Share-based compensation plans (Tables)

3 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Compensation expense by plan

Compensation expenses are classified as selling, general and administrative expenses in the condensed consolidated statements of operations. Compensation expenses for the share-based awards were as follows:

	Compensation Expense
	Three Months Ended March 31,
(in millions)	2024		2023
Performance stock units	$	6.4	7.9
Restricted stock units	2.5		2.7
Deferred stock units and fees paid in stock	0.4		0.3
Cash based awards	0.7		1.1
Share-based payment expense	10.0		12.0
Income tax benefit	(2.3)		(2.8)
Share-based payment expense, net of tax	$	7.7	9.2

Option activity

The following table summarizes performance-based stock option activity during the first three months of 2024:

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Outstanding balance as of December 31, 2023	174.4	$	17.92
Exercised	(174.4)	17.92
Outstanding balance as of March 31, 2024	—	$	—

The following table summarizes time-based stock option activity during the first three months of 2024: 

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Outstanding balance as of December 31, 2023	115.7	$	21.43
Expired	—	—
Outstanding balance as of March 31, 2024	115.7	$	21.43

Nonvested share activity

The following table summarizes RSU activity during the first three months of 2024: 

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2023	320.2	$	65.89
Granted	119.1	80.77
Forfeited	(5.9)	67.99
Vested	(108.0)	68.86
Nonvested balance as of March 31, 2024	325.4	$	70.31

The following table summarizes all PSU activity during the first three months of 2024:

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2023	698.5	$	72.15
Granted	207.0	81.34
Forfeited or expired	(8.6)	67.43
Vested(a)	(228.8)	80.47
Nonvested balance as of March 31, 2024	668.1	$	72.21

(a)The vested PSUs presented are based on the target amount of the award. In accordance with the terms of the underlying award agreements, the actual shares earned and distributed for the performance period ended December 31, 2023 were 437.9 thousand, compared to target shares of 228.8 thousand.

The following table summarizes all DSU activity during the first three months of 2024:

	Shares (in thousands)	Weighted-Average Grant-Date Fair Value
Nonvested balance as of December 31, 2023	19.2	$	62.43
Granted	—	—
Vested	—	—
Nonvested balance as of March 31, 2024	19.2	$	62.43