Share Plans (Tables)

12 Months Ended

Dec. 31, 2016

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

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block]

	December 31
In millions	2016		2015		2014
Restricted stock units	$	17.3	$	21.6	$	22.6
Stock options	10.4		11.4		11.0
Performance share units	6.5		—		—
Total share-based compensation expense	$	34.2	$	33.0	$	33.6

Stock Option Activity

The following table summarizes stock option activity under all plans for the year ended December 31, 2016:

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, 2016	5.6		$	42.55
Granted	1.3		47.99
Exercised	(1.0	)	32.38
Forfeited	(0.1	)	59.24
Expired	(0.1	)	30.18
Outstanding as of December 31, 2016	5.7		$	45.72	5.3	$	74.9
Options exercisable as of December 31, 2016	3.9		$	41.05	3.9	$	67.3
Options expected to vest as of December 31, 2016	1.8		$	56.04	8.6	$	7.6

Stock Option Fair Value Assumptions

We estimated the fair value of each stock option award on the date of grant using a Black-Scholes option pricing model, modified for dividends and using the following weighted average assumptions:

	December 31
	2016		2015		2014
Risk-free interest rate	1.56	%	1.60	%	1.44	%
Expected dividend yield	2.49	%	1.97	%	1.46	%
Expected share price volatility	27.3	%	30.4	%	35.3	%
Expected term (years)	5.9		6.0		5.6

Restricted Stock Activity

The following table summarizes restricted stock unit activity under all plans for the year ended December 31, 2016:

Shares in millions	Number of shares		Weighted average grant date fair value
Outstanding as of January 1, 2016	0.8		$	55.64
Granted	0.4		50.72
Vested	(0.5	)	52.37
Forfeited	—		—
Outstanding as of December 31, 2016	0.7		$	55.31

Share-based Compensation, Performance Shares Award Outstanding Activity [Table Text Block]

The following table summarizes performance share unit activity under all plans for the year ended December 31, 2016:

Shares in millions	Number of shares	Weighted average grant date fair value
Outstanding as of January 1, 2016	—	$	—
Granted	0.3	49.53
Vested	—	—
Forfeited	—	—
Outstanding as of December 31, 2016	0.3	$	49.54