FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2017

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]

The following represents the assets and liabilities of the Company measured at fair value at June 30, 2017 and December 31, 2016:    

	(In Millions)
	June 30, 2017
Description	Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash equivalents	$	40.0	$	120.0	$	—	$	160.0
Derivative assets	—		—		72.5		72.5
Total	$	40.0	$	120.0	$	72.5	$	232.5
Liabilities:
Derivative liabilities	$	—	$	—	$	20.8	$	20.8
Total	$	—	$	—	$	20.8	$	20.8

	(In Millions)
	December 31, 2016
Description	Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Assets:
Cash equivalents	$	177.0	$	—	$	—	$	177.0
Derivative assets	—		1.5		31.6		33.1
Total	$	177.0	$	1.5	$	31.6	$	210.1
Liabilities:
Derivative liabilities	$	—	$	—	$	0.5	$	0.5
Total	$	—	$	—	$	0.5	$	0.5

Fair Value, Recurring and Nonrecurring, Valuation Techniques

The following table illustrates information about quantitative inputs and assumptions for the assets and liabilities categorized in Level 3 of the fair value hierarchy:

Qualitative/Quantitative Information About Level 3 Fair Value Measurements
	(In Millions) Fair Value at June 30, 2017		Balance Sheet Location	Valuation Technique	Unobservable Input	Range or Point Estimate (Weighted Average)
Provisional pricing arrangements	$	6.1	Other current assets	Market Approach	Management's Estimate of Platts 62% Price per dry metric ton	$60 - $75 ($72)
					Market Hot-Rolled Coil Steel Estimate per net ton	$580 - $660 ($634)
Provisional pricing arrangements	$	20.8	Other current liabilities	Market Approach	Management's Estimate of Platts 62% Price per dry metric ton	$60 - $75 ($72)
Customer supply agreements	$	66.4	Other current assets	Market Approach	Customer Hot-Rolled Steel Estimate per net ton	$541 - $630 ($578)
					Market Hot-Rolled Coil Steel Estimate per net ton	$580 - $660 ($634)

Fair Value, Assets Measured On Recurring Basis, Unobservable Input Reconciliation

	(In Millions)
	Level 3 Assets
	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Beginning balance	$	59.4		$	9.0		$	31.6		$	7.8
Total gains (losses)
Included in earnings	53.3			34.5			95.4			45.7
Settlements	(40.2		)	(17.7		)	(54.5		)	(27.7		)
Ending balance - June 30	$	72.5		$	25.8		$	72.5		$	25.8
Total gains for the period included in earnings attributable to the change in unrealized gains on assets still held at the reporting date	$	20.1		$	21.6		$	53.3		$	21.9

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation

	(In Millions)
	Level 3 Liabilities
	Three Months Ended June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Beginning balance	$	(9.1	)	$	(6.2	)	$	(0.5	)	$	(3.4	)
Total gains (losses)
Included in earnings	(36.8		)	(2.8		)	(45.5		)	(8.4		)
Settlements	25.1			6.4			25.2			9.2
Ending balance - June 30	$	(20.8	)	$	(2.6	)	$	(20.8	)	$	(2.6	)
Total losses for the period included in earnings attributable to the change in unrealized losses on liabilities still held at the reporting date	$	(11.7	)	$	(0.7	)	$	(20.8	)	$	(2.6	)

Schedule Of Carrying Value And Fair Value Of Financial Instruments

A summary of the carrying amount and fair value of other financial instruments at June 30, 2017 and December 31, 2016 were as follows:

		(In Millions)
		June 30, 2017				December 31, 2016
	Classification	Carrying Value		Fair Value		Carrying Value		Fair Value
Long-term debt:
Secured Notes
First Senior Lien Notes —$540 million	Level 1	$	477.4	$	550.0	$	506.3	$	595.0
1.5 Senior Lien Notes —$218.5 million	Level 2	—		—		284.2		229.5
Second Senior Lien Notes —$544.2 million	Level 1	—		—		339.1		439.7
Unsecured Notes
Senior Notes—$500 million	Level 1	491.9		473.8		—		—
Senior Notes—$400 million	Level 1	88.5		86.0		224.5		219.6
Senior Notes—$1.3 billion	Level 1	414.5		339.7		528.4		455.8
Senior Notes—$700 million	Level 1	137.9		131.6		308.2		283.1
ABL Facility	Level 2	—		—		—		—
Fair value adjustment to interest rate hedge	Level 2	1.6		1.6		1.9		1.9
Total long-term debt		$	1,611.8	$	1,582.7	$	2,192.6	$	2,224.6

Fair Value Measurements, Nonrecurring [Table Text Block]

Items Measured at Fair Value on a Non-Recurring Basis

The following tables present information about the financial assets and liabilities that were measured on a fair value basis at June 30, 2017 and December 31, 2016 for the Canadian Entities. The tables also indicate the fair value hierarchy of the valuation techniques used to determine such fair value.

	(In Millions)
	June 30, 2017
Description	Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total		Total Gains
Assets:
Loans to and accounts receivables from the Canadian Entities	$	—	$	—	$	50.1	$	50.1	$	1.5
Liabilities:
Guarantees	$	—	$	—	$	38.5	$	38.5	$	1.3

	(In Millions)
	December 31, 2016
Description	Quoted Prices in Active Markets for Identical Assets/ Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total		Total Gains (Losses)
Assets:
Loans to and accounts receivables from the Canadian Entities	$	—	$	—	$	48.6	$	48.6	$	(17.5	)
Liabilities:
Guarantees	$	—	$	—	$	37.2	$	37.2	$	0.4