XML 63 R48.htm IDEA: XBRL DOCUMENT
v3.7.0.1

PROPERTY, PLANT AND EQUIPMENT (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2017 | Mar. 31, 2016
Property, Plant and Equipment [Abstract] |  |
Depreciation and depletion | $ 22.6 | $ 33.8

X
- Definition The aggregate expense recognized in the current period that allocates the cost of tangible assets or depleting assets to periods that benefit from use of the assets. + References No definition available. + Details
Name: | clf_DepreciationAndDepletionExpense
Namespace Prefix: | clf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration