Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2021

Share-Based Compensation Arrangements, Vested Stock Grants

Stock-based compensation expense related to vested stock grants are included in General and administrative expenses within the Consolidated Statements of Income (Loss). The Company’s vested stock grants to the Board and related expense for the years ended December 31, 2021, 2020 and 2019, was as follows:

	Year Ended December 31,
(millions, except stock grants)	2021		2020		2019
Vested stock grants		13,420		25,066		14,076
Stock-based compensation expense	$	0.5	$	0.5	$	0.5

Summary of Nonvested Restricted Stock Units and Changes During the Period

Nonvested restricted stock units as of December 31, 2021, and changes during the year ended December 31, 2021 were as follows:

	Shares			Weighted Average Grant-Date Fair Value
Nonvested as of December 31, 2020		51,276		$	33.24
Granted		313,502			34.45
Vested		(5,615	)		26.71
Forfeited		(3,729	)		33.95
Nonvested as of December 31, 2021		355,434		$	34.40

Summary of Compensation Expense Related to Restricted Stock Units

The Company's stock-based compensation expense related to restricted stock units for the years ended December 31, 2021, 2020 and 2019, which was included in General and administrative expenses within the Consolidated Statements of Income (Loss), was as follows:

	Year Ended December 31,
(millions)	2021		2020		2019
Stock-based compensation expense	$	4.6	$	1.1	$	1.1

The Company's stock-based compensation expense (net reduction of expense) related to PSU’s during the years ended December 31, 2021, 2020 and 2019, which is included in General and administrative expenses within the Consolidated Statements of Income (Loss), was as follows:

	Year Ended December 31,
(millions)	2021		2020			2019
Stock-based compensation expense	$	1.0	$	(1.0	)	$	3.3

Summary of Unrecognized Compensation Expense Related to Share Based Payment

Unrecognized stock-based compensation expense related to restricted stock units and the respective weighted average periods in which the expense will be recognized as of December 31, 2021 was as follows:

	Year Ended December 31,
(millions)	2021
Unrecognized stock-based compensation	$	6.6
Weighted average (years)	1.5

Summary of Nonvested PSU's and Changes During the Period

Nonvested PSU’s as of December 31, 2021, and changes during the year ended December 31, 2021 were as follows:

	Shares			Weighted Average Grant-Date Fair Value
Nonvested as of December 31, 2020		200,218		$	35.27
Granted		50,868			34.97
Forfeited		(3,375	)		35.96
Expired		(112,328	)		33.28
Nonvested as of December 31, 2021		135,383		$	36.79

Performance Shares

Summary of Unrecognized Compensation Expense Related to Share Based Payment

Unrecognized stock-based compensation expense related to PSU’s and the respective weighted average periods in which the expense will be recognized as of December 31, 2021 was as follows:

	Year Ended December 31,
(millions)	2021
Unrecognized stock-based compensation	$	2.5
Weighted average (years)		2.0