Consolidated Statements of Shareholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Capital in Excess of Stated Value	Accumulated Other Comprehensive Income	Retained Earnings	Class A Common Stock	Class A Common Stock Common Stock	Class B Common Stock	Class B Common Stock Common Stock
Beginning Balance (in shares) at May. 31, 2012						180		736
Beginning Balance at May. 31, 2012	$ 10,319	$ 4,641	$ 149	$ 5,526		$ 0		$ 3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised (in shares)								10
Stock options exercised	322	322
Conversion to Class B Common Stock (in shares)						(2)
Conversion of Stock, Shares Issued								2
Conversion to Class B Common Stock	0
Stock Repurchased During Period, Shares								(34)
Stock Repurchased During Period, Value	(1,657)	(10)		(1,647)
Dividends on Common stock	(727)			(727)
Issuance of shares to employees (in shares)								2
Issuance of shares to employees	65	65
Stock-based compensation (Note 11)	174	174
Forfeiture of shares from employees (in shares)								0
Forfeiture of shares from employees	(12)	(8)		(4)
Net income	2,472			2,472
Other comprehensive income (loss)	125		125
Ending Balance (in shares) at May. 31, 2013						178		716
Ending Balance at May. 31, 2013	11,081	5,184	274	5,620		$ 0		$ 3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised (in shares)								11
Stock options exercised	445	445
Stock Repurchased During Period, Shares								(37)
Stock Repurchased During Period, Value	(2,628)	(11)		(2,617)
Dividends on Common stock	(821)			(821)
Issuance of shares to employees (in shares)								2
Issuance of shares to employees	78	78
Stock-based compensation (Note 11)	177	177
Forfeiture of shares from employees (in shares)								0
Forfeiture of shares from employees	(12)	(8)		(4)
Net income	2,693			2,693
Other comprehensive income (loss)	(189)		(189)
Ending Balance (in shares) at May. 31, 2014					178	178	692	692
Ending Balance at May. 31, 2014	10,824	5,865	85	4,871		$ 0		$ 3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock options exercised (in shares)								14
Stock options exercised	639	639
Stock Repurchased During Period, Shares								(29)
Stock Repurchased During Period, Value	(2,534)	(9)		(2,525)
Dividends on Common stock	(931)			(931)
Issuance of shares to employees (in shares)								2
Issuance of shares to employees	92	92
Stock-based compensation (Note 11)	191	191
Forfeiture of shares from employees (in shares)								0
Forfeiture of shares from employees	(8)	(5)		(3)
Net income	3,273			3,273
Other comprehensive income (loss)	1,161		1,161
Ending Balance (in shares) at May. 31, 2015					178	178	679	679
Ending Balance at May. 31, 2015	$ 12,707	$ 6,773	$ 1,246	$ 4,685		$ 0		$ 3