Cleveland-Cliffs Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Cover
- Document and Entity Information
Financial Statements
Notes to Financial Statements
Accounting Policies
- BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Policies)
Notes Tables
Notes Details
Uncategorized
- Uncategorized Items - clf-20181231.xml

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details)

v3.10.0.1

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) gal MMcf	Dec. 31, 2017 USD ($) gal MMcf	Dec. 31, 2016 USD ($)
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 422.6	$ 119.3	$ 57.8
Derivative asset, fair value	91.5	37.9
Derivative liability, fair value	3.7	2.0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative asset, fair value	91.4	37.9
Derivative liability, fair value	0.0	1.7
Provisional Pricing Arrangements [Member] \| Product Revenues [Member]
Derivative [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ (3.2)	$ (42.7)	$ 14.2
Natural Gas [Member]
Derivative [Line Items]
Natural Gas Hedges \| MMcf	1,800,000.0	3,500,000.0
Energy Related Derivative [Member]
Derivative [Line Items]
Natural Gas Hedges \| gal	11,000,000.0	0
Valuation, Market Approach [Member] \| Fair Value, Inputs, Level 3 [Member] \| Customer Supply Agreement [Member] \| Not Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Derivative [Line Items]
Derivative asset, fair value	$ 89.3	$ 37.9
Valuation, Market Approach [Member] \| Fair Value, Inputs, Level 3 [Member] \| Provisional Pricing Arrangements [Member] \| Not Designated as Hedging Instrument [Member] \| Other Current Assets [Member]
Derivative [Line Items]
Derivative asset, fair value	2.1	0.0
Valuation, Market Approach [Member] \| Fair Value, Inputs, Level 3 [Member] \| Provisional Pricing Arrangements [Member] \| Not Designated as Hedging Instrument [Member] \| Other Current Liabilities [Member]
Derivative [Line Items]
Derivative liability, fair value	$ 0.0	$ 1.7

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