XML 66 R48.htm IDEA: XBRL DOCUMENT
v3.8.0.1

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Foreign Currency Translation) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2018 | Mar. 31, 2017
Foreign Currency Transaction Gain (Loss), before Tax | $ (0.3) | $ 13.6
Short-term intercompany loan [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | (0.2) | 15.1
Cash and Cash Equivalents [Member] |  |
Foreign Currency Transaction Gain (Loss), before Tax | 0.1 | (1.2)
Other Remeasurement |  |
Foreign Currency Transaction Gain (Loss), before Tax | $ (0.2) | $ (0.3)

X
- Definition Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30700-110894 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=64836518&loc=d3e30690-110894 + Details
Name: | us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis=clf_ShorttermintercompanyloanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis=us-gaap_CashAndCashEquivalentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IntercompanyForeignCurrencyBalanceByDescriptionAxis=clf_TransactionGainsandLossesResultingfromRemeasurementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |