Share Plans (Tables)

3 Months Ended

Mar. 31, 2019

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Total share-based compensation expense for the three months ended March 31, 2019 and 2018 was as follows:



	Three months ended
In millions	March 31, 2019		March 31, 2018
Restricted stock units	$	2.8	$	2.4
Stock options	1.4		1.2
Performance share units	1.2		2.4
Total share-based compensation expense	$	5.4	$	6.0

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:



	2019 Annual Grant
Risk-free interest rate	2.89	%
Expected dividend yield	1.78	%
Expected share price volatility	23.3	%
Expected term (years)	6.1