Leases (Tables)

3 Months Ended

Mar. 31, 2020

Leases [Abstract]

Lease, Cost [Table Text Block]

The components of lease expense during the three months ended March 31, 2020 and 2019 were as follows:

	Three Months Ended March 31,
	2020		2019
	(Dollars in millions)
Operating lease cost:
Operating lease cost	$	8.6	$	15.5
Short-term lease cost	9.9		8.3
Variable lease cost	1.0		6.0
Sublease income	—		(1.4		)
Total operating lease cost	$	19.5	$	28.4
Finance lease cost:
Amortization of right-of-use assets	$	3.4	$	4.1
Interest on lease liabilities	0.2		0.5
Total finance lease cost	$	3.6	$	4.6

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

Supplemental balance sheet information related to leases at March 31, 2020 and December 31, 2019 was as follows:

	March 31, 2020			December 31, 2019
	(Dollars in millions)
Operating leases:
Operating lease right-of-use assets	$	78.0		$	82.4
Accounts payable and accrued expenses	$	25.2		$	29.6
Operating lease liabilities, less current portion	44.5			52.8
Total operating lease liabilities	$	69.7		$	82.4
Finance leases:
Property, plant, equipment and mine development	$	88.0		$	89.6
Accumulated depreciation	(47.6		)	(45.9		)
Property, plant, equipment and mine development, net	$	40.4		$	43.7
Current portion of long-term debt	$	8.6		$	14.3
Long-term debt, less current portion	0.5			0.9
Total finance lease liabilities	$	9.1		$	15.2
Weighted average remaining lease term (years)
Operating leases	3.7
Finance leases	14.8
Weighted average discount rate
Operating leases	7.3		%
Finance leases	6.0		%

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

Supplemental cash flow information related to leases during the three months ended March 31, 2020 and 2019 was as follows:

	Three Months Ended March 31,
	2020		2019
	(Dollars in millions)
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows for operating leases	$	12.8	$	24.1
Operating cash flows for finance leases	0.2		0.7
Financing cash flows for finance leases	5.8		7.3
Right-of-use assets obtained in exchange for lease obligations:
Operating leases	1.3		0.5
Finance leases	0.1		—

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)
2020	$	21.8		$	0.7
2021	22.6			1.0
2022	13.5			0.7
2023	11.6			0.5
2024	4.7			0.5
2025 and thereafter	7.3			8.2
Total lease payments	81.5			11.6
Less imputed interest	(11.8		)	(2.5		)
Total lease liabilities	$	69.7		$	9.1