Valuation and Qualifying Accounts Schedule II (Tables)

12 Months Ended

Dec. 31, 2022

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Summary of Valuation Allowance

SCHEDULE II — VALUATION AND QUALIFYING ACCOUNTS

Description	Balance at Beginning of Period		Charged to Costs and Expenses		Deductions(1)		Other(2)			Balance at End of Period
	(Dollars in millions)
Year Ended December 31, 2022
Reserves deducted from asset accounts:
Advance royalty recoupment reserve	$	0.3	$	(0.3)	$	—	$	—		$	—
Reserve for materials and supplies	9.0		1.4		(0.9)		—			9.5
Tax valuation allowances	2,120.8		(583.8)		—		(86.0)			1,451.0
Year Ended December 31, 2021
Reserves deducted from asset accounts:
Advance royalty recoupment reserve	$	0.3	$	—	$	—	$	—		$	0.3
Reserve for materials and supplies	10.4		0.6		(2.0)		—			9.0
Tax valuation allowances	2,287.3		(121.7)		—		(44.8)			2,120.8
Year Ended December 31, 2020
Reserves deducted from asset accounts:
Advance royalty recoupment reserve	$	0.3	$	—	$	—	$	—		$	0.3
Reserve for materials and supplies	7.9		3.5		(1.0)		—			10.4
Tax valuation allowances	2,068.4		373.2		—		(154.3)		(3)	2,287.3

(1)Reserves utilized, unless otherwise indicated.

(2)Includes the impact of changes in the Australian dollar exchange rates.

(3)Includes the impact of a decrease in Australia NOLs due to a cancellation of intercompany debt.