Share Plans (Tables)

9 Months Ended

Sep. 30, 2021

Share-based Payment Arrangement [Abstract]

Share-based Compensation Expense

Total share-based compensation expense for the three and nine months ended September 30, 2021 and 2020 was as follows:

	Three months ended				Nine months ended
In millions	September 30, 2021		September 30, 2020		September 30, 2021		September 30, 2020
Restricted stock units	$	2.4	$	3.0	$	9.4	$	9.3
Stock options	0.7		0.6		2.5		2.2
Performance share units	1.1		1.2		8.9		3.7
Total share-based compensation expense	$	4.2	$	4.8	$	20.8	$	15.2

Schedule of Share-based Payment Award, Stock Options, Valuation 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:

	2021 Annual Grant
Risk-free interest rate	0.37	%
Expected dividend yield	1.56	%
Expected share price volatility	29.60	%
Expected term (years)	6.5