Stock-Based Compensation (Tables)

9 Months Ended

Feb. 29, 2016

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 29, 2016		February 28, 2015		February 29, 2016		February 28, 2015
Stock options⁽¹⁾	$	44	$	35	$	128	$	100
ESPPs	7		5		22		17
Restricted stock	9		8		26		23
TOTAL STOCK-BASED COMPENSATION EXPENSE	$	60	$	48	$	176	$	140

(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 $8 million and $5 million for the three month periods ended February 29, 2016 and February 28, 2015, respectively, and $22 million and $14 million for the nine month periods ended February 29, 2016 and February 28, 2015, respectively.

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

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



	Nine Months Ended
	February 29, 2016		February 28, 2015
Dividend yield	1.0	%	1.2	%
Expected volatility	23.6	%	23.6	%
Weighted average expected life (in years)	5.8		5.8
Risk-free interest rate	1.7	%	1.7	%