Share Plans (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Compensation Cost

Total share-based compensation expense for 2022, 2021 and 2020 was as follows:

	December 31
In millions	2022		2021		2020
Restricted stock units	$	14.6	$	13.0	$	12.5
Stock options	3.7		3.4		3.0
Performance share units	6.6		13.4		4.8
Total share-based compensation expense	$	24.9	$	29.8	$	20.3

Stock Option Activity

The following table summarizes stock option activity under all plans for the year ended December 31, 2022:

Shares and intrinsic value in millions	Number of shares	Weighted- average exercise price		Weighted- average remaining contractual life (years)	Aggregate intrinsic value
Outstanding as of January 1, 2022	2.2	$	42.86
Granted	0.3	65.67
Exercised	(0.1)	39.44
Forfeited	(0.1)	52.45
Outstanding as of December 31, 2022	2.3	$	45.16	4.8	$	8.3
Options exercisable as of December 31, 2022	1.8	$	41.69	3.9	$	8.2
Options expected to vest as of December 31, 2022	0.5	$	57.44	7.9	$	0.1

Stock Option Fair Value Assumptions

We estimated the fair value of each stock option award issued in the annual share-based compensation grant using a Black-Scholes option pricing model, modified for dividends and using the following assumptions:

	December 31
	2022		2021		2020
Risk-free interest rate	1.18	%	0.37	%	1.61	%
Expected dividend yield	1.14	%	1.56	%	1.80	%
Expected share price volatility	29.60	%	29.60	%	24.10	%
Expected term (years)	6.4		6.5		6.8

Restricted Stock Activity

The following table summarizes restricted stock unit activity under all plans for the year ended December 31, 2022:

Shares in millions	Number of shares	Weighted average grant date fair value
Outstanding as of January 1, 2022	0.6	$	47.78
Granted	0.3	59.82
Vested	(0.2)	47.18
Forfeited	(0.1)	53.84
Outstanding as of December 31, 2022	0.6	$	53.10

Performance Shares Award Outstanding Activity

The following table summarizes performance share unit activity under all plans for the year ended December 31, 2022:

Shares in millions	Number of shares	Weighted average grant date fair value
Outstanding as of January 1, 2022	0.4	$	45.55
Granted	0.1	68.19
Vested	(0.1)	38.54
Outstanding as of December 31, 2022	0.4	$	55.45