Stock Plans (Tables)

3 Months Ended

Mar. 31, 2020

Share-based Payment Arrangement [Abstract]

Disclosure of share-based compensation arrangements by payment award

During the three months ended March 31, 2020 and 2019, shares granted to eligible employees, the grant date fair value per share and the recorded compensation expense related to PSU awards were as follows:

	Number of Shares Granted	PSU Grant Date Fair Value Subject to Other Performance Factors Per Share		PSU Grant Date Fair Value Subject to TSR Performance Factor Per Share		Compensation Expense Related to PSU Awards (in millions)
2020	643,640	$ 86.69		$ 79.76		$	23
2019	625,200		$ 77.20		$ 83.59	$	18

During the three months ended March 31, 2020 and 2019, shares granted to eligible employees, the weighted-average grant date fair value per share related to RSU awards and the recorded compensation expense related to RSU awards were as follows:

	Number of Shares Granted	Weighted-Average Grant Date Fair Value Per RSU Award Granted		Compensation Expense Related to RSU Awards (in millions)
2020	1,599,380	$ 86.62		$	39
2019	1,621,070		$ 77.13	$	36

Schedule of assumptions used to determine the grant date fair value of the PSU awards subject to the TSR performance factor

The following assumptions were used to determine the grant date fair value of the PSU awards subject to the TSR performance factor:

	2020		2019
Risk-free interest rate (a)	1.4	%	2.4	%
Expected volatility (b)	23.5	%	21.4	%

^(a) Based on the U.S. Treasury yield curve.

^(b) Determined using the observed historical volatility.