Derivatives and Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2019

Fair Value Disclosures [Abstract]

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

The fair value of derivatives reflected in the accompanying condensed consolidated balance sheets are set forth in the table below.

	March 31, 2019						December 31, 2018
	Asset Derivative			Liability Derivative			Asset Derivative			Liability Derivative
	(Dollars in millions)
Foreign currency option contracts	$	1.3		$	—		$	1.2		$	—
Coal contracts related to forecasted sales	23.0			(7.9		)	6.6			(23.1		)
Coal trading contracts	144.9			(137.7		)	59.7			(64.4		)
Total derivatives	169.2			(145.6		)	67.5			(87.5		)
Effect of counterparty netting	(145.5		)	145.5			(64.5		)	64.5
Variation margin (held) posted	(18.2		)	—			—			21.8
Net derivatives and margin as classified in the balance sheets	$	5.5		$	(0.1	)	$	3.0		$	(1.2	)

Derivative Instruments, Gain (Loss) [Table Text Block]

The tables below show the amounts of pre-tax gains and losses related to the Company’s derivatives.

	Three Months Ended March 31, 2019
	Total (loss) gain recognized in income			(Loss) gain realized in income on derivatives			Unrealized (loss) gain recognized in income on derivatives
Financial Instrument
	(Dollars in millions)
Foreign currency option contracts	$	(1.1	)	$	(1.3	)	$	0.2
Coal contracts related to forecasted sales	50.7			10.9			39.8
Coal trading contracts	(1.1		)	(4.8		)	3.7
Total	$	48.5		$	4.8		$	43.7

	Three Months Ended March 31, 2018
	Total (loss) gain recognized in income			(Loss) gain realized in income on derivatives			Unrealized (loss) gain recognized in income on derivatives
Financial Instrument
	(Dollars in millions)
Foreign currency option contracts	$	(4.2	)	$	(2.4	)	$	(1.8	)
Coal contracts related to forecasted sales	59.8			21.2			38.6
Coal trading contracts	(1.0		)	(2.8		)	1.8
Total	$	54.6		$	16.0		$	38.6

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following tables set forth the hierarchy of the Company’s net financial asset positions for which fair value is measured on a recurring basis:

	March 31, 2019
	Level 1		Level 2			Level 3		Total
	(Dollars in millions)
Foreign currency option contracts	$	—	$	1.3		$	—	$	1.3
Coal contracts related to forecasted sales	—		18.8			—		18.8
Coal trading contracts	—		(14.7		)	—		(14.7		)
Equity securities	—		—			10.0		10.0
Total net financial assets	$	—	$	5.4		$	10.0	$	15.4
	December 31, 2018
	Level 1		Level 2			Level 3		Total
	(Dollars in millions)
Foreign currency option contracts	$	—	$	1.2		$	—	$	1.2
Coal contracts related to forecasted sales	—		(21.2		)	—		(21.2		)
Coal trading contracts	—		21.8			—		21.8
Equity securities	—		—			10.0		10.0
Total net financial assets	$	—	$	1.8		$	10.0	$	11.8

Carrying Amounts And Estimated Fair Values Of Companys Debt [Table Text Block]

The carrying amount and estimated fair values of the Company’s current and long-term debt as of March 31, 2019 and December 31, 2018 are summarized as follows:

	March 31, 2019				December 31, 2018
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
	(Dollars in millions)
Current and Long-term debt	$	1,361.7	$	1,406.6	$	1,367.0	$	1,366.2