Common Stock and Stock-Based Compensation (Tables)

12 Months Ended

May. 31, 2015

Common Stock and Stock-based Compensation [Abstract]

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:

	Year Ended May 31,
(In millions)	2015		2014		2013
Stock options(1)	$	136	$	125	$	123
ESPPs	24		22		19
Restricted stock	31		30		32
TOTAL STOCK-BASED COMPENSATION EXPENSE	$	191	$	177	$	174

(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 for the years ended May 31, 2015, 2014 and 2013 was $19 million, $15 million and $22 million, respectively.

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

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

	Year Ended May 31,
	2015		2014		2013
Dividend yield	1.2	%	1.3	%	1.5	%
Expected volatility	23.6	%	27.9	%	35.0	%
Weighted average expected life (in years)	5.8		5.3		5.3
Risk-free interest rate	1.7	%	1.3	%	0.6	%

Schedule of Share-based Compensation, Stock Options, Activity

The following summarizes the stock option transactions under the plan discussed above:

	Shares(1)		Weighted Average Option Price
	(In millions)
Options outstanding May 31, 2012	64.3		$	30.59
Exercised	(9.9	)	24.70
Forfeited	(1.3	)	40.14
Granted	14.6		46.55
Options outstanding May 31, 2013	67.7		$	34.72
Exercised	(11.0	)	28.29
Forfeited	(1.3	)	48.33
Granted	8.1		63.54
Options outstanding May 31, 2014	63.5		$	39.28
Exercised	(13.6	)	30.78
Forfeited	(1.0	)	59.02
Granted	9.2		77.68
Options outstanding May 31, 2015	58.1		$	47.00
Options exercisable at May 31,
2013	35.9		$	27.70
2014	37.0		31.42
2015	34.3		36.53

(1) Includes stock appreciation rights transactions.