Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Share-based Compensation, Activity [Table Text Block]

Stock-based compensation and the income tax benefit recognized during the three months ended March 31, 2020 and 2019 were as follows:

	Three Months Ended March 31
($ in millions)	2020	2019
Stock-based compensation	$7	$9
Income tax benefit recognized	$2	$2

Details of Grants of Stock-based Compensation

Grants of stock-based compensation during the three months ended March 31, 2020 and 2019 were as follows:

	Three Months Ended March 31
	2020		2019
Grant Details	Shares	Fair Value	Shares	Fair Value
Stock options	659,835	$21.93	588,870	$22.50
Restricted stock units	182,276	$112.99	179,564	$103.35
Contingent shares (a)	54,648	$119.52	51,850	$109.74

(a) The number of contingent shares represents the target value of the award.

Weighted Average Assumptions Used in Calculating the Fair Value of Stock Option

The fair value of the stock option grants issued during the three months ended March 31, 2020 was calculated with the following weighted average assumptions:

Weighted average exercise price	$119.52
Risk free interest rate	1.6	%
Expected life of option in years	6.5
Expected dividend yield	1.5	%
Expected volatility	20.0	%