Stock-Based Compensation Plans (Tables)

6 Months Ended

12 Months Ended

Jun. 30, 2024

Dec. 31, 2023

Stock-Based Compensation Plans

Schedule of stock-based awards granted under the Stock-Based Compensation Plans

	For the six months ended June 30,
	2024		2023
	(in millions)
Compensation cost	$	14.4	$	12.8
Related income tax benefit		2.9		2.5
Capitalized as part of an asset		0.7		0.8

	For the year ended December 31,
	2023		2022		2021
	(in millions)
Compensation cost	$	25.3	$	22.2	$	25.2
Related income tax benefit		5.1		4.6		4.3
Capitalized as part of an asset		1.1		1.2		1.4

Summary of the assumptions used in this model for the stock options granted

	For the year ended December 31,
Options	2023			2022			2021
Expected volatility		—	%		—	%		34.2	%
Expected term (in years)		—			—			7.0
Risk-free interest rate		—	%		—	%		1.2	%
Expected dividend yield		—	%		—	%		3.82	%
Weighted average estimated fair value	$	—		$	—		$	15.67