographic location: U.S. Iron Ore, Asia Pacific Iron Ore, North American Coal and Eastern Canadian 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. The North American Coal segment as of December 31, 2014 is comprised of our two low-volatile metallurgical coal operations that provide metallurgical coal primarily to the integrated steel industry. Effective December 31, 2014, we sold our CLCC assets, which consisted of two high-volatile metallurgical coal mines and one thermal coal mine. As such, the results below include the CLCC results through the day of the sale completion. The Eastern Canadian Iron Ore segment is comprised of two Eastern Canadian mines that primarily provided iron ore to the seaborne market for Asian steel producers. Refer to NOTE 21 - SUBSEQUENT EVENTS for further discussion of our Bloom Lake mine, which is in the Eastern Canadian Iron Ore segment. There were no intersegment revenues in 2014 or 2012. Inter-segment revenues for 2013 were eliminated in consolidation.
	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 Income (Loss) before interest, income taxes, depreciation, depletion and amortization, and Adjusted EBITDA, defined as EBITDA excluding certain items such as impairment charges, impacts of permanently idled, closed or sold facilities, foreign currency remeasurement, severance and other costs associated with the acceleration of vesting and payout of outstanding equity grants due to the majority change in our Board of Directors, litigation judgments 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 years ended December 31, 2014, 2013 and 2012, including a reconciliation of segment sales margin to Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures and a reconciliation of Net Income (Loss) to EBITDA and Adjusted EBITDA:
		(In Millions)
		2014					2013					2012
	Revenues from product sales and services:
	U.S. Iron Ore	$	2,506.50		54%		$	2,667.90			47%	$	2,723.30		46%
	Asia Pacific Iron Ore	866.7			19%		1,224.30				22%	1,259.30			22%
	North American Coal	687.1			15%		821.9				14%	881.1			15%
	Eastern Canadian Iron Ore	563.4			12%		978.7				17%	1,008.90			17%
	Other (including inter-segment revenue eliminations)	—			—%		(1.4		)		—%	0.1			—%
	Total revenues from product sales and services	$	4,623.70		100%		$	5,691.40			100%	$	5,872.70		100%
	Sales margin:
	U.S. Iron Ore	$	710.4				$	901.9				$	976.2
	Asia Pacific Iron Ore	121.7					367.1					311
	North American Coal	(135.8		)			(14.5		)			(1.8		)
	Eastern Canadian Iron Ore	(244.9		)			(103.3		)			(121.4		)
	Other (including inter-segment sales margin eliminations)	—					(1.9		)			8.1
	Sales margin	451.4					1,149.30					1,172.10
	Other operating income (expense)	(9,896.7		)			(478.3		)			(1,480.9		)
	Other income (expense)	(158.4		)			(181.7		)			(193.0		)
	Income (loss) from continuing operations before income taxes and equity income (loss) from ventures	$	(9,603.7	)			$	489.3				$	(501.8	)
		(In Millions)
		2014			2013				2012
	Net Income (Loss)	$	(8,311.6	)	$	361.8			$	(1,126.6	)
	Less:
	Interest expense, net	(185.2		)	(179.1		)		(195.6		)
	Income tax benefit (expense)	1,302.00			(55.1		)		(255.9		)
	Depreciation, depletion and amortization	(504.0		)	(593.3		)		(525.8		)
	EBITDA	$	(8,924.4	)	$	1,189.30			$	(149.3	)
	Less:
	Impairment of goodwill and other long-lived assets	$	(9,029.9	)	$	(250.8	)		$	(1,049.9	)
	Impairment of equity method investment	—			—				(365.4		)
	Loss on sale of Cliffs Logan County Coal	(419.6		)	—				—
	Wabush mine impact	(158.7		)	(72.7		)		(30.1		)
	Bloom Lake mine impact	(137.9		)	46.5				6.4
	Foreign exchange remeasurement	30.7			64				(3.2		)
	Proxy contest and change in control costs in SG&A	(26.6		)	—				—
	Litigation judgment	(96.3		)	(9.6		)		—
	Severance in SG&A	(15.8		)	(16.4		)		—
	Total Adjusted EBITDA	$	929.7		$	1,428.30			$	1,292.90
	EBITDA:
	U.S. Iron Ore	$	805.6		$	1,000.10			$	1,045.30
	Asia Pacific Iron Ore	(369.8		)	500.4				387.3
	North American Coal	(1,326.8		)	129.5				74
	Eastern Canadian Iron Ore	(7,673.9		)	(192.8		)		(1,103.3		)
	Other	(359.5		)	(247.9		)		(552.6		)
	Total EBITDA	$	(8,924.4	)	$	1,189.30			$	(149.3	)
	Adjusted EBITDA:
	U.S. Iron Ore	$	831.2		$	1,030.80			$	1,085.60
	Asia Pacific Iron Ore	264.6			525.7				402.1
	North American Coal	(28.5		)	154				106.7
	Eastern Canadian Iron Ore	—			—				—
	Other	(137.6		)	(282.2		)		(301.5		)
	Total Adjusted EBITDA	$	929.7		$	1,428.30			$	1,292.90
		(In Millions)
		2014			2013				2012
	Depreciation, depletion and amortization:
	U.S. Iron Ore	$	107.4		$	120.3			$	100.9
	Asia Pacific Iron Ore	145.9			153.7				151.9
	North American Coal	106.9			128.9				98.2
	Eastern Canadian Iron Ore	135.6			178.5				160.2
	Other	8.2			11.9				14.6
Total depreciation, depletion and amortization	$	504		$	593.3			$	525.8
Capital additions1:
U.S. Iron Ore	$	48.4		$	53.3			$	168.8
Asia Pacific Iron Ore	10.8			13				87.7
North American Coal	28.8			55				144.1
Eastern Canadian Iron Ore	141.2			625.5				865.2
Other	6.3			5.5				69.5
Total capital additions	$	235.5		$	752.3			$	1,335.30
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)
	December 31,			December 31, 2013				December 31, 2012
	2014
Assets:
U.S. Iron Ore	$	1,598.30		$	1,671.60			$	1,735.10
Asia Pacific Iron Ore	274.6			1,078.40				1,506.30
North American Coal	274.2			1,841.80				1,877.80
Eastern Canadian Iron Ore	305.8			7,915.50				7,605.10
Other	164.3			455.6				570.9
Total segment assets	2,617.20			12,962.90				13,295.20
Corporate	546.8			159				279.7
Total assets	$	3,164.00		$	13,121.90			$	13,574.90
Included in the consolidated financial statements are the following amounts relating to geographic location:
	(In Millions)
	2014			2013				2012
Revenue
United States	$	2,139.40		$	1,857.60			$	2,108.50
China	1,049.00			1,909.40				2,008.20
Canada	439.1			871.2				728.1
Other countries	996.2			1,053.20				1,027.90
Total revenue	$	4,623.70		$	5,691.40			$	5,872.70
Property, Plant and Equipment, Net
United States	$	1,093.70		$	2,721.60			$	2,795.30
Australia	72.4			751				1,042.40
Canada	248.8			7,680.80				7,369.60
Total Property, Plant and Equipment, Net	$	1,414.90		$	11,153.40			$	11,207.30
Concentrations in Revenue
In 2014, two customers accounted for more than 10 percent of our consolidated product revenue. In 2013 and 2012, one customer in each year individually accounted for more than 10 percent of our consolidated product revenue. Total revenue from these customers accounted for more than 10 percent of our consolidated product revenues and represents approximately $1.6 billion, $1.0 billion and $0.9 billion of our total consolidated product revenue in 2014, 2013 and 2012, respectively, and is attributable to our U.S. Iron Ore, North American Coal and Eastern Canadian Iron Ore business segments.
The following table represents the percentage of our total revenue contributed by each category of products and services in 2014, 2013, and 2012:
		2014		2013			2012
Revenue Category
Iron ore		78	%	80	%		81	%
Coal		12	%	13	%		13	%
Freight and venture partners’ cost reimbursements		10	%	7	%		6	%
Total revenue		100	%	100	%		100	%

INVENTORIES

INVENTORIES	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Inventories	NOTE 3 - INVENTORIES
	The following table presents the detail of our Inventories in the Statements of Consolidated Financial Position as of December 31, 2014 and 2013:
		(In Millions)
		31-Dec-14						31-Dec-13
	Segment	Finished Goods		Work-in Process		Total Inventory		Finished Goods		Work-in		Total
										Process		Inventory
	U.S. Iron Ore	$	132.1	$	13.5	$	145.6	$	92.1	$	13	$	105.1
	Asia Pacific Iron Ore	26.4		88.1		114.5		39.7		50.6		90.3
	North American Coal	33.1		17.2		50.3		59.4		23.2		82.6
	Eastern Canadian Iron Ore	16.3		—		16.3		65.3		48.1		113.4
	Total	$	207.9	$	118.8	$	326.7	$	256.5	$	134.9	$	391.4
	U.S. Iron Ore
	The excess of current cost over LIFO cost of iron ore inventories was $119.0 million and $115.3 million at December 31, 2014 and 2013, respectively. As of December 31, 2014, the product inventory balance for U.S. Iron Ore increased, resulting in a LIFO increment in 2014. The effect of the inventory build was an increase in Inventories of $44.8 million in the Statements of Consolidated Financial Position for the year ended December 31, 2014. As of December 31, 2013, the product inventory balance for U.S. Iron Ore declined, resulting in liquidation of a LIFO layer in 2013. The effect of the inventory reduction was a decrease in Cost of goods sold and operating expenses of $7.4 million in the Statements of Consolidated Operations for the year ended December 31, 2013.
	North American Coal
	We recorded LCM inventory charges of $44.5 million, $11.1 million and $24.4 million in Cost of goods sold and operating expenses in the Statements of Consolidated Operations for the years ended December 31, 2014, 2013 and 2012, respectively, for our North American Coal operations. The charges in 2014 were a result of market pricing declines. The charges in 2013 and 2012 were a result of market pricing declines and costs associated with operational and geological issues.
	Eastern Canadian Iron Ore
	We recorded LCM inventory charges of $38.9 million in Cost of goods sold and operating expenses in the Statements of Consolidated Operations for the year ended December 31, 2014, for our Eastern Canadian Iron Ore operations. During 2014, we recorded $10.4 million and $17.5 million of LCM inventory charges related to work-in process inventory and finished goods inventory, respectively, for Bloom Lake. Additionally, we recorded $4.9 million and $6.1 million of LCM inventory charges related to work-in process inventory and finished goods inventory, respectively, for Wabush. The charges at Eastern Canadian Iron Ore were primarily a result of declines in Platts 62 percent Fe fines spot pricing and the increased cost of production. At the end of March 2014, we idled our Wabush Scully mine in Newfoundland and Labrador and began to implement the permanent closure plan for the mine. 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.
	For the year ended December 31, 2013, the LCM concentrate and pellet inventory charges recorded were $13.2 million and $11.1 million, respectively, which were recorded in Cost of goods sold and operating expenses in the Statements of Consolidated Operations for our Eastern Canadian Iron Ore operations. Additionally, we recorded unsaleable inventory impairment charges of $10.6 million and $7.9 million, respectively, relating to Wabush pellets and concentrate inventory. Both of these charges were recorded in Cost of goods sold and operating expenses during 2013 and included in the Statements of Consolidated Operations for the year ended December 31, 2013 for our Eastern Canadian Iron Ore operations.
	No LCM inventory adjustments were recorded for the year ended December 31, 2012 within the Eastern Canadian Iron Ore operating segment results.

PROPERTY_PLANT_AND_EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	12 Months Ended
	Dec. 31, 2014
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 December 31, 2014 and 2013:
		(In Millions)
		December 31,
		2014			2013
	Land rights and mineral rights	$	590.2		$	7,819.60
	Office and information technology	75.5			125.7
	Buildings	65.6			255.2
	Mining equipment	732.6			1,819.30
	Processing equipment	567.4			2,148.60
	Electric power facilities	48.8			114.3
	Land improvements	25.5			69.3
	Other	60.8			227.6
	Construction in-progress	51.3			991.3
		2,217.70			13,570.90
	Allowance for depreciation and depletion	(802.8		)	(2,417.5		)
		$	1,414.90		$	11,153.40
	We recorded depreciation expense of $320.6 million, $366.9 million and $293.5 million in the Statements of Consolidated Operations for the years ended December 31, 2014, 2013 and 2012, respectively.
	At December 31, 2014, there was no accumulated amount of capitalized interest included within construction-in-progress. At December 31, 2013, $31.4 million of capitalized interest was included within construction in-progress, of which $17.4 million was capitalized during 2013.
	During the second half of 2014, due to lower than previously expected profits as a result of decreased iron ore pricing expectations and increased costs, we determined that indicators of impairment with respect to certain of our long-lived assets or asset groups existed. Our asset groups generally consist of the assets and liabilities of one or more mines, preparation plants and associated reserves for which the lowest level of identifiable cash flows largely are independent of cash flows of other mines, preparation plants and associated reserves.
	As a result of these assessments during 2014, we determined that the future cash flows associated with our Eastern Canadian Iron Ore, Asia Pacific Iron Ore, North American Coal and Ferroalloys asset groups were not sufficient to support the recoverability of the carrying value of these productive assets. Accordingly, during 2014, an other long-lived asset impairment charge of $8,839.0 million was recorded as Impairment of goodwill and other long-lived assets in the Statements of Consolidated Operations related to property, plant and equipment. The fair value estimates were calculated using income and market approaches. Refer to NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS for further discussion of these impairments and related fair value estimates.
	During the fourth quarter of 2013, we experienced higher than expected production costs and operational inefficiencies at our Wabush operations within our Eastern Canadian Iron Ore operating segment that resulted in continued declines in our profitability of that business, which represented an asset group for purposes of testing our long-lived assets for recoverability. Upon completion of an impairment analysis, it was determined the fair value was less than the carrying value of the asset group, which resulted in an other long-lived asset impairment charge of tangible property, plant and equipment of $140.1 million as Impairment of goodwill and other long-lived assets in the Statements of Consolidated Operations for the year ended December 31, 2013. The fair value estimate was calculated using a market approach.
	The net book value of the land rights and mineral rights as of December 31, 2014 and 2013 is as follows:
		(In Millions)
		December 31,
		2014			2013
	Land rights	$	31.9		$	46.3
	Mineral rights:
	Cost	$	558.3		$	7,773.30
	Depletion	(101.3		)	(942.6		)
	Net mineral rights	$	457		$	6,830.70
	Accumulated depletion relating to mineral rights, which was recorded using the unit-of-production method, is included in Cost of goods sold and operating expenses. We recorded depletion expense of $173.0 million, $206.5 million and $209.8 million in the Statements of Consolidated Operations for the years ended December 31, 2014, 2013 and 2012, respectively. As discussed above, during 2014 we performed impairment assessments with respect to certain of our long-lived assets or asset groups. As a result of these assessments, we recorded an other long-lived asset impairment charge related to mineral rights of $5,772.7 million associated with our Eastern Canadian Iron Ore, Asia Pacific Iron Ore, North American Coal and Ferroalloys asset groups.

DEBT_AND_CREDIT_FACILITIES

DEBT AND CREDIT FACILITIES	12 Months Ended
	Dec. 31, 2014
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 December 31, 2014 and 2013:
	($ in Millions)
	December 31, 2014
	Debt Instrument		Type	Annual Effective Interest Rate	Final Maturity	Total Principal 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		—			-6
	Equipment Loans		Fixed	Various	2020	164.8		140.8
	Fair Value Adjustment to Interest Rate Hedge							2.8
	Total debt					$	4,144.80	$	2,984.10
	Less current portion							21.8
	Long-term debt							$	2,962.30
	($ in Millions)
	31-Dec-13
	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	$	700	$	699.4		-1
	$1.3 Billion Senior Notes:
	$500 Million 4.80% 2020 Senior Notes		Fixed	4.83%	2020	500		499.2			-2
	$800 Million 6.25% 2040 Senior Notes		Fixed	6.34%	2040	800		790.4			-3
	$400 Million 5.90% 2020 Senior Notes		Fixed	5.98%	2020	400		398.4			-4
	$500 Million 3.95% 2018 Senior Notes		Fixed	4.14%	2018	500		496.5			-5
	$1.75 Billion Credit Facility:
	Revolving Loan		Variable	1.64%	2017	1,750.00		—			-6
	Equipment Loans		Fixed	Various	2020	164.8		161.7
	Fair Value Adjustment to Interest Rate Hedge							(2.1		)
	Total debt					$	4,814.80	$	3,043.50
	Less current portion							20.9
	Long-term debt							$	3,022.60
	-1	During the fourth quarter of 2014, we purchased $10.0 million of outstanding 4.875 percent senior notes that were trading at a discount of 40.5 percent which resulted in a gain on the extinguishment of debt of $4.1 million. 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. As of December 31, 2013, the $700.0 million 4.875 percent senior notes were recorded at a par value of $700.0 million less unamortized discounts of $0.6 million, based on an imputed interest rate of 4.88 percent.
	-2	During the fourth quarter of 2014, we purchased $10.0 million of outstanding 4.80 percent senior notes that were trading at a discount of 40.25 percent which resulted in a gain on the extinguishment of debt of $4.0 million. 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. As of December 31, 2013, the $500.0 million 4.80 percent senior notes were recorded at a par value of $500.0 million less unamortized discounts of $0.8 million, based on an imputed interest rate of 4.83 percent.
	-3	As of December 31, 2014 and December 31, 2013, the $800.0 million 6.25 percent senior notes were recorded at par value of $800.0 million less unamortized discounts of $9.5 million and $9.6 million, respectively, based on an imputed interest rate of 6.34 percent.
	-4	During the fourth quarter of 2014, we purchased $5.0 million of outstanding 5.90 percent senior notes that were trading at a discount of 38.125 percent which resulted in a gain on the extinguishment of debt of $1.9 million. 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. As of December 31, 2013, the $400.0 million 5.90 percent senior notes were recorded at a par value of $400.0 million less unamortized discounts of $1.6 million, based on an imputed interest rate of 5.98 percent.
	-5	During the fourth quarter of 2014, we purchased $20.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 30.875 percent which resulted in a gain on the extinguishment of debt of $6.2 million. 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. As of December 31, 2013, the $500.0 million 3.95 percent senior notes were recorded at a par value of $500.0 million less unamortized discounts of $3.5 million, based on an imputed interest rate of 4.14 percent.
	-6	As of December 31, 2014 and 2013, no revolving loans were drawn under the credit facility. We had total availability of $1.125 billion and $1.75 billion on our credit facility as of December 31, 2014 and 2013, respectively. Additionally, as of December 31, 2014 and December 31, 2013, the principal amount of letter of credit obligations totaled $149.5 million and $8.4 million, respectively, thereby reducing available borrowing capacity to $1.0 billion and $1.7 billion for each period, respectively.
	Credit Facility
	On October 24, 2014, we amended the revolving credit agreement (Amendment No 5.) to effect the following:
	•	Reduces the size of the existing facility from $1.25 billion to $1.125 billion.
	•	Grants a valid and perfected first-priority (subject to certain permitted liens) security interest in certain property and assets of the Company and certain of its subsidiaries, subject to customary exclusions all specified in a security agreement.
	•	With effect as of September 30, 2014, removes the maximum balance sheet leverage ratio of debt to capitalization of less than 45 percent, which was a covenant introduced in June 2014, and replaces that covenant with a maximum leverage ratio covenant of secured debt to EBITDA that is not to exceed 3.5 times.
	•	Retains the minimum interest coverage ratio requirement of 3.5 times, and was subsequently reduced to 2.0 times upon completion of certain collateral actions within 60 days of the execution of the amendment. The collateral requirements were satisfied as of December 23, 2014.
	•	Subjects restricted payments (including the $200 million share repurchase, which was approved in September 2014) and current dividend structure to a $400 million liquidity test.
	•	Adds limitations regarding acquisitions, investments (including investments in non-wholly owned subsidiaries and joint ventures) and subsidiary debt.
	•	Eliminates the accounts receivable securitization facility.
	•	Terminates the ability to have foreign borrowers under the revolving credit agreement.
	On September 9, 2014, we amended the revolving credit agreement (Amendment No. 4) to effect the following:
	•	Permitting a one-time exemption of up to $200 million in share repurchases (consummated in a single transaction or series of related transactions), effective until December 31, 2015. We are not obligated to make any purchases and the program may be suspended or discontinued at any time.
	•	Reducing the size of the existing unsecured facility from $1.75 billion to $1.25 billion.
	•	Adding restrictions on the granting of certain pledges and guarantees.
	•	Adding an obligation to enter into a security agreement, on or before June 30, 2015, to grant security interests to secure obligations under the revolving credit agreement on U.S. receivables and inventory, other than receivables and related property subject to certain existing receivable securitization or other facilities, a pledge of 65 percent of the stock of all material, wholly-owned first-tier foreign subsidiaries and a pledge of all of the stock of all material U.S. subsidiaries, in each case, subject to certain limitations.
	All terms of Amendment No. 3 as of June 30, 2014, as discussed below, remained in place and were not changed by Amendment No. 4 as of September 9, 2014.
	On June 30, 2014, we amended the revolving credit agreement (Amendment No. 3) to effect the following:
	•	Replacing the current maximum leverage covenant ratio of debt to earnings of less than 3.5 times with a maximum balance sheet leverage ratio of debt to capitalization of less than 45 percent.
	•	Resetting the minimum interest coverage ratio from 2.5 to 1.0 to the ratio of 3.5 to 1.0.
	•	Amending the definition of EBITDA to include certain cash charges related to the Company’s Wabush mine and other cash restructuring charges and the definition of net worth to exclude up to $1.0 billion in non-cash impairment charges.
	•	Modifying the covenants restricting certain investments and acquisitions, the incurrence of certain indebtedness and liens, and the amount of dividends that may be declared or paid and shares that may be repurchased.
	On January 22, 2015, we further amended the revolving credit agreement. Refer to NOTE 21 - SUBSEQUENT EVENTS for further information regarding Amendment No. 6.
	As of December 31, 2014 and 2013, we were in compliance with all applicable financial covenants related to the revolving credit agreement.
	$500 Million Senior Notes — 2012 Offering
On December 6, 2012, we completed a $500 million public offering of senior notes at 3.95 percent due January 15, 2018. Interest is fixed and is payable on January 15 and July 15 of each year, beginning on July 15, 2013 until maturity. The senior notes are unsecured obligations and rank equally in right of payment with all our other existing and future unsecured and unsubordinated indebtedness. There are no subsidiary guarantees of the interest and principal amounts. A portion of the net proceeds from the senior notes offering were used on December 28, 2012 to repay $270.0 million and $55.0 million outstanding private placement senior notes in the aggregate and also for the repayment of a portion of the borrowings outstanding under the term loan and the revolving credit facility.
The senior notes may be redeemed any time at our option not less than 30 days nor more than 60 days after prior notice is sent to the holders of the applicable series of notes. The senior notes are redeemable at a redemption price equal to the greater of (1) 100 percent of the principal amount of the notes to be redeemed or (2) the sum of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed, discounted to the redemption date on a semi-annual basis at the treasury rate plus 50 basis points with respect to the 2018 senior notes, plus, in each case, accrued and unpaid interest to the date of redemption.
In addition, if a change of control triggering event occurs with respect to the senior notes, as defined in the agreement, we will be required to offer to purchase the notes of the applicable series at a purchase price equal to 101 percent of the principal amount, plus accrued and unpaid interest, if any, to the date of purchase.
The terms of the senior notes contain certain customary covenants; however, there are no financial covenants.
Interest Rate Adjustment Based on Rating Events
The interest rate payable on the $500.0 million 3.95 percent senior notes may be subject to adjustments from time to time if either Moody's or S&P or, in either case, any Substitute Rating Agency thereof downgrades (or subsequently upgrades) the debt rating assigned to the senior notes. In no event shall (1) the interest rate for the senior notes be reduced to below the interest rate payable on the senior notes on the date of the initial issuance of senior notes or (2) the total increase in the interest rate on the senior notes exceed 2.00 percent above the interest rate payable on the senior notes on the date of the initial issuance of senior notes. During 2014, the interest rate payable on the $500.0 million 3.95 percent senior notes was increased from 3.95 percent ultimately to 5.70 percent based on Substitute Rating Agency downgrades throughout the year.
$1 Billion Senior Notes — 2011 Offering
On March 23, 2011 and April 1, 2011, respectively, we completed a $1 billion public offering of senior notes consisting of two tranches: a 10-year tranche of $700 million aggregate principal amount at 4.88 percent senior notes due April 1, 2021, and a 30-year tranche of $300 million aggregate principal amount at 6.25 percent senior notes due October 1, 2040, of which $500 million aggregate principal amount previously was issued during September 2010. Interest is fixed and is payable on April 1 and October 1 of each year, beginning on October 1, 2011, for both series of senior notes until maturity. The senior notes are unsecured obligations and rank equally in right of payment with all our other existing and future unsecured and unsubordinated indebtedness. There are no subsidiary guarantees of the interest and principal amounts. The net proceeds from the senior notes offering were used to fund a portion of the acquisition of Consolidated Thompson and to pay the related fees and expenses.
The senior notes may be redeemed any time at our option not less than 30 days nor more than 60 days after prior notice is sent to the holders of the applicable series of notes. The senior notes are redeemable at a redemption price equal to the greater of (1) 100 percent of the principal amount of the notes to be redeemed or (2) the sum of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed, discounted to the redemption date on a semi-annual basis at the treasury rate plus 25 basis points with respect to the 2021 senior notes and 40 basis points with respect to the 2040 senior notes, plus, in each case, accrued and unpaid interest to the date of redemption. However, if the 2021 senior notes are redeemed on or after the date that is three months prior to their maturity date, the 2021 senior notes will be redeemed at a redemption price equal to 100 percent of the principal amount of the notes to be redeemed plus accrued and unpaid interest to the date of redemption.
In addition, if a change of control triggering event occurs with respect to the senior notes, as defined in the agreement, we will be required to offer to purchase the notes of the applicable series at a purchase price equal to 101 percent of the principal amount, plus accrued and unpaid interest, if any, to the date of purchase.
The terms of the senior notes contain certain customary covenants; however, there are no financial covenants.
$1 Billion Senior Notes — 2010 Offering
On September 20, 2010, we completed a $1 billion public offering of senior notes consisting of two tranches: a 10-year tranche of $500 million aggregate principal amount at 4.80 percent due October 1, 2020, and a 30-year tranche of $500 million aggregate principal amount at 6.25 percent due October 1, 2040. Interest is fixed and is payable on April 1 and October 1 of each year, beginning on April 1, 2011, for both series of senior notes until maturity. The senior notes are unsecured obligations and rank equally in right of payment with all of our other existing and future senior unsecured and unsubordinated indebtedness. There are no subsidiary guarantees of the interest and principal amounts.
A portion of the net proceeds from the senior notes offering was used on September 22, 2010 to repay $350 million outstanding under our credit facility. A portion of the net proceeds was also used for general corporate purposes, including funding of capital expenditures and were used to fund a portion of the acquisition of Consolidated Thompson and related expenses.
The senior notes may be redeemed any time at our option not less than 30 days nor more than 60 days after prior notice is sent to the holders of the applicable series of notes. The senior notes are redeemable at a redemption price equal to the greater of (1) 100 percent of the principal amount of the notes to be redeemed or (2) the sum of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed, discounted to the redemption date on a semi-annual basis at the treasury rate plus 35 basis points with respect to the 2020 senior notes and 40 basis points with respect to the 2040 senior notes, plus, in each case, accrued and unpaid interest to the date of redemption. In addition, if a change of control triggering event occurs with respect to the notes, we will be required to offer to purchase the notes at a purchase price equal to 101 percent of the principal amount, plus accrued and unpaid interest to the date of purchase.
The terms of the senior notes contain certain customary covenants; however, there are no financial covenants.
$400 Million Senior Notes Offering — 2010 Offering
On March 17, 2010, we completed a $400 million public offering of senior notes due March 15, 2020. Interest at a fixed rate of 5.90 percent is payable on March 15 and September 15 of each year, beginning on September 15, 2010, until maturity on March 15, 2020. The senior notes are unsecured obligations and rank equally in right of payment with all of our other existing and future senior unsecured and unsubordinated indebtedness. There are no subsidiary guarantees of the interest and principal amounts.
A portion of the net proceeds from the senior notes offering was used on March 31, 2010 to repay our $200 million term loan under our credit facility, as well as to repay on May 27, 2010 our share of Amapá’s remaining debt outstanding of $100.8 million. In addition, we used the remainder of the net proceeds to help fund the acquisitions of Spider and CLCC during the third quarter of 2010.
The senior notes may be redeemed any time at our option not less than 30 days nor more than 60 days after prior notice is sent to the holders of the applicable series of notes. The senior notes are redeemable at a redemption price equal to the greater of (1) 100 percent of the principal amount of the notes to be redeemed or (2) the sum of the present values of the remaining scheduled payments of principal and interest on the notes to be redeemed, discounted to the redemption date on a semi-annual basis, plus accrued and unpaid interest to the date of redemption. In addition, if a change of control triggering event occurs, we will be required to offer to purchase the notes at a purchase price equal to 101 percent of the principal amount, plus accrued and unpaid interest to the date of purchase.
The terms of the senior notes contain certain customary covenants; however, there are no financial covenants.
Equipment Loans
During the second half of 2013, we entered into $164.8 million of seven-year installment equipment loans with various interest rates.  The loans are secured by equipment from our Eastern Canadian Iron Ore operations as well as a parent guarantee.  Proceeds from the borrowings were used for general corporate purposes.
Short-Term Facilities
Asia Pacific Iron Ore maintains a bank contingent instrument and cash advance facility. The facility, which is renewable annually at the bank’s discretion, provides A$3.0 million ($2.5 million) at December 31, 2014 in credit for contingent instruments, such as performance bonds, and the ability to request a cash advance facility to be provided at the discretion of the bank. The facility limit was reduced from A$30.0 million to A$3.0 million during the fourth quarter of 2014. At December 31, 2013, the facility provided A$30.0 million ($26.8 million) in credit for contingent instruments. As of December 31, 2014, the outstanding bank guarantees under the facility totaled A$1.5 million ($1.2 million), thereby reducing borrowing capacity to A$1.5 million ($1.3 million). As of December 31, 2013, the outstanding bank guarantees under the facility totaled A$23.0 million ($20.5 million), thereby reducing borrowing capacity to A$7.0 million ($6.3 million). We have provided a guarantee of the facility, along with certain of our Australian subsidiaries. The terms of the short-term facility contain certain customary covenants; however, there are no financial covenants.
Letters of Credit
We have outstanding letters of credit provided for under the amended revolving credit agreement which totaled $149.5 million and $8.4 million as of December 31, 2014 and December 31, 2013, respectively. Additionally, we issued standby letters of credit with certain financial institutions in addition to the letters of credit provided for under the revolving credit agreement of $48.0 million as of December 31, 2013.
Debt Maturities
The following represents a summary of our maturities of debt instruments, excluding borrowings on the amended revolving credit agreement, based on the principal amounts outstanding at December 31, 2014:
	(In Millions)
	Maturities of Debt
2015	$	21.8
2016	22.7
2017	23.6
2018	504.6
2019	25.5
2020 and thereafter	2,397.60
Total maturities of debt	$	2,995.80

FAIR_VALUE_OF_FINANCIAL_INSTRU

FAIR VALUE OF FINANCIAL INSTRUMENTS	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS
	The following represents the assets and liabilities of the Company measured at fair value at December 31, 2014 and 2013:
		(In Millions)
		December 31, 2014
	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:
	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	$	—			$	—			$	11.8			$	11.8
	Foreign exchange contracts	—				31.5				—				31.5
	Total	$	—			$	31.5			$	11.8			$	43.3
		(In Millions)
		December 31, 2013
	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:
	Cash equivalents	$	85			$	—			$	—			$	85
	Derivative assets	—				—				58.9				58.9
	Available-for-sale marketable securities	21.4				—				—				21.4
	Foreign exchange contracts	—				0.3				—				0.3
	Total	$	106.4			$	0.3			$	58.9			$	165.6
	Liabilities:
	Derivative liabilities	$	—			$	2.1			$	10.3			$	12.4
	Foreign exchange contracts	—				26.9				—				26.9
	Total	$	—			$	29			$	10.3			$	39.3
	Financial assets classified in Level 1 at December 31, 2014 include available-for-sale marketable securities. Financial assets classified in Level 1 at December 31, 2013 include money market funds and 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 December 31, 2014, such derivative financial instruments included our existing foreign currency exchange contracts. At December 31, 2013, such derivative financial instruments included our existing foreign currency exchange contracts and interest rate swaps. 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 assets classified within Level 3 at December 31, 2014 and December 31, 2013 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 at December 31, 2014 and December 31, 2013 also consisted of derivatives related to certain provisional pricing arrangements with our U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore customers. 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)		Fair Value at				Balance Sheet Location		Valuation Technique		Unobservable Input		Range or Point Estimate
			12/31/14										(Weighted Average)
	Provisional Pricing Arrangements		$	11.8			Other current liabilities		Market Approach		Management's		$72
											Estimate of 62% Fe
	Customer Supply Agreement		$	63.2			Other current assets		Market Approach		Hot-Rolled Steel Estimate		$590 - $640 ($610)
	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 agreements is the future hot-rolled steel price that is estimated based on current market data, analysts' projections, projections provided by the customer 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, including both transfers into and out of levels. There were no transfers between Level 1 and Level 2 of the fair value hierarchy during the years ended December 31, 2014 and 2013. 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 years ended December 31, 2014 and 2013.
		(In Millions)
		Derivative Assets (Level 3)								Derivative Liabilities
										(Level 3)
		Year Ended								Year Ended
		December 31,								December 31,
		2014				2013				2014				2013
	Beginning balance - January 1	$	58.9			$	62.4			$	(10.3	)		$	(11.3	)
	Total gains (losses)
	Included in earnings	187.8				152.3				(11.8		)		(10.3		)
	Settlements	(183.5		)		(155.8		)		10.3				11.3
	Transfers into Level 3	—				—				—				—
	Transfers out of Level 3	—				—				—				—
	Ending balance - December 31	$	63.2			$	58.9			$	(11.8	)		$	(10.3	)
	Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) on assets still held at the reporting date	$	187.8			$	152.3			$	(11.8	)		$	(10.3	)
	Gains and losses included in earnings are reported in Product revenues in the Statements of Consolidated Operations for the years ended December 31, 2014 and 2013.
	The carrying amount for certain financial instruments (e.g. Accounts receivable, net, Accounts payable and Accrued expenses) approximate fair value and, therefore, have been excluded from the table below. A summary of the carrying amount and fair value of other financial instruments at December 31, 2014 and 2013 were as follows:
				(In Millions)
				December 31, 2014								December 31, 2013
		Classification		Carrying				Fair Value				Carrying				Fair Value
				Value								Value
Long-term debt:
Senior notes—$700 million	Level 2		689.5				367.3				699.4				718.2
Senior notes—$1.3 billion	Level 2		1,279.90				704				1,289.60				1,404.90
Senior notes—$400 million	Level 2		393.7				228.1				398.4				432.1
Senior notes—$500 million	Level 2		477.4				312				496.5				523.8
Revolving loan	Level 2		—				—				—				—
Equipment Loan Facilities	Level 2		119				119				140.8				140.8
Fair Value Adjustment to Interest Rate Hedge	Level 2		2.8				2.8				(2.1		)		(2.1		)
Total long-term debt			$	2,962.30			$	1,733.20			$	3,022.60			$	3,217.70
The fair value of long-term debt was determined using quoted market prices or discounted cash flows based upon current borrowing rates. The revolving loan and equipment loan facilities are variable rate interest and approximate 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 impairment charges on both financial and nonfinancial assets that were measured on a fair value basis at December 31, 2014 and December 31, 2013. The table also indicates the fair value hierarchy of the valuation techniques used to determine such fair value.
		(In Millions)
		Year Ended December 31, 2014
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
North American Coal reporting unit
CLCC thermal asset group		—				—				62.6				62.6				195.5
Pinnacle asset group		—				—				30.7				30.7				394.5
Oak Grove asset group		—				—				23.4				23.4				267.5
Eastern Canadian Iron Ore reporting unit
Bloom Lake asset group		—				—				187.9				187.9				7,043.70
Wabush asset group		—				—				42.7				42.7				132.6
Ferroalloys reporting unit		—				—				12.2				12.2				259.5
Other reporting units		—				—				—				—				19.2
Other long-lived assets -
Intangibles and other long-term assets:
Asia Pacific Iron Ore reporting unit		—				—				7				7				24.2
Eastern Canadian Iron Ore reporting unit
Bloom Lake asset group		—				—				—				—				56.2
Wabush asset group		—				—				—				—				36.7
Ferroalloys reporting unit		—				—				—				—				0.3
Investment in ventures		—				—				—				—				9.2
impairment - Global Exploration
		$	—			$	—			$	438.9			$	438.9			$	9,039.10
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, which particularly effects Eastern Canadian Iron Ore and Asia Pacific Iron Ore business segments because their contracts correlate heavily to world market spot pricing, and the benchmark price for premium low-volatile hard coking coal were lower than prior estimates. 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, a new CEO, Lourenco Goncalves, was appointed by the Board of Directors in early August 2014 and subsequently identified as the CODM in accordance with ASC 280, Segment Reporting. The new CODM views Eastern Canadian Iron Ore, Asia Pacific Iron Ore, North American Coal and Ferroalloys as non-core assets and has communicated plans to evaluate the business units 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 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 Wabush operation and Bloom Lake operation within our Eastern Canadian Iron Ore operating segment, our Asia Pacific Iron Ore operating segment and our CLCC thermal operation, Oak Grove operation and Pinnacle operation within our North American Coal 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 $8,956.4 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.
		(In Millions)
		Year Ended December 31, 2013
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 -		$	—			$	—			$	—			$	—			$	80.9
Ferroalloys reporting unit
Other long-lived assets -		—				—				46.3				46.3				155.4
Property, plant and equipment
Other long-lived assets -		—				—				1.6				1.6				14.5
Intangibles and long-term
deposits
Investment in ventures impairment - Amapá		—				—				—				—				67.6
Total		$	—			$	—			$	47.9			$	47.9			$	318.4
Financial Assets
In light of the March 28, 2013 collapse of the Santana port shiploader and subsequent evaluation of the effect that this event had on the carrying value of our investment in Amapá as of June 30, 2013, we recorded an impairment charge of $67.6 million in the second quarter of 2013. The sale of Amapá was completed in the fourth quarter of 2013.
Non-Financial Assets
During the fourth quarter of 2013, a goodwill impairment charge of $80.9 million was recorded for our Cliffs Chromite Ontario and Cliffs Chromite Far North reporting units within our Ferroalloys operating segment. The impairment charge was primarily a result of the decision to indefinitely suspend the Chromite Project and to not allocate additional capital for the project given the uncertain timeline and risks associated with the development of necessary infrastructure to bring the project online. 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 an impairment charges to property, plant and equipment during 2013 related to our Wabush operation within our Eastern Canadian Iron Ore operating segment, our Cliffs Chromite Ontario and Cliffs Chromite Far North reporting units within our Other reportable segments and certain mineral lands at our Asia Pacific Iron Ore operating segment to reduce the related assets to their estimated fair value as we determined that the 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 estimate of liquidation value, which is considered a Level 3 input, and resulted in a charge of $155.4 million.

PENSIONS_AND_OTHER_POSTRETIREM

PENSIONS AND OTHER POSTRETIREMENT BENEFITS	12 Months Ended
	Dec. 31, 2014
Postemployment Benefits [Abstract]
PENSIONS AND OTHER POSTRETIREMENT BENEFITS	NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS
	We offer defined benefit pension plans, defined contribution pension plans and other postretirement benefit plans, primarily consisting of retiree healthcare benefits, to most employees in North America as part of a total compensation and benefits program. We do not have employee retirement benefit obligations at our Asia Pacific Iron Ore operations or our Bloom Lake mine operations within our Eastern Canadian Iron Ore segment. The defined benefit pension plans largely are noncontributory and benefits generally are based on employees’ years of service and average earnings for a defined period prior to retirement or a minimum formula.
	The labor agreements we have with the USW at our U.S. Iron Ore operations cover approximately 2,200 USW-represented employees at our Empire and Tilden mines in Michigan and our United Taconite and Hibbing mines in Minnesota, or 40.9 percent of our total workforce. The 2012 USW agreement sets temporary monthly postretirement OPEB caps for participants who retire prior to January 1, 2015. These premium maximums will expire at the end of the contract period and revert to increasing premiums based on the terms of the 2004 bargaining agreement. The agreements also provide for an OPEB cap that will limit the amount of contributions that we have to make toward medical insurance coverage for each retiree and spouse of a retiree per calendar year after it goes into effect.  The amount of the annual OPEB cap will be based upon the costs we incurred in 2014. The OPEB cap applies to employees who retire on or after January 1, 2015 and will not apply to surviving spouses. In addition, the agreements renewed the lump sum special payments for certain employees retiring in the near future.
	In addition, we currently provide various levels of retirement health care and OPEB to most full-time employees who meet certain length of service and age requirements (a portion of which is pursuant to collective bargaining agreements). Most plans require retiree contributions and have deductibles, co-pay requirements and benefit limits. Most bargaining unit plans require retiree contributions and co-pays for major medical and prescription drug coverage. There is an annual limit on our cost for medical coverage under the U.S. salaried plans. The annual limit applies to each covered participant and equals $7,000 for coverage prior to age 65 and $3,000 for coverage after age 65, with the retiree’s participation adjusted based on the age at which the retiree’s benefits commence. Beginning in 2015, Cliffs is changing the delivery of the post-65 salaried retiree medical benefit program from an employer sponsored plan to the combination of an employer subsidy plan and an individual supplemental Medicare insurance plan purchased through a Medicare exchange. This allows the program to take full advantage of available government subsidies and more efficient pricing in the Medicare market. For participants at our Northshore operation, the annual limit ranges from $4,020 to $4,500 for coverage prior to age 65, and equals $2,000 for coverage after age 65. Covered participants pay an amount for coverage equal to the excess of (i) the average cost of coverage for all covered participants, over (ii) the participant’s individual limit, but in no event will the participant’s cost be less than 15.0 percent of the average cost of coverage for all covered participants. For Northshore participants, the minimum participant cost is a fixed dollar amount. We do not provide OPEB for most U.S. salaried employees hired after January 1, 1993. Retiree healthcare coverage is provided through programs administered by insurance companies whose charges are based on benefits paid.
	Our North American Coal segment is required under an agreement with the UMWA to contribute to the UMWA 1974 Pension Trust based principally on hours worked by UMWA-represented employees. This agreement covers approximately 800 UMWA-represented employees at our Pinnacle Complex in West Virginia and our Oak Grove mine in Alabama, or 15.2 percent of our total workforce. The multi-employer pension trust provides pension benefits to eligible retirees through a defined benefit plan. The UMWA 1993 Benefit Plan is a defined contribution plan that was created as the result of negotiations for the NBCWA of 1993. The plan provides healthcare insurance to orphan UMWA retirees who are not eligible to participate in the UMWA Combined Benefit Fund or the 1992 Benefit Fund or whose last employer signed the 1993 or later NBCWA and who subsequently goes out of business. Contributions to the trust were at a rate of $8.16 per hour worked 2014 and at a rate of $8.10 per hour worked for both 2013 and 2012. These amounted to $13.8 million in 2014 and $14.9 million in both 2013 and 2012, respectively. Our Pinnacle and Oak Grove mines are signatories to labor agreements with the UMWA, making them participants in the UMWA 1974 Pension Plan (the "1974 PP"). As of the most recent estimate, Pinnacle and Oak Grove's combined share of this underfunded liability was estimated to be approximately $330 million. If Pinnacle or Oak Grove were to withdraw from the 1974 PP or if a mass withdrawal were to occur, we would become obligated to satisfy our withdrawal liability to the 1974 PP.
	In December 2003, The Medicare Prescription Drug, Improvement, and Modernization Act of 2003 was enacted. This act introduced a prescription drug benefit under Medicare Part D as well as a federal subsidy to sponsors of retiree healthcare benefit plans that provide a benefit that at least actuarially is equivalent to Medicare Part D. Our measures of the accumulated postretirement benefit obligation and net periodic postretirement benefit cost as of December 31, 2004 and for periods thereafter reflect amounts associated with the subsidy. We elected to adopt the retroactive transition method for recognizing the cost reduction in 2004.
	The shut-down of the Wabush Scully mine on October 31, 2014 and the idling at Bloom Lake as of December 31, 2014 affected employees of both the Wabush Scully mine and Pointe Noire locations, triggering early retirement benefits for those hourly and salaried plan participants who were eligible, and termination of benefits of other participants who were not eligible. Curtailment gains related to these events totaled $7.9 million and were fully recognized in net periodic benefit cost in 2014.
	The following table summarizes the annual expense recognized related to the retirement plans for 2014, 2013 and 2012:
		(In Millions)
		2014				2013				2012
	Defined benefit pension plans	$	31.3			$	52.1			$	55.2
	Defined contribution pension plans	6.3				6.8				6.7
	Other postretirement benefits	(0.7		)		17.4				28.1
	Total	$	36.9			$	76.3			$	90
	The following tables and information provide additional disclosures for our consolidated plans.
	Obligations and Funded Status
	The following tables and information provide additional disclosures for the December 31, 2014 and 2013:
		(In Millions)
		Pension Benefits								Other Benefits
	Change in benefit obligations:	2014				2013				2014				2013
	Benefit obligations — beginning of year	$	1,118.00			$	1,244.30			$	356.2			$	459.8
	Service cost (excluding expenses)	30.8				38.9				6.7				12.3
	Interest cost	49.7				45.9				16.2				17.3
	Plan amendments	—				0.8				(0.9		)		—
	Actuarial (gain) loss	141.6				(121.8		)		51.9				(103.3		)
	Benefits paid	(87.0		)		(72.9		)		(27.4		)		(28.0		)
	Participant contributions	—				—				4.8				5.6
	Federal subsidy on benefits paid	—				—				0.9				0.5
	Exchange rate gain	(18.2		)		(17.2		)		(3.7		)		(8.0		)
	Curtailment gain	(10.9		)		—				(8.8		)		—
	Special termination benefits	3.4				—				—				—
	Benefit obligations — end of year	$	1,227.40			$	1,118.00			$	395.9			$	356.2
	Change in plan assets:
	Fair value of plan assets — beginning of year	$	915.3			$	838.7			$	251.8			$	237
	Actual return on plan assets	78.7				109.5				31.9				11
	Participant contributions	—				—				0.8				1.8
	Employer contributions	60.5				53.7				6.9				20.7
	Benefits paid	(87.0		)		(72.9		)		(22.1		)		(18.7		)
	Exchange rate loss	(17.9		)		(13.7		)		—				—
	Fair value of plan assets — end of year	$	949.6			$	915.3			$	269.3			$	251.8
	Funded status at December 31:
	Fair value of plan assets	$	949.6			$	915.3			$	269.3			$	251.8
	Benefit obligations	(1,227.4		)		(1,118.0		)		(395.9		)		(356.2		)
	Funded status (plan assets less benefit obligations)	$	(277.8	)		$	(202.7	)		$	(126.6	)		$	(104.4	)
	Amount recognized at December 31	$	(277.8	)		$	(202.7	)		$	(126.6	)		$	(104.4	)
	Amounts recognized in Statements of Financial Position:
	Current liabilities	$	(2.4	)		$	(5.2	)		$	(6.8	)		$	(7.9	)
	Noncurrent liabilities	(275.4		)		(197.5		)		(119.8		)		(96.5		)
	Net amount recognized	$	(277.8	)		$	(202.7	)		$	(126.6	)		$	(104.4	)
	Amounts recognized in accumulated other comprehensive income:
	Net actuarial loss	$	341.5			$	230.6			$	97.1			$	67
	Prior service cost	10.6				14.9				(42.9		)		(45.4		)
	Net amount recognized	$	352.1			$	245.5			$	54.2			$	21.6
	The estimated amounts that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2015:
	Net actuarial loss	$	22.3							$	6.3
	Prior service cost	2.4								(3.7		)
	Net amount recognized	$	24.7							$	2.6
		(In Millions)
		2014
		Pension Plans																			Other Benefits
		Salaried				Hourly				Mining				SERP				Total			Salaried			Hourly			Total
	Fair value of plan assets	$	366.4			$	576.6			$	6.6			$	—			$	949.6		$	—		$	269.3		$	269.3
	Benefit obligation	(471.4		)		(739.2		)		(9.2		)		(7.6		)		(1,227.4		)	(54.0		)	(341.9		)	(395.9		)
	Funded status	$	(105.0	)		$	(162.6	)		$	(2.6	)		$	(7.6	)		$	(277.8	)	$	(54.0	)	$	(72.6	)	$	(126.6	)
	2013
	Pension Plans																			Other Benefits
	Salaried				Hourly				Mining				SERP				Total			Salaried			Hourly			Total
Fair value of plan assets	$	357.4			$	552.7			$	5.2			$	—			$	915.3		$	—		$	251.8		$	251.8
Benefit obligation	(427.2		)		(674.8		)		(6.8		)		(9.2		)		(1,118.0		)	(53.6		)	(302.6		)	(356.2		)
Funded status	$	(69.8	)		$	(122.1	)		$	(1.6	)		$	(9.2	)		$	(202.7	)	$	(53.6	)	$	(50.8	)	$	(104.4	)
The accumulated benefit obligation for all defined benefit pension plans was $1,204.4 million and $1,091.4 million at December 31, 2014 and 2013, respectively. The increase in the accumulated benefit obligation primarily is a result of a decrease in the discount rates and adoption of the updated RP-2014 mortality tables.
Components of Net Periodic Benefit Cost
	(In Millions)
	Pension Benefits												Other Benefits
	2014				2013				2012				2014				2013			2012
Service cost	$	30.8			$	38.9			$	32			$	6.7			$	12.3		$	14.7
Interest cost	49.7				45.9				48.4				16.2				17.3			20.6
Expected return on plan assets	(72.3		)		(65.6		)		(59.5		)		(17.1		)		(20.1		)	(17.7		)
Amortization:
Net asset	—				—				—				—				—			(3.0		)
Prior service costs (credits)	2.7				3				3.9				(3.6		)		(3.6		)	1.9
Net actuarial loss	14.1				29.9				30.4				5				11.5			11.6
Curtailments and settlements	2.9				—				—				(7.9		)		—			—
Special termination benefits	3.4				—				—				—				—			—
Net periodic benefit cost	$	31.3			$	52.1			$	55.2			$	(0.7	)		$	17.4		$	28.1
Curtailment effects	—				—				—				(0.8		)		—			—
Current year actuarial (gain)/loss	121.8				(168.8		)		53.1				36.9				(95.2		)	3.2
Amortization of net loss	(15.5		)		(29.9		)		(30.4		)		(5.0		)		(11.5		)	(11.6		)
Current year prior service (credit) cost	(1.5		)		0.8				2.8				(0.9		)		—			(58.3		)
Amortization of prior service (cost) credit	(2.7		)		(3.0		)		(3.9		)		3.6				3.6			(1.9		)
Amortization of transition asset	—				—				—				—				—			3
Total recognized in other comprehensive income	$	102.1			$	(200.9	)		$	21.6			$	33.8			$	(103.1	)	$	(65.6	)
Total recognized in net periodic cost and other	$	133.4			$	(148.8	)		$	76.8			$	33.1			$	(85.7	)	$	(37.5	)
comprehensive income
Additional Information
	(In Millions)
	Pension Benefits												Other Benefits
	2014				2013				2012				2014				2013			2012
Effect of change in mine ownership & noncontrolling interest	$	51.4			$	46.5			$	54.8			$	5.9			$	4.8		$	8.6
Actual return on plan assets	78.7				109.5				92.5				31.9				11			26.1
Assumptions
For our U.S. pension and other postretirement benefit plans, we used a discount rate as of December 31, 2014 of 3.83 percent, compared with a discount rate of 4.57 percent as of December 31, 2013. The U.S. discount rates are determined by matching the projected cash flows used to determine the PBO and APBO to a projected yield curve of 715 Aa graded bonds in the 10th to 90th percentiles. These bonds are either noncallable or callable with make-whole provisions. The duration matching produced rates ranging from 3.72 percent to 3.92 percent for our plans. Based upon these results, we selected a December 31, 2014 discount rate of 3.83 percent for our plans. This methodology is consistent with the calculation of the prior-year discount rate.
On December 31, 2014, we adopted the RP-2014 mortality tables projected generationally using scale MP-2014 with blue collar and white collar adjustments made for certain hourly and salaried groups, to determine the expected life of our plan participants, replacing the IRS 2014 prescribed mortality tables for our U.S. plans. The adoption of the new tables resulted in increases to our U.S. plan projected benefit obligations totaling approximately $30.0 million or 4 percent percent for the pension plans and $20 million or 7 percent for the OPEB plans.
For our Canadian plans, we used a discount rate as of December 31, 2014 of 3.75 percent for the pension plans and the other postretirement benefit plans. Similar to the U.S. plans, the Canadian discount rates are determined by matching the projected cash flows used to determine the PBO and APBO to a projected yield curve of 285 corporate bonds in the 10th to 90th percentiles. The corporate bonds are either Aa graded, or (for maturities of 10 or more years) A or Aaa graded with an appropriate credit spread adjustment. These bonds are either noncallable or callable with make whole provisions. This methodology is consistent with the calculation of the prior-year discount rate.
On December 31, 2014, we adopted the 2014 Private Sector Canadian Pensioners’ Mortality Table for the hourly plans and the 2014 Canadian Pensioners’ Mortality Table for the salaried plans, where both tables were projected generationally using scale CPM-B, replacing the UP 1994 table with full projection. The adoption of the new tables resulted in increases to our Canadian plan projected benefit obligations totaling approximately $12 million or 5 percent for the pension plans and $3 million or 5 percent for the OPEB plans.
Weighted-average assumptions used to determine benefit obligations at December 31 were:
	Pension Benefits				Other Benefits
	2014		2013		2014		2013
U.S. plan discount rate	3.83%		4.57%		3.83%		4.57%
Canadian plan discount rate	3.75		4.5		3.75		4.75
U.S. salaried rate of compensation increase	3		4		3		4
Canadian rate of compensation increase	3		4		N/A		N/A
Hourly rate of compensation increase (ultimate)	2.5		3		N/A		N/A
U.S. expected return on plan assets	8.25		8.25		7		7
Canadian expected return on plan assets	7.25		7.25		N/A		N/A
Weighted-average assumptions used to determine net benefit cost for the years 2014, 2013 and 2012 were:
	Pension Benefits						Other Benefits
	2014		2013		2012		2014		2013		2012
U.S. plan discount rate	4.57	%	3.7	%	4.28	%	4.57	%	3.7	%	4.28/3.51	1%
Canadian plan discount rate	4.5		3.75		4		4.75		4		4.25
U.S. expected return on plan assets	8.25		8.25		8.25		7		8.25		8.25
Canadian expected return on plan assets	7.25		7.25		7.25		N/A		N/A		N/A
U.S. salaried rate of compensation increase	4		4		4		4		4		4
U.S. hourly rate of compensation increase	3		4		4		4		4		4
Canadian rate of compensation increase	4		4		4		4		4		4
1	4.28 percent for the Salaried Plan. For the Hourly Plan, 4.28 percent from January 1, 2012 through October 31, 2012, and 3.51 percent from November 1, 2012 through December 31, 2012.
Assumed health care cost trend rates at December 31 were:
	2014		2013
U.S. plan health care cost trend rate assumed for next year	7	%	7.25	%
Canadian plan health care cost trend rate assumed for next year	4.25		4
Ultimate health care cost trend rate	5		5
U.S. plan year that the ultimate rate is reached	2023		2023
Canadian plan year that the ultimate rate is reached	2018		2018
Assumed health care cost trend rates have a significant effect on the amounts reported for the health care plans. A change of one percentage point in assumed health care cost trend rates would have the following effects:
	(In Millions)
	Increase				Decrease
Effect on total of service and interest cost	$	3.4			$	(2.7	)
Effect on postretirement benefit obligation	49.6				(39.9		)
Plan Assets
Our financial objectives with respect to our pension and VEBA plan assets are to fully fund the actuarial accrued liability for each of the plans, to maximize investment returns within reasonable and prudent levels of risk, and to maintain sufficient liquidity to meet benefit obligations on a timely basis.
Our investment objective is to outperform the expected ROA assumption used in the plans’ actuarial reports over a full market cycle, which is considered a period during which the U.S. economy experiences the effects of both an upturn and a downturn in the level of economic activity. In general, these periods tend to last between three and five years. The expected ROA takes into account historical returns and estimated future long-term returns based on capital market assumptions applied to the asset allocation strategy. The expected return is net of investment expenses paid by the plans.
The asset allocation strategy is determined through a detailed analysis of assets and liabilities by plan, which defines the overall risk that is acceptable with regard to the expected level and variability of portfolio returns, surplus (assets compared to liabilities), contributions and pension expense.
The asset allocation review process involves simulating the effect of financial market performance for various asset allocation scenarios and factoring in the current funded status and likely future funded status levels by taking into account expected growth or decline in the contributions over time. The modeling is then adjusted by simulating unexpected changes in inflation and interest rates. The process also includes quantifying the effect of investment performance and simulated changes to future levels of contributions, determining the appropriate asset mix with the highest likelihood of meeting financial objectives and regularly reviewing our asset allocation strategy.
The asset allocation strategy varies by plan. The following table reflects the actual asset allocations for pension and VEBA plan assets as of December 31, 2014 and 2013, as well as the 2015 weighted average target asset allocations as of December 31, 2014. Equity investments include securities in large-cap, mid-cap and small-cap companies located in the U.S. and worldwide. Fixed income investments primarily include corporate bonds and government debt securities. Alternative investments include hedge funds, private equity, structured credit and real estate.
	Pension Assets									VEBA Assets
Asset Category	2015			Percentage of						2015			Percentage of
	Target			Plan Assets at						Target			Plan Assets at
	Allocation			December 31,						Allocation			December 31,
				2014			2013						2014			2013
Equity securities	48.2	%		48.6	%		51.5	%		8	%		8.6	%		10.4	%
Fixed income	28.4	%		29	%		26.7	%		80.1	%		79.3	%		66.6	%
Hedge funds	6.1	%		6.2	%		6.3	%		4.2	%		4.3	%		9.8	%
Private equity	5.5	%		3.3	%		3.2	%		2.6	%		2.3	%		2.4	%
Structured credit	5.9	%		6.9	%		6.7	%		2.1	%		2.3	%		5.4	%
Real estate	5.9	%		5.3	%		4.5	%		3	%		3.2	%		5.3	%
Cash	—	%		0.7	%		1.1	%		—	%		—	%		0.1	%
Total	100	%		100	%		100	%		100	%		100	%		100	%
Pension
The fair values of our pension plan assets at December 31, 2014 and 2013 by asset category are as follows:
	(In Millions)
	31-Dec-14
Asset Category	Quoted Prices in Active				Significant Other				Significant				Total
	Markets for Identical				Observable				Unobservable
	Assets/Liabilities				Inputs				Inputs
	(Level 1)				(Level 2)				(Level 3)
Equity securities:
U.S. large-cap	$	248.5			$	—			$	—			$	248.5
U.S. small/mid-cap	55.8				—				—				55.8
International	157.4				—				—				157.4
Fixed income	243.7				31.8				—				275.5
Hedge funds	—				—				59.2				59.2
Private equity	—				—				31.2				31.2
Structured credit	—				—				65.4				65.4
Real estate	—				—				50				50
Cash	6.6				—				—				6.6
Total	$	712			$	31.8			$	205.8			$	949.6
	(In Millions)
	31-Dec-13
Asset Category	Quoted Prices in Active				Significant  Other				Significant				Total
	Markets for Identical				Observable				Unobservable
	Assets/Liabilities				Inputs				Inputs
	(Level 1)				(Level 2)				(Level 3)
Equity securities:
U.S. large-cap	$	261.5			$	—			$	—			$	261.5
U.S. small/mid-cap	60.8				—				—				60.8
International	149.3				—				—				149.3
Fixed income	214.8				30.1				—				244.9
Hedge funds	—				—				57.6				57.6
Private equity	—				—				29.1				29.1
Structured credit	—				—				61				61
Real estate	—				—				40.9				40.9
Cash	10.2				—				—				10.2
Total	$	696.6			$	30.1			$	188.6			$	915.3
Following is a description of the inputs and valuation methodologies used to measure the fair value of our plan assets.
Equity Securities
Equity securities classified as Level 1 investments include U.S. large-, small- and mid-cap investments and international equity. These investments are comprised of securities listed on an exchange, market or automated quotation system for which quotations are readily available. The valuation of these securities is determined using a market approach, and is based upon unadjusted quoted prices for identical assets in active markets.
Fixed Income
Fixed income securities classified as Level 1 investments include bonds and government debt securities. These investments are comprised of securities listed on an exchange, market or automated quotation system for which quotations are readily available. The valuation of these securities is determined using a market approach, and is based upon unadjusted quoted prices for identical assets in active markets. Also included in Fixed Income is a portfolio of U.S. Treasury STRIPS, which are zero-coupon bearing fixed income securities backed by the full faith and credit of the U.S. government. The securities sell at a discount to par because there are no incremental coupon payments. STRIPS are not issued directly by the Treasury, but rather are created by a financial institution, government securities broker or government securities dealer. Liquidity on the issue varies depending on various market conditions; however, in general the STRIPS market is slightly less liquid than that of the U.S. Treasury Bond market. The STRIPS are priced daily through a bond pricing vendor and are classified as Level 2.
Hedge Funds
Hedge funds are alternative investments comprised of direct or indirect investment in offshore hedge funds of funds with an investment objective to achieve an attractive risk-adjusted return with moderate volatility and moderate directional market exposure over a full market cycle. The valuation techniques used to measure fair value attempt to maximize the use of observable inputs and minimize the use of unobservable inputs. Considerable judgment is required to interpret the factors used to develop estimates of fair value. Valuations of the underlying investment funds are obtained and reviewed. The securities that are valued by the funds are interests in the investment funds and not the underlying holdings of such investment funds. Thus, the inputs used to value the investments in each of the underlying funds may differ from the inputs used to value the underlying holdings of such funds.
In determining the fair value of a security, the fund managers may consider any information that is deemed relevant, which may include one or more of the following factors regarding the portfolio security, if appropriate: type of security or asset; cost at the date of purchase; size of holding; last trade price; most recent valuation; fundamental analytical data relating to the investment in the security; nature and duration of any restriction on the disposition of the security; evaluation of the factors that influence the market in which the security is purchased or sold; financial statements of the issuer; discount from market value of unrestricted securities of the same class at the time of purchase; special reports prepared by analysts; information as to any transactions or offers with respect to the security; existence of merger proposals or tender offers affecting the security; price and extent of public trading in similar securities of the issuer or compatible companies and other relevant matters; changes in interest rates; observations from financial institutions; domestic or foreign government actions or pronouncements; other recent events; existence of shelf registration for restricted securities; existence of any undertaking to register the security; and other acceptable methods of valuing portfolio securities.
Hedge fund investments in the SEI Special Situations Fund are valued quarterly and recorded on a one-month lag. For alternative investment values reported on a lag, current market information is reviewed for any material changes in values at the reporting date. Share repurchases for the SEI Special Situations Fund are considered semi-annually subject to notice of 95 days.
Private Equity Funds
Private equity funds are alternative investments that represent direct or indirect investments in partnerships, venture funds or a diversified pool of private investment vehicles (fund of funds).
Investment commitments are made in private equity funds of funds based on an asset allocation strategy, and capital calls are made over the life of the funds to fund the commitments. As of December 31, 2014, remaining commitments total $55.5 million for both our pension and other benefits. Of this amount, an additional $45.0 million commitment was executed during the third quarter of 2014 in order to bring the portfolio in line with the target allocation for this asset category. Committed amounts are funded from plan assets when capital calls are made. Investment commitments are not pre-funded in reserve accounts. Refer to the valuation methodologies for equity securities above for further information.
The valuation of investments in private equity funds of funds initially is performed by the underlying fund managers. In determining the fair value, the fund managers may consider any information that is deemed relevant, which may include: type of security or asset; cost at the date of purchase; size of holding; last trade price; most recent valuation; fundamental analytical data relating to the investment in the security; nature and duration of any restriction on the disposition of the security; evaluation of the factors that influence the market in which the security is purchased or sold; financial statements of the issuer; discount from market value of unrestricted securities of the same class at the time of purchase; special reports prepared by analysts; information as to any transactions or offers with respect to the security; existence of merger proposals or tender offers affecting the security; price and extent of public trading in similar securities of the issuer or compatible companies and other relevant matters; changes in interest rates; observations from financial institutions; domestic or foreign government actions or pronouncements; other recent events; existence of shelf registration for restricted securities; existence of any undertaking to register the security; and other acceptable methods of valuing portfolio securities.
The valuations are obtained from the underlying fund managers, and the valuation methodology and process is reviewed for consistent application and adherence to policies. Considerable judgment is required to interpret the factors used to develop estimates of fair value.
Private equity investments are valued quarterly and recorded on a one-quarter lag. For alternative investment values reported on a lag, current market information is reviewed for any material changes in values at the reporting date. Capital distributions for the funds do not occur on a regular frequency. Liquidation of these investments would require sale of the partnership interest.
Structured Credit
Structured credit investments are alternative investments comprised of collateralized debt obligations and other structured credit investments that are priced based on valuations provided by independent, third-party pricing agents, if available. Such values generally reflect the last reported sales price if the security is actively traded. The third-party pricing agents may also value structured credit investments at an evaluated bid price by employing methodologies that utilize actual market transactions, broker-supplied valuations, or other methodologies designed to identify the market value of such securities. Such methodologies generally consider such factors as security prices, yields, maturities, call features, ratings and developments relating to specific securities in arriving at valuations. Securities listed on a securities exchange, market or automated quotation system for which quotations are readily available are valued at the last quoted sale price on the primary exchange or market on which they are traded. Debt obligations with remaining maturities of 60 days or less may be valued at amortized cost, which approximates fair value.
Structured credit investments are valued monthly and recorded on a one-month lag. For alternative investment values reported on a lag, current market information is reviewed for any material changes in values at the reporting date. Redemption requests are considered quarterly subject to notice of 90 days.
Real Estate
The real estate portfolio for the pension plans is an alternative investment comprised of three funds with strategic categories of real estate investments. All real estate holdings are appraised externally at least annually, and appraisals are conducted by reputable, independent appraisal firms that are members of the Appraisal Institute. All external appraisals are performed in accordance with the Uniform Standards of Professional Appraisal Practices. The property valuations and assumptions of each property are reviewed quarterly by the investment advisor and values are adjusted if there has been a significant change in circumstances relating to the property since the last external appraisal. The valuation methodology utilized in determining the fair value is consistent with the best practices prevailing within the real estate appraisal and real estate investment management industries, including the Real Estate Information Standards, and standards promulgated by the National Council of Real Estate Investment Fiduciaries, the National Association of Real Estate Investment Fiduciaries, and the National Association of Real Estate Managers. In addition, the investment advisor may cause additional appraisals to be performed. Two of the funds’ fair values are updated monthly, and there is no lag in reported values. Redemption requests for these two funds are considered on a quarterly basis, subject to notice of 45 days.
Effective October 1, 2009, one of the real estate funds began an orderly wind-down. The decision to wind down the fund primarily was driven by real estate market factors that adversely affected the availability of new investor capital. Third-party appraisals of this fund’s assets were eliminated; however, internal valuation updates for all assets and liabilities of the fund are prepared quarterly. The fund’s asset values are recorded on a one-quarter lag, and current market information is reviewed for any material changes in values at the reporting date. As of December 31, 2014, the fund was largely unwound with no further material distributions expected.
During 2011, a new real estate fund of funds investment was added for the Empire, Tilden, Hibbing and United Taconite VEBA plans as a result of the asset allocation review process. This fund invests in pooled investment vehicles that in turn invest in commercial real estate properties. Valuations are performed quarterly and financial statements are prepared on a semi-annual basis, with annual audited statements. Asset values for this fund are reported with a one-quarter lag and current market information is reviewed for any material changes in values at the reporting date. In most cases, values are based on valuations reported by underlying fund managers or other independent third-party sources, but the fund has discretion to use other valuation methods, subject to compliance with ERISA. Valuations are typically estimates only and subject to upward or downward revision based on each underlying fund’s annual audit. Withdrawals are permitted on the last business day of each quarter subject to a 65-day prior written notice.
The following represents the effect of fair value measurements using significant unobservable inputs (Level 3) on changes in plan assets for the years ended December 31, 2014 and 2013:
	(In Millions)
	Year Ended December 31, 2014
	Hedge Funds				Private Equity				Structured				Real				Total
					Funds				Credit Fund				Estate
Beginning balance — January 1, 2014	$	57.6			$	29.1			$	61			$	40.9			$	188.6
Actual return on plan assets:
Relating to assets still held at	3.1				3.2				4.4				5.2				15.9
the reporting date
Relating to assets sold during	(1.5		)		3				—				—				1.5
the period
Purchases	—				1.4				—				5.4				6.8
Sales	—				(5.5		)		—				(1.5		)		(7.0		)
Ending balance — December 31, 2014	$	59.2			$	31.2			$	65.4			$	50			$	205.8
	(In Millions)
	Year Ended December 31, 2013
	Hedge Funds				Private Equity				Structured				Real				Total
					Funds				Credit Fund				Estate
Beginning balance — January 1, 2013	$	85.6			$	29.3			$	56.2			$	29.4			$	200.5
Actual return on plan assets:
Relating to assets still held at	4.5				(2.1		)		33.5				5.1				41
the reporting date
Relating to assets sold during	(1.2		)		5.2				(28.7		)		(0.4		)		(25.1		)
the period
Purchases	66				14.7				27.5				36.8				145
Sales	(97.3		)		(18.0		)		(27.5		)		(30.0		)		(172.8		)
Ending balance — December 31, 2013	$	57.6			$	29.1			$	61			$	40.9			$	188.6
VEBA
Assets for other benefits include VEBA trusts pursuant to bargaining agreements that are available to fund retired employees’ life insurance obligations and medical benefits. The fair values of our other benefit plan assets at December 31, 2014 and 2013 by asset category are as follows:
	(In Millions)
	31-Dec-14
Asset Category	Quoted Prices in Active				Significant Other				Significant				Total
	Markets for Identical				Observable				Unobservable
	Assets/Liabilities				Inputs				Inputs
	(Level 1)				(Level 2)				(Level 3)
Equity securities:
U.S. large-cap	$	11.6			$	—			$	—			$	11.6
U.S. small/mid-cap	2.9				—				—				2.9
International	8.6				—				—				8.6
Fixed income	174.5				39.1				—				213.6
Hedge funds	—				—				11.5				11.5
Private equity	—				—				6.2				6.2
Structured credit	—				—				6.1				6.1
Real estate	—				—				8.7				8.7
Cash	0.1				—				—				0.1
Total	$	197.7			$	39.1			$	32.5			$	269.3
	(In Millions)
	December 31, 2013
Asset Category	Quoted Prices in Active				Significant Other				Significant				Total
	Markets for Identical				Observable				Unobservable
	Assets/Liabilities				Inputs				Inputs
	(Level 1)				(Level 2)				(Level 3)
Equity securities:
U.S. large-cap	$	15.7			$	—			$	—			$	15.7
U.S. small/mid-cap	2.7				—				—				2.7
International	7.8				—				—				7.8
Fixed income	134.4				33.7				—				168.1
Hedge funds	—				—				24.6				24.6
Private equity	—				—				6				6
Structured credit	—				—				13.5				13.5
Real estate	—				—				13.2				13.2
Cash	0.2				—				—				0.2
Total	$	160.8			$	33.7			$	57.3			$	251.8
Refer to the pension asset discussion above for further information regarding the inputs and valuation methodologies used to measure the fair value of each respective category of plan assets.
The following represents the effect of fair value measurements using significant unobservable inputs (Level 3) on changes in plan assets for the year ended December 31, 2014 and 2013:
	(In Millions)
	Year Ended December 31, 2014
	Hedge				Private Equity				Structured Credit Fund				Real				Total
	Funds				Funds								Estate
Beginning balance — January 1, 2014	$	24.6			$	6			$	13.5			$	13.2			$	57.3
Actual return on plan assets:
Relating to assets still held at the reporting date	0.5				1				0.4				0.9				2.8
Relating to assets sold during the period	0.6				0.4				0.4				0.5				1.9
Purchases	—				0.1				—				—				0.1
Sales	(14.2		)		(1.3		)		(8.2		)		(5.9		)		(29.6		)
Ending balance — December 31, 2014	$	11.5			$	6.2			$	6.1			$	8.7			$	32.5
	(In Millions)
	Year Ended December 31, 2013
	Hedge				Private Equity				Structured Credit Fund				Real				Total
	Funds				Funds								Estate
Beginning balance — January 1, 2014	$	23.2			$	6.2			$	12.5			$	15.9			$	57.8
Actual return on plan assets:
Relating to assets still held at the reporting date	2.1				0.2				2.4				2.8				7.5
Relating to assets sold during the period	(0.7		)		0.4				(1.4		)		(0.7		)		(2.4		)
Purchases	22.5				0.3				11				14.2				48
Sales	(22.5		)		(1.1		)		(11		)		(19.0		)		(53.6		)
Ending balance — December 31, 2014	$	24.6			$	6			$	13.5			$	13.2			$	57.3
Contributions
Annual contributions to the pension plans are made within income tax deductibility restrictions in accordance with statutory regulations. In the event of plan termination, the plan sponsors could be required to fund additional shutdown and early retirement obligations that are not included in the pension obligations. The Company currently has no intention to shutdown, terminate or withdraw from any of its employee benefit plans.
		(In Millions)
		Pension				Other Benefits
Company Contributions		Benefits				VEBA				Direct				Total
										Payments
2013		$	53.7			$	14.6			$	10.9			$	25.5
2014		60.5				—				7.3				7.3
2015 (Expected)*		36.8				—				6.8				6.8
*	Pursuant to the bargaining agreement, benefits can be paid from VEBA trusts that are at least 70 percent funded (all VEBA trusts are over 70 percent funded at December 31, 2014). Funding obligations have been suspended as Hibbing's, UTAC's, Tilden's and Empire's share of the value of their respective trust assets have reached 90 percent of their obligation.
VEBA plans are not subject to minimum regulatory funding requirements. Amounts contributed are pursuant to bargaining agreements.
Contributions by participants to the other benefit plans were $4.8 million for the year ended December 31, 2014 and $5.6 million for the year ended December 31, 2013.
Estimated Cost for 2015
For 2015, we estimate net periodic benefit cost as follows:
	(In Millions)
Defined benefit pension plans	$	23.6
Other postretirement benefits	6
Total	$	29.6
Estimated Future Benefit Payments
	(In Millions)
	Pension				Other Benefits
	Benefits				Gross				Less				Net
					Company				Medicare				Company
					Benefits				Subsidy				Payments
2015	$	89.3			$	23.1			$	0.9			$	22.2
2016	77.7				23				1				22
2017	78.1				23.2				1.1				22.1
2018	79.3				23.3				1.3				22
2019	78.6				22.9				1.4				21.5
2020-2024	402.4				110.7				8.6				102.1
Other Potential Benefit Obligations
While the foregoing reflects our obligation, our total exposure in the event of non-performance is potentially greater. Following is a summary comparison of the total obligation:
	(In Millions)
	31-Dec-14
	Defined				Other
	Benefit				Benefits
	Pensions
Fair value of plan assets	$	949.6			$	269.3
Benefit obligation	(1,227.4		)		(395.9		)
Underfunded status of plan	$	(277.8	)		$	(126.6	)
Additional shutdown and early retirement benefits	$	(26.7	)		$	40.5

STOCK_COMPENSATION_PLANS

STOCK COMPENSATION PLANS	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK COMPENSATION PLANS	NOTE 8 - STOCK COMPENSATION PLANS
	At December 31, 2014, we have two share-based compensation plans, which are described below. The compensation cost that has been charged against income for those plans was $23.7 million, $21.1 million and $20.6 million in 2014, 2013 and 2012, respectively, which primarily was recorded in Selling, general and administrative expenses in the Statements of Consolidated Operations. The total income tax benefit recognized in the Statements of Consolidated Operations for share-based compensation arrangements was $8.3 million, $7.4 million and $7.2 million for 2014, 2013 and 2012, respectively.
	Employees’ Plans
	The 2012 Equity Plan was approved by our Board of Directors on March 13, 2012 and our shareholders approved it on May 8, 2012, effective as of March 13, 2012. The 2012 Equity Plan replaced the ICE Plan. The maximum number of shares that may be issued under the 2012 Equity Plan is 6.0 million common shares. On February 10, 2014, upon recommendation by the Compensation and Organization Committee, Cliffs’ Board of Directors approved and adopted, subject to the approval of Cliffs' shareholders at the 2014 Annual Meeting, the 2012 Amended Equity Plan. The principal reason for amending and restating the 2012 Equity Plan was to increase the number of common shares available for issuance by 5.0 million common shares. This amended plan was approved by Cliffs' shareholders at the 2014 Annual Meeting held on July 29, 2014.
	The Compensation and Organization Committee of the Board of Directors approved grants under the 2012 Equity Plan and the 2012 Amended Equity Plan to certain officers and employees for the 2014 to 2016 performance period. Shares granted under the awards during 2014 consisted of 0.8 million performance shares based on TSR, 0.5 million restricted share units, 0.3 million stock options and 0.4 million performance-based restricted stock units, 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.
	At our July 29, 2014 Annual Meeting, the shareholders voted on the election of eleven directors. Thirteen persons were nominated for election to the eleven board positions. On August 6, 2014, the Company received the final report of the inspector of election that confirmed the election of six new directors to our Board of Directors. Such an event constituted a change in control pursuant to our incentive equity plans. As a result of such change in the majority of our directors and pursuant to the terms of the various plans and applicable award agreements, all of the outstanding and unvested equity incentives awarded to participants prior to October 2013 became vested. Accordingly, this resulted in recognizing $11.7 million of additional equity-based compensation expense in the accompanying financial statements, representing the remaining unrecognized compensation expense of the awards. For any equity grants awarded after September 2013, the vesting of all such grants will accelerate and pay out in cash only following a participant's qualifying termination of employment associated with the change in control and if the common shares are not substituted with a replacement award. This potential liability for additional double-trigger payments for share-based compensation in cash will expire entirely in two years.
	For the outstanding 2012 Equity Plan and 2012 Amended Equity Plan awards that were issued subsequent to October 2013, 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 2014 to 2016 performance periods is measured only 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 2014 to 2016 performance period will vary from zero to 200 percent of the original grant. For the outstanding performance-based restricted stock units, the award may be earned and settled based upon certain VWAP performance for the Company’s common shares, (Threshold VWAP, Target VWAP, or Maximum VWAP) for any period of ninety (90) consecutive calendar days during a performance period commencing August 7, 2014 and ending December 31, 2017 (the “Performance Period”). The stock options vest in equal thirds on each of December 31, 2015, December 31, 2016 and December 31, 2017 subject to continued employment through each vesting date, and are exercisable cumulatively at a strike price of $13.83 after each vesting date and expire on November 17, 2021. The restricted share units are subject to continued employment, are retention based, will vest at the end of the respective performance period, and are payable in common shares or cash in certain circumstances at a time determined by the Committee at its discretion.
	Following is a summary of our performance share award agreements currently outstanding:
	Performance	Performance Shares Granted			Estimated Forfeitures			Expected to Vest			Grant Date		Performance Period
	Share
	Plan Year
	2014	400,000			40,911			359,089			17-Nov-14		8/7/2014 - 12/31/2017
	2014	283,530			24,380			259,150			29-Jul-14		1/1/2014 - 12/31/2016
	2014	124,630			21,098			103,532			12-May-14		1/1/2014 - 12/31/2016
	2014	385,585			120,299			265,286			10-Feb-14		1/1/2014 - 12/31/2016
	Nonemployee Directors
	At our 2014 annual meeting, the shareholders approved the Directors' Plan which became effective December 1, 2014. The Directors’ Plan authorizes us to issue up to 300,000 common shares from time to time to nonemployee Directors. Under the Share Ownership Guidelines in effect for 2014 ("Guidelines"), a Director is required by the end of five years from date of election to hold common shares with a market value of at least $250,000. The Directors’ Plan offers the nonemployee Director the opportunity to defer all or a portion of the awards granted.
	The 2008 Directors’ Plan in effect for most of 2014 provided for an Annual Equity Grant ("Equity Grant") to be awarded at our annual meeting each year to all nonemployee Directors elected or re-elected by the shareholders and a pro-rata amount was awarded to new directors upon their appointment. The value of the Equity Grant was payable in restricted shares with a three-year vesting period from the date of grant. The closing market price of our common shares on October 16, 2014 was divided into the number of common shares remaining available for issuance under the 2008 Directors' Plan to determine the number of restricted shares awarded as the Equity Grant. In 2014, nonemployee Directors each received Equity Grants valued at $85,000 which was bifurcated into two tranches since the 2008 Director's Plan did not have a sufficient number of shares available for issuance. The first tranche of the 2014 Equity Grant was granted under the 2008 Directors' Plan on October 16, 2014 and valued at $42,500. The second tranche was granted under the Directors' Plan on December 2, 2014 and valued at $42,500.
	For the last three years, Equity Grant shares have been awarded to elected or re-elected nonemployee Directors as follows:
	Year of Grant		Unrestricted Equity Grant Shares			Restricted Equity Grant Shares			Deferred Equity Grant Shares
	2012		1,498			8,988			2,996
	2013		3,985			31,506			7,970
	2014		—			73,635			—
	Other Information
	The following table summarizes the share-based compensation expense that we recorded for continuing operations in 2014, 2013 and 2012:
		(In Millions, except  per
		share amounts)
		2014				2013				2012
	Cost of goods sold and operating expenses	$	7.8			$	6.3			$	4
	Selling, general and administrative expenses	15.9				14.8				16.6
	Reduction of operating income from continuing operations before income	23.7				21.1				20.6
	taxes and equity income (loss) from ventures
	Income tax benefit	(8.3		)		(7.4		)		(7.2		)
	Reduction of net income attributable to Cliffs shareholders	$	15.4			$	13.7			$	13.4
	Reduction of earnings per share attributable to Cliffs shareholders:
	Basic	$	0.1			$	0.09			$	0.09
	Diluted	$	0.1			$	0.08			$	0.09
	Determination of Fair Value
	The fair value of each 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 2014 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)
	February 10, 2014		$	20.58			2.89		54.00%		0.54%		2.92%	$	22.21	107.92%
	May 12, 2014		$	17.54			2.61		54.00%		0.54%		2.92%	$	18.93	107.92%
	July 29, 2014		$	17.62			2.42		51.30%		0.83%		3.40%	$	19.02	107.92%
	November 17, 2014		$	10.85			3.12		52.90%		1.18%		4.30%	$	10.61	97.79%
	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.
	Restricted share units, restricted stock awards, deferred stock allocation and performance share activity under our long-term equity plans and Directors’ Plans are as follows:
		2014			2013			2012
		Shares			Shares			Shares
	Stock options:
	Outstanding at beginning of year	—			—			—
	Granted during the year	250,000			—			—
	Vested	—			—			—
	Forfeited/canceled	—			—			—
	Outstanding at end of year	250,000			—			—
	Restricted awards:
	Outstanding and restricted at beginning of year	586,084			393,787			425,166
	Granted during the year	531,030			396,844			151,869
	Vested	(423,822	)		(118,973	)		(161,741	)
	Forfeited/canceled	(170,116	)		(85,574	)		(21,507	)
	Outstanding and restricted at end of year	523,176			586,084			393,787
	Performance shares:
	Outstanding at beginning of year	1,040,453			772,484			877,435
Granted during the year 1	1,233,685			806,271			501,346
Issued 2	(796,624	)		(289,054	)		(574,518	)
Forfeited/canceled	(405,138	)		(249,248	)		(31,779	)
Outstanding at end of year	1,072,376			1,040,453			772,484
Vested or expected to vest as of	1,723,728
December 31, 2014
Directors’ retainer and voluntary shares:
Outstanding at beginning of year	7,329			2,880			2,611
Granted during the year	2,281			8,136			1,823
Forfeited/canceled	—			(1,521	)		—
Vested	(9,610	)		(2,166	)		(1,554	)
Outstanding at end of year	—			7,329			2,880
Reserved for future grants or awards at end
of year:
Employee plans	6,222,434
Directors’ plans	225,955
Total	6,448,389
1	The shares granted in 2013 and 2012 include 54,051 shares and 191,506 shares, respectively, related to the 23% and 50% payouts associated with the prior-year pool as actual payout exceeded target.
2	For the year ended December 31, 2014, the shares vesting on December 31, 2013 were valued as of February 10, 2014, and the shares vesting due to the change in a majority of our Board of Directors that triggered the acceleration of vesting and payout of outstanding equity grants under our equity plans on August 6, 2014, were valued as of that date.
	For the years ended December 31, 2013 and December 31, 2012, the shares vested on December 31, 2012 and December 31, 2011, respectively, and were valued on February 21, 2013 and February 13, 2012, respectively.
A summary of our outstanding share-based awards as of December 31, 2014 is shown below:
	Shares			Weighted
				Average
				Grant Date
				Fair Value
Outstanding, beginning of year	1,633,866				$40.20
Granted	2,016,996				$16.67
Vested	(1,230,056	)			$38.48
Forfeited/expired	(575,254	)			$24.76
Outstanding, end of year	1,845,552				$16.55
The total compensation cost related to outstanding awards not yet recognized is $18.3 million at December 31, 2014. The weighted average remaining period for the awards outstanding at December 31, 2014 is approximately 2.5 years.

INCOME_TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	NOTE 9 - INCOME TAXES
	Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures includes the following components:
		(In Millions)
		2014			2013				2012
	United States	$	(1,884.2	)	$	837.7			$	838.6
	Foreign	(7,719.5		)	(348.4		)		(1,340.4		)
		$	(9,603.7	)	$	489.3			$	(501.8	)
	The components of the provision (benefit) for income taxes on continuing operations consist of the following:
		(In Millions)
		2014			2013				2012
	Current provision (benefit):
	United States federal	$	(159.9	)	$	101.3			$	71.1
	United States state & local	(0.6		)	4				7.6
	Foreign	17.2			87.9				50.2
		(143.3		)	193.2				128.9
	Deferred provision (benefit):
	United States federal	(258.9		)	23.3				221.2
	United States state & local	(43.0		)	3				1.4
	Foreign	(856.8		)	(164.4		)		(95.6		)
		(1,158.7		)	(138.1		)		127
	Total provision on income (loss) from continuing	$	(1,302.0	)	$	55.1			$	255.9
	operations
	Reconciliation of our income tax attributable to continuing operations computed at the U.S. federal statutory rate is as follows:
		(In Millions)
		2014						2013						2012
	Tax at U.S. statutory rate of 35 percent	$	(3,361.3	)	35	%		$	171.3			35	%	$	(175.6	)	35	%
	Increase (decrease) due to:
	Foreign exchange remeasurement	(4.1		)	—			(2.6		)		(0.5	)	62.3			(12.4	)
	Non-taxable income related to noncontrolling interests	290.1			(3.0	)		(1.5		)		(0.3	)	61			(12.0	)
	Impact of tax law change	13			(0.1	)		—				—		(357.1		)	71.2
	Percentage depletion in excess of cost depletion	(87.9		)	0.9			(97.6		)		(19.9	)	(109.1		)	21.7
	Impact of foreign operations	592			(6.2	)		(10.2		)		(2.1	)	65.2			(13.0	)
	Income not subject to tax	(46.5		)	0.5			(106.6		)		(21.8	)	(108.0		)	21.5
	Goodwill impairment	22.7			(0.2	)		20.5				4.2		202.2			(40.3	)
	State taxes, net	(43.6		)	0.5			5.6				1.1		7.3			(1.5	)
	Settlement of financial guaranty	(343.3		)	3.6			—				—		—			—
	Manufacturer’s deduction	—			—			(7.9		)		(1.6	)	(4.7		)	0.9
	Valuation allowance	1,660.60			(17.3	)		73				14.9		634.5			(126.5	)
	Tax uncertainties	0.2			—			19.6				5.3		(14.8		)	2.9
	Prior year adjustment in current year	(10.4		)	0.1			(11.4		)		(3.6	)	(5.7		)	1.1
	Other items — net	16.5			(0.2	)		2.9				0.6		(1.6		)	0.4
	Income tax (benefit) expense	$	(1,302.0	)	13.6	%		$	55.1			11.3	%	$	255.9		(51.0	)%
	The components of income taxes for other than continuing operations consisted of the following:
		(In Millions)
		2014			2013				2012
	Other comprehensive (income) loss:
	Pension/OPEB liability	$	39.8		$	100			$	13.8
	Mark-to-market adjustments	3.6			2				1.7
	Other	(1.1		)	(12.4		)		2.6
	Total	$	42.3		$	89.6			$	18.1
	Paid in capital — acquisition of noncontrolling interest	$	—		$	102.1			$	—
	Paid in capital — stock based compensation	$	(4.8	)	$	3.5			$	(12.8	)
	Discontinued Operations	$	—		$	(2.0	)		$	10.4
	Significant components of our deferred tax assets and liabilities as of December 31, 2014 and 2013 are as follows:
		(In Millions)
		2014			2013
	Deferred tax assets:
	Pensions	$	108.3		$	88.4
	MRRT starting base allowance	—			300.3
	Postretirement benefits other than pensions	63			58
	Alternative minimum tax credit carryforwards	267.7			299.2
	Investments in ventures	6			—
	Asset retirement obligations	48.9			61.7
	Operating loss carryforwards	1,083.50			524.4
Product inventories	32.3			16.4
Property, plant and equipment and mineral rights	901.6			56
State and local	41.9			—
Lease liabilities	14.1			31.9
Other liabilities	153.6			138.3
Total deferred tax assets before valuation allowance	2,720.90			1,574.60
Deferred tax asset valuation allowance	(2,224.5		)	(864.1		)
Net deferred tax assets	496.4			710.5
Deferred tax liabilities:
Property, plant and equipment and mineral rights	(20.0		)	(1,400.8		)
Investment in ventures	(198.0		)	(196.4		)
Intangible assets	(7.3		)	(33.5		)
Income tax uncertainties	(49.5		)	(48.5		)
Product inventories	(16.6		)	(12.8		)
Other assets	(80.2		)	(93.0		)
Total deferred tax liabilities	(371.6		)	(1,785.0		)
Net deferred tax assets (liabilities)	$	124.8		$	(1,074.5	)
The deferred tax amounts are classified in the Statements of Consolidated Financial Position as current or long-term consistently with the underlying asset or liability that generates the basis difference between financial reporting and tax. Following is a summary:
	(In Millions)
	2014			2013
Deferred tax assets:
United States	$	165.9		$	7.2
Foreign
Current	2.2			29.4
Long-term	12			41.5
Total deferred tax assets	180.1			78.1
Deferred tax liabilities:
United States	—			175.3
Foreign
Current	4			6.1
Long-term	51.3			971.2
Total deferred tax liabilities	55.3			1,152.60
Net deferred tax assets (liabilities)	$	124.8		$	(1,074.5	)
At December 31, 2014 and 2013, we had $267.7 million and $299.2 million, respectively, of gross deferred tax assets related to U.S. alternative minimum tax credits that can be carried forward indefinitely.
We had gross domestic (including states) and foreign net operating loss carryforwards of $1.9 billion, and $6.0 billion, respectively, at December 31, 2014. We had gross state and foreign net operating loss carryforwards at December 31, 2013 of $157.9 million and $3.5 billion, respectively. The U.S. Federal net operating losses will begin to expire in 2035 and state net operating losses will begin to expire in 2019. The foreign net operating losses will begin to expire in 2015. We had foreign tax credit carryforwards of $5.8 million at December 31, 2014 and December 31, 2013. The foreign tax credit carryforwards will begin to expire in 2020. Additionally, there is a net operating loss carryforward of $540.7 million for Alternative Minimum Tax. No benefit has been recorded in the financials for this attribute as ASC 740 does not allow for the recording of deferred taxes under alternative taxing systems. However, the future economic realizable benefit for this attribute is expected to be approximately $108.1 million.
We recorded a $1,361.0 million net increase in the valuation allowance of certain deferred tax assets where management believes that realization of the related deferred tax assets is not more likely than not. Of this amount, a $18.2 million increase relates to ordinary losses of certain state operations for which future utilization is currently uncertain, a $291.0 million decrease relates to the reversal of our valuation allowance on MRRT tax credits due to the repeal of the MRRT legislation, and a $28.6 million decrease relates to the change in available Alternative Minimum Tax credits after carryback of current year losses. A $1,273.2 million increase relates to foreign deferred tax assets that management has determined it is more likely than not that the assets will not be realized. A $402.5 million increase relates to U.S. regular tax net operating losses where it has been determined that the full benefit of these losses will not be realized as we are perpetual Alternative Minimum taxpayers.
At December 31, 2014, we had no cumulative undistributed earnings of foreign subsidiaries included in consolidated retained earnings. At December 31, 2013, cumulative undistributed earnings of foreign subsidiaries included in consolidated retained earnings amounted to $1.2 billion. The change in undistributed earnings resulted from transactions executed during 2014 which triggered the realization of losses with respect to the value in our investment in Cliffs Quebec Iron Mines. Accordingly, no provision has been made for U.S. deferred taxes related to future repatriation of earnings.
A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:
	(In Millions)
	2014			2013				2012
Unrecognized tax benefits balance as of January 1	$	74.4		$	55.5			$	102.1
Increases for tax positions in prior years	3.4			13.6				2.7
Increases for tax positions in current year	2.5			5.3				11.1
Increase due to foreign exchange	(0.2		)	—				—
Settlements	(0.5		)	—				(60.4		)
Lapses in statutes of limitations	(3.7		)	—				—
Other	(1.2		)	—				—
Unrecognized tax benefits balance as of December 31	$	74.7		$	74.4			$	55.5
At December 31, 2014 and 2013, we had $74.7 million and $74.4 million, respectively, of unrecognized tax benefits recorded. Of this amount, $25.2 million and $25.9 million were recorded in Other liabilities and $49.5 million and $48.5 million were recorded as Other non-current assets in the Statements of Consolidated Financial Position for both years. If the $74.7 million were recognized, the full amount would impact the effective tax rate. We do not expect that the amount of unrecognized tax benefits will change significantly within the next twelve months. At December 31, 2014 and 2013, we had $2.1 million and $1.2 million, respectively, of accrued interest and penalties related to the unrecognized tax benefits recorded in Other liabilities in the Statements of Consolidated Financial Position.
On July 18, 2013, the FASB issued Accounting Standards Update No. 2013-11. Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists (ASU 2013-11). ASU 2013-11 requires the netting of unrecognized tax benefits against a deferred tax asset for a loss or other carryforward that would apply in settlement of the uncertain tax positions except where the deferred tax asset or other carryforward are not available for use. The adoption of the pronouncement does not have an impact in the presentation of our financial statement.
Tax years that remain subject to examination are years 2010 and forward for the U.S., 2006 and forward for Canada, and 2007 and forward for Australia.

LEASE_OBLIGATIONS

LEASE OBLIGATIONS	12 Months Ended
	Dec. 31, 2014
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 $20.6 million, $29.5 million and $25.8 million for the years ended December 31, 2014, 2013 and 2012, respectively. Capital lease assets were $92.7 million and $404.0 million at December 31, 2014 and 2013, respectively. The value of the capital lease assets in 2014 have decreased due to several factors including impairment charges of $140.4 million on our Asia Pacific Iron Ore, North American Coal and Eastern Canadian Iron Ore operations. Other factors involved are the announced exiting out of Eastern Canadian Iron Ore, additions/deletions of assets, depreciation, etc. Corresponding accumulated amortization of capital leases included in respective allowances for depreciation were $18.1 million and $198.5 million at December 31, 2014 and 2013, respectively.
	Future minimum payments under capital leases and non-cancellable operating leases at December 31, 2014 are as follows:
		(In Millions)
		Capital Leases			Operating Leases
	2015	$	84.8		$	12
	2016	34.1			9.3
	2017	26.9			8.4
	2018	20.4			6.8
	2019	11.4			4.8
	2020 and thereafter	21			9.9
	Total minimum lease payments	$	198.6		$	51.2
	Amounts representing interest	31.3
	Present value of net minimum lease payments	$	167.3	-1
	-1	The total is comprised of $74.5 million and $92.8 million classified as Current portion of capital leases and Other liabilities, respectively, in the Statements of Unaudited Condensed Consolidated Financial Position at December 31, 2014.

ENVIRONMENTAL_AND_MINE_CLOSURE

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS	12 Months Ended
	Dec. 31, 2014
Environmental Remediation Obligations [Abstract]
ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS	NOTE 11 - ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS
	We had environmental and mine closure liabilities of $261.2 million and $321.0 million at December 31, 2014 and 2013, respectively. Payments in 2014 and 2013 were $3.1 million and $8.2 million, respectively. The following is a summary of the obligations as of December 31, 2014 and 2013:
		(In Millions)
		December 31,
		2014			2013
	Environmental	$	5.5		$	8.4
	Mine closure
	LTVSMC	22.9			22
	Operating mines:
	U.S. Iron Ore	120.9			152.2
	Asia Pacific Iron Ore	21.5			25.5
	North American Coal	33.9			34.7
	Eastern Canadian Iron Ore	56.5			78.2
	Total mine closure	255.7			312.6
	Total environmental and mine closure obligations	261.2			321
	Less current portion	5.2			11.3
	Long-term environmental and mine closure obligations	$	256		$	309.7
	Environmental
	Our mining and exploration activities are subject to various laws and regulations governing the protection of the environment. We conduct our operations to protect the public health and environment and believe our operations are in compliance with applicable laws and regulations in all material respects. Our environmental liabilities of $5.5 million and $8.4 million at December 31, 2014 and 2013, respectively, including obligations for known environmental remediation exposures at various active and closed mining operations and other sites, have been recognized based on the estimated cost of investigation and remediation at each site. If the cost only can be estimated as a range of possible amounts with no specific amount being more likely, the minimum of the range is accrued. Future expenditures are not discounted unless the amount and timing of the cash disbursements readily are known. Potential insurance recoveries have not been reflected. Additional environmental obligations could be incurred, the extent of which cannot be assessed.
	As discussed in further detail below, the environmental liability recorded at December 31, 2014 and 2013 primarily is comprised of remediation obligations related to the Rio Tinto mine site in Nevada where we are named as a potentially responsible party.
	The Rio Tinto Mine Site
	The Rio Tinto Mine Site is a historic underground copper mine located near Mountain City, Nevada, where tailings were placed in Mill Creek; a tributary to the Owyhee River. Site investigation and remediation work is being conducted in accordance with a Consent Order dated September 14, 2001 between the NDEP and the Rio Tinto Working Group composed of the Company, Atlantic Richfield Company, Teck Cominco American Incorporated and E. I. duPont de Nemours and Company. The Consent Order provides for technical review by the U.S. Department of the Interior Bureau of Indian Affairs, the U.S. Fish and Wildlife Service, U.S. Department of Agriculture Forest Service, the NDEP and the Shoshone-Paiute Tribe of the Duck Valley Reservation (collectively, "Rio Tinto Trustees"). In recognition of the potential for an NRD claim, the parties actively pursued a global settlement that would include the EPA and encompass both the remedial action and the NRD issues.
	The NDEP published a Record of Decision for the Rio Tinto Mine, which was signed on February 14, 2012 by the NDEP and the EPA. On September 27, 2012, the agencies subsequently issued a proposed Consent Decree, which was lodged with the U.S. District Court for the District of Nevada and opened for 30-day public comment on October 4, 2012. The Consent Decree was subsequently finalized on May 20, 2013. Under the terms of the Consent Decree, the Rio Tinto Working Group has agreed to pay over $29.0 million in cleanup costs and natural resource damages to the site and surrounding area. The Company's share of the total settlement cost, which includes remedial action, insurance and other oversight costs is $12.2 million, of which we have a remaining environmental liability of $2.5 million and $5.3 million in the Statements of Consolidated Financial Position as of December 31, 2014 and 2013, respectively, related to this issue.
	Under the terms of the Consent Decree, the Rio Tinto Working Group will be responsible for removing mine tailings from Mill Creek, improving the creek to support redband trout and improving water quality in Mill Creek and the East Fork Owyhee River. Previous cleanup projects included filling in old mine shafts, grading and covering leach pads and tailings, and building diversion ditches. NDEP will oversee the cleanup, with input from EPA and monitoring from the nearby Shoshone-Paiute Tribes of Duck Valley.
	Mine Closure
	Our mine closure obligations of $255.7 million and $312.6 million at December 31, 2014 and 2013, respectively, include our five consolidated U.S. operating iron ore mines, our Asia Pacific operating iron ore mine, our two operating North American coal mines, our two Eastern Canadian iron ore mines and a closed operation formerly operating as LTVSMC. Additionally, included in the December 31, 2013 mine closure obligation are the mine closure obligations related to the three mines at our CLCC operations. The CLCC assets were sold during the fourth quarter of 2014. As disclosed, at the end of March 2014, we idled our Wabush Scully mine in Newfoundland and Labrador and in the fourth quarter we began to implement the permanent closure plan for the mine. Additionally, we disclosed in November 2014 that we were pursuing exit options for our Bloom Lake mine and as disclosed in January 2015, active production at Bloom Lake mine has completely ceased and the mine has transitioned to "care-and-maintenance" mode.
	Management periodically performs an assessment of the obligation to determine the adequacy of the liability in relation to the closure activities still required at the LTVSMC site. The LTVSMC closure liability was $22.9 million and $22.0 million at December 31, 2014 and 2013, respectively. MPCA is presently working on an NPDES permit reissuance for this facility that could modify the closure liability, but the scale of that change will not be understood until the permit has been drafted and issued.
	The accrued closure obligation for our active mining operations provides for contractual and legal obligations associated with the eventual closure of the mining operations. We performed a detailed assessment of our asset retirement obligations related to our active mining locations most recently in 2014, except for Bloom Lake, in accordance with our accounting policy, which requires us to perform an in-depth evaluation of the liability every three years in addition to routine annual assessments. The most recent assessment for Bloom Lake was performed in 2012.
	For the assessments performed, we determined the obligations based on detailed estimates adjusted for factors that a market participant would consider (i.e., inflation, overhead and profit) and then discounted the obligation using the current credit-adjusted risk-free interest rate based on the corresponding life of mine. The estimate also incorporates incremental increases in the closure cost estimates and changes in estimates of mine lives. The closure date for each location was determined based on the exhaustion date of the remaining iron ore reserves. 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 roll forward of our asset retirement obligation liability related to our active mining locations for the years ended December 31, 2014 and 2013:
		(In Millions)
		December 31,
		2014			2013
	Asset retirement obligation at beginning of period	$	290.6		$	231.1
	Accretion expense	14.5			18.1
	Exchange rate changes	(2.4		)	(3.4		)
	Revision in estimated cash flows	(65.2		)	44.8
	Disposal of CLCC Assets	(4.7		)	$	—
	Asset retirement obligation at end of period	$	232.8		$	290.6
	The revisions in estimated cash flows recorded during the year ended December 31, 2014 relate primarily to a downward revision of estimated asset retirement costs for one of our U.S. Iron Ore mines associated with required storm water management systems.  The mine life was extended during 2014, effectively converting certain asset retirement costs to capital costs over the remaining life-of-mine.  The reduction in estimated cash flows was also attributable to the mine life for one of the Eastern Canadian Iron Ore mines being shortened by seven years along with a decrease in the inflation rate causing additional downward revisions in estimated cash flows recorded during the year ended December 31, 2014.
	For the year ended December 31, 2013, the revisions in estimated cash flows recorded during the year primarily included estimated asset retirement costs for one of our U.S. Iron Ore mines associated with required storm water management systems expected to be implemented subsequent to the closure of the mine, as described above.

GOODWILL_AND_OTHER_INTANGIBLE_

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES	12 Months Ended
	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES	NOTE 12 - GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES
	Goodwill
	Goodwill represents the excess purchase price paid over the fair value of the net assets of acquired companies and is not subject to amortization. We assign goodwill arising from acquired companies to the reporting units that are expected to benefit from the synergies of the acquisition. Our reporting units are either at the operating segment level or a component one level below our operating segments that constitutes a business for which management generally reviews production and financial results of that component. Decisions often are made as to capital expenditures, investments and production plans at the component level as part of the ongoing management of the related operating segment. We have determined that our Asia Pacific Iron Ore and Ferroalloys operating segments constitute separate reporting units, that CQIM and Wabush within our Eastern Canadian Iron Ore operating segment constitute reporting units and that Northshore within our U.S. Iron Ore operating segment constitutes a reporting unit. Goodwill is allocated among and evaluated for impairment at the reporting unit level in the fourth quarter of each year or as circumstances occur that potentially indicate that the carrying amount of these assets may exceed their fair value.
	During the third quarter of 2014, a goodwill impairment charge of $73.5 million was recorded for our Asia Pacific Iron Ore reporting segment. The impairment charge was a result of downward long-term pricing estimates as determined through management's long-range planning process.
	During the fourth quarter of 2013, upon performing our annual goodwill impairment test, a goodwill impairment charge of $80.9 million was recorded for our Cliffs Chromite Ontario and Cliffs Chromite Far North reporting units within our Ferroalloys operating segment. The impairment charge was primarily a result of the decision made in the fourth quarter of 2013 to indefinitely suspend the Chromite Project and to not allocate additional capital for the project given the uncertain timeline and risks associated with the development of necessary infrastructure to bring the project online.
	Refer to NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS for further information.
	The following table summarizes changes in the carrying amount of goodwill allocated by operating segment for the years ended December 31, 2014 and December 31, 2013:
		(In Millions)
		31-Dec-14																				December 31, 2013
		U.S. Iron Ore				Eastern Canadian Iron Ore				Asia Pacific				Other				Total				U.S. Iron Ore				Eastern			Asia Pacific Iron Ore			Other			Total
										Iron Ore																Canadian Iron Ore
	Beginning Balance	$	2			$	—			$	72.5			$	—			$	74.5			$	2			$	—		$	84.5		$	80.9		$	167.4
	Arising in business combinations	—				—				—				—				—				—				—			—			—			—
	Impairment	—				—				(73.5		)		—				(73.5		)		—				—			—			(80.9		)	(80.9		)
	Impact of foreign currency translation	—				—				1				—				1				—				—			(12.0		)	—			(12.0		)
	Ending Balance	$	2			$	—			$	—			$	—			$	2			$	2			$	—		$	72.5		$	—		$	74.5
	Accumulated Goodwill Impairment Loss	$	—			$	(1,000.0	)		$	(73.5	)		$	(80.9	)		$	(1,154.4	)		$	—			$	(1,000.0	)	$	—		$	(80.9	)	$	(1,080.9	)
	Other Intangible Assets and Liabilities
	Following is a summary of intangible assets and liabilities as of December 31, 2014 and December 31, 2013:
				(In Millions)
				31-Dec-14												31-Dec-13
		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		$	79.2			$	(16.5	)		$	62.7			$	127.4			$	(35.9	)		$	91.5
	Utility contracts	Other non-current assets		—				—				—				54.7				(53.1		)		1.6
	Leases	Other non-current assets		—				—				—				2.4				(0.1		)		2.3
	Total intangible assets			$	79.2			$	(16.5	)		$	62.7			$	184.5			$	(89.1	)		$	95.4
	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		)		159.7				(46.2		)
	Total below-market sales contracts			$	(228.9	)		$	182.8			$	(46.1	)		$	(228.9	)		$	159.7			$	(69.2	)
	Amortization expense relating to intangible assets was $10.4 million, $19.9 million and $22.5 million for the years ended December 31, 2014, 2013 and 2012, and is recognized in Cost of goods sold and operating expenses in the Statements of Consolidated Operations. During the year ended December 31, 2014, an impairment charge of $15.5 million was recorded related to the permits intangible asset and is recognized in Impairment of goodwill and other long-lived assets in the Statements of Consolidated Operations. Additionally, during 2013, an impairment charge of $9.5 million was recorded related to the utility contracts intangible asset and was recognized in Impairment of goodwill and other long-lived assets. There was no impairment charge recorded for definite-lived intangible assets in 2012. The estimated amortization expense relating to intangible assets for each of the five succeeding years is as follows:
		(In Millions)
		Amount
	Year Ending December 31
	2015	4.1
	2016	4.2
	2017	4
	2018	3.8
	2019	3.5
	Total	$	19.6
	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 years ended December 31, 2014, 2013 and 2012, we recognized $23.1 million, $45.9 million and $46.3 million, respectively, in Product revenues related to below-market sales contracts. The following amounts are estimated to be recognized in Product revenues for each of the two succeeding fiscal years:
		(In Millions)
		Amount
	Year Ending December 31
	2015	23
	2016	23.1
	Total	$	46.1

DERIVATIVE_INSTRUMENTS_AND_HED

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES	12 Months Ended
	Dec. 31, 2014
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 Consolidated Financial Position as of December 31, 2014 and December 31, 2013:
		(In Millions)
		Derivative Assets												Derivative Liabilities
		December 31, 2014						December 31, 2013						December 31, 2014				31-Dec-13
	Derivative	Balance Sheet Location		Fair				Balance		Fair				Balance Sheet	Fair			Balance Sheet		Fair
	Instrument			Value				Sheet		Value				Location	Value			Location		Value
								Location
	Derivatives designated as hedging instruments under ASC 815:
	Interest-Rate Swaps			$	—					$	—			Other current liabilities	$	—				$	2.1
	Foreign Exchange Contracts	Other current assets		—				Other current assets		0.3				Other current liabilities	21.6			Other current liabilities		25.8
	Total derivatives designated as hedging instruments under ASC 815			$	—					$	0.3				$	21.6				$	27.9
	Derivatives not designated as hedging instruments under ASC 815:
	Foreign Exchange Contracts			$	—					$	—			Other current liabilities	$	9.9		Other current liabilities		$	1.1
	Customer Supply Agreements	Other current assets		63.2				Other current assets		55.8					—					—
	Provisional Pricing Arrangements	Other current assets		—				Other current assets		3.1				Other current liabilities	11.8			Other current liabilities		10.3
	Total derivatives not designated as hedging instruments under ASC 815:			$	63.2					$	58.9				$	21.7				$	11.4
	Total derivatives			$	63.2					$	59.2				$	43.3				$	39.3
	Derivatives Designated as Hedging Instruments
	Cash Flow Hedges
	Australian and Canadian 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. The functional currency of our Canadian operations is the U.S. dollar; however, the production costs for these operations primarily are incurred in the Canadian dollar.
	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. For our Canadian operations, U.S. dollars are converted to Canadian dollars at the exchange rate in effect for the period the operating costs are incurred. 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. If the instruments qualify for hedge accounting treatment, they are tested for effectiveness at inception and at least once each reporting period. If and when any of our contracts that had qualified for hedge accounting treatment 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.
	As of December 31, 2014, we had outstanding Australian foreign currency exchange contracts with notional amounts of $220.0 million in the form of forward contracts with varying maturity dates ranging from January 2015 to October 2015. We had no Canadian foreign currency exchange contracts that were considered cash flow hedges and that qualified for hedge accounting treatment at December 31, 2014, as during the fourth quarter of 2014 the Canadian foreign currency exchange contracts were de-designated. The de-designation of the Canadian hedge contracts is discussed below. This compares with outstanding Australian and Canadian foreign currency exchange contracts with a notional amount of $323.0 million and $285.9 million, respectively, as of December 31, 2013.
	Changes in fair value of highly effective hedges are recorded as a component of Accumulated other comprehensive loss in the Statements of Consolidated Financial Position. Any ineffectiveness is recognized immediately in income. As of December 31, 2014 and 2013, there was no material ineffectiveness recorded for foreign exchange contracts that were classified as cash flow hedges. However, Canadian hedge contracts related to the Bloom Lake operations were deemed ineffective during the fourth quarter of 2014 and no longer qualified for hedge accounting treatment. The Canadian hedge contracts de-designated in the fourth quarter of 2014 were all that remained of the Canadian hedge contracts. Canadian hedge contracts associated with the Wabush and Ferroalloys operations were deemed ineffective during the fourth quarter of 2013 and no longer qualified for hedge accounting treatment. All of the hedges designated in the fourth quarter of 2013 settled and were no longer outstanding by June 30, 2014. 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 Australian hedge contracts, we estimate that losses of $15.1 million (net of tax), respectively, will be reclassified into earnings within the next 12 months. No amounts remain in Accumulated other comprehensive loss related to Canadian hedge contracts.
	Interest Rate Risk Management
	Interest rate risk is managed using a portfolio of variable-rate and fixed-rate debt composed of short-term and long-term instruments, such as U.S. treasury lock agreements and variable-to-fixed interest rate swaps. From time to time, these instruments, which are derivative instruments, are entered into to facilitate the maintenance of the desired ratio of variable-rate to fixed-rate debt.
	In the second quarter of 2012, we entered into U.S. treasury lock agreements with a notional value of $200.0 million to hedge the exposure to the possible rise in the interest rate prior to the issuance of the five-year senior notes due 2018 discussed in NOTE 5 - DEBT AND CREDIT FACILITIES. These derivative instruments were designated and qualified as cash flow hedges. The U.S. treasury locks were settled in the fourth quarter of 2012 upon the issuance of $500.0 million principal amount of the senior notes due 2018 for a cumulative after-tax loss of $1.3 million, which was recorded in Accumulated other comprehensive loss and is being amortized to Other non-operating income (expense) over the life of the senior notes due 2018. Approximately $0.1 million net of tax was recognized in earnings in both 2013 and 2014 and approximately $0.1 million net of tax is expected to be recognized in earnings in 2015.
	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 Consolidated Operations for the years ended December 31, 2014, 2013 and 2012:
		(In Millions)
	Derivatives in Cash Flow	Amount of Gain (Loss)												Location of Gain (Loss)	Amount of Gain (Loss)
		Recognized in OCI on Derivative												Reclassified	Reclassified
														from Accumulated OCI into Earnings	from Accumulated
															OCI into Earnings
	Hedging Relationships	(Effective Portion)												(Effective Portion)	(Effective Portion)
		Year Ended													Year Ended
		December 31,													December 31,
		2014				2013				2012					2014			2013				2012
	Australian Dollar Foreign	$	(13.9	)		$	(34.7	)		$	20.2			Product revenues	$	(13.2	)	$	(11.9	)		$	14.8
	Exchange Contracts
	(hedge designation)
	Canadian Dollar Foreign Exchange Contracts	—				(12.9		)		6.7				Cost of goods sold and operating expenses	—			(8.2		)		3.3
	(hedge designation)
	Canadian Dollar Foreign	(14.3		)		(4.1		)		—				Cost of goods sold and operating expenses	(17.7		)	(1.9		)		—
	Exchange Contracts
	(prior to de-designation)
	Treasury Locks	—				—				(1.3		)		Other non-operating income (expense)	(0.1		)	(0.1		)		—
	Total	$	(28.2	)		$	(51.7	)		$	25.6				$	(31.0	)	$	(22.1	)		$	18.1
	Derivatives Not Designated as Hedging Instruments
	Foreign Exchange Contracts
	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. Subsequent to de-designation, no further foreign currency exchange contracts were entered into for the Bloom Lake operations. As of December 31, 2014,the de-designated outstanding foreign exchange rate contracts had a notional amount of $183.0 million in the form of forward contracts with varying maturity dates ranging from January 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 Consolidated Operations. A corresponding realized gain or loss will be recognized in each period until settlement of the related economic hedge in 2015. Additionally, for the year ended December 31, 2014, prior to the de-designation of the Bloom Lake hedges, we reclassified losses of $9.9 million from Accumulated other comprehensive loss related to contracts that matured during the year, and recorded the amounts as Cost of goods sold and operating expenses on the Statements of Consolidated Operations. As of December 31, 2014, no gains or losses remain in Accumulated other comprehensive loss related to the Bloom Lake effective cash flow hedge contracts prior to de-designation.
	During the fourth quarter of 2013, we discontinued hedge accounting for Canadian foreign currency exchange contracts for all outstanding contracts associated with Wabush and Ferroalloys operations 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 operations. As of December 31, 2014, there were no outstanding de-designated foreign currency exchange rate contracts associated with the Wabush and Ferroalloys operations as all remaining de-designated foreign exchange contracts matured during the second quarter of 2014. This compares with outstanding de-designated foreign currency exchange contracts with a notional amount of $74.8 million as of December 31, 2013.
	As a result of discontinued hedge accounting, the Wabush and Ferroalloys instruments were prospectively marked to fair value each reporting period through Cost of goods sold and operating expenses on the Statements of Consolidated Operations. For the years ended December 31, 2014, and 2013, the change in fair value of our de-designated foreign currency exchange contracts resulted in net losses of $3.3 million and $0.6 million, respectively. 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 years ended December 31, 2014, and 2013, we reclassified losses of $0.5 million and $1.9 million, respectively from Accumulated other comprehensive loss related to contracts that matured during the year, and recorded the amounts as Cost of goods sold and operating expenses on the Statements of Consolidated Operations. All the remaining contracts matured during the second quarter of 2014 and as of the period ended June 30, 2014, no gains or losses remained in Accumulated other comprehensive loss related to the effective cash flow hedge contracts prior to de-designation.
	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 gains recognized in Other non-operating income (expense) for the year ended December 31, 2014 were $0.3 million.
	For the year ended December 31, 2013, the fixed-to-variable 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 was 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 year ended December 31, 2013 was $0.1 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 all commodities, 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.
	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 $187.8 million, $149.2 million and $171.4 million as Product revenues in the Statements of Consolidated Operations for the years ended December 31, 2014, 2013 and 2012, respectively, related to the supplemental payments. Other current assets, representing the fair value of the pricing factors, were $63.2 million and $55.8 million in the December 31, 2014 and December 31, 2013 Statements of Consolidated Financial Position, respectively.
	Provisional Pricing Arrangements
Certain of our U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian 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 December 31, 2014 we had no Other current assets recorded in the Statements of Consolidated Financial Position related to our estimate of the final revenue rate with any of our customers. At December 31, 2013, we recorded $3.1 million as Other current assets in the Statements of Consolidated Financial Position related to our estimate of final revenue rate with our U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore customers. At December 31, 2014 and December 31, 2013, we recorded $11.8 million and $10.3 million, respectively, as Other current liabilities in the Statements of Consolidated Financial Position related to our estimate of final revenue rate with our U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian 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 $11.8 million decrease in Product revenues in the Statements of Consolidated Operations for the year ended December 31, 2014 related to these arrangements. This compares with a net $7.2 million decrease and a net $7.8 million decrease in Product revenues for the comparable periods in 2013 and 2012.
The following summarizes the effect of our derivatives that are not designated as hedging instruments in the Statements of Consolidated Operations for the years ended December 31, 2014, 2013 and 2012:
(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
		Year Ended
		December 31,
		2014				2013				2012
Foreign Exchange Contracts	Cost of goods sold and operating expenses	$	(16.9	)		$	(0.6	)		$	—
Foreign Exchange Contracts	Other income (expense)	—				—				0.3
Foreign Exchange Contracts	Income and Gain on Sale from Discontinued Operations, net of tax	—				—				(0.3		)
Treasury Locks	Other non-operating income (expense)	—				—				(0.4		)
Customer Supply Agreements	Product revenues	187.8				149.2				171.4
Provisional Pricing Arrangements	Product revenues	(11.8		)		(7.2		)		(7.8		)
Total		$	159.1			$	141.4			$	163.2
Refer to NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS for additional information.

DISCONTINUED_OPERATIONS

DISCONTINUED OPERATIONS	12 Months Ended
	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
DISCONTINUED OPERATIONS	NOTE 14 - DISCONTINUED OPERATIONS
	In April 2014, the FASB issued ASU 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which changes the criteria for reporting discontinued operations and requires additional disclosures about discontinued operations. The standard requires that an entity report as a discontinued operation only a disposal that represents a strategic shift in operations that has a major effect on its operations and financial results. ASU 2014-08 is effective prospectively for new disposals that occur within annual periods beginning on or after December 15, 2014. Early adoption is permitted and we adopted ASU 2014-08 during the three months ended December 31, 2014. Adoption of the standard had a material impact on our Statements of Consolidated Operations.
	The Wabush mine was idled by the end of the first quarter of 2014 and we subsequently began to commence permanent closure during the fourth quarter of 2014. As part of these closure activities, we terminated the rail transportation agreement and began implementation of the provincial Rehabilitation and Closure Plan that has been approved by the Canadian Department of Natural Resources. As such, the Wabush mine was deemed abandoned as of December 31, 2014 and meets the disposed by other than sale criteria.
	On December 31, 2014, we completed the sale of our CLCC assets in West Virginia to Coronado Coal II, LLC, an affiliate of Coronado Coal LLC, for $174.0 million in cash and the assumption of certain liabilities, of which $155.0 million has been collected as of December 31, 2014. We recorded the results of this sale in our fourth quarter earnings as the transaction closed on December 31, 2014. As such, CLCC as of December 31, 2014, meets the disposed of by sale criteria.
	As Wabush and CLCC met criteria for discontinued operations, each disposal had to be further evaluated to determine whether the disposal represents a strategic shift that has (or will have) a major effect on our operations and financial results. Wabush and CLCC meet the criteria for discontinued operations as Wabush's closure plan was implemented and CLCC was sold. According to ASU 2014-08, examples of a strategic shift that has (or will have) a major effect on an entity’s operations and financial results could include a disposal of a major geographical area, a major line of business, a major equity method investment, or other major parts of an entity. In order to determine if the disposal of CLCC or Wabush had a major effect on our operations and financial results, we used revenues and assets as a key indicator of significance as those are historically key indicators we have used to measure our components against. For both Wabush and CLCC, the associated revenues and assets were determined not to be a significant percentage of our consolidated results as evidenced by the years ended December 31, 2014, 2013 and 2012. Wabush revenues were less than 8 percent of consolidated revenues and less than 4 percent of total assets for the years ended December 31, 2014, 2013 and 2012. CLCC revenues were less than 5 percent of consolidated revenues and less than 8 percent of total assets for the years ended December 31, 2014, 2013 and 2012.
	Other key indicators such as sales margin, EBITDA and adjusted EBITDA are not relevant for Wabush as Wabush was idled in the first quarter of 2014 and therefore not operational for the majority of 2014. These other key indicators were also not relevant for CLCC as the coal business makes up a small percentage of our overall financial results, approximately 15 percent of consolidated revenues in 2014, as compared to our iron ore business.
	After assessing Wabush and CLCC under the ASU 2014-08 guidance as discussed above, it was determined that Wabush and CLCC do not qualify as discontinued operations as of December 31, 2014. Neither Wabush nor CLCC represent a strategic shift that has or will have a major impact on our operations or financial results.
	The amendments in this ASU 2014-08 require us to provide the Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures for each individually significant component of an entity that does not qualify for discontinued operations presentation in the financial statements. The Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures is to be presented for the component of an entity for the period in which it is disposed of or is classified as held for sale and for all prior periods that are presented in the Statements of Consolidated Operations. As required, the Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures for Wabush and CLCC are presented below:
		(In Millions)
		Year Ended December 31,
		2014			2013			2012
	INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND EQUITY INCOME (LOSS) FROM VENTURES
	Wabush	$	(345.6	)	$	(258.6	)	$	(131.8	)
	CLCC	$	(669.9	)	$	(55.0	)	$	(41.8	)
	The table below sets forth selected financial information related to operating results of our business classified as discontinued operations. While the reclassification of revenues and expenses related to discontinued operations for prior periods has no impact upon previously reported net income, the Statements of Consolidated Operations present the revenues and expenses that were reclassified from the specified line items to discontinued operations. During the fourth quarter of 2012, we sold our 45 percent economic interest in Sonoma. The Sonoma operations previously were included in Other within our reportable segments.
	The following table presents detail of our operations related to our Sonoma operations in the Statements of Consolidated Operations:
		(In Millions)
		Year Ended December 31,
		2014			2013			2012
	REVENUES FROM PRODUCT SALES AND SERVICES
	Product	$	—		$	—		$	151.6
	GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	—			—			38
	INCOME (LOSS) FROM DISCONTINUED OPERATIONS, net of tax	—			2			(2.1		)
	INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	$	—		$	2		$	35.9
	Income and Gain on Sale from Discontinued Operations, net of tax during the year ended December 31, 2013 relates to additional income tax benefit resulting from the actual tax gain from the sale of Sonoma as included on the 2012 tax return, which was filed during the year ended December 31, 2013.
	We recorded a gain of $38.0 million, net of $8.1 million in tax expense in Income and Gain on Sale from Discontinued Operations, net of tax in the Statements of Consolidated Operations for the year ended December 31, 2012 related to our sale of the Sonoma operations, which was completed as of November 12, 2012. We recorded a loss from discontinued operations in 2012 of $2.1 million, net of $2.4 million in tax expense.

CAPITAL_STOCK

CAPITAL STOCK	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
CAPITAL STOCK	NOTE 15 - CAPITAL STOCK
	Depositary Shares
	On February 21, 2013, we issued 29.25 million depositary shares, representing an aggregate of 731,250 preferred shares, comprised of the 27.0 million depositary share offering and the exercise of an underwriters' over-allotment option to purchase an additional 2.25 million depositary shares. Each depositary share represents a 1/40th interest in a share of our 7.00 percent Series A Mandatory Convertible Preferred Stock, Class A, without par value ("Preferred Share") at a price of $25 per depositary share for total net proceeds of approximately $709.4 million, after underwriter fees and discounts. Each Preferred Share has an initial liquidation preference of $1,000 per share (equivalent to a $25 liquidation preference per depositary share). When and if declared by our Board of Directors, we will pay cumulative dividends on each Preferred Share at an annual rate of 7.00 percent on the liquidation preference. We will pay declared dividends in cash on February 1, May 1, August 1 and November 1 of each year, commencing on May 1, 2013 and to, and including February 1, 2016. Holders of the depositary shares are entitled to a proportional fractional interest in the rights and preferences of the Preferred Shares, including conversion, dividend, liquidation and voting rights, subject to the provisions of the deposit agreement.
	The Preferred Shares may be converted, at the option of the holder, at the minimum conversion rate of 28.1480 of our common shares (equivalent to 0.7037 of our common shares per depositary share) at any time prior to February 1, 2016 or other than during a fundamental change conversion period, subject to anti-dilution adjustments. If not converted prior to that time, each Preferred Share will convert automatically on February 1, 2016 into between 28.1480 and 34.4840 common shares, par value $0.125 per share, subject to anti-dilution adjustments. The number of common shares issuable on conversion will be determined based on the average VWAP per share of our common shares during the 20 trading day period beginning on, and including, the 23rd scheduled trading day prior to February 1, 2016, subject to customary anti-dilution adjustments. Upon conversion, a minimum of 20.6 million common shares and a maximum of 25.2 million common shares will be issued.
	If certain fundamental changes involving the Company occur, holders of the Preferred Shares may convert their shares into a number of common shares at the conversion rate that will be adjusted under certain circumstances, and such holders also will be entitled to a fundamental change dividend make-whole amount. The Preferred Shares are not redeemable.
	Common Share Public Offering
	On February 21, 2013, we issued 10.35 million common shares, comprised of the 9.0 million common share offering and the exercise of an underwriters' option to purchase an additional 1.35 million common shares. We received net proceeds of approximately $285.3 million at a closing price of $29.00 per common share.
	Dividends
	On March 20, 2013, our Board of Directors declared a cash dividend of $13.6111 per Preferred Share, which is equivalent to approximately $0.34 per depositary share. The cash dividend was paid on May 1, 2013 to our shareholders of record as of the close of business on April 15, 2013. On May 7, 2013, September 9, 2013, and November 11, 2013, our Board of Directors declared a 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 August 1, 2013, November 1, 2013 and February 3, 2014 to our shareholders of record as of the close of business on July 15, 2013, October 15, 2013 and January 15, 2014, respectively. On February 11, 2014, May 13, 2014, and September 8, 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 and November 3, 2014, to our Preferred Shareholders of record as of the close of business on April 15, 2014, July 15, 2014, and October 15, 2014, respectively. On 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 of $12.8 million was paid on February 2, 2015 to our shareholders of record as of the close of business on January 15, 2015.
	On February 11, 2013, our Board of Directors approved a reduction to our quarterly cash dividend rate by 76 percent to $0.15 per share. Our Board of Directors took this step in order to improve the future cash flows available for investment in the Phase II expansion at Bloom Lake, as well as to preserve our investment-grade credit ratings. The decreased dividend of $0.15 per share was paid on March 1, 2013, June 3, 2013, September 3, 2013 and December 2, 2013 to our common shareholders of record as of the close of business on February 22, 2013, May 17, 2013, August 15, 2013 and November 22, 2013, respectively. Additionally, the 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.

ACCUMULATED_OTHER_COMPREHENSIV

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
ACCUMLATED OTHER COMPREHENSIVE INCOME (LOSS)	NOTE 16 - ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
	The components of Accumulated other comprehensive income (loss) within Cliffs shareholders’ equity and related tax effects allocated to each are shown below as of December 31, 2014, 2013 and 2012:
		(In Millions)
		Pre-tax				Tax				After-tax
		Amount				Benefit				Amount
						(Provision)
	As of December 31, 2012:
	Postretirement benefit liability	$	(576.7	)		$	194			$	(382.7	)
	Foreign currency translation adjustments	316.3				—				316.3
	Unrealized net gain on derivative financial instruments	12.4				(3.7		)		8.7
	Unrealized gain on securities	3.3				(1.2		)		2.1
		$	(244.7	)		$	189.1			$	(55.6	)
	As of December 31, 2013:
	Postretirement benefit liability	$	(299.3	)		$	94.4			$	(204.9	)
	Foreign currency translation adjustments	106.7				—				106.7
	Unrealized net gain on derivative financial instruments	(30.0		)		9.1				(20.9		)
	Unrealized gain on securities	9.3				(3.1		)		6.2
		$	(213.3	)		$	100.4			$	(112.9	)
	As of December 31, 2014:
	Postretirement benefit liability	$	(425.3	)		$	134.2			$	(291.1	)
	Foreign currency translation adjustments	64.4				—				64.4
	Unrealized net loss on derivative financial instruments	(25.9		)		7.8				(18.1		)
	Unrealized gain on securities	(1.3		)		0.3				(1.0		)
		$	(388.1	)		$	142.3			$	(245.8	)
	The following tables reflect the changes in Accumulated other comprehensive income (loss) related to Cliffs shareholders’ equity for December 31, 2014, 2013 and 2012:
		(In Millions)
		Postretirement Benefit Liability, 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	)
	Other comprehensive loss before reclassifications	(1.4		)		(2.4		)		19.7			9.7			25.6
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	4				(1.3		)		—			6.6			9.3
	Balance June 30, 2014	$	(199.4	)		$	6.4			$	166.9		$	5.9		$	(20.2	)
	Other comprehensive income (loss) before reclassifications	3.5				1.3				(65.9		)	(20.0		)	(81.1		)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	7.6				(7.1		)		—			(0.6		)	(0.1		)
	Balance September 30, 2014	$	(188.3	)		$	0.6			$	101		$	(14.7	)	$	(101.4	)
	Other comprehensive income (loss) before reclassifications	$	(98.7	)		$	(1.4	)		$	(36.6	)	$	(15.6	)	$	(152.3	)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	$	(4.1	)		$	(0.2	)		$	—		$	12.2		$	7.9
	Balance December 31, 2014	$	(291.1	)		$	(1.0	)		$	64.4		$	(18.1	)	$	(245.8	)
		(In Millions)
		Postretirement Benefit Liability, 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, 2012	$	(382.7	)		$	2.1			$	316.3		$	8.7		$	(55.6	)
	Other comprehensive income (loss) before reclassifications	(1.1		)		2.5				3.3			(5.0		)	(0.3		)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	6.4				0.1				—			(2.0		)	4.5
	Balance March 31, 2013	$	(377.4	)		$	4.7			$	319.6		$	1.7		$	(51.4	)
	Other comprehensive loss before reclassifications	(1.5		)		(2.0		)		(152.0		)	(42.2		)	(197.7		)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	8.1				3.6				—			(2.2		)	9.5
	Balance June 30, 2013	$	(370.8	)		$	6.3			$	167.6		$	(42.7	)	$	(239.6	)
	Other comprehensive income (loss) before reclassifications	(0.6		)		3.5				22.8			12.1			37.8
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	6.3				0.9				—			16.2			23.4
	Balance September 30, 2013	$	(365.1	)		$	10.7			$	190.4		$	(14.4	)	$	(178.4	)
	Other comprehensive income (loss) before reclassifications	$	154.5			$	(4.9	)		$	(83.7	)	$	(16.6	)	$	49.3
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	$	5.7			$	0.4			$	—		$	10.1		$	16.2
	Balance December 31, 2013	$	(204.9	)		$	6.2			$	106.7		$	(20.9	)	$	(112.9	)
		(In Millions)
		Postretirement Benefit Liability, net of tax				Unrealized Net Gain (Loss) on Securities, net of tax				Unrealized Net Gain on Foreign Currency Translation			Net Unrealized Gain on Derivative Financial Instruments, net of tax			Accumulated Other Comprehensive Income (Loss)
	Balance December 31, 2011	$	(408.9	)		$	2.6			$	312.5		$	1.2		$	(92.6	)
	Change during 2012	26.2				(0.5		)		3.8			7.5			37
	Balance December 31, 2012	$	(382.7	)		$	2.1			$	316.3		$	8.7		$	(55.6	)
	The following table reflects the details about Accumulated other comprehensive income (loss) components related to Cliffs shareholders’ equity for the year ended December 31, 2014:
			(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
			Year Ended				Year Ended
31-Dec-14			31-Dec-13
Amortization of Pension and Postretirement Benefit Liability:
Prior service costs		$	(0.9	)		$	(0.6	)		-1
Net actuarial loss		19.1				41.4				-1
Curtailments/Settlements		(5.0		)		—				-1
Special termination benefits		3.4				—				-1
		16.6				40.8				Total before taxes
		(5.8		)		(14.3		)		Income tax benefit (expense)
		$	10.8			$	26.5			Net of taxes
Unrealized gain (loss) on marketable securities:
Sale of marketable securities		$	(11.4	)		$	(0.2	)		Other non-operating income (expense)
Impairment		(0.5		)		5.3				Other non-operating income (expense)
		(11.9		)		5.1				Total before taxes
		3.4				(0.1		)		Income tax benefit (expense)
		$	(8.5	)		$	5			Net of taxes
Unrealized gain (loss) on derivative financial instruments:
Australian dollar foreign exchange contracts		$	18.9			$	17			Product revenues
Canadian dollar foreign exchange contracts		26.7				15.3				Cost of goods sold and operating expenses
		45.6				32.3				Total before taxes
		(14.6		)		(10.2		)		Income tax benefit (expense)
		$	31			$	22.1			Net of taxes
Total Reclassifications for the Period		$	33.3			$	53.6
-1	These accumulated other comprehensive income components are included in the net periodic benefit cost recognized for the year ended December 31, 2014 and 2013. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

CASH_FLOW_INFORMATION

CASH FLOW INFORMATION	12 Months Ended
	Dec. 31, 2014
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 years ended December 31, 2014, 2013 and 2012 is as follows:
		(In Millions)
		Year Ended December 31,
		2014			2013			2012
	Capital additions	$	235.5		$	752.3		$	1,335.30
	Cash paid for capital expenditures	284.1			861.6			1,127.50
	Difference	$	(48.6	)	$	(109.3	)	$	207.8
	Non-cash accruals	$	(58.5	)	$	(109.3	)	$	152.5
	Capital leases	9.9			—			55.3
	Total	$	(48.6	)	$	(109.3	)	$	207.8
	Cash payments for interest and income taxes in 2014, 2013 and 2012 are as follows:
		(In Millions)
		2014			2013			2012
	Taxes paid on income	$	47.3		$	153.3		$	443.2
	Interest paid on debt obligations	176.5			174.4			207.5
	Non-Cash Financing Activities - Declared Dividends
	On November 19, 2014, 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 Preferred Share. The cash dividend of $12.8 million was paid on February 2, 2015 to our preferred shareholders of record as of the close of business on January 15, 2015.

RELATED_PARTIES

RELATED PARTIES	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
RELATED PARTIES	NOTE 18 - RELATED PARTIES
	Three of our five U.S. iron ore mines and one of our two Eastern Canadian 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 and concentrate 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 December 31, 2014:
	Mine		Cliffs Natural Resources		ArcelorMittal			U.S. Steel Canada			WISCO
	Empire		79	%	21	%		—			—
	Tilden		85	%	—			15	%		—
	Hibbing		23	%	62.3	%		14.7	%		—
	Bloom Lake		82.8	%	—			—			17.2	%
	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)
		Year Ended December 31,
		2014			2013				2012
	Product revenues from related parties	$	1,378.70		$	1,664.80			$	1,660.80
	Total product revenues	4,230.80			5,346.60				5,520.90
	Related party product revenue as a percent of total product revenue	32.6		%	31.1		%		30.1		%
	Amounts due from related parties recorded in Accounts receivable, net and Other current assets, including customer supply agreements and provisional pricing arrangements, were $151.1 million and $132.0 million at December 31, 2014 and 2013, respectively. Amounts due to related parties recorded in Other current liabilities, including provisional pricing arrangements and liabilities to related parties, were $13.6 million and $25.1 million at December 31, 2014 and 2013, respectively.
	Supply agreements with one of our customers include provisions for supplemental revenue or refunds based on the customer’s annual steel pricing for the year the product is consumed in the customer’s blast furnace. The supplemental pricing is characterized as an embedded derivative. Refer to NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES for further information.

EARNINGS_PER_SHARE

EARNINGS PER SHARE	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
EARNINGS PER SHARE	NOTE 19 - EARNINGS PER SHARE
	The following table summarizes the computation of basic and diluted earnings per share attributable to Cliffs shareholders:
		(In Millions, Except Per Share Amounts)
		Year Ended December 31,
		2014			2013			2012
	Net Income (Loss) from Continuing Operations	$	(7,224.2	)	$	411.5		$	(935.3	)
	attributable to Cliffs shareholders
	Income (Loss) and Gain on Sale from Discontinued	—			2			35.9
	Operations, net of tax
	NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	$	(7,224.2	)	$	413.5		$	(899.4	)
	PREFERRED STOCK DIVIDENDS	(51.2		)	(48.7		)	—
	NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	$	(7,275.4	)	$	364.8		$	(899.4	)
	Weighted Average Number of Shares:
	Basic	153.1			151.7			142.4
	Depositary Shares	—			0.5			—
	Employee Stock Plans	—			22.1			—
	Diluted	153.1			174.3			142.4
	Earnings (loss) per Common Share Attributable to
	Cliffs Common Shareholders - Basic:
	Continuing operations	$	(47.52	)	$	2.39		$	(6.57	)
	Discontinued operations	—			0.01			0.25
		$	(47.52	)	$	2.4		$	(6.32	)
	Earnings (loss) per Common Share Attributable to
	Cliffs Common Shareholders - Diluted:
	Continuing operations	$	(47.52	)	$	2.36		$	(6.57	)
	Discontinued operations	—			0.01			0.25
		$	(47.52	)	$	2.37		$	(6.32	)
	The diluted earnings per share calculation excludes 25.2 million depositary shares that were anti-dilutive for the year ended December 31, 2014. Additionally, the diluted earnings per share calculation excludes 0.7 million shares for the year ended December 31, 2014 related to equity plan awards that were anti-dilutive. There was no anti-dilution for the year ended December 31, 2013. For the year ended December 31, 2012, the diluted earnings per share calculation excludes 0.5 million shares related to equity plan awards that were anti-dilutive.

COMMITMENTS_AND_CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2014
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.
	Environmental Matters
	We had environmental liabilities of $5.5 million and $8.4 million at December 31, 2014 and 2013, respectively, including obligations for known environmental remediation exposures at active and closed mining operations and other sites. These amounts have been recognized based on the estimated cost of investigation and remediation at each site, and include site studies, design and implementation of remediation plans, legal and consulting fees, and post-remediation monitoring and related activities. If the cost can only be estimated as a range of possible amounts with no specific amount being more likely, the minimum of the range is accrued. Future expenditures are not discounted unless the amount and timing of the cash disbursements are readily known. Potential insurance recoveries have not been reflected. Additional environmental obligations could be incurred, the extent of which cannot be assessed. The amount of our ultimate liability with respect to these matters may be affected by several uncertainties, primarily the ultimate cost of required remediation and the extent to which other responsible parties contribute. Refer to NOTE 11 - ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS for further information.
	Tax Matters
	The calculation of our tax liabilities involves dealing with uncertainties in the application of complex tax regulations. We recognize liabilities for anticipated tax audit issues based on our estimate of whether, and the extent to which, additional taxes will be due. If we ultimately determine that payment of these amounts is unnecessary, we reverse the liability and recognize a tax benefit during the period in which we determine that the liability is no longer necessary. We also recognize tax benefits to the extent that it is more likely than not that our positions will be sustained when challenged by the taxing authorities. To the extent we prevail in matters for which liabilities have been established, or are required to pay amounts in excess of our liabilities, our effective tax rate in a given period could be materially affected. An unfavorable tax settlement would require use of our cash and result in an increase in our effective tax rate in the year of resolution. A favorable tax settlement would be recognized as a reduction in our effective tax rate in the year of resolution. Refer to NOTE 9 - INCOME TAXES for further information.

SUBSEQUENT_EVENTS

SUBSEQUENT EVENTS	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	NOTE 21 - SUBSEQUENT EVENTS
	Common Share Dividend
	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 the 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. We see accelerated debt reduction as a more effective means of protecting our shareholders than continuing to pay a common share dividend.
	Credit Facility
	On January 22, 2015, we amended the revolving credit agreement (Amendment No. 6) to effect the following:
	•	Reduces the size of the existing facility from $1.125 billion to $900 million at the closing of this amendment with a further reduction to $750 million on May 31, 2015.
	•	Permits certain of our subsidiaries and joint ventures related to our Canadian operations (collectively, the "Canadian Entities") to enter into a restructuring (the "Canadian Restructuring").
	•	Permits costs and expenses incurred in connection with the Canadian Restructuring in an amount not to exceed $75 million to be added back to the calculation of EBITDA.
	•	Adds limitations with respect to investments in the Canadian Entities after the Canadian Restructuring.
	•	Adds limitations on the guaranty of indebtness of a Canadian Entity by us or our subsidiaries (other than by another Canadian Entity).
	•	Permits additional liens on the assets of the Canadian Entities.
	•	Reduces the permitted amount of quarterly dividends on our common shares to not more than $0.01 per share in any fiscal quarter.
	•	Grants a security interest in our as-extracted collateral and certain of our subsidiaries.
	•	Excludes certain indebtness and obligations of the Canadian Entities from the representations, covenants and events of default.
	The amended facility retains substantial financial flexibility for management to execute our strategy and provides us a consistent source of liquidity.
	Bloom Lake Group CCAA Filing
	As we have previously disclosed, despite our cost-cutting progress at our Bloom Lake mine, we concluded that Phase I alone would not be economically feasible based on our current operating plans and that the mine must be further developed to reduce the overall cash cost of operations.  However, also as previously disclosed, we would only develop Phase II of the Bloom Lake mine if we were able to secure new equity partners to share in the capital costs, which we estimated to be approximately $1.2 billion.  As the new equity partners were unable to commit within the short timeframe we required, we determined that the Phase II expansion of the Bloom Lake mine was no longer a viable option for us so we shifted our focus to considering available possibilities and executing an exit option for Eastern Canadian Iron Ore operations that minimized the cash outflows and associated liabilities.  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.
	On January 27, 2015, we announced that the Bloom Lake Group had commenced restructuring proceedings in Montreal, Québec, under the CCAA. The Bloom Lake Group comprises the Canadian affiliates which own and/or operate the Bloom Lake mine or are subsidiaries of such affiliates.
	The decision by the Bloom Lake Group to seek protection under the CCAA was based on a thorough legal and financial analysis of the options available. The Bloom Lake Group was no longer generating any revenues and was not able to meet its obligations as they became due. The initial CCAA order obtained on January 27, 2015 addresses the Bloom Lake Group’s immediate liquidity issues by staying creditor claims and permits the Bloom Lake Group to preserve and protect its assets for the benefit of all stakeholders while restructuring and/or sale options are explored.
	As part of the CCAA process, the Court has appointed FTI Consulting Canada Inc. as the Monitor. The Monitor’s role in the CCAA process is to monitor the activities of the Bloom Lake Group and provide assistance to the Bloom Lake Group and its stakeholders in respect of the CCAA process.
	We also filed on February 2, 2015 a Current Report on Form 8-K that provides pro forma financial information reflecting the deconsolidation of the Bloom Lake Group. Additional information regarding the CCAA proceedings are available on the Monitor’s website at http://cfcanada.fticonsulting.com/bloomlake.

QUARTERLY_RESULTS_OF_OPERATION

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	NOTE 22 - QUARTERLY RESULTS OF OPERATIONS (UNAUDITED)
	The sum of quarterly EPS may not equal EPS for the year due to discrete quarterly calculations.
		(In Millions, Except Per Share Amounts)
		2014
		Quarters
		First			Second			Third			Fourth			Year
	Revenues from product sales and services	$	940		$	1,100.80		$	1,298.20		$	1,284.70		$	4,623.70
	Sales margin	63.2			92			127.5			168.7			451.4
	Net Income (Loss) from Continuing Operations	$	(70.3	)	$	10.9		$	(5,879.6	)	$	(1,285.1	)	$	(7,224.2	)
	attributable to Cliffs shareholders
	Income from Discontinued Operations	—			—			—			—			—
	Net Income (Loss) Attributable to Cliffs Shareholders	$	(70.3	)	$	10.9		$	(5,879.6	)	$	(1,285.1	)	$	(7,224.2	)
	Preferred Stock Dividends	$	(12.8	)	$	(12.8	)	$	(12.8	)	$	(12.8	)	$	(51.2	)
	Net Income (Loss) Attributable to Cliffs Common Shareholders	$	(83.1	)	$	(1.9	)	$	(5,892.4	)	$	(1,297.9	)	$	(7,275.4	)
	Earnings per common share attributable to
	Cliffs common shareholders — Basic:
	Continuing Operations	$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	Discontinued Operations	—			—			—			—			—
		$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	Earnings per common share attributable to
	Cliffs common shareholders — Diluted:
	Continuing Operations	$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	Discontinued Operations	—			—			—			—			—
		$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	The diluted earnings per share calculation for all quarters of 2014 exclude depositary shares that were anti-dilutive totaling 25.2 million million and equity plan awards ranging between 0.3 million and 0.8 million each quarter that were anti-dilutive.
		2013
		Quarters
		First			Second			Third			Fourth			Year
	Revenues from product sales and services	$	1,140.50		$	1,488.50		$	1,546.60		$	1,515.80		$	5,691.40
	Sales margin	237.9			268.2			348.7			294.5			1,149.30
	Net Income (Loss) from Continuing Operations	$	107		$	146		$	115.2		$	43.3		$	411.5
	attributable to Cliffs shareholders
	Income (Loss) and Gain on Sale from	—			—			2			—			2
	Discontinued Operations, net of tax
	Net Income Attributable to Cliffs Shareholders	$	107		$	146		$	117.2		$	43.3		$	413.5
	Earnings per common share attributable to
	Cliffs common shareholders — Basic:
	Continuing Operations	$	0.66		$	0.87		$	0.67		$	0.2		$	2.39
	Discontinued Operations	—			—			0.01			—			0.01
		$	0.66		$	0.87		$	0.68		$	0.2		$	2.4
	Earnings per common share attributable to
	Cliffs common shareholders — Diluted:
	Continuing Operations	$	0.66		$	0.82		$	0.65		$	0.2		$	2.36
	Discontinued Operations	—			—			0.01			—			0.01
		$	0.66		$	0.82		$	0.66		$	0.2		$	2.37
	The diluted earnings per share calculation for the first and fourth quarters of 2013 exclude depositary shares that were anti-dilutive totaling 12.9 million and 25.2 million, respectively.
	Fourth Quarter Results
	During the fourth quarter of 2014, we recorded impairment charges of $1.3 billion primarily related to Bloom Lake and driven mainly by the changes in life-of-mine cash flows due to declining market pricing. Also, during the fourth quarter of 2014, we completed the sale of the CLCC assets for $174.0 million in cash and the assumption of certain liabilities, of which $155.0 million has been collected, and resulted in a loss on the sale of these assets of $419.6 million. The fourth quarter 2014 results additionally included an income tax benefit of $289.7 million, which includes the benefits related to the impairment charges as well as the recognition of a loss on a financial guaranty and the sale of CLCC assets.
	Upon performing our annual goodwill impairment test in the fourth quarter of 2013, a goodwill impairment charge of $80.9 million million was recorded for our Cliffs Chromite Ontario and Cliffs Chromite Far North reporting units within our Ferroalloys operating segment. We also recorded an other long-lived asset impairment charge of $154.6 million related to our Wabush operations within our Eastern Canadian Iron Ore operating segment to reduce those assets to their estimated fair value as of December 31, 2013. All of these charges impacted Impairment of goodwill and other long-lived assets.
	As discussed in NOTE 1 - BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES, we recorded an adjustment to correct an immaterial prior period error in the noncontrolling interest related to Bloom Lake. Accordingly, the adjustment was recorded prospectively in the Statements of Consolidated Operations for the period ended December 31, 2013 and in the Statements of Consolidated Financial Position as of December 31, 2013. The adjustment to noncontrolling interest related to Bloom Lake was approximately $45.1 million and resulted in an increase to Net Income (Loss) Attributable to Cliffs Shareholders and a reduction of Loss attributable to noncontrolling interest and corresponding decrease to Noncontrolling interest in the Statements of Consolidated Financial Position for the three months ended and year ended December 31, 2013. The adjustments also resulted in an increase to basic and diluted earnings per common share of $0.29 for the three months ended December 31, 2013.
	Refer to NOTE 12 - GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES, NOTE 4 - PROPERTY, PLANT AND EQUIPMENT and NOTE 9 - INCOME TAXES for further information.

BASIS_OF_PRESENTATION_AND_SIGN1

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2014

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Use of Estimates

Use of Estimates

The preparation of financial statements, in conformity with GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. The more significant areas requiring the use of management estimates and assumptions related to mineral reserves future realizable cash flow; environmental, reclamation and closure obligations; valuation of long-lived assets and investments; valuation of inventory; valuation of post-employment, post-retirement and other employee benefit liabilities; valuation of tax assets; reserves for contingencies and litigation; and the fair value of derivative instruments. Actual results could differ from estimates. On an ongoing basis, management reviews estimates. Changes in facts and circumstances may alter such estimates and affect results of operations and financial position in future periods.

Basis Of Consolidation

Basis of Consolidation

The consolidated financial statements include our accounts and the accounts of our wholly owned and majority-owned subsidiaries, including the following operations at December 31, 2014:

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

Oak Grove

Alabama

100.00%

Coal

Active

CLCC

West Virginia

100.00%

Coal

Assets sold as of December 31, 2014

Wabush

Newfoundland and Labrador/ Québec, Canada

100.00%

Iron Ore

Permanent closure

Bloom Lake

Québec, Canada

82.80%

Iron Ore

Care-and-maintenance

Cliffs Chromite Ontario - Black Label Deposit

Ontario, Canada

100.00%

Chromite

Suspended

Cliffs Chromite Ontario - Black Thor Deposit

Ontario, Canada

100.00%

Chromite

Suspended

Cliffs Chromite Ontario & Cliffs Chromite Far North - Big Daddy Deposit

Ontario, Canada

70.00%

Chromite

Suspended

Intercompany transactions and balances are eliminated upon consolidation.

Noncontrolling Interests [Policy Text Block]

Noncontrolling Interests

During the fourth quarter of 2013, CQIM’s interest in Bloom Lake increased by an aggregate of 7.8 percent after CQIM paid both its own and WISCO’s proportionate shares of the cash call for the first half of 2013.  As a result of our cash call payments, CQIM was issued a total of 457,556 new Bloom Lake units, increasing our interest to 82.8 percent in Bloom Lake and diluting WISCO’s interest to 17.2 percent.  The new unit issuance decreased equity attributable to WISCO by $314.8 million for the year ended December 31, 2013 by decreasing WISCO’s interest in Bloom Lake’s accumulated deficit.   We accounted for the increase in ownership as an equity transaction, which resulted in a $314.8 million increase to equity attributable to Cliffs’ shareholders.

Immaterial Error Adjustment [Policy Text Block]

Immaterial Error

In connection with our acquisition of Consolidated Thompson in May 2011, the Company acquired a 75 percent controlling interest in Bloom Lake. For financial reporting purposes, the Company fully consolidates Bloom Lake in the accompanying financial statements and allocates a portion of its consolidated results of operations and shareholders’ equity, which is reported as Loss attributable to noncontrolling interest in the Statements of Consolidated Operations and Noncontrolling interest in the Statements of Consolidated Financial Position.

As a result of the application of ASC 805, Business Combinations, we allocated the purchase price to the assets, liabilities and noncontrolling interest at the acquisition date of May 11, 2011 based on their fair values. These fair value adjustments were recorded in the opening balance sheet and consolidated results of operations; however, subsequent effects of the amortization of these fair value adjustments were not allocated to the noncontrolling interest.

In accordance with U.S. GAAP, management has quantitatively and qualitatively evaluated the materiality of the error and has determined that the misstatement was immaterial to the interim and annual financial statements previously filed from June 30, 2011 through December 31, 2013. Accordingly, the adjustment was recorded prospectively in the Statements of Consolidated Operations for the period ended December 31, 2013 and in the Statements of Consolidated Financial Position as of December 31, 2013. The adjustment to noncontrolling interest related to Bloom Lake was approximately $45.1 million and resulted in an increase to Net Income (Loss) Attributable to Cliffs Shareholders and a reduction of Loss attributable to noncontrolling interest and corresponding decrease to Noncontrolling interest in the Statements of Consolidated Financial Position for the year end and as of December 31, 2013. The adjustments also resulted in an increase to basic and diluted earnings per common share of $0.30 and $0.26, respectively, for the year ended December 31, 2013. No other financial statement line items were impacted by this adjustment. The prior period amounts included within the accompanying Consolidated Financial Statements have not been retrospectively adjusted for this impact due to management's materiality assessment as discussed above. The impact of the prospective adjustments in the Statements of Consolidated Operations would have resulted in an increase to basic and diluted earnings per common share of $0.25 and $0.07 for the years ended December 31, 2012 and 2011, respectively.

Cash and Cash Equivalents

Cash Equivalents

Cash and cash equivalents include cash on hand and on deposit as well as all short-term securities held for the primary purpose of general liquidity. We consider investments in highly liquid debt instruments with an original maturity of three months or less from the date of acquisition to be cash equivalents. We routinely monitor and evaluate counterparty credit risk related to the financial institutions by which our short-term investment securities are held.

Trade and Other Accounts Receivable

Trade Accounts Receivable and Allowance for Doubtful Accounts

Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is our best estimate of the amount of probable credit losses in Cliffs' existing accounts receivable. We establish provisions for losses on accounts receivable when it is probable that all or part of the outstanding balance will not be collected. We regularly review our accounts receivable balances and establish or adjust the allowance as necessary using the specific identification method. The allowance for doubtful accounts was $8.1 million at December 31, 2014 and 2013. There was $9.0 million of bad debt expense for the year ended December 31, 2012. There was no bad debt expense for the years ended December 31, 2014 and 2013.

Inventory

Inventories

U.S. Iron Ore

U.S. Iron Ore product inventories are stated at the lower of cost or market. Cost of iron ore inventories is determined using the LIFO method.

We had approximately 1.4 million tons and 1.2 million tons of finished goods stored at ports and customer facilities on the lower Great Lakes to service customers at December 31, 2014 and 2013, respectively. We maintain ownership of the inventories until title has transferred to the customer, usually when payment is received. Maintaining ownership of the iron ore products at ports on the lower Great Lakes reduces risk of non-payment by customers.

Asia Pacific Iron Ore

Asia Pacific Iron Ore product inventories are stated at the lower of cost or market. Costs of inventories are being valued on a weighted average cost basis. We maintain ownership of the inventories until title has transferred to the customer, which generally is when the product is loaded into the vessel.

North American Coal

North American Coal product inventories are stated at the lower of cost or market. Cost of coal inventories is calculated using the weighted average cost. We maintain ownership until coal is loaded into rail cars at the mine for domestic sales and until loaded in the vessels at the terminal for export sales.

Eastern Canadian Iron Ore

Iron ore pellet inventories are stated at the lower of cost or market. Cost is determined using the LIFO method. We maintain ownership of the inventories until title has transferred to the customer, which is generally when the product is loaded into the vessel.

Iron ore concentrate inventories are stated at the lower of cost or market. The cost of iron ore concentrate inventories is determined using weighted average cost. We maintain ownership of the inventories until title has transferred to the customer, which generally is when the product is loaded into the vessel.

Inventory Supplies

Supplies and Other Inventories

Supply inventories include replacement parts, fuel, chemicals and other general supplies, which are expected to be used or consumed in normal operations. Supply inventories also include critical spares. Critical spares are replacement parts for equipment that is critical for the continued operation of the mine or processing facilities.

Supply inventories are stated at the lower of cost or market using average cost, less an allowance for obsolete and surplus items. The allowance for obsolete and surplus items was $68.2 million and $63.4 million at December 31, 2014 and 2013, respectively.

Derivatives

Derivative Financial Instruments and Hedging Activities

We are exposed to certain risks related to the ongoing operations of our business, including those caused by changes in commodity prices, interest rates and foreign currency exchange rates. We have established policies and procedures, including the use of certain derivative instruments, to manage such risks.

Derivative financial instruments are recognized as either assets or liabilities in the Statements of Consolidated Financial Position and measured at fair value. On the date a derivative instrument is entered into, we generally designate a qualifying derivative instrument as a hedge of the variability of cash flows to be received or paid related to a recognized asset or liability or forecasted transaction (cash flow hedge). We formally document all relationships between hedging instruments and hedged items, as well as its risk-management objective and strategy for undertaking various hedge transactions. This process includes linking all derivatives that are designated as cash flow hedges to specific firm commitments or forecasted transactions. We also formally assess both at the hedge's inception and on an ongoing basis, whether the derivatives that are used in hedging transactions are highly effective in offsetting changes in cash flows of the related hedged items. When it is determined that a derivative is not highly effective as a hedge or that it has ceased to be a highly effective hedge, we discontinue hedge accounting prospectively and record all future changes in fair value in the period of the instrument's earnings or losses. The policy allows for 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.

For derivative instruments that have been designated as cash flow hedges, the effective portion of the changes in fair value are recorded in accumulated other comprehensive income (loss) and any portion that is ineffective is recorded in current period earnings or losses. Amounts recorded in accumulated other comprehensive income (loss) are reclassified to earnings or losses in the period the underlying hedged transaction affects earnings or when the underlying hedged transaction is no longer reasonably possible of occurring.

For derivative instruments that have not been designated as cash flow hedges, changes in fair value are recorded in the period of the instrument's earnings or losses.

Refer to NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES for further information.

Property, Plant and Equipment

Property, Plant and Equipment

Our properties are stated at the lower of cost less accumulated depreciation or fair value. Depreciation of plant and equipment is computed principally by the straight-line method based on estimated useful lives, not to exceed the mine lives. The Northshore, United Taconite, Empire, Tilden and Wabush operations use the double-declining balance method of depreciation for certain mining equipment. The Asia Pacific Iron Ore operation uses the production output method for certain mining equipment. Depreciation is provided over the following estimated useful lives:

Asset Class

Basis

Life

Buildings

Straight line

45 Years

Mining equipment

Straight line/Double declining balance

3 to 20 Years

Processing equipment

Straight line

10 to 45 Years

Electric power facilities

Straight line

10 to 45 years

Land improvements

Straight line

20 to 45 years

Office and information technology

Straight line

3 to 15 Years

Depreciation continues to be recognized when operations temporarily are idled.

Our Asia Pacific Iron Ore, Bloom Lake, Wabush, and United Taconite operations' interests in iron ore reserves and mineralized materials were valued when acquired using a discounted cash flow method. The fair value was estimated based upon the present value of the expected future cash flows from iron ore operations over the economic lives of the respective mines.

Our North American Coal operation leases coal mining rights from third parties through lease agreements. The lease agreements are for varying terms and extend through the earlier of their lease termination date or until all merchantable and mineable coal has been extracted. Our interest in coal reserves and non-reserve coal was valued when acquired using a discounted cash flow method. The fair value was estimated based upon the present value of the expected future cash flows from coal operations over the life of the reserves acquired.

Refer to NOTE 4 - PROPERTY, PLANT AND EQUIPMENT for further information.

Capitalized Stripping Costs

Capitalized Stripping Costs

During the development phase, stripping costs are capitalized as a part of the depreciable cost of building, developing and constructing a mine. These capitalized costs are amortized over the productive life of the mine using the units of production method. The production phase does not commence until the removal of more than a de minimis amount of saleable mineral material occurs in conjunction with the removal of overburden or waste material for purposes of obtaining access to an ore body. The stripping costs incurred in the production phase of a mine are variable production costs included in the costs of the inventory produced (extracted) during the period that the stripping costs are incurred.

Stripping costs related to expansion of a mining asset of proven and probable reserves are variable production costs that are included in the costs of the inventory produced during the period that the stripping costs are incurred.

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 Consolidated Financial Position as of December 31, 2014 and December 31, 2013. Parentheses indicate a net liability.

(In Millions)

Investment

Classification

Accounting

Ownership Interest

December 31,

December 31, 2013

Method

2014

Hibbing

Other non-current assets 1

Equity Method

23%

$

3.1

(3.9

)

Other

Other non-current assets

Equity Method

Various

3.9

34.7

$

7

$

30.8

1 At December 31, 2013, the classification for Hibbing was Other liabilities.

During the year ended December 31, 2014, an impairment charge of $21.5 million was recorded related to joint ventures investments and is recognized in Impairment of goodwill and other long-lived assets in the Statements of Consolidated Operations.

Hibbing

Our share of equity income (loss) is eliminated against consolidated product inventory upon production, and against Cost of goods sold and operating expenses when sold. This effectively reduces our cost for our share of the mining ventures' production cost, reflecting the cost-based nature of our participation in unconsolidated ventures.

Amapá

On December 27, 2012, our Board of Directors authorized the sale of our 30 percent interest in Amapá. Per this original agreement, together with Anglo, we were to sell our respective interest in a 100 percent sale transaction to Zamin. The carrying value of our investment was in excess of the net proceeds expected from the sale, which approximated fair value, resulting in a $365.4 million impairment charge, which was recorded through Equity loss from ventures, net of tax in the Statements of Consolidated Operations for the year ended December 31, 2012.

On March 28, 2013, an unknown event caused the Santana port shiploader to collapse into the Amazon River, preventing further ship loading by the mine operator, Anglo. In light of the March 28, 2013 collapse of the Santana port shiploader and subsequent evaluation of the effect that this event had on the carrying value of our investment in Amapá as of June 30, 2013, we recorded an impairment charge of $67.6 million in the second quarter of 2013.

On August 28, 2013, we entered into additional agreements to sell our 30 percent interest in Amapá to Anglo for nominal cash consideration, plus the right to certain contingent deferred consideration upon the two-year anniversary of the closing.  The closing was conditional on obtaining certain regulatory approvals and the additional agreement provided Anglo with an option to request that we transfer our interest in Amapá directly to Zamin.  Anglo exercised this option and the transfer to Zamin was completed in the fourth quarter of 2013.

Cockatoo Island

On July 31, 2012, we entered into a definitive asset sale agreement with our joint venture partner, HWE Cockatoo Pty Ltd., to sell our beneficial interest in the mining tenements and certain infrastructure of Cockatoo Island to Pluton Resources, which was amended on August 31, 2012. On September 7, 2012, the closing date, Pluton Resources paid a nominal sum of AUD $4.00 and assumed ownership of the assets and responsibility for the environmental rehabilitation obligations and other assumed liabilities not inherently attached to the tenements acquired. The rehabilitation obligations and assumed liabilities that are inherently attached to the tenements were transferred to Pluton Resources upon registration by the Department of Mining and Petroleum denoting Pluton Resources as the tenement holder. Upon final settlement of the sale, which was completed during the second quarter of 2013, we extinguished approximately $18.6 million related to the estimated cost of the rehabilitation.

Impairment or Disposal of Long-Lived Assets

Asset Impairment

Long-Lived Tangible and Intangible Assets

We monitor conditions that may affect the carrying value of our long-lived tangible and intangible assets when events and circumstances indicate that the carrying value of the asset groups may not be recoverable. In order to determine if assets have been impaired, assets are grouped and tested at the lowest level for which identifiable, independent cash flows are available ("asset group"). An impairment loss exists when projected undiscounted cash flows are less than the carrying value of the asset group. The measurement of the impairment loss to be recognized is based on the difference between the fair value and the carrying value of the asset group. Fair value can be determined using a market approach, income approach or cost approach.

As a result of these assessments during 2014, we determined that the cash flows associated with our Eastern Canadian Iron Ore, Asia Pacific Iron Ore, North American Coal and Ferroalloys asset groups were not sufficient to support the recoverability of the carrying value of these productive assets. Accordingly, during 2014, we recorded a long-lived tangible asset impairment charge of $8,839.0 million and an intangible asset impairment charge of $15.5 million in our Statements of Consolidated Operations. At December 31, 2013, we determined there were long-lived tangible and intangible asset impairments related to the Wabush operations within our Eastern Canadian Iron Ore operating segment that resulted in impairment charges of $145.1 million and $9.5 million, respectively. At December 31, 2012, we determined there was a long-lived asset impairment related to the Wabush mine's pelletizing operations that resulted in an impairment charge of $49.9 million.

Refer to NOTE 4 - PROPERTY, PLANT AND EQUIPMENT, NOTE 12 - GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES and NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS for further information.

Other Intangible Assets and Liabilities

Goodwill

Goodwill represents the excess purchase price paid over the fair value of the net assets of acquired companies. We had goodwill of $2.0 million and $74.5 million recorded in the Statements of Consolidated Financial Position at December 31, 2014 and 2013, respectively. In accordance with the provisions of ASC 350, we compare the fair value of the respective reporting unit to its carrying value on an annual basis (or more frequently if necessary as discussed below) to determine if there is potential goodwill impairment. If the fair value of the reporting unit is less than its carrying value, an impairment loss is recorded to the extent that the implied value of the goodwill within the reporting unit is less than the carrying value of its goodwill.

During the third quarter of 2014, a goodwill impairment charge of $73.5 million was recorded for our Asia Pacific Iron Ore reporting unit within the Asia Pacific Iron Ore operating segment. The impairment charge was a result of downward long-term pricing estimates as determined through management's long-range planning process.

After performing our annual goodwill impairment test in the fourth quarter of 2013, we determined that $80.9 million of goodwill associated with our Ferroalloys operating segment was impaired. The impairment charge was primarily a result of the decision made in the fourth quarter of 2013 to indefinitely suspend the Chromite Project and to not allocate additional capital for the project given the uncertain timeline and risks associated with the development of necessary infrastructure to bring the project online.

During the fourth quarter of 2012, upon performing our annual goodwill impairment test, a goodwill impairment charge of $997.3 million was recorded for our CQIM reporting unit within the Eastern Canadian Iron Ore operating segment. The impairment charge for our CQIM reporting unit was driven by the project’s lower than anticipated long-term profitability coupled with delays in achieving full operational capacity and higher capital and operating costs. Additionally, the announced delay of the Phase II expansion of the Bloom Lake mine also contributed to the impairment.

Refer to NOTE 12 - GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES and NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS for further information.

Other Intangible Assets and Liabilities

Other intangible assets are subject to periodic amortization on a straight-line basis over their estimated useful lives as follows:

Intangible Assets

Basis

Useful Life (years)

Permits - Asia Pacific Iron Ore

Units of production

Life of mine

Permits - All Other

Straight line

15 - 40

Utility Contracts

Straight line

5

Leases - North American Coal

Units of production

Life of mine

Leases - All Other

Straight line

4.5 - 17.5

Fair Value of Financial Instruments

Fair Value Measurements

Valuation Hierarchy

ASC 820 establishes a three-level valuation hierarchy for classification of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. Inputs refer broadly to the assumptions that market participants would use in pricing an asset or liability. Inputs may be observable or unobservable. Observable inputs are inputs that reflect the assumptions market participants would use in pricing the asset or liability developed based on market data obtained from independent sources. Unobservable inputs are inputs that reflect our own assumptions about the assumptions market participants would use in pricing the asset or liability developed based on the best information available in the circumstances. The three-tier hierarchy of inputs is summarized below:

•

Level 1 — Valuation is based upon quoted prices (unadjusted) for identical assets or liabilities in active markets.

•

Level 2 — Valuation is based upon quoted prices for similar assets and liabilities in active markets, or other inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the financial instrument.

•

Level 3 — Valuation is based upon other unobservable inputs that are significant to the fair value measurement.

The classification of assets and liabilities within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement in its entirety. Valuation methodologies used for assets and liabilities measured at fair value are as follows:

Cash Equivalents

Where quoted prices are available in an active market, cash equivalents are classified within Level 1 of the valuation hierarchy. Cash equivalents classified in Level 1 at December 31, 2014 and 2013 include money market funds. Valuation of these instruments is determined using a market approach and is based upon unadjusted quoted prices for identical assets in active markets.

Marketable Securities

Where quoted prices are available in an active market, marketable securities are classified within Level 1 of the valuation hierarchy. Marketable securities classified in Level 1 at December 31, 2014 and 2013 include available-for-sale securities. The valuation of these instruments is determined using a market approach and is based upon unadjusted quoted prices for identical assets in active markets.

Derivative Financial Instruments

Derivative financial instruments valued using financial models that use as their basis readily observable market parameters are classified within Level 2 of the valuation hierarchy. Such derivative financial instruments include substantially all of our foreign currency exchange contracts and derivative financial instruments that are valued based upon published pricing settlements realized by other companies in the industry. Derivative financial instruments that are valued based upon models with significant unobservable market parameters and are normally traded less actively, are classified within Level 3 of the valuation hierarchy.

Refer to NOTE 6 - FAIR VALUE OF FINANCIAL INSTRUMENTS and NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

Pension and Other Postretirement Plans

Pensions and Other Postretirement Benefits

We offer defined benefit pension plans, defined contribution pension plans and other postretirement benefit plans, primarily consisting of retiree healthcare benefits, to most employees in North America as part of a total compensation and benefits program. We do not have employee pension or post-retirement benefit obligations at our Asia Pacific Iron Ore operations or our Bloom Lake mine operations within our Eastern Canadian Iron Ore segment.

We recognize the funded or unfunded status of our postretirement benefit obligations on our December 31, 2014 and 2013 Statements of Consolidated Financial Position based on the difference between the market value of plan assets and the actuarial present value of our retirement obligations on that date, on a plan-by-plan basis. If the plan assets exceed the retirement obligations, the amount of the surplus is recorded as an asset; if the retirement obligations exceed the plan assets, the amount of the underfunded obligations are recorded as a liability. Year-end balance sheet adjustments to postretirement assets and obligations are recorded as Accumulated other comprehensive loss.

The actuarial estimates of the PBO and APBO retirement obligations incorporate various assumptions including the discount rates, the rates of increases in compensation, healthcare cost trend rates, mortality, retirement timing and employee turnover. For the U.S. and Canadian plans, the discount rate is determined based on the prevailing year-end rates for high-grade corporate bonds with a duration matching the expected cash flow timing of the benefit payments from the various plans. The remaining assumptions are based on our estimates of future events by incorporating historical trends and future expectations. The amount of net periodic cost that is recorded in the Statements of Consolidated Operations consists of several components including service cost, interest cost, expected return on plan assets, and amortization of previously unrecognized amounts. Service cost represents the value of the benefits earned in the current year by the participants. Interest cost represents the cost associated with the passage of time. Certain items, such as plan amendments, gains and/or losses resulting from differences between actual and assumed results for demographic and economic factors affecting the obligations and assets of the plans, and changes in other assumptions are subject to deferred recognition for income and expense purposes. The expected return on plan assets is determined utilizing the weighted average of expected returns for plan asset investments in various asset categories based on historical performance, adjusted for current trends. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

Asset Retirement Obligations

Asset Retirement Obligations

Asset retirement obligations are recognized when incurred and recorded as liabilities at fair value. The fair value of the liability is determined as the discounted value of the expected future cash flow. The asset retirement obligation is accreted over time through periodic charges to earnings. In addition, the asset retirement cost is capitalized as part of the asset’s carrying value and amortized over the life of the related asset. Reclamation costs are adjusted periodically to reflect changes in the estimated present value resulting from the passage of time and revisions to the estimates of either the timing or amount of the reclamation costs. We review, on an annual basis, unless otherwise deemed necessary, the asset retirement obligation at each mine site in accordance with the provisions of ASC 410. We perform an in-depth evaluation of the liability every three years in addition to routine annual assessments.

Future remediation costs for inactive mines are accrued based on management’s best estimate at the end of each period of the costs expected to be incurred at a site. Such cost estimates include, where applicable, ongoing maintenance and monitoring costs. Changes in estimates at inactive mines are reflected in earnings in the period an estimate is revised. See NOTE 11 - ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS for further information.

Environmental Costs

Environmental Remediation Costs

We have a formal policy for environmental protection and restoration. Our mining and exploration activities are subject to various laws and regulations governing protection of the environment. We conduct our operations to protect the public health and environment and believe our operations are in compliance with applicable laws and regulations in all material respects. Our environmental liabilities, including obligations for known environmental remediation exposures at active and closed mining operations and other sites, have been recognized based on the estimated cost of investigation and remediation at each site. If the cost only can be estimated as a range of possible amounts with no point in the range being more likely, the minimum of the range is accrued. Future expenditures are not discounted unless the amount and timing of the cash disbursements reasonably can be estimated. It is possible that additional environmental obligations could be incurred, the extent of which cannot be assessed. Potential insurance recoveries have not been reflected in the determination of the liabilities. See NOTE 11 - ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS for further information.

Revenue Recognition

Revenue Recognition

U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore

We sell our products pursuant to comprehensive supply agreements negotiated and executed with our customers. Revenue is recognized from a sale when persuasive evidence of an arrangement exists, the price is fixed or determinable, the product is delivered in accordance with F.O.B. terms, title and risk of loss have transferred to the customer in accordance with the specified provisions of each supply agreement and collection of the sales price reasonably is assured. Our U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore supply agreements provide that title and risk of loss transfer to the customer either upon loading of the vessel, shipment or, as is the case with some of our U.S. Iron Ore supply agreements, when payment is received. Under certain term supply agreements, we ship the product to ports on the lower Great Lakes or to the customers’ facilities prior to the transfer of title. Our rationale for shipping iron ore products to certain customers and retaining title until payment is received for these products is to minimize credit risk exposure.

Iron ore sales are recorded at a sales price specified in the relevant supply agreements resulting in revenue and a receivable at the time of sale. Upon revenue recognition for provisionally priced sales, a freestanding derivative is created for the difference between the sales price used and expected future settlement price. The derivative, which does not qualify for hedge accounting, is adjusted to fair value through Product revenues as a revenue adjustment each reporting period based upon current market data and forward-looking estimates determined by management until the final sales price is determined. The principal risks associated with recognition of sales on a provisional basis include iron ore price fluctuations between the date initially recorded and the date of final settlement. For revenue recognition, we estimate the future settlement rate; however, if significant changes in iron ore prices occur between the provisional pricing date and the final settlement date, we might be required to either return a portion of the sales proceeds received or bill for the additional sales proceeds due based on the provisional sales price. Refer to NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES for further information.

In addition, certain supply agreements with one customer include provisions for supplemental revenue or refunds based on the customer’s annual steel pricing for the year 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 record this provision at fair value until the year the product is consumed and the amounts are settled as an adjustment to revenue. Refer to NOTE 13 - DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES for further information.

Revenue from product sales also includes reimbursement for freight charges paid on behalf of customers and freight costs to move product from the Upper Great Lakes to ports in Québec to use for exports and from the port of Esperance to ports in China, which are included in Freight and venture partners' cost reimbursements separate from Product revenues. Revenue is recognized for the expected reimbursement of services when the services are performed.

North American Coal

We sell our products pursuant to supply agreements negotiated and executed with our customers. Revenue is recognized when persuasive evidence of an arrangement exists, the price is fixed or determinable, the product is delivered in accordance with F.O.B. terms, title and risk of loss have transferred to the customer in accordance with the specified provisions of each supply agreement and collection of the sales price reasonably is assured. Delivery on our coal sales is determined to be complete for revenue recognition purposes when title and risk of loss has passed to the customer in accordance with stated contractual terms and there are no other future obligations related to the shipment. For domestic shipments, title and risk of loss generally passes as the coal is loaded into transport carriers for delivery to the customer. For international shipments, title generally passes at the time coal is loaded onto the shipping vessel. Revenue from product sales in 2014, 2013 and 2012 included reimbursement for freight charges paid to move coal from the mine to port locations of $115.0 million, $85.8 million and $101.0 million, respectively, and is recorded in Freight and venture partners' cost reimbursements on the Statements of Consolidated Operations.

Revenue Recognition, Deferred Revenue

Deferred Revenue

The terms of one of our U.S. Iron Ore pellet supply agreements required supplemental payments to be paid by the customer during the period 2009 through 2012, with the option to defer a portion of the 2009 monthly amount in exchange for interest payments until the deferred amount was repaid in 2013. Installment amounts received under this arrangement in excess of sales are classified as deferred revenue in the Statements of Consolidated Financial Position upon receipt of payment. Revenue is recognized over the life of the supply agreement, which extends until 2022, in equal annual installments. As of December 31, 2014 and 2013, installment amounts received in excess of sales totaled $102.8 million and $115.6 million, respectively. As of December 31, 2014, deferred revenue of $12.8 million was recorded in Other current liabilities and $90.0 million was recorded as long term in Other liabilities in the Statements of Consolidated Financial Position. As of December 31, 2013, deferred revenue of $12.8 million was recorded in Other current liabilities and $102.8 million was recorded as long term in Other liabilities in the Statements of Consolidated Financial Position.

In 2014 and 2013, due to the payment terms and the timing of cash receipts near year-end, cash receipts exceeded shipments. The shipments were completed early in the subsequent years. We considered whether revenue should be recognized on these sales under the “bill and hold” guidance provided by the SEC Staff; however, based upon the assessment performed, revenue recognition on these transactions totaling $29.3 million and $13.5 million, respectively, was deferred on the December 31, 2014 and December 31, 2013 Statements of Consolidated Financial Position.

Cost of Sales

Cost of Goods Sold

U.S. Iron Ore, Asia Pacific Iron Ore and Eastern Canadian Iron Ore

Cost of goods sold and operating expenses represents all direct and indirect costs and expenses applicable to the sales and revenues of our mining operations. Operating expenses primarily represent the portion of the Tilden mining venture costs for which we do not own; that is, the costs attributable to the share of the mine’s production owned by the other joint venture partner in the Tilden mine. The mining venture functions as a captive cost company; it supplies product only to its owners effectively for the cost of production. Accordingly, the noncontrolling interests’ revenue amounts are stated at cost of production and are offset by an equal amount included in Cost of goods sold and operating expenses resulting in no sales margin reflected for the noncontrolling partner participant. As we are responsible for product fulfillment, we act as a principal in the transaction and, accordingly, record revenue under these arrangements on a gross basis.

The following table is a summary of reimbursements in our U.S. Iron Ore operations for the years ended December 31, 2014, 2013 and 2012:

(In Millions)

Year Ended December 31,

2014

2013

2012

Reimbursements for:

Freight

$

163

$

177.3

$

142

Venture partners’ cost

108

82.2

108.8

Total reimbursements

$

271

$

259.5

$

250.8

In 2014, we began selling a portion of its Asia Pacific Iron Ore product on a CFR basis. As a result, $6.9 million of freight was included in Cost of goods sold and operating expenses. There was no freight for the year ended December 31, 2013.

Where we have joint ownership of a mine, our contracts entitle us to receive royalties and/or management fees, which we earn as the pellets are produced.

North American Coal

Cost of goods sold and operating expenses represent all direct and indirect costs and expenses applicable to the sales and revenues of our mining operations.

Repairs And Maintenance

Repairs and Maintenance

Repairs, maintenance and replacement of components are expensed as incurred. The cost of major equipment overhauls is capitalized and depreciated over the estimated useful life, which is the period until the next scheduled overhaul, generally five years. All other planned and unplanned repairs and maintenance costs are expensed when incurred.

Share-based Compensation, Option and Incentive Plans

Share-Based Compensation

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. Consistent with the guidelines of ASC 718, a correlation matrix of historic and projected stock prices was developed for both the Company and its 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 estimated 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 plans.

The fair value of stock options is estimated on the date of grant using a Black-Scholes model using the grant date price of our common shares and option exercise price, and assumptions regarding the option’s expected term, the volatility of our common shares, the risk-free interest rate, and the dividend yield over the option’s expected term.

Refer to NOTE 8 - STOCK COMPENSATION PLANS for additional information.

Income Tax

Income Taxes

Income taxes are based on income for financial reporting purposes, calculated using tax rates by jurisdiction, and reflect a current tax liability or asset for the estimated taxes payable or recoverable on the current year tax return and expected annual changes in deferred taxes. Any interest or penalties on income tax are recognized as a component of income tax expense.

We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined based on the differences between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

We record net deferred tax assets to the extent we believe these assets will more likely than not be realized. In making such determination, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax planning strategies and recent financial results of operations.

Accounting for uncertainty in income taxes recognized in the financial statements requires that a tax benefit from an uncertain tax position be recognized when it is more likely than not that the position will be sustained upon examination, including resolutions of any related appeals or litigation processes, based on technical merits.

See NOTE 9 - INCOME TAXES for further information.

Discontinued Operations

Discontinued Operations

On July 10, 2012, we entered into a definitive share and asset sale agreement to sell our 45 percent economic interest in the Sonoma joint venture coal mine located in Queensland, Australia. Upon completion of the transaction on November 12, 2012, we collected approximately AUD $141.0 million in net cash proceeds. The assets sold included our interests in the Sonoma mine along with our ownership of the affiliated washplant. The Sonoma operations previously were included in Other within our reportable segments.

In April 2014, the FASB issued ASU 2014-08, Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity, which changes the criteria for reporting discontinued operations and requires additional disclosures about discontinued operations. The standard requires that an entity report as a discontinued operation only a disposal that represents a strategic shift in operations that has a major effect on its operations and financial results. ASU 2014-08 is effective prospectively for new disposals that occur within annual periods beginning on or after December 15, 2014. Early adoption is permitted and we adopted ASU 2014-08 during the three months ended December 31, 2014. Both Wabush and CLCC did not qualify as discontinued operations as determined under the new guidance. Neither the closure of Wabush nor the sale of the CLCC assets was considered a strategic shift in operations that had a major effect on our operations. Refer to NOTE 14 - DISCONTINUED OPERATIONS for further discussion of our adoption of ASU 2014-08.

Foreign Currency Transactions and Translations

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. Where the U.S. dollar is the functional currency, translation adjustments are recorded in the Statements of Consolidated Operations. Income taxes generally are not provided for foreign currency translation adjustments.

Earnings Per Share

Earnings Per Share

We present both basic and diluted earnings per share amounts. Basic earnings per share amounts are calculated by dividing Net Income (Loss) Attributable to Cliffs Shareholders less any paid or declared but unpaid dividends on our depositary shares by the weighted average number of common shares outstanding during the period presented. Diluted earnings per share amounts are calculated by dividing Net Income (Loss) Attributable to Cliffs Shareholders by the weighted average number of common shares, common share equivalents under stock plans using the treasury stock method and the number of common shares that would be issued under an assumed conversion of our outstanding depositary shares, each representing a 1/40th interest in a share of our Series A Mandatory Convertible Preferred Stock, Class A, under the if-converted method. Our outstanding depositary shares are convertible into common shares based on the volume weighted average of closing prices of our common shares over the 20 consecutive trading day period ending on the third day immediately preceding the end of the reporting period. Common share equivalents are excluded from EPS computations in the periods in which they have an anti-dilutive effect. See NOTE 19 - EARNINGS PER SHARE for further information.

Recent Accounting Pronouncements

Recent Accounting Pronouncements

Issued and Not Effective

In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties About an Entity's Ability to Continue as a Going Concern. ASU 2014-15 will explicitly require management to assess an entity's ability to continue as a going concern, and to provide related footnote disclosure in certain circumstances. ASU 2014-15 is intended to define management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. Specifically, ASU 2014-15 provides a definition of the term "substantial doubt" and requires an assessment for a period of one year after the date that the financial statements are issued (or available to be issued). It also requires certain disclosures when substantial doubt is alleviated as a result of consideration of management’s plans and requires an express statement and other disclosures when substantial doubt is not alleviated. The new standard will be effective for all entities in the first annual period ending after December 15, 2016 and for annual periods and interim periods thereafter. Earlier adoption is permitted. We are currently evaluating the impact the adoption of the guidance will have on the Statements of Consolidated Financial Position, Statements of Consolidated Operations or Statements of Consolidated Cash Flows.

In June 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers.  The new revenue guidance broadly replaces the revenue guidance provided throughout the Codification.  The core principle of the revenue guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services.  To achieve that core principle, an entity should apply the following steps: (1) identify the contract(s) with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price to the performance obligations in the contract, and (5) recognize revenue when (or as) the entity satisfies a performance obligation.  The new revenue guidance also requires the capitalization of certain contract acquisition costs.  Reporting entities must provide new disclosures providing qualitative and quantitative information on the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers.  New disclosures also include qualitative and quantitative information on significant judgments, changes in judgments, and contract acquisition assets.  The update is effective for annual periods and interim periods within those annual periods beginning after December 15, 2016 and may be adopted either retrospectively or retrospectively with the cumulative effect.  Earlier adoption is not permitted. We are still evaluating the impact of the updated guidance on the Statements of Consolidated Financial Position, Statements of Consolidated Operations or Statements of Consolidated Cash Flows.

BASIS_OF_PRESENTATION_AND_SIGN2

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2014

Estimated Useful Lives Of Intangible Assets Subject To Periodic Amortization On Straight Line Basis Table [Text Block]

Other intangible assets are subject to periodic amortization on a straight-line basis over their estimated useful lives as follows:

Intangible Assets

Basis

Useful Life (years)

Permits - Asia Pacific Iron Ore

Units of production

Life of mine

Permits - All Other

Straight line

15 - 40

Utility Contracts

Straight line

5

Leases - North American Coal

Units of production

Life of mine

Leases - All Other

Straight line

4.5 - 17.5

Schedule Of Subsidiaries

The consolidated financial statements include our accounts and the accounts of our wholly owned and majority-owned subsidiaries, including the following operations at December 31, 2014:

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

Oak Grove

Alabama

100.00%

Coal

Active

CLCC

West Virginia

100.00%

Coal

Assets sold as of December 31, 2014

Wabush

Newfoundland and Labrador/ Québec, Canada

100.00%

Iron Ore

Permanent closure

Bloom Lake

Québec, Canada

82.80%

Iron Ore

Care-and-maintenance

Cliffs Chromite Ontario - Black Label Deposit

Ontario, Canada

100.00%

Chromite

Suspended

Cliffs Chromite Ontario - Black Thor Deposit

Ontario, Canada

100.00%

Chromite

Suspended

Cliffs Chromite Ontario & Cliffs Chromite Far North - Big Daddy Deposit

Ontario, Canada

70.00%

Chromite

Suspended

Depreciation Disclosure [Table Text Block]

Depreciation is provided over the following estimated useful lives:

Asset Class

Basis

Life

Buildings

Straight line

45 Years

Mining equipment

Straight line/Double declining balance

3 to 20 Years

Processing equipment

Straight line

10 to 45 Years

Electric power facilities

Straight line

10 to 45 years

Land improvements

Straight line

20 to 45 years

Office and information technology

Straight line

3 to 15 Years

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 Consolidated Financial Position as of December 31, 2014 and December 31, 2013. Parentheses indicate a net liability.

(In Millions)

Investment

Classification

Accounting

Ownership Interest

December 31,

December 31, 2013

Method

2014

Hibbing

Other non-current assets 1

Equity Method

23%

$

3.1

(3.9

)

Other

Other non-current assets

Equity Method

Various

3.9

34.7

$

7

$

30.8

1 At December 31, 2013, the classification for Hibbing was Other liabilities.

Reimbursements Revenue Disclosure [Table Text Block]

The following table is a summary of reimbursements in our U.S. Iron Ore operations for the years ended December 31, 2014, 2013 and 2012:

(In Millions)

Year Ended December 31,

2014

2013

2012

Reimbursements for:

Freight

$

163

$

177.3

$

142

Venture partners’ cost

108

82.2

108.8

Total reimbursements

$

271

$

259.5

$

250.8

SEGMENT_REPORTING_Tables

SEGMENT REPORTING (Tables)	12 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Schedule Of Segment Reporting Information, By Segment	The following tables present a summary of our reportable segments for the years ended December 31, 2014, 2013 and 2012, including a reconciliation of segment sales margin to Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures and a reconciliation of Net Income (Loss) to EBITDA and Adjusted EBITDA:
		(In Millions)
		2014					2013					2012
	Revenues from product sales and services:
	U.S. Iron Ore	$	2,506.50		54%		$	2,667.90			47%	$	2,723.30		46%
	Asia Pacific Iron Ore	866.7			19%		1,224.30				22%	1,259.30			22%
	North American Coal	687.1			15%		821.9				14%	881.1			15%
	Eastern Canadian Iron Ore	563.4			12%		978.7				17%	1,008.90			17%
	Other (including inter-segment revenue eliminations)	—			—%		(1.4		)		—%	0.1			—%
	Total revenues from product sales and services	$	4,623.70		100%		$	5,691.40			100%	$	5,872.70		100%
	Sales margin:
	U.S. Iron Ore	$	710.4				$	901.9				$	976.2
	Asia Pacific Iron Ore	121.7					367.1					311
	North American Coal	(135.8		)			(14.5		)			(1.8		)
	Eastern Canadian Iron Ore	(244.9		)			(103.3		)			(121.4		)
	Other (including inter-segment sales margin eliminations)	—					(1.9		)			8.1
	Sales margin	451.4					1,149.30					1,172.10
	Other operating income (expense)	(9,896.7		)			(478.3		)			(1,480.9		)
	Other income (expense)	(158.4		)			(181.7		)			(193.0		)
	Income (loss) from continuing operations before income taxes and equity income (loss) from ventures	$	(9,603.7	)			$	489.3				$	(501.8	)
		(In Millions)
		2014			2013				2012
	Net Income (Loss)	$	(8,311.6	)	$	361.8			$	(1,126.6	)
	Less:
	Interest expense, net	(185.2		)	(179.1		)		(195.6		)
	Income tax benefit (expense)	1,302.00			(55.1		)		(255.9		)
	Depreciation, depletion and amortization	(504.0		)	(593.3		)		(525.8		)
	EBITDA	$	(8,924.4	)	$	1,189.30			$	(149.3	)
	Less:
	Impairment of goodwill and other long-lived assets	$	(9,029.9	)	$	(250.8	)		$	(1,049.9	)
	Impairment of equity method investment	—			—				(365.4		)
	Loss on sale of Cliffs Logan County Coal	(419.6		)	—				—
	Wabush mine impact	(158.7		)	(72.7		)		(30.1		)
	Bloom Lake mine impact	(137.9		)	46.5				6.4
	Foreign exchange remeasurement	30.7			64				(3.2		)
	Proxy contest and change in control costs in SG&A	(26.6		)	—				—
	Litigation judgment	(96.3		)	(9.6		)		—
	Severance in SG&A	(15.8		)	(16.4		)		—
	Total Adjusted EBITDA	$	929.7		$	1,428.30			$	1,292.90
	EBITDA:
	U.S. Iron Ore	$	805.6		$	1,000.10			$	1,045.30
	Asia Pacific Iron Ore	(369.8		)	500.4				387.3
	North American Coal	(1,326.8		)	129.5				74
	Eastern Canadian Iron Ore	(7,673.9		)	(192.8		)		(1,103.3		)
	Other	(359.5		)	(247.9		)		(552.6		)
	Total EBITDA	$	(8,924.4	)	$	1,189.30			$	(149.3	)
	Adjusted EBITDA:
	U.S. Iron Ore	$	831.2		$	1,030.80			$	1,085.60
	Asia Pacific Iron Ore	264.6			525.7				402.1
	North American Coal	(28.5		)	154				106.7
	Eastern Canadian Iron Ore	—			—				—
	Other	(137.6		)	(282.2		)		(301.5		)
	Total Adjusted EBITDA	$	929.7		$	1,428.30			$	1,292.90
		(In Millions)
		2014			2013				2012
	Depreciation, depletion and amortization:
	U.S. Iron Ore	$	107.4		$	120.3			$	100.9
	Asia Pacific Iron Ore	145.9			153.7				151.9
	North American Coal	106.9			128.9				98.2
	Eastern Canadian Iron Ore	135.6			178.5				160.2
	Other	8.2			11.9				14.6
	Total depreciation, depletion and amortization	$	504		$	593.3			$	525.8
	Capital additions1:
	U.S. Iron Ore	$	48.4		$	53.3			$	168.8
Asia Pacific Iron Ore	10.8			13				87.7
North American Coal	28.8			55				144.1
Eastern Canadian Iron Ore	141.2			625.5				865.2
Other	6.3			5.5				69.5
Total capital additions	$	235.5		$	752.3			$	1,335.30
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)
		December 31,			December 31, 2013				December 31, 2012
		2014
	Assets:
	U.S. Iron Ore	$	1,598.30		$	1,671.60			$	1,735.10
	Asia Pacific Iron Ore	274.6			1,078.40				1,506.30
	North American Coal	274.2			1,841.80				1,877.80
	Eastern Canadian Iron Ore	305.8			7,915.50				7,605.10
	Other	164.3			455.6				570.9
	Total segment assets	2,617.20			12,962.90				13,295.20
	Corporate	546.8			159				279.7
	Total assets	$	3,164.00		$	13,121.90			$	13,574.90
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	Included in the consolidated financial statements are the following amounts relating to geographic location:
		(In Millions)
		2014			2013				2012
	Revenue
	United States	$	2,139.40		$	1,857.60			$	2,108.50
	China	1,049.00			1,909.40				2,008.20
	Canada	439.1			871.2				728.1
	Other countries	996.2			1,053.20				1,027.90
	Total revenue	$	4,623.70		$	5,691.40			$	5,872.70
	Property, Plant and Equipment, Net
	United States	$	1,093.70		$	2,721.60			$	2,795.30
	Australia	72.4			751				1,042.40
	Canada	248.8			7,680.80				7,369.60
	Total Property, Plant and Equipment, Net	$	1,414.90		$	11,153.40			$	11,207.30
Revenue from External Customers by Products and Services	The following table represents the percentage of our total revenue contributed by each category of products and services in 2014, 2013, and 2012:
			2014		2013			2012
	Revenue Category
	Iron ore		78	%	80	%		81	%
	Coal		12	%	13	%		13	%
	Freight and venture partners’ cost reimbursements		10	%	7	%		6	%
	Total revenue		100	%	100	%		100	%

INVENTORIES_Tables

INVENTORIES (Tables)	12 Months Ended
	Dec. 31, 2014
Inventory Disclosure [Abstract]
Schedule Of Inventories	The following table presents the detail of our Inventories in the Statements of Consolidated Financial Position as of December 31, 2014 and 2013:
		(In Millions)
		31-Dec-14						31-Dec-13
	Segment	Finished Goods		Work-in Process		Total Inventory		Finished Goods		Work-in		Total
										Process		Inventory
	U.S. Iron Ore	$	132.1	$	13.5	$	145.6	$	92.1	$	13	$	105.1
	Asia Pacific Iron Ore	26.4		88.1		114.5		39.7		50.6		90.3
	North American Coal	33.1		17.2		50.3		59.4		23.2		82.6
	Eastern Canadian Iron Ore	16.3		—		16.3		65.3		48.1		113.4
	Total	$	207.9	$	118.8	$	326.7	$	256.5	$	134.9	$	391.4

PROPERTY_PLANT_AND_EQUIPMENT_T

PROPERTY, PLANT AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2014
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 December 31, 2014 and 2013:
		(In Millions)
		December 31,
		2014			2013
	Land rights and mineral rights	$	590.2		$	7,819.60
	Office and information technology	75.5			125.7
	Buildings	65.6			255.2
	Mining equipment	732.6			1,819.30
	Processing equipment	567.4			2,148.60
	Electric power facilities	48.8			114.3
	Land improvements	25.5			69.3
	Other	60.8			227.6
	Construction in-progress	51.3			991.3
		2,217.70			13,570.90
	Allowance for depreciation and depletion	(802.8		)	(2,417.5		)
		$	1,414.90		$	11,153.40
Book Value of Land and Mineral Rights Disclosure [Table Text Block]	The net book value of the land rights and mineral rights as of December 31, 2014 and 2013 is as follows:
		(In Millions)
		December 31,
		2014			2013
	Land rights	$	31.9		$	46.3
	Mineral rights:
	Cost	$	558.3		$	7,773.30
	Depletion	(101.3		)	(942.6		)
	Net mineral rights	$	457		$	6,830.70

DEBT_AND_CREDIT_FACILITIES_Tab

DEBT AND CREDIT FACILITIES (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule Of Long-Term Debt	The following represents a summary of our long-term debt as of December 31, 2014 and 2013:
	($ in Millions)
	December 31, 2014
	Debt Instrument		Type	Annual Effective Interest Rate	Final Maturity	Total Principal 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		—			-6
	Equipment Loans		Fixed	Various	2020	164.8		140.8
	Fair Value Adjustment to Interest Rate Hedge							2.8
	Total debt					$	4,144.80	$	2,984.10
	Less current portion							21.8
	Long-term debt							$	2,962.30
	($ in Millions)
	31-Dec-13
	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	$	700	$	699.4		-1
	$1.3 Billion Senior Notes:
	$500 Million 4.80% 2020 Senior Notes		Fixed	4.83%	2020	500		499.2			-2
	$800 Million 6.25% 2040 Senior Notes		Fixed	6.34%	2040	800		790.4			-3
	$400 Million 5.90% 2020 Senior Notes		Fixed	5.98%	2020	400		398.4			-4
	$500 Million 3.95% 2018 Senior Notes		Fixed	4.14%	2018	500		496.5			-5
	$1.75 Billion Credit Facility:
	Revolving Loan		Variable	1.64%	2017	1,750.00		—			-6
	Equipment Loans		Fixed	Various	2020	164.8		161.7
	Fair Value Adjustment to Interest Rate Hedge							(2.1		)
	Total debt					$	4,814.80	$	3,043.50
	Less current portion							20.9
	Long-term debt							$	3,022.60
	-1	During the fourth quarter of 2014, we purchased $10.0 million of outstanding 4.875 percent senior notes that were trading at a discount of 40.5 percent which resulted in a gain on the extinguishment of debt of $4.1 million. 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. As of December 31, 2013, the $700.0 million 4.875 percent senior notes were recorded at a par value of $700.0 million less unamortized discounts of $0.6 million, based on an imputed interest rate of 4.88 percent.
	-2	During the fourth quarter of 2014, we purchased $10.0 million of outstanding 4.80 percent senior notes that were trading at a discount of 40.25 percent which resulted in a gain on the extinguishment of debt of $4.0 million. 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. As of December 31, 2013, the $500.0 million 4.80 percent senior notes were recorded at a par value of $500.0 million less unamortized discounts of $0.8 million, based on an imputed interest rate of 4.83 percent.
	-3	As of December 31, 2014 and December 31, 2013, the $800.0 million 6.25 percent senior notes were recorded at par value of $800.0 million less unamortized discounts of $9.5 million and $9.6 million, respectively, based on an imputed interest rate of 6.34 percent.
	-4	During the fourth quarter of 2014, we purchased $5.0 million of outstanding 5.90 percent senior notes that were trading at a discount of 38.125 percent which resulted in a gain on the extinguishment of debt of $1.9 million. 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. As of December 31, 2013, the $400.0 million 5.90 percent senior notes were recorded at a par value of $400.0 million less unamortized discounts of $1.6 million, based on an imputed interest rate of 5.98 percent.
	-5	During the fourth quarter of 2014, we purchased $20.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 30.875 percent which resulted in a gain on the extinguishment of debt of $6.2 million. 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. As of December 31, 2013, the $500.0 million 3.95 percent senior notes were recorded at a par value of $500.0 million less unamortized discounts of $3.5 million, based on an imputed interest rate of 4.14 percent.
	-6	As of December 31, 2014 and 2013, no revolving loans were drawn under the credit facility. We had total availability of $1.125 billion and $1.75 billion on our credit facility as of December 31, 2014 and 2013, respectively. Additionally, as of December 31, 2014 and December 31, 2013, the principal amount of letter of credit obligations totaled $149.5 million and $8.4 million, respectively, thereby reducing available borrowing capacity to $1.0 billion and $1.7 billion for each period, respectively.
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 amended revolving credit agreement, based on the principal amounts outstanding at December 31, 2014:
		(In Millions)
		Maturities of Debt
	2015	$	21.8
	2016	22.7
	2017	23.6
	2018	504.6
	2019	25.5
	2020 and thereafter	2,397.60
	Total maturities of debt	$	2,995.80

FAIR_VALUE_OF_FINANCIAL_INSTRU1

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)	12 Months Ended
	Dec. 31, 2014																				Dec. 31, 2013
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 December 31, 2014 and 2013:
		(In Millions)
		December 31, 2014
	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:
	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	$	—			$	—			$	11.8			$	11.8
	Foreign exchange contracts	—				31.5				—				31.5
	Total	$	—			$	31.5			$	11.8			$	43.3
		(In Millions)
		December 31, 2013
	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:
	Cash equivalents	$	85			$	—			$	—			$	85
	Derivative assets	—				—				58.9				58.9
	Available-for-sale marketable securities	21.4				—				—				21.4
	Foreign exchange contracts	—				0.3				—				0.3
	Total	$	106.4			$	0.3			$	58.9			$	165.6
	Liabilities:
	Derivative liabilities	$	—			$	2.1			$	10.3			$	12.4
	Foreign exchange contracts	—				26.9				—				26.9
	Total	$	—			$	29			$	10.3			$	39.3
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)		Fair Value at				Balance Sheet Location		Valuation Technique		Unobservable Input		Range or Point Estimate
			12/31/14										(Weighted Average)
	Provisional Pricing Arrangements		$	11.8			Other current liabilities		Market Approach		Management's		$72
											Estimate of 62% Fe
	Customer Supply Agreement		$	63.2			Other current assets		Market Approach		Hot-Rolled Steel Estimate		$590 - $640 ($610)
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 years ended December 31, 2014 and 2013.
		(In Millions)
		Derivative Assets (Level 3)								Derivative Liabilities
										(Level 3)
		Year Ended								Year Ended
		December 31,								December 31,
		2014				2013				2014				2013
	Beginning balance - January 1	$	58.9			$	62.4			$	(10.3	)		$	(11.3	)
	Total gains (losses)
	Included in earnings	187.8				152.3				(11.8		)		(10.3		)
	Settlements	(183.5		)		(155.8		)		10.3				11.3
	Transfers into Level 3	—				—				—				—
	Transfers out of Level 3	—				—				—				—
	Ending balance - December 31	$	63.2			$	58.9			$	(11.8	)		$	(10.3	)
	Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) on assets still held at the reporting date	$	187.8			$	152.3			$	(11.8	)		$	(10.3	)
Schedule Of Carrying Value And Fair Value Of Financial Instruments	A summary of the carrying amount and fair value of other financial instruments at December 31, 2014 and 2013 were as follows:
				(In Millions)
				December 31, 2014								December 31, 2013
		Classification		Carrying				Fair Value				Carrying				Fair Value
				Value								Value
	Long-term debt:
	Senior notes—$700 million	Level 2		689.5				367.3				699.4				718.2
	Senior notes—$1.3 billion	Level 2		1,279.90				704				1,289.60				1,404.90
	Senior notes—$400 million	Level 2		393.7				228.1				398.4				432.1
	Senior notes—$500 million	Level 2		477.4				312				496.5				523.8
	Revolving loan	Level 2		—				—				—				—
	Equipment Loan Facilities	Level 2		119				119				140.8				140.8
	Fair Value Adjustment to Interest Rate Hedge	Level 2		2.8				2.8				(2.1		)		(2.1		)
	Total long-term debt			$	2,962.30			$	1,733.20			$	3,022.60			$	3,217.70
Fair Value Measurements, Nonrecurring	The following tables present information about the impairment charges on both financial and nonfinancial assets that were measured on a fair value basis at December 31, 2014 and December 31, 2013. The table also indicates the fair value hierarchy of the valuation techniques used to determine such fair value.
																						(In Millions)
			(In Millions)																			Year Ended December 31, 2013
			Year Ended December 31, 2014																		Description	Quoted Prices in Active		Significant Other Observable Inputs		Significant Unobservable Inputs		Total		Total Losses
	Description		Quoted Prices in Active				Significant Other Observable Inputs				Significant Unobservable Inputs				Total				Total Losses			Markets for Identical Assets/		(Level 2)		(Level 3)
			Markets for Identical Assets/				(Level 2)				(Level 3)											Liabilities
			Liabilities																			(Level 1)
			(Level 1)																		Assets:
	Assets:																				Goodwill impairment -	$	—	$	—	$	—	$	—	$	80.9
	Goodwill impairment -		$	—			$	—			$	—			$	—			$	73.5	Ferroalloys reporting unit
	Asia Pacific Iron Ore reporting unit																				Other long-lived assets -	—		—		46.3		46.3		155.4
	Other long-lived assets -																				Property, plant and equipment
	Property, plant and equipment																				Other long-lived assets -	—		—		1.6		1.6		14.5
	and Mineral rights:																				Intangibles and long-term
	Asia Pacific Iron Ore reporting unit		—				—				72.4				72.4				526.5		deposits
																					Investment in ventures impairment - Amapá	—		—		—		—		67.6
	North American Coal reporting unit
	CLCC thermal asset group		—				—				62.6				62.6				195.5		Total	$	—	$	—	$	47.9	$	47.9	$	318.4
	Pinnacle asset group		—				—				30.7				30.7				394.5
	Oak Grove asset group		—				—				23.4				23.4				267.5
	Eastern Canadian Iron Ore reporting unit
	Bloom Lake asset group		—				—				187.9				187.9				7,043.70
	Wabush asset group		—				—				42.7				42.7				132.6
	Ferroalloys reporting unit		—				—				12.2				12.2				259.5
	Other reporting units		—				—				—				—				19.2
	Other long-lived assets -
	Intangibles and other long-term assets:
	Asia Pacific Iron Ore reporting unit		—				—				7				7				24.2
	Eastern Canadian Iron Ore reporting unit
	Bloom Lake asset group		—				—				—				—				56.2
	Wabush asset group		—				—				—				—				36.7
	Ferroalloys reporting unit		—				—				—				—				0.3
	Investment in ventures		—				—				—				—				9.2
	impairment - Global Exploration
			$	—			$	—			$	438.9			$	438.9			$	9,039.10

PENSIONS_AND_OTHER_POSTRETIREM1

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Tables)	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Retirement And Defined Compensation Plans Disclosures [Table Text Block]	The following table summarizes the annual expense recognized related to the retirement plans for 2014, 2013 and 2012:
		(In Millions)
		2014				2013				2012
	Defined benefit pension plans	$	31.3			$	52.1			$	55.2
	Defined contribution pension plans	6.3				6.8				6.7
	Other postretirement benefits	(0.7		)		17.4				28.1
	Total	$	36.9			$	76.3			$	90
Obligations and Funded Status	The following tables and information provide additional disclosures for the December 31, 2014 and 2013:
		(In Millions)
		Pension Benefits								Other Benefits
	Change in benefit obligations:	2014				2013				2014				2013
	Benefit obligations — beginning of year	$	1,118.00			$	1,244.30			$	356.2			$	459.8
	Service cost (excluding expenses)	30.8				38.9				6.7				12.3
	Interest cost	49.7				45.9				16.2				17.3
	Plan amendments	—				0.8				(0.9		)		—
	Actuarial (gain) loss	141.6				(121.8		)		51.9				(103.3		)
	Benefits paid	(87.0		)		(72.9		)		(27.4		)		(28.0		)
	Participant contributions	—				—				4.8				5.6
	Federal subsidy on benefits paid	—				—				0.9				0.5
	Exchange rate gain	(18.2		)		(17.2		)		(3.7		)		(8.0		)
	Curtailment gain	(10.9		)		—				(8.8		)		—
	Special termination benefits	3.4				—				—				—
	Benefit obligations — end of year	$	1,227.40			$	1,118.00			$	395.9			$	356.2
	Change in plan assets:
	Fair value of plan assets — beginning of year	$	915.3			$	838.7			$	251.8			$	237
	Actual return on plan assets	78.7				109.5				31.9				11
	Participant contributions	—				—				0.8				1.8
	Employer contributions	60.5				53.7				6.9				20.7
	Benefits paid	(87.0		)		(72.9		)		(22.1		)		(18.7		)
	Exchange rate loss	(17.9		)		(13.7		)		—				—
	Fair value of plan assets — end of year	$	949.6			$	915.3			$	269.3			$	251.8
	Funded status at December 31:
	Fair value of plan assets	$	949.6			$	915.3			$	269.3			$	251.8
	Benefit obligations	(1,227.4		)		(1,118.0		)		(395.9		)		(356.2		)
	Funded status (plan assets less benefit obligations)	$	(277.8	)		$	(202.7	)		$	(126.6	)		$	(104.4	)
	Amount recognized at December 31	$	(277.8	)		$	(202.7	)		$	(126.6	)		$	(104.4	)
	Amounts recognized in Statements of Financial Position:
	Current liabilities	$	(2.4	)		$	(5.2	)		$	(6.8	)		$	(7.9	)
	Noncurrent liabilities	(275.4		)		(197.5		)		(119.8		)		(96.5		)
	Net amount recognized	$	(277.8	)		$	(202.7	)		$	(126.6	)		$	(104.4	)
	Amounts recognized in accumulated other comprehensive income:
	Net actuarial loss	$	341.5			$	230.6			$	97.1			$	67
	Prior service cost	10.6				14.9				(42.9		)		(45.4		)
	Net amount recognized	$	352.1			$	245.5			$	54.2			$	21.6
	The estimated amounts that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2015:
	Net actuarial loss	$	22.3							$	6.3
	Prior service cost	2.4								(3.7		)
	Net amount recognized	$	24.7							$	2.6
Fair Value Of Plan Assets, Benefit Obligation And Funded Status
		(In Millions)
		2014
		Pension Plans																			Other Benefits
		Salaried				Hourly				Mining				SERP				Total			Salaried			Hourly			Total
	Fair value of plan assets	$	366.4			$	576.6			$	6.6			$	—			$	949.6		$	—		$	269.3		$	269.3
	Benefit obligation	(471.4		)		(739.2		)		(9.2		)		(7.6		)		(1,227.4		)	(54.0		)	(341.9		)	(395.9		)
	Funded status	$	(105.0	)		$	(162.6	)		$	(2.6	)		$	(7.6	)		$	(277.8	)	$	(54.0	)	$	(72.6	)	$	(126.6	)
		2013
		Pension Plans																			Other Benefits
		Salaried				Hourly				Mining				SERP				Total			Salaried			Hourly			Total
	Fair value of plan assets	$	357.4			$	552.7			$	5.2			$	—			$	915.3		$	—		$	251.8		$	251.8
	Benefit obligation	(427.2		)		(674.8		)		(6.8		)		(9.2		)		(1,118.0		)	(53.6		)	(302.6		)	(356.2		)
	Funded status	$	(69.8	)		$	(122.1	)		$	(1.6	)		$	(9.2	)		$	(202.7	)	$	(53.6	)	$	(50.8	)	$	(104.4	)
Components Of Net Periodic Benefit Cost	Components of Net Periodic Benefit Cost
		(In Millions)
		Pension Benefits												Other Benefits
		2014				2013				2012				2014				2013			2012
	Service cost	$	30.8			$	38.9			$	32			$	6.7			$	12.3		$	14.7
	Interest cost	49.7				45.9				48.4				16.2				17.3			20.6
	Expected return on plan assets	(72.3		)		(65.6		)		(59.5		)		(17.1		)		(20.1		)	(17.7		)
	Amortization:
	Net asset	—				—				—				—				—			(3.0		)
	Prior service costs (credits)	2.7				3				3.9				(3.6		)		(3.6		)	1.9
	Net actuarial loss	14.1				29.9				30.4				5				11.5			11.6
	Curtailments and settlements	2.9				—				—				(7.9		)		—			—
	Special termination benefits	3.4				—				—				—				—			—
	Net periodic benefit cost	$	31.3			$	52.1			$	55.2			$	(0.7	)		$	17.4		$	28.1
	Curtailment effects	—				—				—				(0.8		)		—			—
	Current year actuarial (gain)/loss	121.8				(168.8		)		53.1				36.9				(95.2		)	3.2
	Amortization of net loss	(15.5		)		(29.9		)		(30.4		)		(5.0		)		(11.5		)	(11.6		)
	Current year prior service (credit) cost	(1.5		)		0.8				2.8				(0.9		)		—			(58.3		)
	Amortization of prior service (cost) credit	(2.7		)		(3.0		)		(3.9		)		3.6				3.6			(1.9		)
	Amortization of transition asset	—				—				—				—				—			3
	Total recognized in other comprehensive income	$	102.1			$	(200.9	)		$	21.6			$	33.8			$	(103.1	)	$	(65.6	)
	Total recognized in net periodic cost and other	$	133.4			$	(148.8	)		$	76.8			$	33.1			$	(85.7	)	$	(37.5	)
	comprehensive income
Additional Information	Additional Information
		(In Millions)
		Pension Benefits												Other Benefits
		2014				2013				2012				2014				2013			2012
	Effect of change in mine ownership & noncontrolling interest	$	51.4			$	46.5			$	54.8			$	5.9			$	4.8		$	8.6
	Actual return on plan assets	78.7				109.5				92.5				31.9				11			26.1
Weighted-Average Assumptions Used to Determine Benefit Obligations	Weighted-average assumptions used to determine benefit obligations at December 31 were:
		Pension Benefits				Other Benefits
		2014		2013		2014		2013
	U.S. plan discount rate	3.83%		4.57%		3.83%		4.57%
	Canadian plan discount rate	3.75		4.5		3.75		4.75
	U.S. salaried rate of compensation increase	3		4		3		4
	Canadian rate of compensation increase	3		4		N/A		N/A
	Hourly rate of compensation increase (ultimate)	2.5		3		N/A		N/A
	U.S. expected return on plan assets	8.25		8.25		7		7
	Canadian expected return on plan assets	7.25		7.25		N/A		N/A
Weighted-Average Assumptions Used To Determine Net Benefit Costs	Weighted-average assumptions used to determine net benefit cost for the years 2014, 2013 and 2012 were:
		Pension Benefits						Other Benefits
		2014		2013		2012		2014		2013		2012
	U.S. plan discount rate	4.57	%	3.7	%	4.28	%	4.57	%	3.7	%	4.28/3.51	1%
	Canadian plan discount rate	4.5		3.75		4		4.75		4		4.25
	U.S. expected return on plan assets	8.25		8.25		8.25		7		8.25		8.25
	Canadian expected return on plan assets	7.25		7.25		7.25		N/A		N/A		N/A
	U.S. salaried rate of compensation increase	4		4		4		4		4		4
	U.S. hourly rate of compensation increase	3		4		4		4		4		4
	Canadian rate of compensation increase	4		4		4		4		4		4
	1	4.28 percent for the Salaried Plan. For the Hourly Plan, 4.28 percent from January 1, 2012 through October 31, 2012, and 3.51 percent from November 1, 2012 through December 31, 2012.
Assumed Health Care Cost Trend Rates	Assumed health care cost trend rates at December 31 were:
		2014		2013
	U.S. plan health care cost trend rate assumed for next year	7	%	7.25	%
	Canadian plan health care cost trend rate assumed for next year	4.25		4
	Ultimate health care cost trend rate	5		5
	U.S. plan year that the ultimate rate is reached	2023		2023
	Canadian plan year that the ultimate rate is reached	2018		2018
Effect of One Percentage Point Change in Assumed Health Care Cost Trend Rates	A change of one percentage point in assumed health care cost trend rates would have the following effects:
		(In Millions)
		Increase				Decrease
	Effect on total of service and interest cost	$	3.4			$	(2.7	)
	Effect on postretirement benefit obligation	49.6				(39.9		)
Plan Assets and Asset Allocation	The following table reflects the actual asset allocations for pension and VEBA plan assets as of December 31, 2014 and 2013, as well as the 2015 weighted average target asset allocations as of December 31, 2014. Equity investments include securities in large-cap, mid-cap and small-cap companies located in the U.S. and worldwide. Fixed income investments primarily include corporate bonds and government debt securities. Alternative investments include hedge funds, private equity, structured credit and real estate.
		Pension Assets									VEBA Assets
	Asset Category	2015			Percentage of						2015			Percentage of
		Target			Plan Assets at						Target			Plan Assets at
		Allocation			December 31,						Allocation			December 31,
					2014			2013						2014			2013
	Equity securities	48.2	%		48.6	%		51.5	%		8	%		8.6	%		10.4	%
	Fixed income	28.4	%		29	%		26.7	%		80.1	%		79.3	%		66.6	%
	Hedge funds	6.1	%		6.2	%		6.3	%		4.2	%		4.3	%		9.8	%
	Private equity	5.5	%		3.3	%		3.2	%		2.6	%		2.3	%		2.4	%
	Structured credit	5.9	%		6.9	%		6.7	%		2.1	%		2.3	%		5.4	%
	Real estate	5.9	%		5.3	%		4.5	%		3	%		3.2	%		5.3	%
	Cash	—	%		0.7	%		1.1	%		—	%		—	%		0.1	%
	Total	100	%		100	%		100	%		100	%		100	%		100	%
Fair Value, Assets and Liabilities Measured on Recurring Basis	Pension
	The fair values of our pension plan assets at December 31, 2014 and 2013 by asset category are as follows:
		(In Millions)
		31-Dec-14
	Asset Category	Quoted Prices in Active				Significant Other				Significant				Total
		Markets for Identical				Observable				Unobservable
		Assets/Liabilities				Inputs				Inputs
		(Level 1)				(Level 2)				(Level 3)
	Equity securities:
	U.S. large-cap	$	248.5			$	—			$	—			$	248.5
	U.S. small/mid-cap	55.8				—				—				55.8
	International	157.4				—				—				157.4
	Fixed income	243.7				31.8				—				275.5
	Hedge funds	—				—				59.2				59.2
	Private equity	—				—				31.2				31.2
	Structured credit	—				—				65.4				65.4
	Real estate	—				—				50				50
	Cash	6.6				—				—				6.6
	Total	$	712			$	31.8			$	205.8			$	949.6
		(In Millions)
		31-Dec-13
	Asset Category	Quoted Prices in Active				Significant  Other				Significant				Total
		Markets for Identical				Observable				Unobservable
		Assets/Liabilities				Inputs				Inputs
		(Level 1)				(Level 2)				(Level 3)
	Equity securities:
	U.S. large-cap	$	261.5			$	—			$	—			$	261.5
	U.S. small/mid-cap	60.8				—				—				60.8
	International	149.3				—				—				149.3
	Fixed income	214.8				30.1				—				244.9
	Hedge funds	—				—				57.6				57.6
	Private equity	—				—				29.1				29.1
	Structured credit	—				—				61				61
	Real estate	—				—				40.9				40.9
	Cash	10.2				—				—				10.2
	Total	$	696.6			$	30.1			$	188.6			$	915.3
Effect of Fair Value Measurements Using Significant Unobservable Inputs on Changes in Plan Assets	The following represents the effect of fair value measurements using significant unobservable inputs (Level 3) on changes in plan assets for the years ended December 31, 2014 and 2013:
		(In Millions)
		Year Ended December 31, 2014
		Hedge Funds				Private Equity				Structured				Real				Total
						Funds				Credit Fund				Estate
	Beginning balance — January 1, 2014	$	57.6			$	29.1			$	61			$	40.9			$	188.6
	Actual return on plan assets:
	Relating to assets still held at	3.1				3.2				4.4				5.2				15.9
	the reporting date
	Relating to assets sold during	(1.5		)		3				—				—				1.5
	the period
	Purchases	—				1.4				—				5.4				6.8
	Sales	—				(5.5		)		—				(1.5		)		(7.0		)
	Ending balance — December 31, 2014	$	59.2			$	31.2			$	65.4			$	50			$	205.8
		(In Millions)
		Year Ended December 31, 2013
		Hedge Funds				Private Equity				Structured				Real				Total
						Funds				Credit Fund				Estate
	Beginning balance — January 1, 2013	$	85.6			$	29.3			$	56.2			$	29.4			$	200.5
	Actual return on plan assets:
	Relating to assets still held at	4.5				(2.1		)		33.5				5.1				41
	the reporting date
	Relating to assets sold during	(1.2		)		5.2				(28.7		)		(0.4		)		(25.1		)
	the period
	Purchases	66				14.7				27.5				36.8				145
	Sales	(97.3		)		(18.0		)		(27.5		)		(30.0		)		(172.8		)
	Ending balance — December 31, 2013	$	57.6			$	29.1			$	61			$	40.9			$	188.6
Schedule Of Annual Contributions
			(In Millions)
			Pension				Other Benefits
	Company Contributions		Benefits				VEBA				Direct				Total
											Payments
	2013		$	53.7			$	14.6			$	10.9			$	25.5
	2014		60.5				—				7.3				7.3
	2015 (Expected)*		36.8				—				6.8				6.8
	*	Pursuant to the bargaining agreement, benefits can be paid from VEBA trusts that are at least 70 percent funded (all VEBA trusts are over 70 percent funded at December 31, 2014). Funding obligations have been suspended as Hibbing's, UTAC's, Tilden's and Empire's share of the value of their respective trust assets have reached 90 percent of their obligation.
Estimated Net Periodic Benefit Cost	Estimated Cost for 2015
	For 2015, we estimate net periodic benefit cost as follows:
		(In Millions)
	Defined benefit pension plans	$	23.6
	Other postretirement benefits	6
	Total	$	29.6
Estimated Future Benefit Payments	Estimated Future Benefit Payments
		(In Millions)
		Pension				Other Benefits
		Benefits				Gross				Less				Net
						Company				Medicare				Company
						Benefits				Subsidy				Payments
	2015	$	89.3			$	23.1			$	0.9			$	22.2
	2016	77.7				23				1				22
	2017	78.1				23.2				1.1				22.1
	2018	79.3				23.3				1.3				22
	2019	78.6				22.9				1.4				21.5
	2020-2024	402.4				110.7				8.6				102.1
Other Potential Benefit Obligations	Other Potential Benefit Obligations
	While the foregoing reflects our obligation, our total exposure in the event of non-performance is potentially greater. Following is a summary comparison of the total obligation:
		(In Millions)
		31-Dec-14
		Defined				Other
		Benefit				Benefits
		Pensions
	Fair value of plan assets	$	949.6			$	269.3
	Benefit obligation	(1,227.4		)		(395.9		)
	Underfunded status of plan	$	(277.8	)		$	(126.6	)
	Additional shutdown and early retirement benefits	$	(26.7	)		$	40.5
Veba Trust [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value, Assets and Liabilities Measured on Recurring Basis	The fair values of our other benefit plan assets at December 31, 2014 and 2013 by asset category are as follows:
		(In Millions)
		31-Dec-14
	Asset Category	Quoted Prices in Active				Significant Other				Significant				Total
		Markets for Identical				Observable				Unobservable
		Assets/Liabilities				Inputs				Inputs
		(Level 1)				(Level 2)				(Level 3)
	Equity securities:
	U.S. large-cap	$	11.6			$	—			$	—			$	11.6
	U.S. small/mid-cap	2.9				—				—				2.9
	International	8.6				—				—				8.6
	Fixed income	174.5				39.1				—				213.6
	Hedge funds	—				—				11.5				11.5
	Private equity	—				—				6.2				6.2
	Structured credit	—				—				6.1				6.1
	Real estate	—				—				8.7				8.7
	Cash	0.1				—				—				0.1
	Total	$	197.7			$	39.1			$	32.5			$	269.3
		(In Millions)
		December 31, 2013
	Asset Category	Quoted Prices in Active				Significant Other				Significant				Total
		Markets for Identical				Observable				Unobservable
		Assets/Liabilities				Inputs				Inputs
		(Level 1)				(Level 2)				(Level 3)
	Equity securities:
	U.S. large-cap	$	15.7			$	—			$	—			$	15.7
	U.S. small/mid-cap	2.7				—				—				2.7
	International	7.8				—				—				7.8
	Fixed income	134.4				33.7				—				168.1
	Hedge funds	—				—				24.6				24.6
	Private equity	—				—				6				6
	Structured credit	—				—				13.5				13.5
	Real estate	—				—				13.2				13.2
	Cash	0.2				—				—				0.2
	Total	$	160.8			$	33.7			$	57.3			$	251.8
Effect of Fair Value Measurements Using Significant Unobservable Inputs on Changes in Plan Assets	The following represents the effect of fair value measurements using significant unobservable inputs (Level 3) on changes in plan assets for the year ended December 31, 2014 and 2013:
		(In Millions)
		Year Ended December 31, 2014
		Hedge				Private Equity				Structured Credit Fund				Real				Total
		Funds				Funds								Estate
	Beginning balance — January 1, 2014	$	24.6			$	6			$	13.5			$	13.2			$	57.3
	Actual return on plan assets:
	Relating to assets still held at the reporting date	0.5				1				0.4				0.9				2.8
	Relating to assets sold during the period	0.6				0.4				0.4				0.5				1.9
	Purchases	—				0.1				—				—				0.1
	Sales	(14.2		)		(1.3		)		(8.2		)		(5.9		)		(29.6		)
	Ending balance — December 31, 2014	$	11.5			$	6.2			$	6.1			$	8.7			$	32.5
		(In Millions)
		Year Ended December 31, 2013
		Hedge				Private Equity				Structured Credit Fund				Real				Total
		Funds				Funds								Estate
	Beginning balance — January 1, 2014	$	23.2			$	6.2			$	12.5			$	15.9			$	57.8
	Actual return on plan assets:
	Relating to assets still held at the reporting date	2.1				0.2				2.4				2.8				7.5
	Relating to assets sold during the period	(0.7		)		0.4				(1.4		)		(0.7		)		(2.4		)
	Purchases	22.5				0.3				11				14.2				48
	Sales	(22.5		)		(1.1		)		(11		)		(19.0		)		(53.6		)
	Ending balance — December 31, 2014	$	24.6			$	6			$	13.5			$	13.2			$	57.3

STOCK_COMPENSATION_PLANS_Table

STOCK COMPENSATION PLANS (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock Incentive Plans Disclosure [Table Text Block]	Following is a summary of our performance share award agreements currently outstanding:
	Performance	Performance Shares Granted			Estimated Forfeitures			Expected to Vest			Grant Date		Performance Period
	Share
	Plan Year
	2014	400,000			40,911			359,089			17-Nov-14		8/7/2014 - 12/31/2017
	2014	283,530			24,380			259,150			29-Jul-14		1/1/2014 - 12/31/2016
	2014	124,630			21,098			103,532			12-May-14		1/1/2014 - 12/31/2016
	2014	385,585			120,299			265,286			10-Feb-14		1/1/2014 - 12/31/2016
Incentive Compensation and Other Benefit Plans for Employees and Directors [Table Text Block]	For the last three years, Equity Grant shares have been awarded to elected or re-elected nonemployee Directors as follows:
	Year of Grant		Unrestricted Equity Grant Shares			Restricted Equity Grant Shares			Deferred Equity Grant Shares
	2012		1,498			8,988			2,996
	2013		3,985			31,506			7,970
	2014		—			73,635			—
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]	The following table summarizes the share-based compensation expense that we recorded for continuing operations in 2014, 2013 and 2012:
		(In Millions, except  per
		share amounts)
		2014				2013				2012
	Cost of goods sold and operating expenses	$	7.8			$	6.3			$	4
	Selling, general and administrative expenses	15.9				14.8				16.6
	Reduction of operating income from continuing operations before income	23.7				21.1				20.6
	taxes and equity income (loss) from ventures
	Income tax benefit	(8.3		)		(7.4		)		(7.2		)
	Reduction of net income attributable to Cliffs shareholders	$	15.4			$	13.7			$	13.4
	Reduction of earnings per share attributable to Cliffs shareholders:
	Basic	$	0.1			$	0.09			$	0.09
	Diluted	$	0.1			$	0.08			$	0.09
Schedule Of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions	The following assumptions were utilized to estimate the fair value for the 2014 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)
	February 10, 2014		$	20.58			2.89		54.00%		0.54%		2.92%	$	22.21	107.92%
	May 12, 2014		$	17.54			2.61		54.00%		0.54%		2.92%	$	18.93	107.92%
	July 29, 2014		$	17.62			2.42		51.30%		0.83%		3.40%	$	19.02	107.92%
	November 17, 2014		$	10.85			3.12		52.90%		1.18%		4.30%	$	10.61	97.79%
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]	Restricted share units, restricted stock awards, deferred stock allocation and performance share activity under our long-term equity plans and Directors’ Plans are as follows:
		2014			2013			2012
		Shares			Shares			Shares
	Stock options:
	Outstanding at beginning of year	—			—			—
	Granted during the year	250,000			—			—
	Vested	—			—			—
	Forfeited/canceled	—			—			—
	Outstanding at end of year	250,000			—			—
	Restricted awards:
	Outstanding and restricted at beginning of year	586,084			393,787			425,166
	Granted during the year	531,030			396,844			151,869
	Vested	(423,822	)		(118,973	)		(161,741	)
	Forfeited/canceled	(170,116	)		(85,574	)		(21,507	)
	Outstanding and restricted at end of year	523,176			586,084			393,787
	Performance shares:
	Outstanding at beginning of year	1,040,453			772,484			877,435
	Granted during the year 1	1,233,685			806,271			501,346
	Issued 2	(796,624	)		(289,054	)		(574,518	)
	Forfeited/canceled	(405,138	)		(249,248	)		(31,779	)
	Outstanding at end of year	1,072,376			1,040,453			772,484
	Vested or expected to vest as of	1,723,728
	December 31, 2014
	Directors’ retainer and voluntary shares:
	Outstanding at beginning of year	7,329			2,880			2,611
	Granted during the year	2,281			8,136			1,823
	Forfeited/canceled	—			(1,521	)		—
	Vested	(9,610	)		(2,166	)		(1,554	)
	Outstanding at end of year	—			7,329			2,880
	Reserved for future grants or awards at end
	of year:
	Employee plans	6,222,434
	Directors’ plans	225,955
	Total	6,448,389
	1	The shares granted in 2013 and 2012 include 54,051 shares and 191,506 shares, respectively, related to the 23% and 50% payouts associated with the prior-year pool as actual payout exceeded target.
	2	For the year ended December 31, 2014, the shares vesting on December 31, 2013 were valued as of February 10, 2014, and the shares vesting due to the change in a majority of our Board of Directors that triggered the acceleration of vesting and payout of outstanding equity grants under our equity plans on August 6, 2014, were valued as of that date.
		For the years ended December 31, 2013 and December 31, 2012, the shares vested on December 31, 2012 and December 31, 2011, respectively, and were valued on February 21, 2013 and February 13, 2012, respectively.
Employee Stock Awards Outstanding [Table Text Block]	A summary of our outstanding share-based awards as of December 31, 2014 is shown below:
		Shares			Weighted
					Average
					Grant Date
					Fair Value
	Outstanding, beginning of year	1,633,866				$40.20
	Granted	2,016,996				$16.67
	Vested	(1,230,056	)			$38.48
	Forfeited/expired	(575,254	)			$24.76
	Outstanding, end of year	1,845,552				$16.55

INCOME_TAXES_Tables

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Contingency [Line Items]
Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]	Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures includes the following components:
		(In Millions)
		2014			2013				2012
	United States	$	(1,884.2	)	$	837.7			$	838.6
	Foreign	(7,719.5		)	(348.4		)		(1,340.4		)
		$	(9,603.7	)	$	489.3			$	(501.8	)
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The components of the provision (benefit) for income taxes on continuing operations consist of the following:
		(In Millions)
		2014			2013				2012
	Current provision (benefit):
	United States federal	$	(159.9	)	$	101.3			$	71.1
	United States state & local	(0.6		)	4				7.6
	Foreign	17.2			87.9				50.2
		(143.3		)	193.2				128.9
	Deferred provision (benefit):
	United States federal	(258.9		)	23.3				221.2
	United States state & local	(43.0		)	3				1.4
	Foreign	(856.8		)	(164.4		)		(95.6		)
		(1,158.7		)	(138.1		)		127
	Total provision on income (loss) from continuing	$	(1,302.0	)	$	55.1			$	255.9
	operations
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Reconciliation of our income tax attributable to continuing operations computed at the U.S. federal statutory rate is as follows:
		(In Millions)
		2014						2013						2012
	Tax at U.S. statutory rate of 35 percent	$	(3,361.3	)	35	%		$	171.3			35	%	$	(175.6	)	35	%
	Increase (decrease) due to:
	Foreign exchange remeasurement	(4.1		)	—			(2.6		)		(0.5	)	62.3			(12.4	)
	Non-taxable income related to noncontrolling interests	290.1			(3.0	)		(1.5		)		(0.3	)	61			(12.0	)
	Impact of tax law change	13			(0.1	)		—				—		(357.1		)	71.2
	Percentage depletion in excess of cost depletion	(87.9		)	0.9			(97.6		)		(19.9	)	(109.1		)	21.7
	Impact of foreign operations	592			(6.2	)		(10.2		)		(2.1	)	65.2			(13.0	)
	Income not subject to tax	(46.5		)	0.5			(106.6		)		(21.8	)	(108.0		)	21.5
	Goodwill impairment	22.7			(0.2	)		20.5				4.2		202.2			(40.3	)
	State taxes, net	(43.6		)	0.5			5.6				1.1		7.3			(1.5	)
	Settlement of financial guaranty	(343.3		)	3.6			—				—		—			—
	Manufacturer’s deduction	—			—			(7.9		)		(1.6	)	(4.7		)	0.9
	Valuation allowance	1,660.60			(17.3	)		73				14.9		634.5			(126.5	)
	Tax uncertainties	0.2			—			19.6				5.3		(14.8		)	2.9
	Prior year adjustment in current year	(10.4		)	0.1			(11.4		)		(3.6	)	(5.7		)	1.1
	Other items — net	16.5			(0.2	)		2.9				0.6		(1.6		)	0.4
	Income tax (benefit) expense	$	(1,302.0	)	13.6	%		$	55.1			11.3	%	$	255.9		(51.0	)%
Income Taxes Other Than Continuing Operations Disclosure Text Block [Table Text Block]	The components of income taxes for other than continuing operations consisted of the following:
		(In Millions)
		2014			2013				2012
	Other comprehensive (income) loss:
	Pension/OPEB liability	$	39.8		$	100			$	13.8
	Mark-to-market adjustments	3.6			2				1.7
	Other	(1.1		)	(12.4		)		2.6
	Total	$	42.3		$	89.6			$	18.1
	Paid in capital — acquisition of noncontrolling interest	$	—		$	102.1			$	—
	Paid in capital — stock based compensation	$	(4.8	)	$	3.5			$	(12.8	)
	Discontinued Operations	$	—		$	(2.0	)		$	10.4
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	Significant components of our deferred tax assets and liabilities as of December 31, 2014 and 2013 are as follows:
		(In Millions)
		2014			2013
	Deferred tax assets:
	Pensions	$	108.3		$	88.4
	MRRT starting base allowance	—			300.3
	Postretirement benefits other than pensions	63			58
	Alternative minimum tax credit carryforwards	267.7			299.2
	Investments in ventures	6			—
	Asset retirement obligations	48.9			61.7
	Operating loss carryforwards	1,083.50			524.4
	Product inventories	32.3			16.4
	Property, plant and equipment and mineral rights	901.6			56
	State and local	41.9			—
	Lease liabilities	14.1			31.9
	Other liabilities	153.6			138.3
	Total deferred tax assets before valuation allowance	2,720.90			1,574.60
	Deferred tax asset valuation allowance	(2,224.5		)	(864.1		)
	Net deferred tax assets	496.4			710.5
	Deferred tax liabilities:
	Property, plant and equipment and mineral rights	(20.0		)	(1,400.8		)
	Investment in ventures	(198.0		)	(196.4		)
	Intangible assets	(7.3		)	(33.5		)
	Income tax uncertainties	(49.5		)	(48.5		)
	Product inventories	(16.6		)	(12.8		)
	Other assets	(80.2		)	(93.0		)
	Total deferred tax liabilities	(371.6		)	(1,785.0		)
	Net deferred tax assets (liabilities)	$	124.8		$	(1,074.5	)
Deferred Tax Assets and Liabilities by Location [Table Text Block]	The deferred tax amounts are classified in the Statements of Consolidated Financial Position as current or long-term consistently with the underlying asset or liability that generates the basis difference between financial reporting and tax. Following is a summary:
		(In Millions)
		2014			2013
	Deferred tax assets:
	United States	$	165.9		$	7.2
	Foreign
	Current	2.2			29.4
	Long-term	12			41.5
	Total deferred tax assets	180.1			78.1
	Deferred tax liabilities:
	United States	—			175.3
	Foreign
	Current	4			6.1
	Long-term	51.3			971.2
	Total deferred tax liabilities	55.3			1,152.60
	Net deferred tax assets (liabilities)	$	124.8		$	(1,074.5	)
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:
		(In Millions)
		2014			2013				2012
	Unrecognized tax benefits balance as of January 1	$	74.4		$	55.5			$	102.1
	Increases for tax positions in prior years	3.4			13.6				2.7
	Increases for tax positions in current year	2.5			5.3				11.1
	Increase due to foreign exchange	(0.2		)	—				—
	Settlements	(0.5		)	—				(60.4		)
	Lapses in statutes of limitations	(3.7		)	—				—
	Other	(1.2		)	—				—
	Unrecognized tax benefits balance as of December 31	$	74.7		$	74.4			$	55.5

LEASE_OBLIGATIONS_Tables

LEASE OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2014
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 December 31, 2014 are as follows:
		(In Millions)
		Capital Leases			Operating Leases
	2015	$	84.8		$	12
	2016	34.1			9.3
	2017	26.9			8.4
	2018	20.4			6.8
	2019	11.4			4.8
	2020 and thereafter	21			9.9
	Total minimum lease payments	$	198.6		$	51.2
	Amounts representing interest	31.3
	Present value of net minimum lease payments	$	167.3	-1
	-1	The total is comprised of $74.5 million and $92.8 million classified as Current portion of capital leases and Other liabilities, respectively, in the Statements of Unaudited Condensed Consolidated Financial Position at December 31, 2014.

ENVIRONMENTAL_AND_MINE_CLOSURE1

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Environmental Remediation Obligations [Abstract]
Summary Of Mine Closure Obligations	The following is a summary of the obligations as of December 31, 2014 and 2013:
		(In Millions)
		December 31,
		2014			2013
	Environmental	$	5.5		$	8.4
	Mine closure
	LTVSMC	22.9			22
	Operating mines:
	U.S. Iron Ore	120.9			152.2
	Asia Pacific Iron Ore	21.5			25.5
	North American Coal	33.9			34.7
	Eastern Canadian Iron Ore	56.5			78.2
	Total mine closure	255.7			312.6
	Total environmental and mine closure obligations	261.2			321
	Less current portion	5.2			11.3
	Long-term environmental and mine closure obligations	$	256		$	309.7
Asset Retirement Obligation Disclosure	The following represents a roll forward of our asset retirement obligation liability related to our active mining locations for the years ended December 31, 2014 and 2013:
		(In Millions)
		December 31,
		2014			2013
	Asset retirement obligation at beginning of period	$	290.6		$	231.1
	Accretion expense	14.5			18.1
	Exchange rate changes	(2.4		)	(3.4		)
	Revision in estimated cash flows	(65.2		)	44.8
	Disposal of CLCC Assets	(4.7		)	$	—
	Asset retirement obligation at end of period	$	232.8		$	290.6

GOODWILL_AND_OTHER_INTANGIBLE_1

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Tables)	12 Months Ended
	Dec. 31, 2014
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 years ended December 31, 2014 and December 31, 2013:
		(In Millions)
		31-Dec-14																				December 31, 2013
		U.S. Iron Ore				Eastern Canadian Iron Ore				Asia Pacific				Other				Total				U.S. Iron Ore				Eastern			Asia Pacific Iron Ore			Other			Total
										Iron Ore																Canadian Iron Ore
	Beginning Balance	$	2			$	—			$	72.5			$	—			$	74.5			$	2			$	—		$	84.5		$	80.9		$	167.4
	Arising in business combinations	—				—				—				—				—				—				—			—			—			—
	Impairment	—				—				(73.5		)		—				(73.5		)		—				—			—			(80.9		)	(80.9		)
	Impact of foreign currency translation	—				—				1				—				1				—				—			(12.0		)	—			(12.0		)
	Ending Balance	$	2			$	—			$	—			$	—			$	2			$	2			$	—		$	72.5		$	—		$	74.5
	Accumulated Goodwill Impairment Loss	$	—			$	(1,000.0	)		$	(73.5	)		$	(80.9	)		$	(1,154.4	)		$	—			$	(1,000.0	)	$	—		$	(80.9	)	$	(1,080.9	)
Schedule Of Finite-Lived Intangible Assets By Major Class	Following is a summary of intangible assets and liabilities as of December 31, 2014 and December 31, 2013:
				(In Millions)
				31-Dec-14												31-Dec-13
		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		$	79.2			$	(16.5	)		$	62.7			$	127.4			$	(35.9	)		$	91.5
	Utility contracts	Other non-current assets		—				—				—				54.7				(53.1		)		1.6
	Leases	Other non-current assets		—				—				—				2.4				(0.1		)		2.3
	Total intangible assets			$	79.2			$	(16.5	)		$	62.7			$	184.5			$	(89.1	)		$	95.4
	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		)		159.7				(46.2		)
	Total below-market sales contracts			$	(228.9	)		$	182.8			$	(46.1	)		$	(228.9	)		$	159.7			$	(69.2	)
Estimated Amortization Expense Relating To Intangible Assets	The estimated amortization expense relating to intangible assets for each of the five succeeding years is as follows:
		(In Millions)
		Amount
	Year Ending December 31
	2015	4.1
	2016	4.2
	2017	4
	2018	3.8
	2019	3.5
	Total	$	19.6
Schedule Of Earnings To Be Recognized On Below-Market Sales Contract	The following amounts are estimated to be recognized in Product revenues for each of the two succeeding fiscal years:
		(In Millions)
		Amount
	Year Ending December 31
	2015	23
	2016	23.1
	Total	$	46.1

DERIVATIVE_INSTRUMENTS_AND_HED1

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Tables)	12 Months Ended
	Dec. 31, 2014
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 Consolidated Financial Position as of December 31, 2014 and December 31, 2013:
		(In Millions)
		Derivative Assets												Derivative Liabilities
		December 31, 2014						December 31, 2013						December 31, 2014				31-Dec-13
	Derivative	Balance Sheet Location		Fair				Balance		Fair				Balance Sheet	Fair			Balance Sheet		Fair
	Instrument			Value				Sheet		Value				Location	Value			Location		Value
								Location
	Derivatives designated as hedging instruments under ASC 815:
	Interest-Rate Swaps			$	—					$	—			Other current liabilities	$	—				$	2.1
	Foreign Exchange Contracts	Other current assets		—				Other current assets		0.3				Other current liabilities	21.6			Other current liabilities		25.8
	Total derivatives designated as hedging instruments under ASC 815			$	—					$	0.3				$	21.6				$	27.9
	Derivatives not designated as hedging instruments under ASC 815:
	Foreign Exchange Contracts			$	—					$	—			Other current liabilities	$	9.9		Other current liabilities		$	1.1
	Customer Supply Agreements	Other current assets		63.2				Other current assets		55.8					—					—
	Provisional Pricing Arrangements	Other current assets		—				Other current assets		3.1				Other current liabilities	11.8			Other current liabilities		10.3
	Total derivatives not designated as hedging instruments under ASC 815:			$	63.2					$	58.9				$	21.7				$	11.4
	Total derivatives			$	63.2					$	59.2				$	43.3				$	39.3
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 Consolidated Operations for the years ended December 31, 2014, 2013 and 2012:
		(In Millions)
	Derivatives in Cash Flow	Amount of Gain (Loss)												Location of Gain (Loss)	Amount of Gain (Loss)
		Recognized in OCI on Derivative												Reclassified	Reclassified
														from Accumulated OCI into Earnings	from Accumulated
															OCI into Earnings
	Hedging Relationships	(Effective Portion)												(Effective Portion)	(Effective Portion)
		Year Ended													Year Ended
		December 31,													December 31,
		2014				2013				2012					2014			2013				2012
	Australian Dollar Foreign	$	(13.9	)		$	(34.7	)		$	20.2			Product revenues	$	(13.2	)	$	(11.9	)		$	14.8
	Exchange Contracts
	(hedge designation)
	Canadian Dollar Foreign Exchange Contracts	—				(12.9		)		6.7				Cost of goods sold and operating expenses	—			(8.2		)		3.3
	(hedge designation)
	Canadian Dollar Foreign	(14.3		)		(4.1		)		—				Cost of goods sold and operating expenses	(17.7		)	(1.9		)		—
	Exchange Contracts
	(prior to de-designation)
	Treasury Locks	—				—				(1.3		)		Other non-operating income (expense)	(0.1		)	(0.1		)		—
	Total	$	(28.2	)		$	(51.7	)		$	25.6				$	(31.0	)	$	(22.1	)		$	18.1
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 Consolidated Operations for the years ended December 31, 2014, 2013 and 2012:
	(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
			Year Ended
			December 31,
			2014				2013				2012
	Foreign Exchange Contracts	Cost of goods sold and operating expenses	$	(16.9	)		$	(0.6	)		$	—
	Foreign Exchange Contracts	Other income (expense)	—				—				0.3
	Foreign Exchange Contracts	Income and Gain on Sale from Discontinued Operations, net of tax	—				—				(0.3		)
	Treasury Locks	Other non-operating income (expense)	—				—				(0.4		)
	Customer Supply Agreements	Product revenues	187.8				149.2				171.4
	Provisional Pricing Arrangements	Product revenues	(11.8		)		(7.2		)		(7.8		)
	Total		$	159.1			$	141.4			$	163.2

DISCONTINUED_OPERATIONS_Tables

DISCONTINUED OPERATIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Income from Continuing Operations of Disposal Groups not Classified as Discontinued Operations [Table Text Block]	As required, the Income (Loss) from Continuing Operations Before Income Taxes and Equity Income (Loss) from Ventures for Wabush and CLCC are presented below:
		(In Millions)
		Year Ended December 31,
		2014			2013			2012
	INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND EQUITY INCOME (LOSS) FROM VENTURES
	Wabush	$	(345.6	)	$	(258.6	)	$	(131.8	)
	CLCC	$	(669.9	)	$	(55.0	)	$	(41.8	)
Discontinued Operations, Statements of Consolidated Financial Position and Statements of Consolidated Operations Information	The following table presents detail of our operations related to our Sonoma operations in the Statements of Consolidated Operations:
		(In Millions)
		Year Ended December 31,
		2014			2013			2012
	REVENUES FROM PRODUCT SALES AND SERVICES
	Product	$	—		$	—		$	151.6
	GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	—			—			38
	INCOME (LOSS) FROM DISCONTINUED OPERATIONS, net of tax	—			2			(2.1		)
	INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	$	—		$	2		$	35.9

ACCUMULATED_OTHER_COMPREHENSIV1

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) ACCUMULATED OTHERCOMPREHENSIVE INCOME (LOSS) (Tables)	12 Months Ended
	Dec. 31, 2014
Equity [Abstract]
Schedule of Accumulate Other Comprehensive Income (Loss) and Related Tax Effects [Table Text Block]	The components of Accumulated other comprehensive income (loss) within Cliffs shareholders’ equity and related tax effects allocated to each are shown below as of December 31, 2014, 2013 and 2012:
		(In Millions)
		Pre-tax				Tax				After-tax
		Amount				Benefit				Amount
						(Provision)
	As of December 31, 2012:
	Postretirement benefit liability	$	(576.7	)		$	194			$	(382.7	)
	Foreign currency translation adjustments	316.3				—				316.3
	Unrealized net gain on derivative financial instruments	12.4				(3.7		)		8.7
	Unrealized gain on securities	3.3				(1.2		)		2.1
		$	(244.7	)		$	189.1			$	(55.6	)
	As of December 31, 2013:
	Postretirement benefit liability	$	(299.3	)		$	94.4			$	(204.9	)
	Foreign currency translation adjustments	106.7				—				106.7
	Unrealized net gain on derivative financial instruments	(30.0		)		9.1				(20.9		)
	Unrealized gain on securities	9.3				(3.1		)		6.2
		$	(213.3	)		$	100.4			$	(112.9	)
	As of December 31, 2014:
	Postretirement benefit liability	$	(425.3	)		$	134.2			$	(291.1	)
	Foreign currency translation adjustments	64.4				—				64.4
	Unrealized net loss on derivative financial instruments	(25.9		)		7.8				(18.1		)
	Unrealized gain on securities	(1.3		)		0.3				(1.0		)
		$	(388.1	)		$	142.3			$	(245.8	)
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following tables reflect the changes in Accumulated other comprehensive income (loss) related to Cliffs shareholders’ equity for December 31, 2014, 2013 and 2012:
		(In Millions)
		Postretirement Benefit Liability, 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	)
	Other comprehensive loss before reclassifications	(1.4		)		(2.4		)		19.7			9.7			25.6
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	4				(1.3		)		—			6.6			9.3
	Balance June 30, 2014	$	(199.4	)		$	6.4			$	166.9		$	5.9		$	(20.2	)
	Other comprehensive income (loss) before reclassifications	3.5				1.3				(65.9		)	(20.0		)	(81.1		)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	7.6				(7.1		)		—			(0.6		)	(0.1		)
	Balance September 30, 2014	$	(188.3	)		$	0.6			$	101		$	(14.7	)	$	(101.4	)
	Other comprehensive income (loss) before reclassifications	$	(98.7	)		$	(1.4	)		$	(36.6	)	$	(15.6	)	$	(152.3	)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	$	(4.1	)		$	(0.2	)		$	—		$	12.2		$	7.9
	Balance December 31, 2014	$	(291.1	)		$	(1.0	)		$	64.4		$	(18.1	)	$	(245.8	)
		(In Millions)
		Postretirement Benefit Liability, 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, 2012	$	(382.7	)		$	2.1			$	316.3		$	8.7		$	(55.6	)
	Other comprehensive income (loss) before reclassifications	(1.1		)		2.5				3.3			(5.0		)	(0.3		)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	6.4				0.1				—			(2.0		)	4.5
	Balance March 31, 2013	$	(377.4	)		$	4.7			$	319.6		$	1.7		$	(51.4	)
	Other comprehensive loss before reclassifications	(1.5		)		(2.0		)		(152.0		)	(42.2		)	(197.7		)
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	8.1				3.6				—			(2.2		)	9.5
	Balance June 30, 2013	$	(370.8	)		$	6.3			$	167.6		$	(42.7	)	$	(239.6	)
	Other comprehensive income (loss) before reclassifications	(0.6		)		3.5				22.8			12.1			37.8
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	6.3				0.9				—			16.2			23.4
	Balance September 30, 2013	$	(365.1	)		$	10.7			$	190.4		$	(14.4	)	$	(178.4	)
	Other comprehensive income (loss) before reclassifications	$	154.5			$	(4.9	)		$	(83.7	)	$	(16.6	)	$	49.3
	Net loss (gain) reclassified from accumulated other comprehensive income (loss)	$	5.7			$	0.4			$	—		$	10.1		$	16.2
	Balance December 31, 2013	$	(204.9	)		$	6.2			$	106.7		$	(20.9	)	$	(112.9	)
		(In Millions)
		Postretirement Benefit Liability, net of tax				Unrealized Net Gain (Loss) on Securities, net of tax				Unrealized Net Gain on Foreign Currency Translation			Net Unrealized Gain on Derivative Financial Instruments, net of tax			Accumulated Other Comprehensive Income (Loss)
	Balance December 31, 2011	$	(408.9	)		$	2.6			$	312.5		$	1.2		$	(92.6	)
	Change during 2012	26.2				(0.5		)		3.8			7.5			37
	Balance December 31, 2012	$	(382.7	)		$	2.1			$	316.3		$	8.7		$	(55.6	)
Details of Accumulated Other Comprehensive Income (Loss) Components [Table Text Block]	he following table reflects the details about Accumulated other comprehensive income (loss) components related to Cliffs shareholders’ equity for the year ended December 31, 2014:
			(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
			Year Ended				Year Ended
			31-Dec-14				31-Dec-13
	Amortization of Pension and Postretirement Benefit Liability:
	Prior service costs		$	(0.9	)		$	(0.6	)		-1
	Net actuarial loss		19.1				41.4				-1
	Curtailments/Settlements		(5.0		)		—				-1
	Special termination benefits		3.4				—				-1
			16.6				40.8				Total before taxes
			(5.8		)		(14.3		)		Income tax benefit (expense)
			$	10.8			$	26.5			Net of taxes
	Unrealized gain (loss) on marketable securities:
	Sale of marketable securities		$	(11.4	)		$	(0.2	)		Other non-operating income (expense)
	Impairment		(0.5		)		5.3				Other non-operating income (expense)
			(11.9		)		5.1				Total before taxes
			3.4				(0.1		)		Income tax benefit (expense)
			$	(8.5	)		$	5			Net of taxes
	Unrealized gain (loss) on derivative financial instruments:
	Australian dollar foreign exchange contracts		$	18.9			$	17			Product revenues
	Canadian dollar foreign exchange contracts		26.7				15.3				Cost of goods sold and operating expenses
			45.6				32.3				Total before taxes
			(14.6		)		(10.2		)		Income tax benefit (expense)
			$	31			$	22.1			Net of taxes
	Total Reclassifications for the Period		$	33.3			$	53.6
	-1	These accumulated other comprehensive income components are included in the net periodic benefit cost recognized for the year ended December 31, 2014 and 2013. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

CASH_FLOW_INFORMATION_Tables

CASH FLOW INFORMATION (Tables)	12 Months Ended
	Dec. 31, 2014
Supplemental Cash Flow Information [Abstract]
Supplemental Cash Flow Disclosures	Cash payments for interest and income taxes in 2014, 2013 and 2012 are as follows:
		(In Millions)
		2014			2013			2012
	Taxes paid on income	$	47.3		$	153.3		$	443.2
	Interest paid on debt obligations	176.5			174.4			207.5
	A reconciliation of capital additions to cash paid for capital expenditures for the years ended December 31, 2014, 2013 and 2012 is as follows:
		(In Millions)
		Year Ended December 31,
		2014			2013			2012
	Capital additions	$	235.5		$	752.3		$	1,335.30
	Cash paid for capital expenditures	284.1			861.6			1,127.50
	Difference	$	(48.6	)	$	(109.3	)	$	207.8
	Non-cash accruals	$	(58.5	)	$	(109.3	)	$	152.5
	Capital leases	9.9			—			55.3
	Total	$	(48.6	)	$	(109.3	)	$	207.8

RELATED_PARTIES_Tables

RELATED PARTIES (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Summary Of Other Ownership Interests	The following is a summary of the mine ownership of these iron ore mines at December 31, 2014:
	Mine		Cliffs Natural Resources		ArcelorMittal			U.S. Steel Canada			WISCO
	Empire		79	%	21	%		—			—
	Tilden		85	%	—			15	%		—
	Hibbing		23	%	62.3	%		14.7	%		—
	Bloom Lake		82.8	%	—			—			17.2	%
Summary Of Related Party Transactions Table Disclosure	Product revenues from related parties were as follows:
		(In Millions)
		Year Ended December 31,
		2014			2013				2012
	Product revenues from related parties	$	1,378.70		$	1,664.80			$	1,660.80
	Total product revenues	4,230.80			5,346.60				5,520.90
	Related party product revenue as a percent of total product revenue	32.6		%	31.1		%		30.1		%

EARNINGS_PER_SHARE_Tables

EARNINGS PER SHARE (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share [Abstract]
Earnings Per Share Computation	The following table summarizes the computation of basic and diluted earnings per share attributable to Cliffs shareholders:
		(In Millions, Except Per Share Amounts)
		Year Ended December 31,
		2014			2013			2012
	Net Income (Loss) from Continuing Operations	$	(7,224.2	)	$	411.5		$	(935.3	)
	attributable to Cliffs shareholders
	Income (Loss) and Gain on Sale from Discontinued	—			2			35.9
	Operations, net of tax
	NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	$	(7,224.2	)	$	413.5		$	(899.4	)
	PREFERRED STOCK DIVIDENDS	(51.2		)	(48.7		)	—
	NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	$	(7,275.4	)	$	364.8		$	(899.4	)
	Weighted Average Number of Shares:
	Basic	153.1			151.7			142.4
	Depositary Shares	—			0.5			—
	Employee Stock Plans	—			22.1			—
	Diluted	153.1			174.3			142.4
	Earnings (loss) per Common Share Attributable to
	Cliffs Common Shareholders - Basic:
	Continuing operations	$	(47.52	)	$	2.39		$	(6.57	)
	Discontinued operations	—			0.01			0.25
		$	(47.52	)	$	2.4		$	(6.32	)
	Earnings (loss) per Common Share Attributable to
	Cliffs Common Shareholders - Diluted:
	Continuing operations	$	(47.52	)	$	2.36		$	(6.57	)
	Discontinued operations	—			0.01			0.25
		$	(47.52	)	$	2.37		$	(6.32	)
	The diluted earnings per share calculation excludes 25.2 million depositary shares that were anti-dilutive for the year ended December 31, 2014. Additionally, the diluted earnings per share calculation excludes 0.7 million shares for the year ended December 31, 2014 related to equity plan awards that were anti-dilutive. There was no anti-dilution for the year ended December 31, 2013. For the year ended December 31, 2012, the diluted earnings per share calculation excludes 0.5 million shares related to equity plan awards that were anti-dilutive.

QUARTERLY_RESULTS_OF_OPERATION1

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) QUARTERLY RESULTS OF OPERATIONS (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	The sum of quarterly EPS may not equal EPS for the year due to discrete quarterly calculations.
		(In Millions, Except Per Share Amounts)
		2014
		Quarters
		First			Second			Third			Fourth			Year
	Revenues from product sales and services	$	940		$	1,100.80		$	1,298.20		$	1,284.70		$	4,623.70
	Sales margin	63.2			92			127.5			168.7			451.4
	Net Income (Loss) from Continuing Operations	$	(70.3	)	$	10.9		$	(5,879.6	)	$	(1,285.1	)	$	(7,224.2	)
	attributable to Cliffs shareholders
	Income from Discontinued Operations	—			—			—			—			—
	Net Income (Loss) Attributable to Cliffs Shareholders	$	(70.3	)	$	10.9		$	(5,879.6	)	$	(1,285.1	)	$	(7,224.2	)
	Preferred Stock Dividends	$	(12.8	)	$	(12.8	)	$	(12.8	)	$	(12.8	)	$	(51.2	)
	Net Income (Loss) Attributable to Cliffs Common Shareholders	$	(83.1	)	$	(1.9	)	$	(5,892.4	)	$	(1,297.9	)	$	(7,275.4	)
	Earnings per common share attributable to
	Cliffs common shareholders — Basic:
	Continuing Operations	$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	Discontinued Operations	—			—			—			—			—
		$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	Earnings per common share attributable to
	Cliffs common shareholders — Diluted:
	Continuing Operations	$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	Discontinued Operations	—			—			—			—			—
		$	(0.54	)	$	(0.01	)	$	(38.49	)	$	(8.48	)	$	(47.52	)
	The diluted earnings per share calculation for all quarters of 2014 exclude depositary shares that were anti-dilutive totaling 25.2 million million and equity plan awards ranging between 0.3 million and 0.8 million each quarter that were anti-dilutive.
		2013
		Quarters
		First			Second			Third			Fourth			Year
	Revenues from product sales and services	$	1,140.50		$	1,488.50		$	1,546.60		$	1,515.80		$	5,691.40
	Sales margin	237.9			268.2			348.7			294.5			1,149.30
	Net Income (Loss) from Continuing Operations	$	107		$	146		$	115.2		$	43.3		$	411.5
	attributable to Cliffs shareholders
	Income (Loss) and Gain on Sale from	—			—			2			—			2
	Discontinued Operations, net of tax
	Net Income Attributable to Cliffs Shareholders	$	107		$	146		$	117.2		$	43.3		$	413.5
	Earnings per common share attributable to
	Cliffs common shareholders — Basic:
	Continuing Operations	$	0.66		$	0.87		$	0.67		$	0.2		$	2.39
	Discontinued Operations	—			—			0.01			—			0.01
		$	0.66		$	0.87		$	0.68		$	0.2		$	2.4
	Earnings per common share attributable to
	Cliffs common shareholders — Diluted:
	Continuing Operations	$	0.66		$	0.82		$	0.65		$	0.2		$	2.36
	Discontinued Operations	—			—			0.01			—			0.01
		$	0.66		$	0.82		$	0.66		$	0.2		$	2.37
	The diluted earnings per share calculation for the first and fourth quarters of 2013 exclude depositary shares that were anti-dilutive totaling 12.9 million and 25.2 million, respectively.

BASIS_OF_PRESENTATION_AND_SIGN3

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Narrative) (Details)

12 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

12 Months Ended

12 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Jul. 10, 2012

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

USD ($)

USD ($)

USD ($)

Northern Lands [Member]

Amapa [Member]

Amapa [Member]

U.S. Iron Ore [Member]

U.S. Iron Ore [Member]

U.S. Iron Ore [Member]

Asia Pacific [Member]

Asia Pacific Iron Ore [Member]

Asia Pacific Iron Ore [Member]

Asia Pacific Iron Ore [Member]

Asia Pacific Iron Ore [Member]

Asia Pacific Iron Ore [Member]

Other Segment [Member]

Other Segment [Member]

Other Segment [Member]

North American Coal [Member]

North American Coal [Member]

North American Coal [Member]

Eastern Canadian Iron Ore [Member]

Eastern Canadian Iron Ore [Member]

Eastern Canadian Iron Ore [Member]

Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]

CQIM Reporting Unit [Member]

Wabush [Member]

Wabush [Member]

Sonoma [Member]

Sonoma [Member]

Empire [Member]

Big Daddy Chromite Deposit [Member]

CLCC [Member]

Wabush [Member]

Bloom Lake [Member]

Bloom Lake [Member]

Bloom Lake [Member]

Bloom Lake [Member]

Bloom Lake [Member]

Investments in Ventures [Member]

Low Volatile Metallurgical Coal Mines [Member]

High volatile metallurgical coal mines [Member]

Thermal Coal Mines [Member]

Take or Pay Contracts [Member]

Take or Pay Contracts [Member]

Customer Supplemental Payments [Member]

Customer Supplemental Payments [Member]

Wisco [Member]

Wisco [Member]

Bloom Lake [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Cockatoo [Member]

Cockatoo [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Asia Pacific Coal [Member]

Asia Pacific Coal [Member]

USD ($)

USD ($)

USD ($)

USD ($)

Amapa [Member]

North American Coal [Member]

North American Coal [Member]

North American Coal [Member]

USD ($)

USD ($)

U.S. Iron Ore [Member]

U.S. Iron Ore [Member]

USD ($)

USD ($)

Other Machinery and Equipment [Member]

Electric Power Facilities [Member]

Land Improvements [Member]

Equipment [Member]

Other Machinery and Equipment [Member]

Electric Power Facilities [Member]

Land Improvements [Member]

Equipment [Member]

Facility

T

Facility

USD ($)

AUD

Facility

AUD

Facility

Facility

Facility

USD ($)

USD ($)

T

Related Party Transaction [Line Items]

Tangible Asset Impairment Charges

$8,839,000,000

$145,100,000

Impairment of Long-Lived Assets Held-for-use

140,100,000

49,900,000

Inventory Valuation Reserves

68,200,000

63,400,000

Number Of Mines

5

1

2

2

2

1

Trading Day Window Determining Number of Common Shares Issuable on Conversion

20

Depositary Share Interest in a Share of 7% Series A Mandatory Convertible Preferred Stock, Class A

0.025

Current Fiscal Year End Date

-19

Deferred Revenue

29,300,000

13,500,000

102,800,000

115,600,000

Ownership Interest

45.00%

Increase in Subsidiary or Equity Method Investee Percentage Ownership Acquired

7.80%

Units Issued by CQIM to Bloom Lake for Acquisition of Noncontrolling Interest

457,556

Ownership interest, equity method investment

30.00%

Total percentage of Amapa sold

100.00%

Equity Method Investment, Other than Temporary Impairment

0

0

-365,400,000

21,500,000

67,600,000

-365,400,000

Proceeds from sale of economic interest (in AUD)

4

141,000,000

Estimated rehabilitation costs

18,600,000

Goodwill

2,000,000

74,500,000

167,400,000

2,000,000

2,000,000

2,000,000

0

72,500,000

84,500,000

0

0

80,900,000

0

0

0

Reimbursement Revenue

392,900,000

344,800,000

351,800,000

271,000,000

259,500,000

250,800,000

6,900,000

115,000,000

85,800,000

101,000,000

Allowance for Doubtful Accounts Receivable

8,100,000

8,100,000

Provision for Doubtful Accounts

0

0

9,000,000

Quantity Of Finished Goods

1,400,000

1,200,000

Derivative, Policy, Percentage of Amount Permitted to be Hedged

75.00%

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%

Deferred Revenue, Current

12,800,000

12,800,000

Deferred Revenue, Noncurrent

90,000,000

102,800,000

Asset Impairment Charges

9,029,900,000

250,800,000

1,049,900,000

154,600,000

Noncontrolling Interest, Ownership Percentage by Parent

79.00%

70.00%

100.00%

100.00%

75.00%

82.80%

Subsidiary Or Equity Method Investee Percentage Ownership Acquired

17.15%

Increase/Decrease in Equity for WISCO/Bloom Lake through Acquisition of Noncontrolling Interest

314,800,000

Increase to Cliffs' Shareholders Equity through Acquisition of Noncontrolling Interest

314,800,000

Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition

45,100,000

Change in Basic EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition

$0.29

$0.30

$0

$0.07

Change in Diluted EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition

$0.26

$0.25

$0.07

Goodwill, Impairment Loss

73,500,000

80,900,000

0

0

73,500,000

0

-80,900,000

0

0

80,900,000

997,300,000

Property, Plant and Equipment, Useful Life

10 years

10 years

20 years

3 years

45 years

45 years

45 years

20 years

Impairment of Intangible Assets (Excluding Goodwill)

$15,500,000

$14,500,000

$9,500,000

BASIS_OF_PRESENTATION_AND_SIGN4

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Schedule Of Subsidiaries) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2012
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/ QuC)bec, 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	QuC)bec, Canada
Noncontrolling Interest, Ownership Percentage by Parent	82.80%	75.00%
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
CLCC [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
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)

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

USD ($)

USD ($)

Asia Pacific Iron Ore [Member]

Asia Pacific Iron Ore [Member]

Investments in Ventures [Member]

Investments in Ventures [Member]

Investments in Ventures [Member]

Investments in Ventures [Member]

Other Noncurrent Liabilities [Member]

Other Noncurrent Liabilities [Member]

Facility

Cockatoo [Member]

Amapa [Member]

Hibbing [Member]

Other Equity Investees [Member]

Other Equity Investees [Member]

Hibbing [Member]

Hibbing [Member]

AUD

USD ($)

USD ($)

USD ($)

USD ($)

Schedule of Equity Method Investments [Line Items]

Ownership interest, equity method investment

30.00%

23.00%

[1]

Total percentage of Amapa sold

100.00%

Investment

$7,000,000

$30,800,000

$3,900,000

$34,700,000

$3,100,000

[1]

($3,900,000)

[1]

Proceeds from sale of economic interest (in AUD)

4

Number Of Mines

1

[1]

1 At December 31, 2013, the classification for Hibbing was Other liabilities.

BASIS_OF_PRESENTATION_AND_SIGN6

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Schedule of Intangible Asset Lives) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
All Other Segments [Member] | Permits [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
All Other Segments [Member] | Permits [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	40 years
All Other Segments [Member] | Utility Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
All Other Segments [Member] | Leases [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	4 years 6 months
All Other Segments [Member] | Leases [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	17 years 6 months
Amapa [Member] | Investments in Ventures [Member]
Finite-Lived Intangible Assets [Line Items]
Ownership interest, equity method investment		30.00%

BASIS_OF_PRESENTATION_AND_SIGN7

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Depreciation Methods and Useful Lives) (Details)	12 Months Ended
	Dec. 31, 2014
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	45 years
Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Other Machinery and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Other Machinery and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	45 years
Electric Power Facilities [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Electric Power Facilities [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	45 years
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	45 years
Computer Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Computer Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	15 years

BASIS_OF_PRESENTATION_AND_SIGN8

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Revenue Reimbursement) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reimbursement Revenue	$392.90	$344.80	$351.80
U.S. Iron Ore [Member]
Reimbursement Revenue	271	259.5	250.8
U.S. Iron Ore [Member] | Freight Revenue [Member]
Reimbursement Revenue	163	177.3	142
U.S. Iron Ore [Member] | Co-venturer [Member]
Reimbursement Revenue	$108	$82.20	$108.80

SEGMENT_REPORTING_Narrative_De

SEGMENT REPORTING (Narrative) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Asset Impairment Charges									$9,029,900,000	$250,800,000	$1,049,900,000
Revenues	1,284,700,000	1,298,200,000	1,100,800,000	940,000,000	1,515,800,000	1,546,600,000	1,488,500,000	1,140,500,000	4,623,700,000	5,691,400,000	5,872,700,000
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Number Of Mines									5
Revenues									2,506,500,000	2,667,900,000	2,723,300,000
Eastern Canadian Iron Ore [Member]
Segment Reporting Information [Line Items]
Number Of Mines									2
Revenues									563,400,000	978,700,000	1,008,900,000
Asia Pacific Iron Ore [Member]
Segment Reporting Information [Line Items]
Number Of Mines									1
Revenues									866,700,000	1,224,300,000	1,259,300,000
North American Coal [Member]
Segment Reporting Information [Line Items]
Revenues									687,100,000	821,900,000	881,100,000
North American Coal [Member] | Low Volatile Metallurgical Coal Mines [Member]
Segment Reporting Information [Line Items]
Number Of Mines									2
North American Coal [Member] | High volatile metallurgical coal mines [Member]
Segment Reporting Information [Line Items]
Number Of Mines									2
North American Coal [Member] | Thermal Coal Mines [Member]
Segment Reporting Information [Line Items]
Number Of Mines									1
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Segment Reporting Information [Line Items]
Number of Customers									2	1	1,000,000
Concentration Risk, Percentage									10.00%	10.00%	10.00%
Revenues									$1,600,000,000	$1,000,000,000	$900,000,000

SEGMENT_REPORTING_Schedule_Of_

SEGMENT REPORTING (Schedule Of Segment Reporting Information, By Segment) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Net income (loss)									($8,311.60)		$361.80		($1,126.60)
Revenues from product sales and services	1,284.70	1,298.20	1,100.80	940	1,515.80	1,546.60	1,488.50	1,140.50	4,623.70		5,691.40		5,872.70
Revenues from producet sales and services, percent									100.00%		100.00%		100.00%
SALES MARGIN	168.7	127.5	92	63.2	294.5	348.7	268.2	237.9	451.4		1,149.30		1,172.10
Other operating expense									-9,896.70		-478.3		-1,480.90
Other expense									-158.4		-181.7		-193
Income (loss) from continuing operations before income taxes and equity income (loss) from ventures									-9,603.70		489.3		-501.8
Depreciation, depletion and amortization									504		593.3		525.8
Capital Additions									235.5		752.3		1,335.30
Interest expense, net									-185.2		-179.1		-195.6
Income Tax Expense (Benefit)	-289.7								-1,302		55.1		255.9
EBITDA									-8,924.40		1,189.30		-149.3
Equity Method Investment, Other than Temporary Impairment									0		0		-365.4
Loss on sale of Cliffs Logan County Coal									419.6		0		0
Adjusted EBITDA									929.7		1,428.30		1,292.90
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Revenues from product sales and services									2,506.50		2,667.90		2,723.30
Revenues from producet sales and services, percent									54.00%		47.00%		46.00%
SALES MARGIN									710.4		901.9		976.2
Depreciation, depletion and amortization									107.4		120.3		100.9
Capital Additions									48.4	[1]	53.3	[1]	168.8	[1]
EBITDA									805.6		1,000.10		1,045.30
Adjusted EBITDA									831.2		1,030.80		1,085.60
Eastern Canadian Iron Ore [Member]
Segment Reporting Information [Line Items]
Revenues from product sales and services									563.4		978.7		1,008.90
Revenues from producet sales and services, percent									12.00%		17.00%		17.00%
SALES MARGIN									-244.9		-103.3		-121.4
Depreciation, depletion and amortization									135.6		178.5		160.2
Capital Additions									141.2	[1]	625.5	[1]	865.2	[1]
EBITDA									-7,673.90		-192.8		-1,103.30
Adjusted EBITDA									0		0		0
Asia Pacific Iron Ore [Member]
Segment Reporting Information [Line Items]
Revenues from product sales and services									866.7		1,224.30		1,259.30
Revenues from producet sales and services, percent									19.00%		22.00%		22.00%
SALES MARGIN									121.7		367.1		311
Depreciation, depletion and amortization									145.9		153.7		151.9
Capital Additions									10.8	[1]	13	[1]	87.7	[1]
EBITDA									-369.8		500.4		387.3
Adjusted EBITDA									264.6		525.7		402.1
North American Coal [Member]
Segment Reporting Information [Line Items]
Revenues from product sales and services									687.1		821.9		881.1
Revenues from producet sales and services, percent									15.00%		14.00%		15.00%
SALES MARGIN									-135.8		-14.5		-1.8
Depreciation, depletion and amortization									106.9		128.9		98.2
Capital Additions									28.8	[1]	55	[1]	144.1	[1]
EBITDA									-1,326.80		129.5		74
Adjusted EBITDA									-28.5		154		106.7
All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenues from product sales and services									0		-1.4		0.1
Revenues from producet sales and services, percent									0.00%		0.00%		0.00%
SALES MARGIN									0		-1.9		8.1
Depreciation, depletion and amortization									8.2		11.9		14.6
Capital Additions									6.3	[1]	5.5	[1]	69.5	[1]
Other Segment [Member]
Segment Reporting Information [Line Items]
EBITDA									-359.5		-247.9		-552.6
Adjusted EBITDA									-137.6		-282.2		-301.5
EBITDA Calculation [Member]
Segment Reporting Information [Line Items]
Depreciation, depletion and amortization									-504		-593.3		-525.8
Amapa [Member]
Segment Reporting Information [Line Items]
Equity Method Investment, Other than Temporary Impairment											67.6		-365.4
Adjusted EBITDA Calculation [Member]
Segment Reporting Information [Line Items]
Loss on sale of Cliffs Logan County Coal									-419.6		0		0
Wabush mine related costs									-158.7		-72.7		-30.1
Bloom Lake mine costs									-137.9		46.5		6.4
Foreign Exchange Remeasurement									30.7		64		-3.2
Proxy contest and change in control costs in SG&A									-26.6		0		0
Litigation Judgment Costs									-96.3		-9.6		0
Severance Costs in SG&A									($15.80)		($16.40)		$0
[1]	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 $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Segment Reporting Information [Line Items]
Assets	$3,164	$13,121.90	$13,574.90
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	1,598.30	1,671.60	1,735.10
Eastern Canadian Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	305.8	7,915.50	7,605.10
Asia Pacific Iron Ore [Member]
Segment Reporting Information [Line Items]
Assets	274.6	1,078.40	1,506.30
North American Coal [Member]
Segment Reporting Information [Line Items]
Assets	274.2	1,841.80	1,877.80
All Other Segments [Member]
Segment Reporting Information [Line Items]
Assets	164.3	455.6	570.9
Total Segment Assets [Member]
Segment Reporting Information [Line Items]
Assets	2,617.20	12,962.90	13,295.20
Corporate [Member]
Segment Reporting Information [Line Items]
Assets	$546.80	$159	$279.70

SEGMENT_REPORTING_SEGMENTS_REP

SEGMENT REPORTING SEGMENTS REPORTING (Revenue by Geographical Location) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$1,284.70	$1,298.20	$1,100.80	$940	$1,515.80	$1,546.60	$1,488.50	$1,140.50	$4,623.70	$5,691.40	$5,872.70
PROPERTY, PLANT AND EQUIPMENT, NET	1,414.90				11,153.40				1,414.90	11,153.40	11,207.30
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									2,139.40	1,857.60	2,108.50
PROPERTY, PLANT AND EQUIPMENT, NET	1,093.70				2,721.60				1,093.70	2,721.60	2,795.30
AUSTRALIA
Revenues from External Customers and Long-Lived Assets [Line Items]
PROPERTY, PLANT AND EQUIPMENT, NET	72.4				751				72.4	751	1,042.40
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									1,049	1,909.40	2,008.20
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									439.1	871.2	728.1
PROPERTY, PLANT AND EQUIPMENT, NET	248.8				7,680.80				248.8	7,680.80	7,369.60
Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$996.20	$1,053.20	$1,027.90

Recovered_Sheet1

SEGMENT REPORTING SEGMENT REPORTING (Revenue from External Customers by Products and Services) (Details) (Sales Revenue, Net [Member], Product Concentration Risk [Member])	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%
Iron Ore Revenue [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage	78.00%	80.00%	81.00%
Coal Revenue [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage	12.00%	13.00%	13.00%
Freight and Venture Partners' Cost Reimbursements [Member]
Revenue from External Customer [Line Items]
Concentration Risk, Percentage	10.00%	7.00%	6.00%

INVENTORIES_Narrative_Details

INVENTORIES (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
U.S. Iron Ore [Member]
Inventory [Line Items]
Inventory, LIFO Reserve	$119	$115.30
Effect of LIFO Inventory Liquidation on Income	44.8
Increase in Inventories due to build up of LIFO layers		7.4
Cost of Sales [Member] | Eastern Canadian Iron Ore [Member]
Inventory [Line Items]
Inventory Write-down	38.9		0
Cost of Sales [Member] | North American Coal [Member]
Inventory [Line Items]
Inventory Write-down	44.5	11.1	24.4
Work in process inventory [Member] | Bloom Lake [Member] | Cost of Sales [Member]
Inventory [Line Items]
Inventory Write-down	0
Work in process inventory [Member] | Wabush [Member] | Cost of Sales [Member]
Inventory [Line Items]
Inventory Write-down	0
Finished goods inventory [Member] | Bloom Lake [Member] | Cost of Sales [Member]
Inventory [Line Items]
Inventory Write-down	0
Finished goods inventory [Member] | Wabush [Member] | Cost of Sales [Member]
Inventory [Line Items]
Inventory Write-down	0
Pellets [Member] | Cost of Sales [Member] | Eastern Canadian Iron Ore [Member]
Inventory [Line Items]
Inventory Write-down		11.1
Pellets [Member] | Wabush [Member] | Cost of Sales [Member]
Inventory [Line Items]
Unsaleable Inventory Impairment Charge		10.6
Concentrate [Member] | Cost of Sales [Member] | Eastern Canadian Iron Ore [Member]
Inventory [Line Items]
Inventory Write-down		13.2
Concentrate [Member] | Wabush [Member] | Cost of Sales [Member]
Inventory [Line Items]
Unsaleable Inventory Impairment Charge		$7.90

INVENTORIES_Schedule_Of_Invent

INVENTORIES (Schedule Of Inventories) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Inventory, Net [Abstract]
Finished Goods	$207.90	$256.50
Work-in Process	118.8	134.9
Total Inventory	326.7	391.4
U.S. Iron Ore [Member]
Inventory, Net [Abstract]
Finished Goods	132.1	92.1
Work-in Process	13.5	13
Total Inventory	145.6	105.1
Eastern Canadian Iron Ore [Member]
Inventory, Net [Abstract]
Finished Goods	16.3	65.3
Work-in Process	0	48.1
Total Inventory	16.3	113.4
Asia Pacific Iron Ore [Member]
Inventory, Net [Abstract]
Finished Goods	26.4	39.7
Work-in Process	88.1	50.6
Total Inventory	114.5	90.3
North American Coal [Member]
Inventory, Net [Abstract]
Finished Goods	33.1	59.4
Work-in Process	17.2	23.2
Total Inventory	$50.30	$82.60

PROPERTY_PLANT_AND_EQUIPMENT_N

PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Depletion	$173	$206.50	$209.80
Depreciation	320.6	366.9	293.5
Document Fiscal Year Focus	2014
Tangible Asset Impairment Charges	8,839
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Accumulated amount of capitalized interest included within construction in progress		31.4
Interest costs capitalized during the period		17.4
Wabush [Member]
Property, Plant and Equipment [Line Items]
Tangible Asset Impairment Charges		145.1
Impairment of Long-Lived Assets Held-for-use	140.1	49.9
Land Rights And Mineral Rights [Member]
Property, Plant and Equipment [Line Items]
Tangible Asset Impairment Charges	$5,772.70

PROPERTY_PLANT_AND_EQUIPMENT_V

PROPERTY, PLANT AND EQUIPMENT (Value Of Each Of The Major Classes Of Consolidated Depreciable Assets) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$2,217.70	$13,570.90
Accumulated Depreciation and Depletion, Property, Plant and Equipment	802.8	2,417.50
Property, plant and equipment, net	1,414.90	11,153.40	11,207.30
Land Rights And Mineral Rights [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	590.2	7,819.60
Office And Information Technology [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	75.5	125.7
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	65.6	255.2
Mining Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	732.6	1,819.30
Processing Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	567.4	2,148.60
Electric Power Facilities [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	48.8	114.3
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	25.5	69.3
Other Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	60.8	227.6
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$51.30	$991.30

PROPERTY_PLANT_AND_EQUIPMENT_P

PROPERTY, PLANT AND EQUIPMENT PROPERTY, PLANT AND EQUIPMENT (Book Value of Land and Mineral Rights Disclosure) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Property, Plant and Equipment [Abstract]
Land Rights	$31.90	$46.30
Mineral Rights [Abstract]
Mineral Properties, Gross	558.3	7,773.30
Mineral Properties, Accumulated Depletion	-101.3	-942.6
Mineral Properties, Net	$457	$6,830.70

DEBT_AND_CREDIT_FACILITIES_Nar

DEBT AND CREDIT FACILITIES (Narrative) (Details)

Dec. 31, 2014

Dec. 31, 2013

Aug. 11, 2011

27-May-10

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Sep. 22, 2010

Dec. 31, 2014

Dec. 31, 2013

Sep. 30, 2014

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

Dec. 31, 2014

USD ($)

USD ($)

Term Loan [Member]

Amapa's Debt [Member]

Senior Notes - $400 Million [Member]

Senior Notes - $400 Million [Member]

Senior Notes - $400 Million [Member]

Senior Notes - $400 Million [Member]

Five Hundred Million Four Point Eight Zero Percent Senior Note [Member]

Five Hundred Million Four Point Eight Zero Percent Senior Note [Member]

Five Hundred Million Six Point Two Five Percent Two Thousand And Forty [Member]

Senior Notes10 Year Tranche [Member]

Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]

Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

$270 Million Senior Notes [Member]

Series Two Thousand And Eight Tranche B [Member]

Senior Notes Five Hundred Million [Member]

Senior Notes Five Hundred Million [Member]

Senior Notes Five Hundred Million [Member]

Five Hundred Million Three Point Nine Five Two Thousand Eighteen Senior Note [Member]

Five Hundred Million Three Point Nine Five Two Thousand Eighteen Senior Note [Member]

Equipment Loans [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Line of Credit [Member]

Senior Notes30 Year Tranche [Member]

Senior Notes One Billion Two Thousand Eleven Offering [Member]

Senior Notes One Billion Two Thousand Eleven Offering [Member]

Senior Notes One Billion Two Thousand Eleven Offering [Member]

Senior Notes One Billion Two Thousand Ten Offering [Member]

Senior Notes One Billion Two Thousand Ten Offering [Member]

Senior Notes One Billion Two Thousand Ten Offering [Member]

USD ($)

USD ($)

USD ($)

USD ($)

Maximum [Member]

Minimum [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Maximum [Member]

Minimum [Member]

USD ($)

USD ($)

USD ($)

USD ($)

AUD

USD ($)

AUD

USD ($)

USD ($)

Maximum [Member]

Minimum [Member]

USD ($)

Maximum [Member]

Minimum [Member]

Line of Credit Facility [Line Items]

liquidity test

$400,000,000

Stock Repurchase Program, Authorized Amount

200,000,000

Debt Instrument, Repurchased Face Amount

5,000,000

10,000,000

10,000,000

20,000,000

Long-term Line of Credit, Noncurrent

200,000,000

Repayments of Debt

100,800,000

350,000,000

270,000,000

55,000,000

Revolving credit facility, borrowing capacity

2,500,000

3,000,000

26,800,000

30,000,000

Debt Instrument, Face Amount

400,000,000

400,000,000

500,000,000

500,000,000

500,000,000

700,000,000

700,000,000

500,000,000

500,000,000

300,000,000

1,000,000,000

1,000,000,000

Financial covenant, interest coverage ratio

3.5

2.5

Credit facility, amount outstanding

0

[1]

0

[1]

1,200,000

1,500,000

20,500,000

23,000,000

Credit facility remaining capacity

1,000,000,000

1,700,000,000

1,300,000

1,500,000

6,300,000

7,000,000

Letters of credit outstanding

48,000,000

Time Period During Which Senior Notes May Be Redeemed at Company's Option, Number of Days From When Prior Notice Sent to Holders

60 days

30 days

60 days

30 days

60 days

30 days

60 days

30 days

Note Redemption Price, Percent of Principal Amount to be Redeemed

100.00%

100.00%

100.00%

100.00%

Redemption Price, Percent Of Principal In The Event Of Change Of Control

101.00%

101.00%

101.00%

Debt Instrument, Par Value

4,144,800,000

4,814,800,000

395,000,000

400,000,000

490,000,000

500,000,000

690,000,000

700,000,000

1,125,000,000

1,750,000,000

1,250,000,000

480,000,000

500,000,000

164,800,000

Percentage of Stock to Pledge

65.00%

Total Funded Debt to Total Capitalization

0.45

Debt to Earnings

3.5

Limit on Increase in Interest Rate Above Initial Interest Rate, Based on Rating Events

2.00%

Debt Instrument, Redemption Period, Time Period Prior to Maturity Date

3 months

Note Redemption Price if Redemption Period is During Specified Time Period, Percent of Principal Amount to be Redeemed

100.00%

Senior Notes, Noncurrent

$500,000,000

$700,000,000

Debt Instrument, Interest Rate, Stated Percentage

5.90%

5.90%

4.80%

4.80%

4.88%

3.95%

Interest Rate Due to Rating Downgrades

5.70%

[1]

As of DecemberB 31, 2014 and 2013, no revolving loans were drawn under the credit facility. We had total availability of $1.125 billion and $1.75 billion on our credit facility as of December 31, 2014 and 2013, respectively. Additionally, as of December 31, 2014 and December 31, 2013, the principal amount of letter of credit obligations totaled $149.5 million and $8.4 million, respectively, thereby reducing available borrowing capacity to $1.0 billion and $1.7 billion for each period, respectively.

DEBT_AND_CREDIT_FACILITIES_Sch

DEBT AND CREDIT FACILITIES (Schedule Of Long-Term Debt) (Details) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2014		Dec. 31, 2014		Dec. 31, 2013		Sep. 30, 2014
Debt Instrument [Line Items]
Maximum Impairment Permitted to be Excluded from Net Worth Calculation for Debt Covenants	$1,000,000,000		$1,000,000,000
Stock Repurchase Program, Authorized Amount	200,000,000		200,000,000
Debt Instrument, Par Value	4,144,800,000		4,144,800,000		4,814,800,000
Long-term Debt	2,984,100,000		2,984,100,000		3,043,500,000
Current portion of long-term debt	21,800,000		21,800,000		20,900,000
Long-term debt noncurrent portion	2,962,300,000		2,962,300,000		3,022,600,000
Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	10,000,000		10,000,000
Stated interest rate	4.88%		4.88%
Debt Instrument, Par Value	690,000,000		690,000,000		700,000,000
Debt Instrument, Unamortized Discount	500,000		500,000		600,000
Debt Repurchase Discount	40.50%		40.50%
Gains (Losses) on Extinguishment of Debt			4,100,000
Type			Fixed		Fixed
Final Maturity			2021		2021
Long-term Debt	689,500,000	[1]	689,500,000	[1]	699,400,000	[1]
Imputed interest rate	4.88%		4.88%		4.88%
Debt Instrument, Face Amount	700,000,000		700,000,000		700,000,000
$500 million 4.80% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	10,000,000		10,000,000
Stated interest rate	4.80%		4.80%		4.80%
Debt Instrument, Par Value	490,000,000		490,000,000		500,000,000
Debt Instrument, Unamortized Discount	600,000		600,000		800,000
Debt Repurchase Discount	40.25%		40.25%
Gains (Losses) on Extinguishment of Debt			4,000,000
Type			Fixed		Fixed
Final Maturity			2020		2020
Long-term Debt	489,400,000	[2]	489,400,000	[2]	499,200,000	[2]
Imputed interest rate	4.83%		4.83%		4.83%
Debt Instrument, Face Amount	500,000,000		500,000,000		500,000,000
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Variable Rate Basis			treasury rate
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Spread on Rate Basis	0.35%		0.35%
$800 Million 6.25% 2040 Senior Notes [Member]
Debt Instrument [Line Items]
Stated interest rate	6.25%		6.25%		6.25%
Debt Instrument, Par Value	800,000,000		800,000,000		800,000,000
Debt Instrument, Unamortized Discount	9,500,000		9,500,000		9,600,000
Type			Fixed		Fixed
Final Maturity			2040		2040
Long-term Debt	790,500,000	[3]	790,500,000	[3]	790,400,000	[3]
Imputed interest rate	6.34%		6.34%		6.34%
Debt Instrument, Face Amount	800,000,000		800,000,000
$400 Million 5.90% 2020 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	5,000,000		5,000,000
Stated interest rate	5.90%		5.90%		5.90%
Debt Instrument, Par Value	395,000,000		395,000,000		400,000,000
Debt Instrument, Unamortized Discount	1,300,000		1,300,000		1,600,000
Debt Repurchase Discount	38.13%		38.13%
Gains (Losses) on Extinguishment of Debt			1,900,000
Type			Fixed		Fixed
Final Maturity			2020		2020
Long-term Debt	393,700,000	[4]	393,700,000	[4]	398,400,000	[4]
Imputed interest rate	5.98%		5.98%		5.98%
Debt Instrument, Face Amount	400,000,000		400,000,000		400,000,000
$500 Million 3.95% 2018 Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Repurchased Face Amount	20,000,000		20,000,000
Stated interest rate	3.95%		3.95%
Debt Instrument, Par Value	480,000,000		480,000,000		500,000,000
Debt Instrument, Unamortized Discount	2,600,000		2,600,000		3,500,000
Debt Repurchase Discount	30.88%		30.88%
Gains (Losses) on Extinguishment of Debt			6,200,000
Type			Fixed		Fixed
Final Maturity			2018		2018
Long-term Debt	477,400,000	[5]	477,400,000	[5]	496,500,000	[5]
Imputed interest rate	5.17%		5.17%		4.14%
Debt Instrument, Face Amount	500,000,000		500,000,000		500,000,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Coverage Ratio Of Earnings Before Interest Tax Depreciation And Amortization To Total Interest Expense	3.5				2.5
Coverage Ratio Of Earnings Before Interest Tax Depreciation And Amortization To Total Interest Expense, Subsequent Event - Revolving Credit Facility Amendment	2
Number of Days to complete collateral action in order to reduce minimum interest coverage ratio, Subsequent Event - Revolving Credit Facility Amendment	60
Debt Instrument, Par Value	1,125,000,000		1,125,000,000		1,750,000,000		1,250,000,000
Type			Variable		Variable
Final Maturity			2017		2017
Credit facility, amount outstanding	0	[6]	0	[6]	0	[6]
Imputed interest rate	2.94%		2.94%		1.64%
Credit facility remaining capacity	1,000,000,000		1,000,000,000		1,700,000,000
Letter of Credit [Member]
Debt Instrument [Line Items]
Credit facility, amount outstanding	149,500,000		149,500,000		8,400,000
Equipment Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Par Value	164,800,000		164,800,000
Type			Fixed		Fixed
Long-term Debt	140,800,000		140,800,000		161,700,000
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Fair Value Adjustment to Interest Rate Hedge	2,800,000		2,800,000		-2,100,000
Senior Notes Five Hundred Million [Member]
Debt Instrument [Line Items]
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Variable Rate Basis			treasury rate
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Spread on Rate Basis	0.50%		0.50%
Senior Notes10 Year Tranche [Member]
Debt Instrument [Line Items]
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Variable Rate Basis			treasury rate
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Spread on Rate Basis	0.25%		0.25%
Senior Notes30 Year Tranche [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	300,000,000		300,000,000
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Variable Rate Basis			treasury rate
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Spread on Rate Basis	0.40%		0.40%
Five Hundred Million Six Point Two Five Percent Two Thousand And Forty [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$500,000,000		$500,000,000
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Variable Rate Basis			treasury rate
Discount Rate Used to Calculate Present Values of Remaining Scheduled Payments of Principal and Interest on Notes to Be Redeemed, Spread on Rate Basis	0.40%		0.40%
[1]	During the fourth quarter of 2014, we purchased $10.0 million of outstanding 4.875 percent senior notes that were trading at a discount of 40.5 percent which resulted in a gain on the extinguishment of debt of $4.1 million. 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. As of DecemberB 31, 2013, the $700.0 million 4.875 percent senior notes were recorded at a par value of $700.0 million less unamortized discounts of $0.6 million, based on an imputed interest rate of 4.88 percent.
[2]	During the fourth quarter of 2014, we purchased $10.0 million of outstanding 4.80 percent senior notes that were trading at a discount of 40.25 percent which resulted in a gain on the extinguishment of debt of $4.0 million. 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. As of DecemberB 31, 2013, the $500.0 million 4.80 percent senior notes were recorded at a par value of $500.0 million less unamortized discounts of $0.8 million, based on an imputed interest rate of 4.83 percent.
[3]	As of DecemberB 31, 2014 and DecemberB 31, 2013, the $800.0 million 6.25 percent senior notes were recorded at par value of $800.0 million less unamortized discounts of $9.5 million and $9.6 million, respectively, based on an imputed interest rate of 6.34 percent.
[4]	During the fourth quarter of 2014, we purchased $5.0 million of outstanding 5.90 percent senior notes that were trading at a discount of 38.125 percent which resulted in a gain on the extinguishment of debt of $1.9 million. 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. As of DecemberB 31, 2013, the $400.0 million 5.90 percent senior notes were recorded at a par value of $400.0 million less unamortized discounts of $1.6 million, based on an imputed interest rate of 5.98 percent.
[5]	During the fourth quarter of 2014, we purchased $20.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 30.875 percent which resulted in a gain on the extinguishment of debt of $6.2 million. 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. As of DecemberB 31, 2013, the $500.0 million 3.95 percent senior notes were recorded at a par value of $500.0 million less unamortized discounts of $3.5 million, based on an imputed interest rate of 4.14 percent.
[6]	As of DecemberB 31, 2014 and 2013, no revolving loans were drawn under the credit facility. We had total availability of $1.125 billion and $1.75 billion on our credit facility as of December 31, 2014 and 2013, respectively. Additionally, as of December 31, 2014 and December 31, 2013, the principal amount of letter of credit obligations totaled $149.5 million and $8.4 million, respectively, thereby reducing available borrowing capacity to $1.0 billion and $1.7 billion for each period, respectively.

DEBT_AND_CREDIT_FACILITIES_DEB

DEBT AND CREDIT FACILITIES DEBT AND CREDIT FACILITIES (Schedule of Debt Maturities) (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Debt Disclosure [Abstract]
Debt Maturities 2015	$21.80
Debt Maturities 2016	22.7
Debt Maturities 2017	23.6
Debt Maturities 2018	504.6
Debt Maturities 2019	25.5
Debt Maturities 2020 and After	2,397.60
Long-term Debt, Maturities, Total	$2,995.80

FAIR_VALUE_OF_FINANCIAL_INSTRU2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets And Liabilities Components [Line Items]
Management Estimate of 62% Fe	62.00%
Equity Method Investment, Other than Temporary Impairment	$0	$0	($365.40)
Goodwill, Impairment Loss	73.5	80.9
Other Asset Impairment Charges	8,956.40
Tangible Asset Impairment Charges	8,839
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	9.2
Amapa [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Equity Method Investments, Fair Value Disclosure		0
Equity Method Investment, Other than Temporary Impairment		67.6	-365.4
Asia Pacific Iron Ore [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Goodwill, Impairment Loss	73.5
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Goodwill, Impairment Loss		80.9
CQIM Reporting Unit [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Goodwill, Impairment Loss		997.3
Wabush [Member]
Fair Value, Assets And Liabilities Components [Line Items]
Impairment of Long-Lived Assets Held-for-use	140.1	49.9
Tangible Asset Impairment Charges		$145.10

FAIR_VALUE_OF_FINANCIAL_INSTRU3

FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value Of Assets And Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Assets:
Cash equivalents		$85
Derivative assets	63.2	58.9
Marketable Securities	4.3	21.4
Foreign exchange contracts		0.3
Total	67.5	165.6
Liabilities:
Derivative liabilities	11.8	12.4
Foreign exchange contracts	31.5	26.9
Total	43.3	39.3
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents		85
Marketable Securities	4.3	21.4
Total	4.3	106.4
Fair Value, Inputs, Level 2 [Member]
Assets:
Foreign exchange contracts		0.3
Total		0.3
Liabilities:
Derivative liabilities		2.1
Foreign exchange contracts	31.5	26.9
Total	31.5	29
Fair Value, Inputs, Level 3 [Member]
Assets:
Derivative assets	63.2	58.9
Total	63.2	58.9
Liabilities:
Derivative liabilities	11.8	10.3
Total	$11.80	$10.30

FAIR_VALUE_OF_FINANCIAL_INSTRU4

FAIR VALUE OF FINANCIAL INSTRUMENTS (Schedule Of Quantitative Inputs And Assumptions For Level 3 Assets And Liabilities) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative asset, fair value	$63,200,000	$59,200,000
Derivative liability, fair value	43,300,000	39,300,000
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	63,200,000	58,900,000
Derivative liability, fair value	21,700,000	11,400,000
Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Managements Estimate Of 62% Fe [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% Fe [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value measurement with unobservable inputs derivative asset range	72
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	640
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	590
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	610
Other Current 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	11,800,000	10,300,000
Other Current 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	3,100,000
Other Current 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	$63,200,000	$55,800,000

FAIR_VALUE_OF_FINANCIAL_INSTRU5

FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value, Assets and Liabilities Measured On Recurring Basis, Unobservable Input Reconciliation) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured On Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance - January 1	$58.90	$62.40
Total gains
Included in earnings	187.8	152.3
Settlements	-183.5	-155.8
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance - December 31	63.2	58.9
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) on assets still held at the reporting date	187.8	152.3
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance - January 1	-10.3	-11.3
Total gains
Included in earnings	-11.8	-10.3
Settlements	10.3	11.3
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending balance - September 30	-11.8	-10.3
Total gains (losses) for the period included in earnings attributable to the change in unrealized gains (losses) on liabilities still held at the reporting date	($11.80)	($10.30)

FAIR_VALUE_OF_FINANCIAL_INSTRU6

FAIR VALUE OF FINANCIAL INSTRUMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013
Long-term debt:
Term loan, carrying value	$2,984,100,000		$3,043,500,000
Total long-term debt, carrying value	2,962,300,000		3,022,600,000
Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one 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:
Term loan, carrying value	689,500,000	[1]	699,400,000	[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
Senior Notes - $400 Million [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	400,000,000		400,000,000
Long-term debt:
Term loan, carrying value	393,700,000	[2]	398,400,000	[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:
Term loan, carrying value	477,400,000	[3]	496,500,000	[3]
Revolving Credit Facility [Member]
Long-term debt:
Revolving loan, carrying value	0	[4]	0	[4]
Equipment Loans [Member]
Long-term debt:
Term loan, carrying value	140,800,000		161,700,000
Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	2,800,000		-2,100,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Long-term debt:
Total long-term debt, fair value	1,733,200,000		3,217,700,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	367,300,000		718,200,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $1.3 Billion [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	704,000,000		1,404,900,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $400 Million [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	228,100,000		432,100,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | $500 Million 3.95% 2018 Senior Notes [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	312,000,000		523,800,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Long-term debt:
Revolving loan, fair value	0		0
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Equipment Loans [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	119,000,000		140,800,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	2,800,000		-2,100,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Long-term debt:
Total long-term debt, carrying value	2,962,300,000		3,022,600,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
Long-term debt:
Senior notes, carrying value	689,500,000		699,400,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $1.3 Billion [Member]
Long-term debt:
Senior notes, carrying value	1,279,900,000		1,289,600,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $400 Million [Member]
Long-term debt:
Senior notes, carrying value	393,700,000		398,400,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | $500 Million 3.95% 2018 Senior Notes [Member]
Long-term debt:
Senior notes, carrying value	477,400,000		496,500,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Long-term debt:
Revolving loan, carrying value	0		0
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Equipment Loans [Member]
Long-term debt:
Term loan, carrying value	119,000,000		140,800,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Long-term debt:
Carrying Value of Fair Value Adjustment to Interest Rate Hedge	$2,800,000		($2,100,000)
[1]	During the fourth quarter of 2014, we purchased $10.0 million of outstanding 4.875 percent senior notes that were trading at a discount of 40.5 percent which resulted in a gain on the extinguishment of debt of $4.1 million. 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. As of DecemberB 31, 2013, the $700.0 million 4.875 percent senior notes were recorded at a par value of $700.0 million less unamortized discounts of $0.6 million, based on an imputed interest rate of 4.88 percent.
[2]	During the fourth quarter of 2014, we purchased $5.0 million of outstanding 5.90 percent senior notes that were trading at a discount of 38.125 percent which resulted in a gain on the extinguishment of debt of $1.9 million. 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. As of DecemberB 31, 2013, the $400.0 million 5.90 percent senior notes were recorded at a par value of $400.0 million less unamortized discounts of $1.6 million, based on an imputed interest rate of 5.98 percent.
[3]	During the fourth quarter of 2014, we purchased $20.0 million of outstanding 3.95 percent senior notes that were trading at a discount of 30.875 percent which resulted in a gain on the extinguishment of debt of $6.2 million. 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. As of DecemberB 31, 2013, the $500.0 million 3.95 percent senior notes were recorded at a par value of $500.0 million less unamortized discounts of $3.5 million, based on an imputed interest rate of 4.14 percent.
[4]	As of DecemberB 31, 2014 and 2013, no revolving loans were drawn under the credit facility. We had total availability of $1.125 billion and $1.75 billion on our credit facility as of December 31, 2014 and 2013, respectively. Additionally, as of December 31, 2014 and December 31, 2013, the principal amount of letter of credit obligations totaled $149.5 million and $8.4 million, respectively, thereby reducing available borrowing capacity to $1.0 billion and $1.7 billion for each period, respectively.

FAIR_VALUE_OF_FINANCIAL_INSTRU7

FAIR VALUE OF FINANCIAL INSTRUMENTS FAIR VALUE OF FINANCIAL INSTRUMENTS (Impairment Charges on Financial and Nonfinancial Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss	$73.50	$80.90
Tangible Asset Impairment Charges	8,839
Finite-lived Intangible Assets, Fair Value Disclosure		1.6
Impairment of Intangible Assets (Excluding Goodwill)	15.5	14.5
Other Asset Impairment Charges	8,956.40
Equity Method Investment, Other than Temporary Impairment	0	0	-365.4
Assets, Fair Value Disclosure, Nonrecurring	438.9	47.9
Impairment Charges	9,039.10	318.4
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	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure		1.6
Assets, Fair Value Disclosure, Nonrecurring	438.9	47.9
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
Amapa [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		67.6	-365.4
Amapa [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
Amapa [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
Amapa [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
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Fair Value Disclosure		0
Goodwill, Impairment Loss		80.9
Cliffs Chromite Ontario and Cliffs Chromite Far North [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
Cliffs Chromite Ontario and Cliffs Chromite Far North [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
Cliffs Chromite Ontario and Cliffs Chromite Far North [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
Wabush [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Tangible Asset Impairment Charges		145.1
Impairment of Long-Lived Assets Held-for-use	140.1	49.9
Impairment of Intangible Assets (Excluding Goodwill)		9.5
Wabush [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure		0
Wabush [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Finite-lived Intangible Assets, Fair Value Disclosure		0
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure		46.3
Tangible Asset Impairment Charges		155.4
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [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
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [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
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [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		46.3
CQIM Reporting Unit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill, Impairment Loss		997.3
Other Reporting Units [Member] | 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	19.2
Other Reporting Units [Member] | 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] | 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] | 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
Bloom Lake [Member] | Eastern Canadian Iron Ore [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	187.9
Tangible Asset Impairment Charges	7,043.70
Finite-lived Intangible Assets, Fair Value Disclosure	0
Impairment of Intangible Assets (Excluding Goodwill)	56.2
Bloom Lake [Member] | Eastern Canadian 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
Bloom Lake [Member] | Eastern Canadian 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
Bloom Lake [Member] | Eastern Canadian 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	187.9
Finite-lived Intangible Assets, Fair Value Disclosure	0
CLCC [Member] | North American Coal [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	62.6
Tangible Asset Impairment Charges	195.5
CLCC [Member] | North American Coal [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
CLCC [Member] | North American Coal [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
CLCC [Member] | North American Coal [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	62.6
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
Finite-lived Intangible Assets, Fair Value Disclosure	7
Impairment of Intangible Assets (Excluding Goodwill)	24.2
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
Ferroalloys [Member] | Ferroalloys [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	12.2
Tangible Asset Impairment Charges	259.5
Finite-lived Intangible Assets, Fair Value Disclosure	0
Impairment of Intangible Assets (Excluding Goodwill)	0.3
Ferroalloys [Member] | Ferroalloys [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
Ferroalloys [Member] | Ferroalloys [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
Ferroalloys [Member] | Ferroalloys [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	12.2
Finite-lived Intangible Assets, Fair Value Disclosure	0
Wabush [Member] | Eastern Canadian Iron Ore [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	42.7
Tangible Asset Impairment Charges	132.6
Finite-lived Intangible Assets, Fair Value Disclosure	0
Impairment of Intangible Assets (Excluding Goodwill)	36.7
Wabush [Member] | Eastern Canadian 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
Wabush [Member] | Eastern Canadian 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
Wabush [Member] | Eastern Canadian 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	42.7
Finite-lived Intangible Assets, Fair Value Disclosure	0
Oak Grove [Member] | North American Coal [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	23.4
Tangible Asset Impairment Charges	267.5
Oak Grove [Member] | North American Coal [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
Oak Grove [Member] | North American Coal [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
Oak Grove [Member] | North American Coal [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	23.4
Pinnacle [Member] | North American Coal [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	30.7
Tangible Asset Impairment Charges	394.5
Pinnacle [Member] | North American Coal [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
Pinnacle [Member] | North American Coal [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
Pinnacle [Member] | North American Coal [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	$30.70

PENSIONS_AND_OTHER_POSTRETIREM2

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014
Defined Benefit Plan Disclosure [Line Items]
Current Fiscal Year End Date	-19
Minimum participants percentage	15.00%
Accumulated benefit obligation for defined benefit pension plans	$1,204,400,000	$1,091,400,000
Maturity period of security	10 years
Reserve for investment commitments	55,500,000			45,000,000
Sei Special Situations Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Redemption request notice period, days	95 days
Structured Finance [Member]
Defined Benefit Plan Disclosure [Line Items]
Redemption request notice period, days	90 days
Real Estate [Member]
Defined Benefit Plan Disclosure [Line Items]
Redemption request notice period, days	45 days
Withdrawal request notice period, days	65 days
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase in Projected Benefit Obligation due to new mortality tables	30,000,000
Percentage Increase in Projected Benefit Obligation due to new mortality tables	4.00%
Defined Benefit Plan, Net Periodic Benefit Cost	31,300,000	52,100,000	55,200,000
Annual costs for defined contribution plan	6,300,000	6,800,000	6,700,000
Participant contributions	0	0
Other Postretirement Benefit Expense	-700,000	17,400,000	28,100,000
Pension and Other Postretirement Benefit Expense	36,900,000	76,300,000	90,000,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	-10,900,000	0
Increase in Canadian Plan Projected Benefit Obligation due to new mortality tables	12,000,000
Percentage Increase in Canadian Plan Projected Benefit Obligation due to new mortality tables	5.00%
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	-2,900,000	0	0
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Increase in Projected Benefit Obligation due to new mortality tables	20,000,000
Percentage Increase in Projected Benefit Obligation due to new mortality tables	7.00%
Defined Benefit Plan, Net Periodic Benefit Cost	-700,000	17,400,000	28,100,000
Participant contributions	4,800,000	5,600,000
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	-8,800,000	0
Increase in Canadian Plan Projected Benefit Obligation due to new mortality tables	3,000,000
Percentage Increase in Canadian Plan Projected Benefit Obligation due to new mortality tables	5.00%
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	7,900,000	0	0
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.72%
Expected period of long-term return on assets	3 years
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.92%
Expected period of long-term return on assets	5 years
United States [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.83%	4.57%
Projected yield, number of bonds used	715
United States [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.83%	4.57%
Canada [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.75%	4.50%
Projected yield, number of bonds used	285
Canada [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.75%	4.75%
Tilden, Empire, Hibbing and United Taconite [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of USW employees covered by labor contracts	2,200
Percentage of total workforce covered by labor contract	40.90%
Pinnacle Complex and Oak Grove [Member]
Defined Benefit Plan Disclosure [Line Items]
Number of USW employees covered by labor contracts	800
Percentage of total workforce covered by labor contract	15.20%
Contribution rate per hour worked	8.16	8.1	8.1
Annual costs for defined contribution plan	14,900,000	13,800,000
Underfunded Liability Estimate	330,000,000
Prior To Age65 [Member] | Defined Benefit Postretirement Health Coverage [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual limit on medical coverage for each participant	7,000
Prior To Age65 [Member] | Minimum [Member] | Defined Benefit Postretirement Health Coverage [Member] | Northshore [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual limit on medical coverage for each participant	4,020
Prior To Age65 [Member] | Maximum [Member] | Defined Benefit Postretirement Health Coverage [Member] | Northshore [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual limit on medical coverage for each participant	4,500
After Age65 [Member] | Defined Benefit Postretirement Health Coverage [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual limit on medical coverage for each participant	3,000
After Age65 [Member] | Defined Benefit Postretirement Health Coverage [Member] | Northshore [Member]
Defined Benefit Plan Disclosure [Line Items]
Annual limit on medical coverage for each participant	$2,000

PENSIONS_AND_OTHER_POSTRETIREM3

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Annual Costs Related to Retirement Plans) (Details) (Pension Benefits [Member], USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit pension plans	$31.30	$52.10	$55.20
Defined contribution pension plans	6.3	6.8	6.7
Other Postretirement Benefit Expense	-0.7	17.4	28.1
Total	$36.90	$76.30	$90

PENSIONS_AND_OTHER_POSTRETIREM4

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Benefit Obligations, Fair Value of Plan Assets, and Net Funded Status) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014								Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b beginning of year	$188.60								$200.50
Employer contributions	7.3								25.5
Fair value of plan assets b end of year	205.8								188.6
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	205.8								188.6
Amounts recognized in Statements of Financial Position:
Noncurrent liabilities	-395.2								-294
Amounts recognized in accumulated other comprehensive income:
Retirement And Defined Compensation Plans Disclosures [Table Text Block]	The following table summarizes the annual expense recognized related to the retirement plans for 2014, 2013 and 2012:
		(In Millions)
		2014			2013		2012
	Defined benefit pension plans	$	31.3		$	52.1	$	55.2
	Defined contribution pension plans	6.3			6.8		6.7
	Other postretirement benefits	(0.7		)	17.4		28.1
	Total	$	36.9		$	76.3	$	90
Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b beginning of year	-1,118								-1,244.30
Service cost (excluding expenses)	30.8								38.9	32
Interest cost	49.7								45.9	48.4
Plan amendments	0								0.8
Actuarial loss	-14.1								-29.9	-30.4
Defined Benefit Plan, Change in Actuarial (gain) loss	141.6								-121.8
Benefits paid	-87								-72.9
Participant contributions	0								0
Federal subsidy on benefits paid	0								0
Exchange rate gain	-18.2								-17.2
Benefit obligations b end of year	-1,227.40								-1,118	-1,244.30
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b beginning of year	915.3								838.7
Actual return on plan assets	78.7								109.5	92.5
Participant contributions	0								0
Employer contributions	60.5								53.7
Benefits paid	-87								-72.9
Exchange rate gain	-17.9								-13.7
Fair value of plan assets b end of year	949.6								915.3	838.7
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	949.6								915.3	838.7
Defined Benefit Plan, Benefit Obligation	-1,227.40								-1,118	-1,244.30
Underfunded status of plan	-277.8								-202.7
Amount recognized at December 31	-277.8								-202.7
Amounts recognized in Statements of Financial Position:
Current liabilities	-2.4								-5.2
Noncurrent liabilities	-275.4								-197.5
Net amount recognized	-277.8								-202.7
Amounts recognized in accumulated other comprehensive income:
Prior service cost	10.6								14.9
Net actuarial loss	341.5								230.6
Net amount recognized	352.1								245.5
The estimated amounts that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2013:
Net actuarial loss	22.3
Prior service cost	2.4
Net amount recognized	24.7
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	-10.9								0
Defined Benefit Plan, Special Termination Benefits	3.4								0
Other Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b beginning of year	-356.2								-459.8
Service cost (excluding expenses)	6.7								12.3	14.7
Interest cost	16.2								17.3	20.6
Plan amendments	-0.9								0
Actuarial loss	-5								-11.5	-11.6
Defined Benefit Plan, Change in Actuarial (gain) loss	51.9								-103.3
Benefits paid	-27.4								-28
Participant contributions	4.8								5.6
Federal subsidy on benefits paid	0.9								0.5
Exchange rate gain	-3.7								-8
Benefit obligations b end of year	-395.9								-356.2	-459.8
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b beginning of year	251.8								237
Actual return on plan assets	31.9								11	26.1
Participant contributions	0.8								1.8
Employer contributions	6.9								20.7
Benefits paid	-22.1								-18.7
Exchange rate gain	0								0
Fair value of plan assets b end of year	269.3								251.8	237
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	269.3								251.8	237
Defined Benefit Plan, Benefit Obligation	-395.9								-356.2	-459.8
Underfunded status of plan	-126.6								-104.4
Amount recognized at December 31	-126.6								-104.4
Amounts recognized in Statements of Financial Position:
Current liabilities	-6.8								-7.9
Noncurrent liabilities	-119.8								-96.5
Net amount recognized	-126.6								-104.4
Amounts recognized in accumulated other comprehensive income:
Prior service cost	-42.9								-45.4
Net actuarial loss	97.1								67
Net amount recognized	54.2								21.6
The estimated amounts that will be amortized from accumulated other comprehensive income into net periodic benefit cost in 2013:
Net actuarial loss	6.3
Prior service cost	-3.7
Net amount recognized	2.6
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Curtailments	-8.8								0
Defined Benefit Plan, Special Termination Benefits	0								0
Salaried Employees [Member] | Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b end of year	-471.4								-427.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b end of year	366.4								357.4
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	366.4								357.4
Defined Benefit Plan, Benefit Obligation	-471.4								-427.2
Underfunded status of plan	-105								-69.8
Salaried Employees [Member] | Other Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b end of year	-54								-53.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b end of year	0								0
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	0								0
Defined Benefit Plan, Benefit Obligation	-54								-53.6
Underfunded status of plan	-54								-53.6
Hourly Employees [Member] | Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b end of year	-739.2								-674.8
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b end of year	576.6								552.7
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	576.6								552.7
Defined Benefit Plan, Benefit Obligation	-739.2								-674.8
Underfunded status of plan	-162.6								-122.1
Hourly Employees [Member] | Other Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b end of year	-341.9								-302.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b end of year	269.3								251.8
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	269.3								251.8
Defined Benefit Plan, Benefit Obligation	-341.9								-302.6
Underfunded status of plan	-72.6								-50.8
Mining Employees [Member] | Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b end of year	-9.2								-6.8
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b end of year	6.6								5.2
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	6.6								5.2
Defined Benefit Plan, Benefit Obligation	-9.2								-6.8
Underfunded status of plan	-2.6								-1.6
Supplemental Executive Retirement Plan S E R P [Member] | Pension Benefits [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligations b end of year	-7.6								-9.2
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets b end of year	0								0
Funded status at December 31:
Defined Benefit Plan, Fair Value of Plan Assets	0								0
Defined Benefit Plan, Benefit Obligation	-7.6								-9.2
Underfunded status of plan	($7.60)								($9.20)

PENSIONS_AND_OTHER_POSTRETIREM5

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Components Of Net Periodic Benefit Cost) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$205.80	$188.60	$200.50
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss)	14.1	29.9	30.4
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	2.9	0	0
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period	3.4	0	0
Defined Benefit Plan, Fair Value of Plan Assets	949.6	915.3	838.7
Service cost	30.8	38.9	32
Interest cost	49.7	45.9	48.4
Expected return on plan assets	-72.3	-65.6	-59.5
Amortization:
Net asset	0	0	0
Prior service costs (credits)	2.7	3	3.9
Net actuarial loss	15.5	29.9	30.4
Net periodic benefit cost	31.3	52.1	55.2
Effect of Curtailment	0	0	0
Current year actuarial (gain)/loss	121.8	-168.8	53.1
Amortization of net loss	15.5	29.9	30.4
Current year prior service cost	-1.5	0.8	2.8
Amortization of prior service (cost) credit	-2.7	-3	-3.9
Amortization of transition asset	0	0	0
Total recognized in other comprehensive income	102.1	-200.9	21.6
Total recognized in net periodic cost and other comprehensive income	133.4	-148.8	76.8
Defined Benefit Plan, Benefit Obligation	-1,227.40	-1,118	-1,244.30
Defined Benefit Plan, Funded Status of Plan	-277.8	-202.7
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss)	5	11.5	11.6
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements and Curtailments	-7.9	0	0
Defined Benefit Plan, Cost of Providing Special or Contractual Termination Benefits Recognized During Period	0	0	0
Defined Benefit Plan, Fair Value of Plan Assets	269.3	251.8	237
Service cost	6.7	12.3	14.7
Interest cost	16.2	17.3	20.6
Expected return on plan assets	-17.1	-20.1	-17.7
Amortization:
Net asset	0	0	-3
Prior service costs (credits)	-3.6	-3.6	1.9
Net actuarial loss	5	11.5	11.6
Net periodic benefit cost	-0.7	17.4	28.1
Effect of Curtailment	-0.8	0	0
Current year actuarial (gain)/loss	36.9	-95.2	3.2
Amortization of net loss	5	11.5	11.6
Current year prior service cost	-0.9	0	-58.3
Amortization of prior service (cost) credit	3.6	3.6	-1.9
Amortization of transition asset	0	0	3
Total recognized in other comprehensive income	33.8	-103.1	-65.6
Total recognized in net periodic cost and other comprehensive income	33.1	-85.7	-37.5
Defined Benefit Plan, Benefit Obligation	-395.9	-356.2	-459.8
Defined Benefit Plan, Funded Status of Plan	-126.6	-104.4
Salaried Employees [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	366.4	357.4
Amortization:
Defined Benefit Plan, Benefit Obligation	-471.4	-427.2
Defined Benefit Plan, Funded Status of Plan	-105	-69.8
Salaried Employees [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Amortization:
Defined Benefit Plan, Benefit Obligation	-54	-53.6
Defined Benefit Plan, Funded Status of Plan	-54	-53.6
Hourly Employees [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	576.6	552.7
Amortization:
Defined Benefit Plan, Benefit Obligation	-739.2	-674.8
Defined Benefit Plan, Funded Status of Plan	-162.6	-122.1
Hourly Employees [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	269.3	251.8
Amortization:
Defined Benefit Plan, Benefit Obligation	-341.9	-302.6
Defined Benefit Plan, Funded Status of Plan	-72.6	-50.8
Mining Employees [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.6	5.2
Amortization:
Defined Benefit Plan, Benefit Obligation	-9.2	-6.8
Defined Benefit Plan, Funded Status of Plan	-2.6	-1.6
Supplemental Executive Retirement Plan S E R P [Member] | Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Amortization:
Defined Benefit Plan, Benefit Obligation	-7.6	-9.2
Defined Benefit Plan, Funded Status of Plan	($7.60)	($9.20)

PENSIONS_AND_OTHER_POSTRETIREM6

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Additional Information) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect of change in mine ownership & noncontrolling interest	$51.40	$46.50	$54.80
Actual return on plan assets	78.7	109.5	92.5
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect of change in mine ownership & noncontrolling interest	5.9	4.8	8.6
Actual return on plan assets	$31.90	$11	$26.10

PENSIONS_AND_OTHER_POSTRETIREM7

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Weighted-Average Assumptions Used to Determine Benefit Obligations) (Details)	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits [Member] | United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.83%	4.57%
Expected return on plan assets	8.25%	8.25%
Pension Benefits [Member] | Canada [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.75%	4.50%
Expected return on plan assets	7.25%	7.25%
Other Benefits [Member] | United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.83%	4.57%
Expected return on plan assets	7.00%	7.00%
Other Benefits [Member] | Canada [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.75%	4.75%
Salary [Member] | Pension Benefits [Member] | United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Rate of compensation increase	3.00%	4.00%
Salary [Member] | Pension Benefits [Member] | Canada [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Rate of compensation increase	3.00%	4.00%
Hourly [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Rate of compensation increase	2.50%	3.00%

PENSIONS_AND_OTHER_POSTRETIREM8

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Weighted-Average Assumptions Used to Determine Net Benefit Cost) (Details)	12 Months Ended			2 Months Ended	10 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012	Oct. 31, 2012
Pension Benefits [Member] | United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.57%	3.70%	4.28%
Expected return on plan assets	8.25%	8.25%	8.25%
Pension Benefits [Member] | Canada [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.50%	3.75%	4.00%
Expected return on plan assets	7.25%	7.25%	7.25%
Other Benefits [Member] | United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.57%	3.70%
Expected return on plan assets	7.00%	8.25%	8.25%
Other Benefits [Member] | Canada [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	4.75%	4.00%	4.25%
Hourly [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Rate of compensation increase	4.00%	4.00%	4.00%
Salary [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Rate of compensation increase	4.00%	4.00%	4.00%
Salary [Member] | Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Rate of compensation increase	4.00%	4.00%	4.00%
Salaried Plan [Member] | United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate			4.28%
Hourly Plan [Member] | United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate				3.51%	4.28%

PENSIONS_AND_OTHER_POSTRETIREM9

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Assumed Health Care Cost Trend Rates) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Ultimate health care cost trend rate	5.00%	5.00%
United States [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care cost trend rate assumed for next year	7.00%	7.25%
Canada [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Health care cost trend rate assumed for next year	4.25%	4.00%

Recovered_Sheet2

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Change of One Percentage Point in Assumed Health Care Cost Trend Rates) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Effect on total of service and interest cost due to one percentage point increase	$3.40
Effect on total of service and interest cost due to one percentage point decrease	-2.7
Effect on postretirement benefit obligation due to one percentage point increase	49.6
Effect on postretirement benefit obligation due to one percentage point decrease	($39.90)
Minimum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Period of Long-term Return on Assets	3 years
Maximum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Period of Long-term Return on Assets	5 years

Recovered_Sheet3

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Target Allocation and Actual Asset Allocations for Pension and VEBA Plan Assets) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	100.00%	100.00%
Defined Benefit Plan, Target Plan Asset Allocations	100.00%
Pension Benefits [Member] | Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	48.60%	51.50%
Defined Benefit Plan, Target Plan Asset Allocations	48.20%
Pension Benefits [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	29.00%	26.70%
Defined Benefit Plan, Target Plan Asset Allocations	28.40%
Pension Benefits [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	6.20%	6.30%
Defined Benefit Plan, Target Plan Asset Allocations	6.10%
Pension Benefits [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	3.30%	3.20%
Defined Benefit Plan, Target Plan Asset Allocations	5.50%
Pension Benefits [Member] | Structured Finance [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	6.90%	6.70%
Defined Benefit Plan, Target Plan Asset Allocations	5.90%
Pension Benefits [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	5.30%	4.50%
Defined Benefit Plan, Target Plan Asset Allocations	5.90%
Pension Benefits [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	0.70%	1.10%
Defined Benefit Plan, Target Plan Asset Allocations	0.00%
Veba Trust [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	100.00%	100.00%
Defined Benefit Plan, Target Plan Asset Allocations	100.00%
Veba Trust [Member] | Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	8.60%	10.40%
Defined Benefit Plan, Target Plan Asset Allocations	8.00%
Veba Trust [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	79.30%	66.60%
Defined Benefit Plan, Target Plan Asset Allocations	80.10%
Veba Trust [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	4.30%	9.80%
Defined Benefit Plan, Target Plan Asset Allocations	4.20%
Veba Trust [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	2.30%	2.40%
Defined Benefit Plan, Target Plan Asset Allocations	2.60%
Veba Trust [Member] | Structured Finance [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	2.30%	5.40%
Defined Benefit Plan, Target Plan Asset Allocations	2.10%
Veba Trust [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	3.20%	5.30%
Defined Benefit Plan, Target Plan Asset Allocations	3.00%
Veba Trust [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Weighted-average asset allocation	0.00%	0.10%
Defined Benefit Plan, Target Plan Asset Allocations	0.00%

Recovered_Sheet4

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Fair Values of Pension Plan Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Reserve For Investment Commitments	$55.50	$45
Fair value of plan assets	205.8		188.6	200.5
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	949.6		915.3	838.7
Equity Securities [Member] | U S Large Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	248.5		261.5
Equity Securities [Member] | U S Small Mid Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	55.8		60.8
Equity Securities [Member] | International [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	157.4		149.3
Fixed Income Investments [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	275.5		244.9
Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	59.2		57.6	85.6
Hedge Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	59.2		57.6
Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	31.2		29.1	29.3
Private Equity Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	31.2		29.1
Structured Finance [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	65.4		61	56.2
Redemption Request Notice Period	90 days
Structured Finance [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	65.4		61
Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	50		40.9	29.4
Redemption Request Notice Period	45 days
Real Estate [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	50		40.9
Cash [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	6.6		10.2
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	712		696.6
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | U S Large Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	248.5		261.5
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | U S Small Mid Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	55.8		60.8
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | International [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	157.4		149.3
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fixed Income Investments [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	243.7		214.8
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Hedge Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Private Equity Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Structured Finance [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Real Estate [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Cash [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	6.6		10.2
Fair Value, Inputs, Level 2 [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	31.8		30.1
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | U S Large Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | U S Small Mid Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | International [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Fixed Income Investments [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	31.8		30.1
Fair Value, Inputs, Level 2 [Member] | Hedge Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Private Equity Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Structured Finance [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Real Estate [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Fair Value, Inputs, Level 2 [Member] | Cash [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Significant Unobservable Inputs (Level 3) [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	205.8		188.6
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | U S Large Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | U S Small Mid Cap [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | International [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Significant Unobservable Inputs (Level 3) [Member] | Fixed Income Investments [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	0		0
Significant Unobservable Inputs (Level 3) [Member] | Hedge Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	59.2		57.6
Significant Unobservable Inputs (Level 3) [Member] | Private Equity Funds [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	31.2		29.1
Significant Unobservable Inputs (Level 3) [Member] | Structured Finance [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	65.4		61
Significant Unobservable Inputs (Level 3) [Member] | Real Estate [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	50		40.9
Significant Unobservable Inputs (Level 3) [Member] | Cash [Member] | Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets	$0		$0

Recovered_Sheet5

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Fair Values of Other Benefit Plan Assets) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$205.80	$188.60	$200.50
Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	59.2	57.6	85.6
Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	31.2	29.1	29.3
Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	50	40.9	29.4
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	269.3	251.8	237
Other Benefits [Member] | Equity Securities [Member] | U S Large Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.6	15.7
Other Benefits [Member] | Equity Securities [Member] | U S Small Mid Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2.9	2.7
Other Benefits [Member] | Equity Securities [Member] | International [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.6	7.8
Other Benefits [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	213.6	168.1
Other Benefits [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	24.6
Other Benefits [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.2	6
Other Benefits [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.1	13.5
Other Benefits [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.7	13.2
Other Benefits [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0.1	0.2
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	197.7	160.8
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | U S Large Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.6	15.7
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | U S Small Mid Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2.9	2.7
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Equity Securities [Member] | International [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.6	7.8
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	174.5	134.4
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0.1	0.2
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	39.1	33.7
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | U S Large Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | U S Small Mid Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | International [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	39.1	33.7
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Fair Value, Inputs, Level 2 [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	32.5	57.3	57.8
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | U S Large Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | U S Small Mid Cap [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Equity Securities [Member] | International [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	24.6	23.2
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.2	6	6.2
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.1	13.5	12.5
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.7	13.2	15.9
Other Benefits [Member] | Significant Unobservable Inputs (Level 3) [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$0	$0

Recovered_Sheet6

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Annual Contributions To The Pension Plans) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	$7.30	$25.50
Expected company contributions, next fiscal year	6.8
Funded percentage	70.00%
Value of VEBA Trust Assets as a Percentage of the Funding Obligation	0.9
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	60.5	53.7
Expected company contributions, next fiscal year	36.8
Veba Trust [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	0	14.6
Expected company contributions, next fiscal year	0
Direct Payments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	7.3	10.9
Expected company contributions, next fiscal year	$6.80

Recovered_Sheet7

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Estimated Net Periodic Benefit Cost) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated net periodic benefit cost	$29.60
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Plan Participants	0	0
Estimated net periodic benefit cost	23.6
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Plan Participants	4.8	5.6
Estimated net periodic benefit cost	$6

Recovered_Sheet8

PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Other Potential Benefit Obligations) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$205.80	$188.60	$200.50
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	949.6	915.3	838.7
Defined Benefit Plan, Benefit Obligation	-1,227.40	-1,118	-1,244.30
Defined Benefit Plan, Funded Status of Plan	-277.8	-202.7
Additional shutdown and early retirement benefits	-26.7
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	269.3	251.8	237
Defined Benefit Plan, Benefit Obligation	-395.9	-356.2	-459.8
Defined Benefit Plan, Funded Status of Plan	-126.6	-104.4
Additional shutdown and early retirement benefits	$40.50

PENSIONS_AND_POSTRETIREMENT_BE

PENSIONS AND POSTRETIREMENT BENEFITS (Effect of Fair Value Measurements Using Significant Unobservable Inputs (Level 3) on Changes in Pension Plan Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014																Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block]	The following represents the effect of fair value measurements using significant unobservable inputs (Level 3) on changes in plan assets for the years ended December 31, 2014 and 2013:
		(In Millions)
		Year Ended December 31, 2014
		Hedge Funds			Private Equity			Structured			Real			Total
					Funds			Credit Fund			Estate
	Beginning balance — January 1, 2014	$	57.6		$	29.1		$	61		$	40.9		$	188.6
	Actual return on plan assets:
	Relating to assets still held at	3.1			3.2			4.4			5.2			15.9
	the reporting date
	Relating to assets sold during	(1.5		)	3			—			—			1.5
	the period
	Purchases	—			1.4			—			5.4			6.8
	Sales	—			(5.5		)	—			(1.5		)	(7.0		)
	Ending balance — December 31, 2014	$	59.2		$	31.2		$	65.4		$	50		$	205.8
		(In Millions)
		Year Ended December 31, 2013
		Hedge Funds			Private Equity			Structured			Real			Total
					Funds			Credit Fund			Estate
	Beginning balance — January 1, 2013	$	85.6		$	29.3		$	56.2		$	29.4		$	200.5
	Actual return on plan assets:
	Relating to assets still held at	4.5			(2.1		)	33.5			5.1			41
	the reporting date
	Relating to assets sold during	(1.2		)	5.2			(28.7		)	(0.4		)	(25.1		)
	the period
	Purchases	66			14.7			27.5			36.8			145
	Sales	(97.3		)	(18.0		)	(27.5		)	(30.0		)	(172.8		)
	Ending balance — December 31, 2013	$	57.6		$	29.1		$	61		$	40.9		$	188.6
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Roll Forward]
Fair value of plan assets b beginning of year	$188.60																$200.50
Actual return on plan assets:
Relating to assets still held at the reporting date	15.9																41
Relating to assets sold during the period	1.5																-25.1
Purchases	6.8																145
Sales	-7																-172.8
Fair value of plan assets b end of year	205.8																188.6
Hedge Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Roll Forward]
Fair value of plan assets b beginning of year	57.6																85.6
Actual return on plan assets:
Relating to assets still held at the reporting date	3.1																4.5
Relating to assets sold during the period	-1.5																-1.2
Purchases	0																66
Sales	0																-97.3
Fair value of plan assets b end of year	59.2																57.6
Private Equity Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Roll Forward]
Fair value of plan assets b beginning of year	29.1																29.3
Actual return on plan assets:
Relating to assets still held at the reporting date	3.2																-2.1
Relating to assets sold during the period	3																5.2
Purchases	1.4																14.7
Sales	-5.5																-18
Fair value of plan assets b end of year	31.2																29.1
Structured Finance [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Roll Forward]
Fair value of plan assets b beginning of year	61																56.2
Actual return on plan assets:
Relating to assets still held at the reporting date	4.4																33.5
Relating to assets sold during the period	0																-28.7
Purchases	0																27.5
Sales	0																-27.5
Fair value of plan assets b end of year	65.4																61
Real Estate [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Roll Forward]
Fair value of plan assets b beginning of year	40.9																29.4
Actual return on plan assets:
Relating to assets still held at the reporting date	5.2																5.1
Relating to assets sold during the period	0																-0.4
Purchases	5.4																36.8
Sales	-1.5																-30
Fair value of plan assets b end of year	$50																$40.90
Veba Trust [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block]	The following represents the effect of fair value measurements using significant unobservable inputs (Level 3) on changes in plan assets for the year ended December 31, 2014 and 2013:
		(In Millions)
		Year Ended December 31, 2014
		Hedge			Private Equity			Structured Credit Fund			Real			Total
		Funds			Funds						Estate
	Beginning balance — January 1, 2014	$	24.6		$	6		$	13.5		$	13.2		$	57.3
	Actual return on plan assets:
	Relating to assets still held at the reporting date	0.5			1			0.4			0.9			2.8
	Relating to assets sold during the period	0.6			0.4			0.4			0.5			1.9
	Purchases	—			0.1			—			—			0.1
	Sales	(14.2		)	(1.3		)	(8.2		)	(5.9		)	(29.6		)
	Ending balance — December 31, 2014	$	11.5		$	6.2		$	6.1		$	8.7		$	32.5
		(In Millions)
		Year Ended December 31, 2013
		Hedge			Private Equity			Structured Credit Fund			Real			Total
		Funds			Funds						Estate
	Beginning balance — January 1, 2014	$	23.2		$	6.2		$	12.5		$	15.9		$	57.8
	Actual return on plan assets:
	Relating to assets still held at the reporting date	2.1			0.2			2.4			2.8			7.5
	Relating to assets sold during the period	(0.7		)	0.4			(1.4		)	(0.7		)	(2.4		)
	Purchases	22.5			0.3			11			14.2			48
	Sales	(22.5		)	(1.1		)	(11		)	(19.0		)	(53.6		)
	Ending balance — December 31, 2014	$	24.6		$	6		$	13.5		$	13.2		$	57.3

PENSION_AND_OTHER_POSTRETIREME

PENSION AND OTHER POSTRETIREMENT BENEFITS (Effect of Fair Value Measurements Using Significant Unobservable Inputs (Level 3) on Changes in Other Benefit Plan Assets) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	$188.60	$200.50
Actual return on plan assets:
Relating to assets still held at the reporting date	15.9	41
Acquired through business combinations	6.8	145
Sales	-7	-172.8
Fair value of plan assets b end of year	205.8	188.6
Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	57.6	85.6
Actual return on plan assets:
Relating to assets still held at the reporting date	3.1	4.5
Acquired through business combinations	0	66
Sales	0	-97.3
Fair value of plan assets b end of year	59.2	57.6
Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	29.1	29.3
Actual return on plan assets:
Relating to assets still held at the reporting date	3.2	-2.1
Acquired through business combinations	1.4	14.7
Sales	-5.5	-18
Fair value of plan assets b end of year	31.2	29.1
Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	40.9	29.4
Actual return on plan assets:
Relating to assets still held at the reporting date	5.2	5.1
Acquired through business combinations	5.4	36.8
Sales	-1.5	-30
Fair value of plan assets b end of year	50	40.9
Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year			237
Actual return on plan assets:
Fair value of plan assets b end of year	269.3	251.8	237
Other Benefits [Member] | Hedge Funds [Member]
Actual return on plan assets:
Fair value of plan assets b end of year	11.5	24.6
Other Benefits [Member] | Private Equity Funds [Member]
Actual return on plan assets:
Fair value of plan assets b end of year	6.2	6
Other Benefits [Member] | Structured Credit [Member]
Actual return on plan assets:
Fair value of plan assets b end of year	6.1	13.5
Other Benefits [Member] | Real Estate [Member]
Actual return on plan assets:
Fair value of plan assets b end of year	8.7	13.2
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	57.3	57.8
Actual return on plan assets:
Relating to assets still held at the reporting date	2.8	7.5
Acquired through business combinations	0.1	48
Sales	-29.6	-53.6
Fair value of plan assets b end of year	32.5	57.3
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	24.6	23.2
Actual return on plan assets:
Relating to assets still held at the reporting date	0.5	2.1
Acquired through business combinations	0	22.5
Sales	-14.2	-22.5
Fair value of plan assets b end of year	11.5	24.6
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	6	6.2
Actual return on plan assets:
Relating to assets still held at the reporting date	1	0.2
Acquired through business combinations	0.1	0.3
Sales	-1.3	-1.1
Fair value of plan assets b end of year	6.2	6
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	13.5	12.5
Actual return on plan assets:
Relating to assets still held at the reporting date	0.4	2.4
Acquired through business combinations	0	11
Sales	-8.2	-11
Fair value of plan assets b end of year	6.1	13.5
Significant Unobservable Inputs (Level 3) [Member] | Other Benefits [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Fair value of plan assets b beginning of year	13.2	15.9
Actual return on plan assets:
Relating to assets still held at the reporting date	0.9	2.8
Acquired through business combinations	0	14.2
Sales	-5.9	-19
Fair value of plan assets b end of year	$8.70	$13.20

PENSION_AND_OTHER_POSTRETIREME1

PENSION AND OTHER POSTRETIREMENT BENEFITS (Estimated Future Benefit Payments) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan Expected Net Periodic Benefit Cost	$29.60
Pension Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan Expected Net Periodic Benefit Cost	23.6
2015	89.3
2016	77.7
2017	78.1
2018	79.3
2019	78.6
2020-2024	402.4
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan Expected Net Periodic Benefit Cost	6
Gross Company Benefits [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2015	23.1
2016	23
2017	23.2
2018	23.3
2019	22.9
2020-2024	110.7
Less Medicare Subsidy [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2015	0.9
2016	1
2017	1.1
2018	1.3
2019	1.4
2020-2024	8.6
Net Company Payments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
2015	22.2
2016	22
2017	22.1
2018	22
2019	21.5
2020-2024	$102.10

Recovered_Sheet9

PENSIONS AND OTHER POSTRETIREMENT BENEFITS PENSIONS AND OTHER POSTRETIREMENT BENEFITS (Unobservable Inputs, Level 3) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$205.80	$188.60	$200.50
Defined Benefit Plan, Actual Return on Plan Assets Still Held	15.9	41
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	1.5	-25.1
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	6.8	145
Defined Benefit Plan, Divestitures, Plan Assets	-7	-172.8
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	269.3	251.8	237
Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	31.2	29.1	29.3
Defined Benefit Plan, Actual Return on Plan Assets Still Held	3.2	-2.1
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	3	5.2
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	1.4	14.7
Defined Benefit Plan, Divestitures, Plan Assets	-5.5	-18
Private Equity Funds [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.2	6
Structured Finance [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	65.4	61	56.2
Defined Benefit Plan, Actual Return on Plan Assets Still Held	4.4	33.5
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	-28.7
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0	27.5
Defined Benefit Plan, Divestitures, Plan Assets	0	-27.5
Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	50	40.9	29.4
Defined Benefit Plan, Actual Return on Plan Assets Still Held	5.2	5.1
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0	-0.4
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	5.4	36.8
Defined Benefit Plan, Divestitures, Plan Assets	-1.5	-30
Real Estate [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.7	13.2
Structured Credit [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.1	13.5
Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	59.2	57.6	85.6
Defined Benefit Plan, Actual Return on Plan Assets Still Held	3.1	4.5
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	-1.5	-1.2
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0	66
Defined Benefit Plan, Divestitures, Plan Assets	0	-97.3
Hedge Funds [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	24.6
Fair Value, Inputs, Level 3 [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	32.5	57.3	57.8
Defined Benefit Plan, Actual Return on Plan Assets Still Held	2.8	7.5
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	1.9	-2.4
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0.1	48
Defined Benefit Plan, Divestitures, Plan Assets	-29.6	-53.6
Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.2	6	6.2
Defined Benefit Plan, Actual Return on Plan Assets Still Held	1	0.2
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0.4	0.4
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0.1	0.3
Defined Benefit Plan, Divestitures, Plan Assets	-1.3	-1.1
Fair Value, Inputs, Level 3 [Member] | Real Estate [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.7	13.2	15.9
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0.9	2.8
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0.5	-0.7
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0	14.2
Defined Benefit Plan, Divestitures, Plan Assets	-5.9	-19
Fair Value, Inputs, Level 3 [Member] | Structured Credit [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.1	13.5	12.5
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0.4	2.4
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0.4	-1.4
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0	11
Defined Benefit Plan, Divestitures, Plan Assets	-8.2	-11
Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member] | Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	24.6	23.2
Defined Benefit Plan, Actual Return on Plan Assets Still Held	0.5	2.1
Defined Benefit Plan, Actual Return on Plan Assets Sold During Period	0.6	-0.7
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0	22.5
Defined Benefit Plan, Divestitures, Plan Assets	($14.20)	($22.50)

Recovered_Sheet10

PENSIONS AND OTHER POSTRETIREMENT BENEFITS PENSIONS AND OTHER POSTRETIREMENT BENEFITS ( Fair Value of Recurring) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$205.80	$188.60	$200.50
Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	59.2	57.6	85.6
Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	31.2	29.1	29.3
Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	50	40.9	29.4
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	269.3	251.8	237
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	39.1	33.7
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	32.5	57.3	57.8
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	197.7	160.8
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	213.6	168.1
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	39.1	33.7
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Fixed Income Investments [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	174.5	134.4
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	24.6
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.5	24.6	23.2
Other Postretirement Benefit Plan, Defined Benefit [Member] | Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.2	6
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.2	6	6.2
Other Postretirement Benefit Plan, Defined Benefit [Member] | Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.1	13.5
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	6.1	13.5	12.5
Other Postretirement Benefit Plan, Defined Benefit [Member] | Structured Credit [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.7	13.2
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.7	13.2	15.9
Other Postretirement Benefit Plan, Defined Benefit [Member] | Real Estate [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0.1	0.2
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0.1	0.2
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2.9	2.7
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Small Mid Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	2.9	2.7
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.6	7.8
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | International [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	8.6	7.8
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	11.6	15.7
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | U S Large Cap [Member] | Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$11.60	$15.70

STOCK_COMPENSATION_PLANS_Narra

STOCK COMPENSATION PLANS (Narrative) (Details) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
	Agreement
	Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Plans	2
Allocated Share-based Compensation Expense	$23.70	$21.10	$20.60
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	8.3	7.4	7.2
Share-based Compensation Arrangement by Share-based Payment Award, Number of Plan Year Agreements	3
Number of performance shares granted	2,016,996
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	18.3
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 6 months
Option Indexed to Issuer's Equity, Strike Price	$13.83
2012 Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted under the award	800,000
Number of performance shares granted	400,000
Number of restricted shares granted	300,000
2012 Equity Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum number of shares that may be issued (in shares)	6,000,000
Two Thousand Twelve Equity Plan and Amended Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance/vesting period	3 years
Payout rate, as a percentage of the original grant		23.00%	50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Available for Issuance Proposed to be added to the Plan	5,000,000
Change in Control [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	$11.70
Two Thousand Fourteen to Two Thousand Sixteen Performance Period [Member] | Two Thousand Twelve Equity Plan and Amended 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%
Two Thousand Fourteen to Two Thousand Sixteen Performance Period [Member] | Two Thousand Twelve Equity Plan and Amended 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%

STOCK_COMPENSATION_PLANS_Assum

STOCK COMPENSATION PLANS (Assumptions Utilized To Estimate Fair Value For Performance Share Grants) (Details) (USD $)	3 Months Ended			12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair Value				$16.67
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Market Price	$17.62	$17.54	$20.58	$10.85
Average Expected Term (Years)	2 years 5 months	2 years 7 months 11 days	2 years 10 months 21 days	3 years 1 month 14 days
Expected Volatility	51.30%	54.00%	54.00%	52.90%
Risk-Free Interest Rate	0.83%	0.54%	0.54%	1.18%
Dividend Yield	3.40%	2.92%	2.92%	4.30%
Fair Value	$19.02	$18.93	$22.21	$10.61
Fair Value (Percent of Grant Date Market Price)	107.92%	107.92%	107.92%	97.79%

STOCK_COMPENSATION_PLANS_STOCK

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Employee Plans) (Details) (Two Thousand Twelve Equity Plan [Member])	12 Months Ended
	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Gross	300,000
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	6,000,000
Additional Restricted Stock Awards for New Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, Restricted Stock Award, Gross	500,000

STOCK_COMPENSATION_PLANS_STOCK1

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Incentive Plan Details) (Details)	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance shares granted					2,016,996
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance shares granted	400,000	283,530	124,630	385,585	1,233,685	806,271	501,346
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Estimated Forfeitures	40,911	24,380	21,098	120,299
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Expected to Vest	359,089	259,150	103,532	265,286

STOCK_COMPENSATION_PLANS_STOCK2

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Nonemployee Directors) (Details) (Directors Plan [Member], USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period from Date of Election, at End of Such Director is Required to Hold Certain Number of Shares			5 years
Deferred Compensation Arrangement with Individual, Fair Value of Shares Issued			$250,000
Stock Issued During Period Value Director Stock Award	$42,500	$42,500	$85,000
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	300,000		300,000

STOCK_COMPENSATION_PLANS_STOCK3

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Incentive Compensation and Other Benefit Plans for Employees and Directors) (Details)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Equity Grant Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period Shares Director Stock Award	73,635	31,506	8,988
Deferred Equity Grant Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period Shares Director Stock Award	0	7,970	2,996
Unrestricted Equity Grant Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period Shares Director Stock Award	0	3,985	1,498

STOCK_COMPENSATION_PLANS_STOCK4

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Schedule of Compensation Costs) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Selling, General and Administrative Expense									$208.70	$231.60	$282.50
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									-9,603.70	489.3	-501.8
Income Tax Expense (Benefit)	-289.7								-1,302	55.1	255.9
Net Income (Loss) Attributable to Parent	-1,285.10	-5,879.60	10.9	-70.3	43.3	117.2	146	107	-7,224.20	413.5	-899.4
Earnings Per Share, Basic	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.68	$0.87	$0.66	($47.52)	$2.40	($6.32)
Earnings Per Share, Diluted	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.66	$0.82	$0.66	($47.52)	$2.37	($6.32)
Deferred Compensation, Share-based Payments [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Costs and Expenses									7.8	6.3	4
Selling, General and Administrative Expense									15.9	14.8	16.6
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest									23.7	21.1	20.6
Income Tax Expense (Benefit)									-8.3	-7.4	-7.2
Net Income (Loss) Attributable to Parent									$15.40	$13.70	$13.40
Earnings Per Share, Basic									$0.10	$0.09	$0.09
Earnings Per Share, Diluted									$0.10	$0.08	$0.09

STOCK_COMPENSATION_PLANS_STOCK5

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Outstanding Employee Awards) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,845,552	1,633,866
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$16.55	$40.20
Number of performance shares granted	2,016,996
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$16.67
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	-1,230,056
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value	$38.48
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	-575,254
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value	$24.76

STOCK_COMPENSATION_PLANS_STOCK6

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Share Based Compensation Arrangement by Share-based Payment Award) (Details)	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,845,552				1,845,552	1,633,866
Number of performance shares granted					2,016,996
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					-1,230,056
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					-575,254
Common Stock, Capital Shares Reserved for Future Issuance	6,448,389				6,448,389
Restricted Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	250,000				250,000	0	0	0
Number of performance shares granted					250,000	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					0	0	0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	523,176				523,176	586,084	393,787	425,166
Number of performance shares granted					531,030	396,844	151,869
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					-423,822	-118,973	-161,741
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					-170,116	-85,574	-21,507
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	1,072,376				1,072,376	1,040,453	772,484	877,435
Number of performance shares granted	400,000	283,530	124,630	385,585	1,233,685	806,271	501,346
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					-796,624	-289,054	-574,518
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					-405,138	-249,248	-31,779
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested or Expected to Vest, Outstanding, Number	1,723,728				1,723,728
Directors Retainer and Voluntary Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	0				0	7,329	2,880	2,611
Number of performance shares granted					2,281	8,136	1,823
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period					-9,610	-2,166	-1,554
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period					0		0
Employee Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	6,222,434				6,222,434
Directors Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	225,955				225,955
Two Thousand Twelve Equity Plan and Amended Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share Based Goods And Nonemployee Services Transaction Valuation Method Payout Rate						23.00%	50.00%
Grants Associated with a Prior Period Payout Exceeding Target [Member] | Two Thousand Twelve Equity Plan and Amended Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of performance shares granted						54,051	191,506

INCOME_TAXES_Narrative_Details

INCOME TAXES (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$74,700,000	$74,400,000	$55,500,000	$102,100,000
Undistributed Earnings of Foreign Subsidiaries	0	1,200,000,000
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	1,900,000,000	157,900,000
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	6,000,000,000	3,500,000,000
Future Economic Realizable Benefit	108,100,000
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	5,800,000	5,800,000
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	267,700,000	299,200,000
Income Tax Effects Allocated Directly To Equity, Equity Transactions, Acquisition of Noncontrolling Interest	0	102,100,000	0
Valuation Allowance, Deferred Tax Asset, Change in Amount	1,361,000,000
Document Fiscal Year Focus	2014
Effective Income Tax Rate, Continuing Operations	35.00%	35.00%	35.00%
Current Fiscal Year End Date	-19
Reversal of Valuation Allowance on MRRT credits [Member]
Income Tax Contingency [Line Items]
Valuation Allowance, Deferred Tax Asset, Change in Amount	291,000,000
Deferred Tax Asset, Canadian Deferred Tax Asset that will not be realized [Member]
Income Tax Contingency [Line Items]
Valuation Allowance, Deferred Tax Asset, Change in Amount	1,273,200,000
Deferred Tax Asset, Alternative Minimum Tax Credit Not Utilized [Member]
Income Tax Contingency [Line Items]
Valuation Allowance, Deferred Tax Asset, Change in Amount	28,600,000
Deferred Ordinary Losses [Member]
Income Tax Contingency [Line Items]
Valuation Allowance, Deferred Tax Asset, Change in Amount	18,200,000
Deferred Tax Asset, Domestic Deferred Tax Asset that will not be realized [Member]
Income Tax Contingency [Line Items]
Valuation Allowance, Deferred Tax Asset, Change in Amount	402,500,000
Deferred Tax Assets [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	49,500,000	48,500,000
Other Liabilities [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	25,200,000	25,900,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	2,100,000	1,200,000
Deferred Tax Asset, Alternative Minimum Tax Credit Not Utilized [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	$540,700,000

INCOME_TAXES_INCOME_TAXES_SCHE

INCOME TAXES INCOME TAXES (SCHEDULE OF INCOME BEFORE INCOME TAXES) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Income (Loss) from Continuing Operations before Income Taxes, Domestic	($1,884.20)	$837.70	$838.60
Income (Loss) from Continuing Operations before Income Taxes, Foreign	-7,719.50	-348.4	-1,340.40
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	($9,603.70)	$489.30	($501.80)

Recovered_Sheet11

INCOME TAXES INCOME TAXES (Schedule of Components of Income Taxes) (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Current Federal Tax Expense (Benefit)		($159.90)	$101.30	$71.10
Current State and Local Tax Expense (Benefit)		-0.6	4	7.6
Current Foreign Tax Expense (Benefit)		17.2	87.9	50.2
Current Income Tax Expense (Benefit)		-143.3	193.2	128.9
Deferred Federal Income Tax Expense (Benefit)		-258.9	23.3	221.2
Deferred State and Local Income Tax Expense (Benefit)		-43	3	1.4
Deferred Foreign Income Tax Expense (Benefit)		-856.8	-164.4	-95.6
Deferred Income Tax Expense (Benefit)		-1,153.90	-138.1	127
Income Tax Expense (Benefit)	-289.7	-1,302	55.1	255.9
Deferred Provision (Benefit) [Member]
Income Tax Contingency [Line Items]
Deferred Income Tax Expense (Benefit)		($1,158.70)	($138.10)	$127

INCOME_TAXES_INCOME_TAXES_Sche1

INCOME TAXES INCOME TAXES (Schedule of Effective Rate Reconciliation) (Details)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2012
	USD ($)	USD ($)		USD ($)		USD ($)
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount		($3,361.30)		$171.30		($175.60)
Effective Income Tax Rate Reconciliation, Percent		35.00%	35.00%	35.00%	35.00%	35.00%	35.00%
Foreign Currency Transaction Gain, before Tax		-4.1		-2.6		62.3
Foreign Currency Transaction Gain Before Tax Percent		0.00%	0.00%	-0.50%	-0.50%	-12.40%	-12.40%
Non-taxable loss (income) related to noncontrolling interests		290.1		-1.5		61
Non-taxable loss (income) related to noncontrolling interests percent		-3.00%	-3.00%	-0.30%	-0.30%	-12.00%	-12.00%
Impact Of Tax Law Change		13		0		-357.1
Impact Of Tax Law Change Percent		-0.10%	-0.10%	0.00%	0.00%	71.20%	71.20%
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion		-87.9		-97.6		-109.1
Income Tax Reconciliation Tax Deduction for percentage depletion in excess of cost depletion percent		0.90%	0.90%	-19.90%	-19.90%	21.70%	21.70%
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount		592		-10.2		65.2
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent		-6.20%	-6.20%	-2.10%	-2.10%	-13.00%	-13.00%
Income not subject to tax		-46.5		-106.6		-108
Income not subject to tax percent		0.50%	0.50%	-21.80%	-21.80%	21.50%	21.50%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Amount		22.7		20.5		202.2
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent		-0.20%	-0.20%	4.20%	4.20%	-40.30%	-40.30%
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount		-43.6		5.6		7.3
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent		0.50%	0.50%	1.10%	1.10%	-1.50%	-1.50%
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount		-343.3		0		0
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent		3.60%	3.60%	0.00%	0.00%	0.00%	0.00%
Income Tax Reconciliation Manufacturers Deduction		0		-7.9		-4.7
Income Tax Reconciliation, Manufacturers Deduction Percent		0.00%	0.00%	-1.60%	-1.60%	0.90%	0.90%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount		1,660.60		73		634.5
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent		-17.30%	-17.30%	14.90%	14.90%	-126.50%	-126.50%
Tax Adjustments, Settlements, and Unusual Provisions		0.2		19.6		-14.8
Tax Adjustments Settlements And Unusual Provisions Percent		0.00%	0.00%	5.30%	5.30%	2.90%	2.90%
Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Percent		0.10%	-1040000000.00%	-3.60%	-1140000000.00%	1.10%	-570000000.00%
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount		16.5		2.9		-1.6
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent		-0.20%	-0.20%	0.60%	0.60%	0.40%	0.40%
Income Tax Expense (Benefit)	($289.70)	($1,302)		$55.10		$255.90
Income Tax Expense Benefit Percent		13.60%	13.60%	11.30%	11.30%	-51.00%	-51.00%

INCOME_TAXES_INCOME_TAXES_Inco

INCOME TAXES INCOME TAXES (Income Taxes for Other than Continuing Operations) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	$39.80	$100	$13.80
Other Comprehensive Income Unrealized Gain Loss On Mark To Market Adjustments Arising During Period Tax	3.6	2	1.7
Other Comprehensive Income (Loss), Other Tax	-1.1	-12.4	2.6
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	42.3	89.6	18.1
Income Tax Effects Allocated Directly To Equity, Equity Transactions, Acquisition of Noncontrolling Interest	0	102.1	0
Income Tax Effects Allocated Directly to Equity, Equity Transactions	-4.8	3.5	-12.8
Income Tax Refunds, Discontinued Operations	$0	($2)	$10.40

INCOME_TAXES_INCOME_TAXES_Sche2

INCOME TAXES INCOME TAXES (Schedule of Deferred Tax Assets and Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Income Tax Contingency [Line Items]
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions	$108.30	$88.40
Deferred Tax Assets, MMRT Starting Base Allowance	0	300.3
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Postretirement Benefits	63	58
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	267.7	299.2
Deferred Tax Assets Development Costs	6	0
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Asset Retirement Obligations	48.9	61.7
Deferred Tax Assets, Operating Loss Carryforwards	1,083.50	524.4
Deferred Tax Assets, Inventory	32.3	16.4
Deferred Tax Assets, Property, Plant and Equipment	901.6	56
Deferred Tax Assets, State Taxes	41.9	0
Deferred Tax Assets Leasing Arrangements	14.1	31.9
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other	153.6	138.3
Deferred Tax Assets, Gross	2,720.90	1,574.60
Deferred Tax Assets, Valuation Allowance	-2,224.50	-864.1
Deferred Tax Assets, Net of Valuation Allowance	496.4	710.5
Deferred Tax Liabilities, Property, Plant and Equipment	-20	-1,400.80
Deferred Tax Liabilities Investment In Ventures	-198	-196.4
Deferred Tax Liabilities, Intangible Assets	-7.3	-33.5
Deferred Tax Liabilities Income Tax Uncertainties	-49.5	-48.5
Deferred Tax Liabilities, Tax Deferred Income	-16.6	-12.8
Deferred Tax Liabilities Other Assets	-80.2	-93
Deferred Tax Liabilities, Net	-371.6	-1,785
Deferred Tax Assets, Net	$124.80	($1,074.50)

INCOME_TAXES_INCOME_TAXES_Sche3

INCOME TAXES INCOME TAXES (Schedule of Deferred Tax Assets and Liabilities by Location) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Income Tax Contingency [Line Items]
Deferred Tax Liabilities, Net, Noncurrent	$51.30	$1,146.50
Deferred Tax Assets, Net	124.8	-1,074.50
Foreign [Member]
Income Tax Contingency [Line Items]
Income tax receivable	2.2	29.4
Deferred Tax Assets, Net of Valuation Allowance, Noncurrent	12	41.5
Deferred Tax Liabilities, Net, Noncurrent	51.3	971.2
Deferred Tax Liabilities, Net, Current	4	6.1
United States and Foreign [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets	180.1	78.1
Deferred Tax Liability	55.3	1,152.60
United States [Member]
Income Tax Contingency [Line Items]
Income tax receivable	165.9	7.2
Deferred Tax Liabilities, Net, Noncurrent	$0	$175.30

INCOME_TAXES_INCOME_TAXES_Sche4

INCOME TAXES INCOME TAXES (Schedule of Unrecognized Tax Benefits Rollforward) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2010
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$74.70	$74.40	$55.50	$102.10
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	3.4	13.6	2.7
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	2.5	5.3	11.1
Unrecognized Tax Benefits Increases Decreases Resulting From Currency Translation	-0.2	0	0
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	-0.5	0	-60.4
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	-3.7	0	0
Other Increases decreases to unrecognized tax benefits	($1.20)	$0	$0

LEASE_OBLIGATIONS_Narrative_De

LEASE OBLIGATIONS (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Leased Assets [Line Items]
Capital Leased Assets, Gross	$92,700,000	$404,000,000
Asset Impairment Charges	9,029,900,000	250,800,000	1,049,900,000
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	18,100,000	198,500,000
Operating lease expense	20,600,000	29,500,000	25,800,000
Assets Held under Capital Leases [Member]
Operating Leased Assets [Line Items]
Asset Impairment Charges	$140.40

LEASE_OBLIGATIONS_Future_Minim

LEASE OBLIGATIONS (Future Minimum Lease Payments) (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Capital Leases
2014	$84.80
2015	34.1
2016	26.9
2017	20.4
Operating Leases, Future Minimum Payments, Due in Five Years	4.8
2018 and thereafter	21
Total minimum lease payments	198.6
Amounts representing interest	31.3
Present value of net minimum lease payments	167.3	[1]
Operating Leases
2014	12
2015	9.3
2016	8.4
2017	6.8
2018 and thereafter	9.9
Total minimum lease payments	51.2
Capital Leases, Future Minimum Payments Due in Five Years	11.4
Other Current Liabilities [Member]
Capital Leases
Present value of net minimum lease payments	74.5
Other Liabilities [Member]
Capital Leases
Present value of net minimum lease payments	$92.80
[1]	The total is comprised of $74.5 million and $92.8 million classified as Current portion of capital leases and Other liabilities, respectively, in the Statements of Unaudited Condensed Consolidated Financial Position at DecemberB 31, 2014.

ENVIRONMENTAL_AND_MINE_CLOSURE2

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Site Contingency [Line Items]
Payments for Environmental Liabilities	$3.10	$8.20
Accrual for Environmental Loss Contingencies	5.5	8.4
Mine Reclamation and Closing Liability, current and noncurrent	255.7	312.6
Total environmental and mine closure obligations	261.2	321
Current Fiscal Year End Date	-19
U.S. Iron Ore [Member]
Site Contingency [Line Items]
Mine closure obligation, number of mines (in number of facilities)	5
Eastern Canadian Iron Ore [Member]
Site Contingency [Line Items]
Mine closure obligation, number of mines (in number of facilities)	2
Asia Pacific Iron Ore [Member]
Site Contingency [Line Items]
Mine closure obligation, number of mines (in number of facilities)	1
North American Coal [Member]
Site Contingency [Line Items]
Mine closure obligation, number of mines (in number of facilities)	2
LTV Steel Mining Company [Member]
Site Contingency [Line Items]
Mine closure obligation, number of mines (in number of facilities)	1
Rio Tinto Mine Site [Member]
Site Contingency [Line Items]
Accrual for Environmental Loss Contingencies	2.5	5.3
Loss Contingency, Range of Possible Loss, Maximum		12.2
Rio Tinto Mine Site [Member] | Rio Tinto Working Group RTWG [Member]
Site Contingency [Line Items]
Accrual for Environmental Loss Contingencies		$29

ENVIRONMENTAL_AND_MINE_CLOSURE3

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Summary Of Mine Closure Obligations) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Loss Contingencies [Line Items]
Environmental	$5.50	$8.40
Mine Reclamation and Closing Liability, current and noncurrent	255.7	312.6
Total environmental and mine closure obligations	261.2	321
Less current portion	5.2	11.3
Long term environmental and mine closure obligations	256	309.7
U.S. Iron Ore [Member] | Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	120.9	152.2
Eastern Canadian Iron Ore [Member] | Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	56.5	78.2
Asia Pacific Iron Ore [Member] | Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	21.5	25.5
North American Coal [Member] | Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	33.9	34.7
LTV Steel Mining Company [Member] | Previously Owned Or Operating Facilities [Member]
Loss Contingencies [Line Items]
Mine Reclamation and Closing Liability, current and noncurrent	$22.90	$22

ENVIRONMENTAL_AND_MINE_CLOSURE4

ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Asset Retirement Obligation Disclosure) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Asset Retirement Obligation [Roll Forward]
Asset retirement obligation at beginning of period	$290.60	$231.10
Accretion expense	14.5	18.1
Exchange rate changes	-2.4	-3.4
Revision in estimated cash flows	-65.2	44.8
Payments	4.7	0
Asset retirement obligation at end of period	$232.80	$290.60

GOODWILL_AND_OTHER_INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill [Line Items]
Goodwill, Impairment Loss	$73.50	$80.90
Product	4,230.80	5,346.60	5,520.90
Below-market sales contracts, remaining contract life	2 years
Cost of Sales [Member]
Goodwill [Line Items]
Amortization expense relating to intangible assets	10.4	19.9	22.5
Product Revenues [Member] | Sales Revenue, Goods, Net [Member]
Goodwill [Line Items]
Product	23.1	45.9	46.3
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
Goodwill [Line Items]
Goodwill, Impairment Loss		80.9
Permits [Member]
Goodwill [Line Items]
Impairment of Intangible Assets, Finite-lived	15.5
Utility Contracts [Member]
Goodwill [Line Items]
Impairment of Intangible Assets, Finite-lived		$9.50	$0

GOODWILL_AND_OTHER_INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Goodwill) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Goodwill [Roll Forward]
Beginning Balance	$74.50	$167.40
Arising in business combinations	0	0
Impairment	-73.5	-80.9
Impact of foreign currency translation	1	-12
Ending Balance	2	74.5
Accumulated Goodwill Impairment Loss	-1,154.40	-1,080.90
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
Eastern Canadian Iron Ore [Member]
Goodwill [Roll Forward]
Beginning Balance	0	0
Arising in business combinations	0	0
Impairment	0	0
Impact of foreign currency translation	0	0
Ending Balance	0	0
Accumulated Goodwill Impairment Loss	-1,000	-1,000
Asia Pacific Iron Ore [Member]
Goodwill [Roll Forward]
Beginning Balance	72.5	84.5
Arising in business combinations	0	0
Impairment	-73.5	0
Impact of foreign currency translation	1	-12
Ending Balance	0	72.5
Accumulated Goodwill Impairment Loss	-73.5	0
Other Segment [Member]
Goodwill [Roll Forward]
Beginning Balance	0	80.9
Arising in business combinations	0	0
Impairment		80.9
Impact of foreign currency translation	0	0
Ending Balance	0	0
Accumulated Goodwill Impairment Loss	-80.9	-80.9
Other Segment [Member]
Goodwill [Roll Forward]
Impairment	$0

GOODWILL_AND_OTHER_INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Schedule Of Finite-Lived Intangible Assets By Major Class) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount	$79.20	$184.50
Definite lived intangible assets - Accumulated Amortization	-16.5	-89.1
Definite lived intangible assets - Net Carrying Amount	62.7	95.4
Permits [Member] | Other Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount	79.2	127.4
Definite lived intangible assets - Accumulated Amortization	-16.5	-35.9
Definite lived intangible assets - Net Carrying Amount	62.7	91.5
Utility Contracts [Member] | Other Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount		54.7
Definite lived intangible assets - Accumulated Amortization		-53.1
Definite lived intangible assets - Net Carrying Amount		1.6
Leases [Member] | Other Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Definite lived intangible assets - Gross Carrying Amount		2.4
Definite lived intangible assets - Accumulated Amortization		-0.1
Definite lived intangible assets - Net Carrying Amount		2.3
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	159.7
Definite lived intangible assets - Net Carrying Amount	-46.1	-69.2
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	159.7
Definite lived intangible assets - Net Carrying Amount	($23.10)	($46.20)

GOODWILL_AND_OTHER_INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Estimated Amortization Expense Relating To Intangible Assets) (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Estimated amortization expense, intangible assets [Abstract]
2015	$4.10
2016	4.2
2017	4
2018	3.8
2019	3.5
Total	$19.60

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 $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014
Estimated recognition of product revenues, below-market sales contracts [Abstract]
2015	$23
2016	23.1
Total	$46.10

DERIVATIVE_INSTRUMENTS_AND_HED2

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details) (USD $)	12 Months Ended			9 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013
Derivative [Line Items]
Current Fiscal Year End Date	-19
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	($28,200,000)	($51,700,000)	$25,600,000
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-31,000,000	-22,100,000	18,100,000
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	159,100,000	141,400,000	163,200,000
Accounts receivable, net	205,600,000	270,000,000
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	-14,300,000	-4,100,000	0
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-17,700,000	-1,900,000	0
Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	0
Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [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	0
Foreign Exchange Contract [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-16,900,000		0
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	-13,900,000	-34,700,000	20,200,000
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	-13,200,000	-11,900,000	14,800,000
Australian Dollar Foreign Exchange Contract Hedge Designation [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	220,000,000	323,000,000
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	-15,100,000
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	0	-12,900,000	6,700,000
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	-8,200,000	3,300,000
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	0	285,900,000
Interest Rate Swap [Member] | Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	300,000			100,000
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	250,000,000
Treasury Lock [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net			-1,300,000
Treasury Lock [Member] | Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-100,000	-100,000	0
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	0	-400,000
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	-100,000
Treasury Lock [Member] | Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount			200,000,000
Treasury Lock [Member] | Designated as Hedging Instrument [Member] | Accumulated Other Comprehensive Income (Loss) [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		-1,300,000
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	187,800,000	149,200,000	171,400,000
Customer Supply Agreement [Member] | Not Designated as Hedging Instrument [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	63,200,000	55,800,000
Provisional Pricing Arrangements [Member] | Product Revenues [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-11,800,000	-7,200,000	-7,800,000
Provisional Pricing Arrangements [Member] | Not Designated as Hedging Instrument [Member] | U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member] | Product Revenues [Member]
Derivative [Line Items]
Amount of gain/(loss) recognized in income on derivative	-11,800,000	-7,200,000
Provisional Pricing Arrangements [Member] | Not Designated as Hedging Instrument [Member] | U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member] | Other Current Assets [Member]
Derivative [Line Items]
Derivative assets	0	3,100,000
Provisional Pricing Arrangements [Member] | Not Designated as Hedging Instrument [Member] | U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member] | Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liabilities	11,800,000	10,300,000
Provisional Pricing Arrangements [Member] | Not Designated as Hedging Instrument [Member] | U.S. Iron Ore and Eastern Canadian Iron Ore [Member] | Product Revenues [Member]
Derivative [Line Items]
Amount of gain/(loss) recognized in income on derivative			-7,800,000
$500 Million 3.95% 2018 Senior Notes [Member]
Derivative [Line Items]
Debt Instrument, Face Amount	500,000,000	500,000,000
Bloom Lake [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	-9,900,000
Bloom Lake [Member] | Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	183,000,000
Bloom Lake [Member] | Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [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	0
Bloom Lake [Member] | Foreign Exchange Contract [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-7,300,000
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [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	-500,000
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount		74,800,000
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [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	0
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Foreign Exchange Contract [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	3,300,000	-600,000
Wabush [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		($1,900,000)

DERIVATIVE_INSTRUMENTS_AND_HED3

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Schedule Of Derivative Instruments In Statement Of Financial Position, Fair Value) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	$63.20	$59.20
Derivative liability, fair value	43.3	39.3
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0.3
Derivative liability, fair value	21.6	27.9
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	63.2	58.9
Derivative liability, fair value	21.7	11.4
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	0	2.1
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	0.3
Fair Value, Inputs, Level 2 [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	21.6	25.8
Fair Value, Inputs, Level 2 [Member] | Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member] | Other Current 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] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	9.9	1.1
Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Customer Supply Agreement [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	63.2	55.8
Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	0	3.1
Market Approach Valuation Technique [Member] | Fair Value, Inputs, Level 3 [Member] | Not Designated as Hedging Instrument [Member] | Provisional Pricing Arrangements [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	$11.80	$10.30

DERIVATIVE_INSTRUMENTS_AND_HED4

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Statements Of Financial Performance Location Table) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	($28.20)	($51.70)	$25.60
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-31	-22.1	18.1
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	-13.9	-34.7	20.2
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	-13.2	-11.9	14.8
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	0	-12.9	6.7
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	-8.2	3.3
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	-14.3	-4.1	0
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member] | Cost of Sales [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-17.7	-1.9	0
Treasury Lock [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net			-1.3
Treasury Lock [Member] | Other Nonoperating Income (Expense) [Member]
Derivative [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	-0.1	-0.1	0
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [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	($0.50)

DERIVATIVE_INSTRUMENTS_AND_HED5

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Schedule of Derivative Instruments Designated as Fair Value Hedges) (Details) (Other Nonoperating Income (Expense) [Member], Interest Rate Swap [Member], USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2014
Other Nonoperating Income (Expense) [Member] | Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net	$0.10	$0.30

DERIVATIVE_INSTRUMENTS_AND_HED6

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Schedule Of Derivatives Not Designated As Hedging Instruments) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$159.10	$141.40	$163.20
Foreign Exchange Contract [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-16.9		0
Foreign Exchange Contract [Member] | Other Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	0	0.3
Foreign Exchange Contract [Member] | Discontinued Operations [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	0	-0.3
Treasury Lock [Member] | Other Nonoperating Income (Expense) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	0	-0.4
Customer Supply Agreements [Member] | Product Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	187.8	149.2	171.4
Provisional Pricing Arrangements [Member] | Product Revenues [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	($11.80)	($7.20)	($7.80)

DISCONTINUED_OPERATIONS_Detail

DISCONTINUED OPERATIONS (Details) (USD $)	3 Months Ended						12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jul. 10, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale Price of CLCC Assets							$174
Proceeds from sale of Cliffs Logan County Coal							155	0	0
Statements of Consolidated Operations
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	0	0	0	2	0	0	0	2	35.9
Sonoma [Member]
Statements of Consolidated Operations
Disposal Group, Including Discontinued Operation, Revenue							0	0	151.6
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	0						0	2	35.9
Sonoma [Member] | Asia Pacific Coal [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage Of Ownership Interests										45.00%
Income (Loss) From Discontinued Operations [Member] | Sonoma [Member]
Statements of Consolidated Operations
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax							0	0	38
Discontinued Operation, Tax (Expense) Benefit from Provision for (Gain) Loss on Disposal									8.1
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax									-2.1
Discontinued Operation, Tax Effect of Discontinued Operation									$2.40
Wabush [Member]
Statements of Consolidated Operations
Percentage of Consolidated Revenues							8.00%
Percentage of Consolidated Assets							4.00%
CLCC [Member]
Statements of Consolidated Operations
Percentage of Consolidated Revenues							5.00%
Percentage of Consolidated Assets							8.00%
Coal Revenue [Member]
Statements of Consolidated Operations
Percentage of Consolidated Revenues							15.00%

DISCONTINUED_OPERATIONS_SCHEDU

DISCONTINUED OPERATIONS SCHEDULE OF DISPOSAL GROUPS (Details) (USD $)	3 Months Ended						12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest							($9,603.70)	$489.30	($501.80)
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	0	0	0	2	0	0	0	2	35.9
Sonoma [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Revenue							0	0	151.6
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	0						0	2	35.9
Income (Loss) From Discontinued Operations [Member] | Sonoma [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax							0	0	38
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax									-2.1
Wabush [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest							-345.6	-258.6	-131.8
CLCC [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest							($669.90)	($55)	($41.80)

CAPITAL_STOCK_Details

CAPITAL STOCK (Details) (USD $)	3 Months Ended				12 Months Ended			2 Months Ended	3 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 21, 2013	Feb. 11, 2013	Nov. 19, 2014	Nov. 03, 2014	Aug. 01, 2014	Feb. 03, 2014	Nov. 01, 2013	Aug. 01, 2013	Mar. 20, 2013	Sep. 02, 2014	Jun. 03, 2014	Mar. 03, 2014	Dec. 02, 2013	Sep. 03, 2013	Jun. 03, 2013	Mar. 01, 2013
Class of Stock [Line Items]
Depositary Share Interest in a Share of 7% Series A Mandatory Convertible Preferred Stock, Class A					0.025
Common Stock, Par or Stated Value Per Share	$0.13				$0.13	$0.13
Trading Day Window Determining Number of Common Shares Issuable on Conversion					20
Net proceeds from issuance of Series A, Mandatory Convertible Preferred Stock, Class A					$0	$709.40	$0
Dividends, Preferred Stock	12.8	12.8	12.8	12.8	51.2	48.7	0
Common shares, issued (in shares)	159,546,224				159,546,224	159,546,224
Net proceeds from issuance of common shares					0	285.3	0
Over Allotment Option [Member]
Class of Stock [Line Items]
Common shares, issued (in shares)								1,350,000
Preferred Class A [Member]
Class of Stock [Line Items]
Series A Mandatory Convertible Preferred Stock, Class A, Percentage					7.00%
Preferred Stock, Liquidation Preference Per Share	$1,000				$1,000	$1,000
Dividends payable, per share										$17.50	$17.50	$0.44	$0.44	$0.44	$17.50	$13.61
Dividends, Preferred Stock	$12.80				$51.20
Issuance of common shares, public offering (in shares)								731,250
Closing price per share (in usd per share)								$25
Common Stock [Member]
Class of Stock [Line Items]
Dividends payable, per share																	$0.15	$0.15	$0.15	$0.15	$0.15	$0.15	$0.15
Percentage increase (decrease) in dividends payable									76.00%
Issuance of common shares, public offering (in shares)								10,350,000
Common shares, issued (in shares)								9,000,000
Closing price per share (in usd per share)								$29
Common Stock [Member] | Minimum [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion	28.148				28.148
Convertible Preferred Stock, Shares Issued Upon Conversion per Depositary Share	0.7037				0.7037
Number of Common Shares Mandatory Convertible Stock Converts to on February 1, 2016	20,600,000				20,600,000
Common Stock [Member] | Maximum [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Shares Issued upon Conversion	34.484				34.484
Number of Common Shares Mandatory Convertible Stock Converts to on February 1, 2016	25,200,000				25,200,000
Common Stock from when Mandatory Convertible Preferred Stock Converts on February 1, 2016 [Member]
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share	$0.13				$0.13
Depositary Shares [Member]
Class of Stock [Line Items]
Depositary Share Offering included in Depositary Share Issuance								27,000,000
Number of Shares included in Depositary Share Issuance due to Exercise of								2,250,000
Preferred Stock, Liquidation Preference Per Share	$25				$25
Dividends payable, per share										$0.44	$0.44	$17.50	$17.50	$17.50	$0.44	$0.34
Issuance of common shares, public offering (in shares)								29,250,000

ACCUMULATED_OTHER_COMPREHENSIV2

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Accumulated Other Comprehensive Income (Loss) and Related Tax Effects (Details) (USD $)	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Millions, unless otherwise specified
Accumulated Other Comprehensive Income (Loss), Before Taxes	($388.10)				($213.30)				($244.70)
Accumulated Other Comprehensive Income (Loss), Tax	142.3				100.4				189.1
Accumulated other comprehensive loss	-245.8	-101.4	-20.2	-55.1	-112.9	-178.4	-239.6	-51.4	-55.6	-92.6
Postretirement Benefit Liability [Member]
Accumulated Other Comprehensive Income (Loss), Before Taxes	-425.3				-299.3				-576.7
Accumulated Other Comprehensive Income (Loss), Tax	134.2				94.4				194
Accumulated other comprehensive loss	-291.1				-204.9				-382.7
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Before Taxes	64.4				106.7				316.3
Accumulated Other Comprehensive Income (Loss), Tax	0				0				0
Accumulated other comprehensive loss	64.4				106.7				316.3
Unrealized Gain Loss On Derivatives [Member]
Accumulated Other Comprehensive Income (Loss), Before Taxes	-25.9				-30				12.4
Accumulated Other Comprehensive Income (Loss), Tax	7.8				9.1				-3.7
Accumulated other comprehensive loss	-18.1				-20.9				8.7
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss), Before Taxes	-1.3				9.3				3.3
Accumulated Other Comprehensive Income (Loss), Tax	0.3				-3.1				-1.2
Accumulated other comprehensive loss	($1)				$6.20				$2.10

ACCUMULATED_OTHER_COMPREHENSIV3

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Accumulated Other Comprehensive Income (Loss) (Details) (USD $)	12 Months Ended			3 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	($291.10)	($204.90)	($382.70)	($291.10)	($188.30)	($199.40)	($202)	($204.90)	($365.10)	($370.80)	($377.40)	($408.90)
Accumulated other comprehensive loss	-245.8	-112.9	-55.6	-245.8	-101.4	-20.2	-55.1	-112.9	-178.4	-239.6	-51.4	-92.6
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	-1	6.2	2.1	-1	0.6	6.4	10.1	6.2	10.7	6.3	4.7	2.6
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	64.4	106.7	316.3	64.4	101	166.9	147.2	106.7	190.4	167.6	319.6	312.5
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	-18.1	-20.9	8.7	-18.1	-14.7	5.9	-10.4	-20.9	-14.4	-42.7	1.7	1.2
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	91	-208.3	-33.8
Unrealized net gain (loss) on marketable securities, net of tax	-7.2	3.1	-0.5
Unrealized net gain (loss) on foreign currency translation	-42.3	-208.6	3.8
Other Comprehensive Income (Loss), Net of Tax	-137.7	-26.8	44.6
Accumulated Other Comprehensive Income (Loss) [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax				-152.3	-81.1	25.6	41.6	49.3	37.8	-197.7	-0.3
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)				7.9	-0.1	9.3	16.2	16.2	23.4	9.5	4.5
Accumulated Defined Benefit Plans Adjustment [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax				-98.7	3.5	-1.4	-0.4	154.5	-0.6	-1.5	-1.1
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax				-1.4	1.3	-2.4	3.8	-4.9	3.5	-2	2.5
Accumulated Translation Adjustment [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax				-36.6	-65.9	19.7	40.5	-83.7	22.8	-152	3.3
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Other Comprehensive Income (Loss), before Reclassifications, before Tax				-15.6	-20	9.7	-2.3	-16.6	12.1	-42.2	-5
Accumulated Defined Benefit Plans Adjustment [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)				-4.1	7.6	4	3.3	5.7	6.3	8.1	6.4
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)				-0.2	-7.1	-1.3	0.1	0.4	0.9	3.6	0.1
Accumulated Translation Adjustment [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)				0	0	0	0	0	0	0	0
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)				12.2	-0.6	6.6	12.8	10.1	16.2	-2.2	-2
Cliffs Shareholders Equity [Member]
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax			26.2
Unrealized net gain (loss) on marketable securities, net of tax			-0.5
Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax			3.8
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax			7.5
Other Comprehensive Income (Loss), Net of Tax			$37

ACCUMULATED_OTHER_COMPREHENSIV4

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) Details of Accumulated Other Comprehensive Income (Loss) Components (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Details of Accumulated Other Comprehensive Income (Loss) Components [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	($31)		($22.10)		$18.10
Total Amount Reclassified from Accumulated Other Comprehensive Income (Loss) During the Period	33.3		53.6
Accumulated Defined Benefit Plans Adjustment [Member]
Details of Accumulated Other Comprehensive Income (Loss) Components [Line Items]
Amortization of prior service (cost) credit	0.9	[1]	0.6	[1]
Defined Benefit Plan, Amortization of Gains (Losses)	19.1	[1]	41.4	[1]
Defined Benefit Plan, Curtailments	-5		0
Defined Benefit Plan, Special Termination Benefits	3.4		0
Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax	16.6		40.8
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	-5.8		-14.3
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss)	10.8		26.5
Unrealized Gain (Loss) on Marketable Securities [Member] [Member]
Details of Accumulated Other Comprehensive Income (Loss) Components [Line Items]
Marketable Securities, Unrealized Gain (Loss)	-11.4		-0.2
Accumulated Other-than-Temporary Impairment [Member]
Details of Accumulated Other Comprehensive Income (Loss) Components [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	-0.5		5.3
Unrealized Gain (Loss) on Marketable Securities and Other than Temporary Impairment [Member] [Member]
Details of Accumulated Other Comprehensive Income (Loss) Components [Line Items]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	-11.9		5.1
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	3.4		-0.1
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	-8.5		5
Unrealized Gain Loss On Derivatives [Member]
Details of Accumulated Other Comprehensive Income (Loss) Components [Line Items]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	45.6		32.3
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	-14.6		-10.2
Unrealized net gain (loss) on derivative financial instruments, net of tax	31		22.1
Unrealized Gain Loss On Derivatives [Member] | Australian Hedge Contracts [Member]
Details of Accumulated Other Comprehensive Income (Loss) Components [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	18.9		17
Unrealized Gain Loss On Derivatives [Member] | Canadian Hedge Contracts [Member]
Details of Accumulated Other Comprehensive Income (Loss) Components [Line Items]
Derivative Instruments, (Gain) Loss Reclassified from Accumulated OCI into Income, Effective Portion, Net	$26.70		$15.30
[1]	hese accumulated other comprehensive income components are included in the net periodic benefit cost recognized for the year ended December 31, 2014 and 2013. See NOTE 7 - PENSIONS AND OTHER POSTRETIREMENT BENEFITS for further information.

CASH_FLOW_INFORMATION_Narrativ

CASH FLOW INFORMATION (Narrative) (Details) (USD $)	3 Months Ended				12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Nov. 19, 2014	Nov. 03, 2014	Aug. 01, 2014	Feb. 03, 2014	Nov. 01, 2013	Aug. 01, 2013	Mar. 20, 2013
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	$12.80	$12.80	$51.20	$48.70	$0
Preferred Class A [Member]
Dividends Payable [Line Items]
Series A Mandatory Convertible Preferred Stock, Class A, Percentage					7.00%
Dividends payable, per share								$17.50	$17.50	$0.44	$0.44	$0.44	$17.50	$13.61
Preferred stock cash dividend	$12.80				$51.20
Depositary Shares [Member]
Dividends Payable [Line Items]
Dividends payable, per share								$0.44	$0.44	$17.50	$17.50	$17.50	$0.44	$0.34

CASH_FLOW_INFORMATION_Reconcil

CASH FLOW INFORMATION (Reconciliation Of Capital Additions To Cash Paid For Capital Expenditures) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Payments To Acquire Property Plant And Equipment Net	$284.10	$861.60	$1,127.50
Property, Plant and Equipment, Additions	235.5	752.3	1,335.30
Non-cash accruals	-58.5	-109.3	152.5
Capital leases	9.9	0	55.3
Total	($48.60)	($109.30)	$207.80

CASH_FLOW_INFORMATION_CASH_FLO

CASH FLOW INFORMATION CASH FLOW INFORMATION (Cash Paid for Income Taxes) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract]
Income Taxes Paid	$47.30	$153.30	$443.20
Interest Paid	$176.50	$174.40	$207.50

RELATED_PARTIES_Narrative_Deta

RELATED PARTIES (Narrative) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
	Facility
Segment Reporting Information [Line Items]
Due from Related Parties, Current	151.1	$132
Due to Related Parties, Current	13.6	$25.10
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Number Of Mines	5
Eastern Canadian Iron Ore [Member]
Segment Reporting Information [Line Items]
Number Of Mines	2
Joint Venture Partners [Member] | U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Number Of Mines	3
Joint Venture Partners [Member] | Eastern Canadian Iron Ore [Member]
Segment Reporting Information [Line Items]
Number Of Mines	1

RELATED_PARTIES_Summary_Of_Oth

RELATED PARTIES (Summary Of Other Ownership Interests) (Details)	Dec. 31, 2014		Dec. 31, 2012
Hibbing [Member] | Arcelor Mittal [Member]
Related Party Transaction [Line Items]
Ownership interest, equity method investment	62.30%
Hibbing [Member] | WISCO [Member]
Related Party Transaction [Line Items]
Ownership interest, equity method investment	0.00%
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] | WISCO [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%
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] | WISCO [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%		75.00%
Bloom Lake [Member] | Arcelor Mittal [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%
Bloom Lake [Member] | WISCO [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	17.20%
Bloom Lake [Member] | U. S. Steel Canada [Member]
Related Party Transaction [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	0.00%
Investments in Ventures [Member] | Hibbing [Member]
Related Party Transaction [Line Items]
Ownership interest, equity method investment	23.00%	[1]
[1]	1 At December 31, 2013, the classification for Hibbing was Other liabilities.

RELATED_PARTIES_Summary_Of_Rel

RELATED PARTIES (Summary Of Related Party Transactions Table Disclosure) (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions [Abstract]
Product revenues from related parties	$1,378.70	$1,664.80	$1,660.80
Product	$4,230.80	$5,346.60	$5,520.90
Related party product revenue as a percent of total product revenue	32.60%	31.10%	30.10%

EARNINGS_PER_SHARE_Earnings_Pe

EARNINGS PER SHARE (Earnings Per Share Computation) (Details) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	25,200,000							12,900,000	25,200,000
Income (Loss) from Continuing Operations Attributable to Parent	($1,285.10)	($5,879.60)	$10.90	($70.30)	$43.30	$115.20	$146	$107	($7,224.20)	$411.50	($935.30)
Income (Loss) and Gain on Sale from Discontinued Operations, net of tax	0	0			0	2	0	0	0	2	35.9
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	-1,285.10	-5,879.60	10.9	-70.3	43.3	117.2	146	107	-7,224.20	413.5	-899.4
PREFERRED STOCK DIVIDENDS	-12.8	-12.8	-12.8	-12.8					-51.2	-48.7	0
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	-1,297.90	-5,892.40	-1.9	-83.1					-7,275.40	364.8	-899.4
Antidilutive Incremental Common Shares Excluded and Attributable to Share-based Payment Arrangements									700,000	0	500,000
Weighted Average Number of Shares:
Basic									153,098,000	151,726,000	142,351,000
Depositary Shares									0	458,000	0
Employee Stock Plans									0	22,139,000	0
Diluted									153,098,000	174,323,000	142,351,000
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Basic:
Continuing operations	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.67	$0.87	$0.66	($47.52)	$2.39	($6.57)
Discontinued operations	$0	$0			$0	$0.01	$0	$0	$0	$0.01	$0.25
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Basic:	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.68	$0.87	$0.66	($47.52)	$2.40	($6.32)
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Diluted:
Continuing operations	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.65	$0.82	$0.66	($47.52)	$2.36	($6.57)
Discontinued operations	$0	$0			$0	$0.01	$0	$0	$0	$0.01	$0.25
Earnings (loss) per Common Share Attributable to Cliffs Common Shareholders - Diluted:	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.66	$0.82	$0.66	($47.52)	$2.37	($6.32)
Preferred Class A [Member]
PREFERRED STOCK DIVIDENDS	($12.80)								($51.20)

Recovered_Sheet12

EARNINGS PER SHARE EARNINGS PER SHARE (Narrative Details) (Details)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share [Abstract]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	25.2	12.9	25.2
Antidilutive Incremental Common Shares Excluded and Attributable to Share-based Payment Arrangements			0.7	0	0.5

COMMITMENTS_AND_CONTINGENCIES_

COMMITMENTS AND CONTINGENCIES (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Commitments [Line Items]
Capital investment, future payments	($58.50)	($109.30)	$152.50
Accrual for Environmental Loss Contingencies	$5.50	$8.40

SUBSEQUENT_EVENTS_Narrative_De

SUBSEQUENT EVENTS Narrative (Details) (USD $)	12 Months Ended	11 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2013	Jan. 26, 2015	Sep. 30, 2014	31-May-15	Jan. 22, 2015
Subsequent Event [Line Items]
Debt Instrument, Par Value	$4,144,800,000		$4,814,800,000
Estimated Capital Costs to Develop Bloom Lake Phase II	1,200,000,000
Elimination of Dividend [Member]
Subsequent Event [Line Items]
Elimination of Dividend				$0.15
Free Cash Flow Due to Quarterly Dividend Elimination				92,000,000
Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Debt Instrument, Par Value	1,125,000,000		1,750,000,000		1,250,000,000
Revolving Credit Facility [Member] | Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Debt Instrument, Face Amount, Subsequent Event - Revolving Credit Facility Amendment						750,000,000	900,000,000
Permit Costs and Expenses in connection with Canadian Restructuring EBITDA Add back- Subsequent Event - Revolving Credit Facility Amendment		$75,000,000
Limit on Dividend per Share - Subsequent Event - Revolving Credit Facility Amendment		$0.01

QUARTERLY_RESULTS_OF_OPERATION2

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) QUARTERLY RESULTS OF OPERATIONS (Schedule of Quarterly Financial Information) (Tables) (USD $)	3 Months Ended								12 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenues	$1,284.70	$1,298.20	$1,100.80	$940	$1,515.80	$1,546.60	$1,488.50	$1,140.50	$4,623.70	$5,691.40	$5,872.70
SALES MARGIN	168.7	127.5	92	63.2	294.5	348.7	268.2	237.9	451.4	1,149.30	1,172.10
Income (Loss) from Continuing Operations Attributable to Parent	-1,285.10	-5,879.60	10.9	-70.3	43.3	115.2	146	107	-7,224.20	411.5	-935.3
INCOME and GAIN ON SALE FROM DISCONTINUED OPERATIONS, net of tax	0	0			0	2	0	0	0	2	35.9
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS SHAREHOLDERS	-1,285.10	-5,879.60	10.9	-70.3	43.3	117.2	146	107	-7,224.20	413.5	-899.4
Dividends, Preferred Stock	12.8	12.8	12.8	12.8					51.2	48.7	0
NET INCOME (LOSS) ATTRIBUTABLE TO CLIFFS COMMON SHAREHOLDERS	($1,297.90)	($5,892.40)	($1.90)	($83.10)					($7,275.40)	$364.80	($899.40)
Continuing operations	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.67	$0.87	$0.66	($47.52)	$2.39	($6.57)
Discontinued operations	$0	$0			$0	$0.01	$0	$0	$0	$0.01	$0.25
Earnings Per Share, Basic	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.68	$0.87	$0.66	($47.52)	$2.40	($6.32)
Continuing operations	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.65	$0.82	$0.66	($47.52)	$2.36	($6.57)
Discontinued operations	$0	$0			$0	$0.01	$0	$0	$0	$0.01	$0.25
Earnings Per Share, Diluted	($8.48)	($38.49)	($0.01)	($0.54)	$0.20	$0.66	$0.82	$0.66	($47.52)	$2.37	($6.32)

QUARTERLY_RESULTS_OF_OPERATION3

QUARTERLY RESULTS OF OPERATIONS (UNAUDITED) QUARTERLY RESULTS OF OPERATIONS (Details) (USD $)	3 Months Ended								12 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income (Loss) from Continuing Operations Attributable to Parent	($1,285,100,000)	($5,879,600,000)	$10,900,000	($70,300,000)	$43,300,000	$115,200,000	$146,000,000	$107,000,000	($7,224,200,000)	$411,500,000	($935,300,000)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	25.2							12.9	25.2
Goodwill, Impairment Loss									73,500,000	80,900,000
Loss on sale of Cliffs Logan County Coal									419,600,000	0	0
Sale Price of CLCC Assets									174,000,000
Proceeds from sale of Cliffs Logan County Coal									155,000,000	0	0
Income Tax Expense (Benefit)	-289,700,000								-1,302,000,000	55,100,000	255,900,000
Asset Impairment Charges									9,029,900,000	250,800,000	1,049,900,000
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
Goodwill, Impairment Loss										80,900,000
Wabush [Member]
Asset Impairment Charges									154,600,000
Bloom Lake [Member]
Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition										45,100,000
Change in Basic EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition					$0.29					$0.30	$0	$0.07
Change in Diluted EPS for Immaterial Error Adjustment Related to Bloom Lake Purchase Price Acquisition										$0.26	$0.25	$0.07
Minimum [Member]
Income (Loss) from Continuing Operations Attributable to Parent									300,000
Maximum [Member]
Income (Loss) from Continuing Operations Attributable to Parent									800,000
Bloom Lake [Member]
Asset Impairment Charges									$1,300,000,000

SCHEDULE_II_VALUATION_AND_QUAL

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS Schedule II - Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Valuation Allowance of Deferred Tax Assets [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance	$2,225.10	$864.10	$858.40	$223.90
Valuation Allowances and Reserves, Charged to Cost and Expense	1,689.20	86.6	635.8
Valuation Allowances and Reserves, Charged to Other Accounts	-8.6	-65.5	0
Valuation Allowances and Reserves, Reserves of Businesses Acquired	0	0	0
Valuation Allowances and Reserves, Deductions	319.6	15.4	1.3
Allowance for Trade Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Balance	8.1	8.1	8.1	0
Valuation Allowances and Reserves, Charged to Cost and Expense	0	0	8.1
Valuation Allowances and Reserves, Charged to Other Accounts	0	0	0
Valuation Allowances and Reserves, Reserves of Businesses Acquired	0	0	0
Valuation Allowances and Reserves, Deductions	$0	$0	$0