Condensed Consolidated Statements of Changes in Common Stockholders' Investment - USD ($) $ in Millions		3 Months Ended
		Aug. 31, 2020	Aug. 31, 2019
Beginning Balance		$ 18,295
Net income		1,245	$ 745
Other comprehensive income, net of tax (expense)/benefit		127	(104)
Ending Balance		19,462	18,166
Common Stock
Beginning Balance		32	32
Ending Balance		32	32
Additional Paid-In Capital
Beginning Balance		3,356	3,231
Employee incentive plans and other		19	26
Ending Balance		3,375	3,257
Retained Earnings
Beginning Balance		25,216	24,648
Net income		1,245	745
Cash dividends declared		(341)	(339)
Employee incentive plans and other		(12)	(2)
Ending Balance		26,108	25,048
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-02 and 2018-02
Beginning Balance	[1]		(4)
Accumulated Other Comprehensive Income
Beginning Balance		(1,147)	(865)
Other comprehensive income, net of tax (expense)/benefit		127	(104)
Ending Balance		(1,020)	(918)
Accumulated Other Comprehensive Income | Accounting Standards Update 2018-02
Reclassification to retained earnings due to the adoption of a new accounting standard on June 1, 2019	[2]		51
Treasury Stock
Beginning Balance		(9,162)	(9,289)
Purchase of treasury stock			(3)
Employee incentive plans and other		129	39
Ending Balance		$ (9,033)	$ (9,253)

[1] Relates to the adoption of Accounting Standards Update (“ASU”) 2016-02 and ASU 2018-02.

[2] Relates to the adoption of ASU 2018-02.