Annual report pursuant to Section 13 and 15(d)

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Schedule of Intangible Asset Lives) (Details)

betfred games-free to play_Schedule II - Valuation v2.4.1.9
betfred games
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
All Other Segments [Member] | Permits [Member] | Minimum [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 15 years  
All Other Segments [Member] | Permits [Member] | Maximum [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 40 years  
All Other Segments [Member] | Utility Contracts [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 5 years  
All Other Segments [Member] | Leases [Member] | Minimum [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 4 years 6 months  
All Other Segments [Member] | Leases [Member] | Maximum [Member]    
Finite-Lived Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 17 years 6 months  
Amapa [Member] | Investments in Ventures [Member]    
Finite-Lived Intangible Assets [Line Items]    
Ownership interest, equity method investment   30.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_BalanceSheetLocationAxis
= clf_InvestmentsinVenturesMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= clf_AmapaMember