Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Allocation of Share-based Compensation Costs by Plan

The following table summarizes our stock-based compensation expense recorded within selling, general and administrative expenses for the years ended December 31:

($ in millions)	2023		2022		2021
Stock option and appreciation rights	$	11.3	$	5.6	$	12.5
Performance share units, stock-settled	5.5		15.6		17.6
Performance share units, cash-settled	0.3		(0.1)		1.0
Performance share units, dividend equivalents	0.1		0.1		0.2
Employee stock purchase plan	1.3		1.3		1.4
Deferred compensation plans and restricted share awards	4.8		1.2		4.8
Total stock-based compensation expense	$	23.3	$	23.7	$	37.5

Schedule of Stock Options Activity

The following table summarizes changes in outstanding options:

(in millions, except per share data)	2023
Options outstanding, January 1	1.9
Granted	0.1
Exercised	(0.6)
Forfeited	0.0
Options outstanding, December 31	1.4
Options vested and expected to vest, December 31	1.4
Options vested and exercisable, December 31	1.1

Weighted Average Exercise Price	2023
Options outstanding, January 1	$	118.72
Granted	306.97
Exercised	80.18
Forfeited	289.70
Options outstanding, December 31	$	145.40
Options vested and expected to vest, December 31	$	143.46
Options vested and exercisable, December 31	$	105.08

Schedule of Stock Appreciation Rights Award Activity

The following table summarizes changes in outstanding SARs:

	2023
SARs outstanding, January 1	20,402
Granted	228
Exercised	(4,646)
Forfeited	(577)
SARs outstanding, December 31	15,407
SARs vested and expected to vest, December 31	15,407
SARs vested and exercisable, December 31	14,355

Weighted Average Exercise Price	2023
SARs outstanding, January 1	$	97.28
Granted	306.68
Exercised	67.89
Forfeited	287.26
SARs outstanding, December 31	$	102.12
SARs vested and expected to vest, December 31	$	102.12
SARs vested and exercisable, December 31	$	89.44

Schedule of Nonvested Performance-based Share Activity

The following table summarizes changes in our outstanding stock-settled PSU awards:

	2023
Non-vested stock-settled PSU awards, January 1	112,553
Granted at target level	37,736
Adjustments above/(below) target	47,154
Vested and converted	(93,902)
Forfeited	(5,100)
Non-vested stock-settled PSU awards, December 31	98,441
Weighted Average Fair Value	2023
Non-vested stock-settled PSU awards, January 1	$	278.38
Granted at target level	306.97
Adjustments above/(below) target	181.31
Vested and converted	306.68
Forfeited	317.85
Non-vested stock-settled PSU awards, December 31	$	334.03

Schedule of Nonvested Performance-based Units Activity

The following table summarizes changes in our outstanding cash-settled PSU awards:

	2023
Non-vested cash-settled PSU awards, January 1	890
Granted at target level	82
Adjustments above/(below) target	591
Vested and converted	(1,181)
Forfeited	(178)
Non-vested cash-settled PSU awards, December 31	204

Weighted Average Fair Value	2023
Non-vested cash-settled PSU awards, January 1	$	242.29
Granted at target level	306.68
Adjustments above/(below) target	191.43
Vested and converted	306.68
Forfeited	310.52
Non-vested cash-settled PSU awards, December 31	$	355.74