Share-based Payments (Tables)

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Compensation Costs Related to Share-Based Payments

The following table summarizes the components of share-based payment expense by consolidated income statement classification:

	Three months ended September 30,				Nine months ended September 30,
	2024		2023		2024		2023
Selling, general and administrative:
Stock option compensation expense	$	0.7	$	1.1	$	3.0	$	5.4
Equity-classified share units	7.3		10.9		32.9		23.8
Liability-classified share units	0.6		0.1		2.1		0.6
Employee share purchase plan	1.2		1.3		5.8		2.6
	9.8		13.4		43.8		32.4
Acquisition-related and integration costs:
Acceleration of share-based payments expense	0.1		0.6		1.0		6.5
Share-based continuing employment costs	0.2		0.9		0.4		2.9
	0.3		1.5		1.4		9.4
	$	10.1	$	14.9	$	45.2	$	41.8

Share-Based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity

The following table summarizes share unit activity for the nine months ended September 30, 2024:

	Equity-classified									Liability-classified
	Performance Share Units (Performance Conditions)			Performance Share Units (Market Conditions)			Restricted Share Units			Deferred Share Units
	Number	WA grant date fair value		Number	WA grant date fair value		Number	WA grant date fair value		Number	WA grant date fair value
Outstanding, December 31, 2023	415,429	$	58.35	174,260	$	74.83	539,671	$	53.64	100,560	$	38.36
Granted	161,579	75.93		160,223	122.42		322,471	75.76		11,667	72.48
Vested and settled	(114,315)	58.79		(58,511)	66.08		(232,451)	53.47		(3,759)	59.05
Forfeited	(15,342)	58.10		(9,618)	83.59		(26,885)	59.15		—	—
Outstanding at September 30, 2024	447,351	$	64.59	266,354	$	105.06	602,806	$	65.29	108,468	$	41.31

Summary of Significant Assumptions Used to Estimate the Fair Value of Stock Options

The fair value of PSUs with market vesting conditions granted during the nine months ended September 30, 2024 were estimated using a Monte Carlo simulation model on the respective grant dates incorporating the following significant assumptions, presented on a weighted average basis:

Risk free interest rate	4.4	%
Expected lives of the PSUs	3 years
Expected volatility	32.2	%
Average expected volatility of comparable companies	48.3	%