XML 81 R54.htm IDEA: XBRL DOCUMENT
v3.3.1.900

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Investments In Unconsolidated Ventures) (Details) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2015 USD ($) Facility | Dec. 31, 2014 USD ($) | Dec. 31, 2013
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Investment |  | $ (2.4) |  | $ 4.1 |
Asia Pacific Iron Ore [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Number Of Mines | Facility |  | 1 |  |  |
Investments in Ventures [Member] | Amapa [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership interest, equity method investment |  |  |  |  | 30.00%
Investments in Ventures [Member] | Hibbing [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership interest, equity method investment | [1] | 23.00% |  |  |
Other Noncurrent Liabilities [Member] | Hibbing [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Investment |  | $ (2.4) |  |  |
Other Noncurrent Assets [Member] | Hibbing [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Investment |  |  |  | 3.1 |
Other Noncurrent Assets [Member] | Other Equity Investees [Member] |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Investment |  | $ 0.0 | [2] | $ 1.0 |
[1] | At December 31, 2014, the classification for Hibbing was Other non-current assets.
[2] | At December 31, 2015, no Other equity method investments remain.

X
- Definition Number of mines + References No definition available. + Details
Name: | clf_NumberOfMines
Namespace Prefix: | clf_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_EquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=clf_AsiaPacificIronOreMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=clf_InvestmentsinVenturesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=clf_AmapaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=clf_HibbingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=clf_OtherEquityInvesteesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |