Common Stock and Stock-Based Compensation (Tables)

9 Months Ended

Feb. 28, 2017

Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan

The following table summarizes the Company’s total stock-based compensation expense recognized in Operating overhead expense:



	Three Months Ended				Nine Months Ended
(In millions)	February 28, 2017		February 29, 2016		February 28, 2017		February 29, 2016
Stock options⁽¹⁾	$	35	$	44	$	110	$	128
ESPPs	7		7		27		22
Restricted stock	9		9		25		26
TOTAL STOCK-BASED COMPENSATION EXPENSE	$	51	$	60	$	162	$	176

(1)

Expense for stock options includes the expense associated with stock appreciation rights. Accelerated stock option expense is recorded for employees eligible for accelerated stock option vesting upon retirement. Accelerated stock option expense was $3 million and $8 million for the three months ended February 28, 2017 and February 29, 2016, respectively, and $11 million and $22 million for the nine months ended February 28, 2017 and February 29, 2016, respectively.

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

The weighted average assumptions used to estimate these fair values were as follows:



	Nine Months Ended
	February 28, 2017		February 29, 2016
Dividend yield	1.1	%	1.0	%
Expected volatility	17.4	%	23.6	%
Weighted average expected life (in years)	6.0		5.8
Risk-free interest rate	1.3	%	1.7	%