XML 77 R55.htm IDEA: XBRL DOCUMENT
v3.6.0.2

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Revenue Reimbursement) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Freight and venture partners' cost reimbursements | $ 195.5 | $ 180.9 | $ 278.0
U.S. Iron Ore [Member] |  |  |
Freight and venture partners' cost reimbursements | 174.8 | 157.3 | 271.0
U.S. Iron Ore [Member] | Freight Revenue [Member] |  |  |
Freight and venture partners' cost reimbursements | 106.8 | 105.3 | 163.0
U.S. Iron Ore [Member] | Co-venturer [Member] |  |  |
Freight and venture partners' cost reimbursements | $ 68.0 | $ 52.0 | $ 108.0

X
- Definition Repayment received or receivable for expenses incurred on behalf of a client or customer, other than those reimbursements received by landlords from tenants. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 605 -SubTopic 45 -Section 45 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=68075638&loc=d3e60722-111653 + Details
Name: | us-gaap_ReimbursementRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Details
Name: | clf_ReimbursementRevenueByTypeAxis=clf_FreightRevenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | clf_ReimbursementRevenueByTypeAxis=us-gaap_CoVenturerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |