XML 127 R100.htm IDEA: XBRL DOCUMENT
v3.3.1.900

STOCK COMPENSATION PLANS STOCK COMPENSATION PLANS (Incentive Plan Details) (Details) - shares |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Feb. 09, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Number of performance shares granted |  |  |  |  |  |  | 3,769,700 |  |
Performance Shares [Member] |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |
Number of performance shares granted | 410,105 | 464,470 | 400,000 | 199,450 | 106,120 | 230,265 | 874,575 | 1,233,685 | 806,271
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Estimated Forfeitures |  | 96,149 | 27,774 | 32,653 | 16,351 | 142,017 | 111,877 |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Expected to Vest |  | 368,321 | 372,226 | 166,797 | 89,769 | 88,248 | 298,228 |  |

X
- Definition Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Expected to Vest + References No definition available. + Details
Name: | clf_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsExpectedtoVest
Namespace Prefix: | clf_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Estimated Forfeitures + References No definition available. + Details
Name: | clf_SharebasedCompensationArrangementbySharebasedPaymentAwardNonOptionEquityInstrumentsEstimatedForfeitures
Namespace Prefix: | clf_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |