Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Share-based compensation expense

Share-based compensation expense and cash flow amounts were as follows:

	Year Ended December 31,
	2021		2020		2019
	(Dollars in millions)
Share-based compensation expense	$	10.0	$	13.5	$	38.3
Tax benefit	—		—		—
Share-based compensation expense, net of tax benefit	$	10.0	$	13.5	$	38.3
Cash received upon the exercise of stock options	—		—		—
Write-off tax benefits related to share-based compensation	—		—		—

Schedule of Share-based Compensation, Restricted Stock Units Activity

A summary of restricted stock unit activity is as follows:

	Year Ended December 31, 2021	Weighted Average Grant-Date Fair Value
Nonvested at December 31, 2020	1,629,956	$	14.49
Granted	752,039	4.14
Vested	(826,473)	13.81
Forfeited	(451,694)	9.90
Nonvested at December 31, 2021	1,103,828	$	8.99

Schedule of Performance Units Activity

A summary of performance unit activity is as follows:

	Year Ended December 31, 2021	Weighted Average Remaining Contractual Life
Nonvested at December 31, 2020	858,588	1.5
Granted	—
Vested	(118,031)
Forfeited	(89,651)
Nonvested at December 31, 2021	650,906	0.7

Schedule of Share-based Payment Award, Performance Units, Valuation Assumptions

The assumptions used in the valuations for grants were as follows:

	Year Ended December 31,
	2021		2020
Risk-free interest rate	—	%	1.45	%
Expected volatility	—	%	49.34	%
Dividend yield	—	%	—	%