Leases (Tables)

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

Lease, Cost [Table Text Block]

The components of lease expense during the three and six months ended June 30, 2019 were as follows:

	Three Months Ended June 30, 2019			Six Months Ended June 30, 2019
	(Dollars in millions)
Operating lease cost:
Operating lease cost	$	11.8		$	27.2
Short-term lease cost	7.4			15.7
Variable lease cost	8.5			14.5
Sublease income	(0.4		)	(0.8		)
Total operating lease cost	$	27.3		$	56.6
Finance lease cost:
Amortization of right-of-use assets	$	1.9		$	8.6
Interest on lease liabilities	0.4			0.9
Total finance lease cost	$	2.3		$	9.5

Schedule of Supplemental Balance Sheet Information Related to Leases [Table Text Block]

Supplemental balance sheet information related to leases at June 30, 2019 was as follows:

	June 30, 2019
	(Dollars in millions)
Operating leases:
Operating lease right-of-use assets	$	93.1
Accounts payable and accrued expenses	$	(29.4	)
Operating lease liabilities, less current portion	(58.0		)
Total operating lease liabilities	$	(87.4	)
Finance leases:
Property, plant, equipment and mine development	$	96.8
Accumulated depreciation	(47.8		)
Property, plant, equipment and mine development, net	$	49.0
Current portion of long-term debt	$	24.5
Long-term debt, less current portion	—
Total finance lease liabilities	$	24.5
Weighted average remaining lease term (years)
Operating leases	4.1
Finance leases	0.7
Weighted average discount rate
Operating leases	7.4		%
Finance leases	5.9		%

Schedule of Supplemental Cash Flow Information Related to Leases [Table Text Block]

Supplemental cash flow information related to leases during the three and six months ended June 30, 2019 was as follows:

	Three Months Ended June 30, 2019		Six Months Ended June 30, 2019
	(Dollars in millions)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	9.3	$	33.3
Operating cash flows for finance leases	0.4		1.2
Financing cash flows for finance leases	8.2		18.4
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	$	27.3	$	27.8
Finance leases	1.4		1.4

Schedule of Maturities of Operating and Finance Lease Liabilities [Table Text Block]

Maturities of lease liabilities were as follows:

Period Ending December 31,	Operating Leases			Finance Leases
	(Dollars in millions)
2019	$	16.8		$	17.4
2020	30.0			7.6
2021	18.4			—
2022	13.3			—
2023	12.2			—
2024 and thereafter	12.1			—
Total lease payments	102.8			25.0
Less imputed interest	(15.4		)	(0.5		)
Total lease liabilities	$	87.4		$	24.5