Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Nonvested Restricted Stock Units and Changes During the Period

Nonvested restricted stock units as of September 30, 2022, and changes during the nine months ended September 30, 2022 (unaudited) were as follows:

	Shares			Weighted Average Grant-Date Fair Value
Nonvested as of December 31, 2021		355,434		$	34.40
Granted		136,111			30.76
Vested		(37,235	)		33.61
Forfeited		(7,178	)		34.33
Nonvested as of September 30, 2022		447,132		$	33.36

Schedule of Stock-Based Compensation Expense

The Company's stock-based compensation expense related to the restricted stock units during the three and nine months ended September 30, 2022 and 2021 (unaudited), respectively, which was included in General and administrative expenses within the Condensed Consolidated Statements of Income, was as follows:

	Three Months Ended				Nine Months Ended
(millions)	September 30, 2022		September 30, 2021		September 30, 2022		September 30, 2021
Stock-based compensation expense	$	1.5	$	1.2	$	4.3	$	3.3

The Company's stock-based compensation expense related to PSUs during the three and nine months ended September 30, 2022 and 2021 (unaudited), which is included in General and administrative expenses within the Condensed Consolidated Statements of Income, was as follows:

	Three Months Ended				Nine Months Ended
(millions)	September 30, 2022		September 30, 2021		September 30, 2022		September 30, 2021
Stock-based compensation expense	$	0.7	$	0.3	$	1.9	$	0.7

Summary of Nonvested PSU's and Changes During the Period

Nonvested PSUs as of September 30, 2022, and changes during the nine months ended September 30, 2022 (unaudited) were as follows:

	Shares			Weighted Average Grant-Date Fair Value
Nonvested as of December 31, 2021		135,383		$	36.79
Granted		132,304			30.80
Forfeited		(2,660	)		36.91
Nonvested as of September 30, 2022		265,027		$	33.80