Retirement Plans - Schedule of Weighted-Average Asset Allocations for U.S Pension Plans and International Pension Plans (Details) - Pension Plans [Member] - USD ($) $ in Millions		May 31, 2021	May 31, 2020	May 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 31,918	$ 28,691
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 29,785	$ 26,978	$ 23,320
Actual %		100.00%	100.00%
U.S. Plans [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 614	$ 709
Actual %		2.00%	3.00%
U.S. Plans [Member] | Cash And Cash Equivalents [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1]	0.00%	0.00%
U.S. Plans [Member] | Cash And Cash Equivalents [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1]	5.00%	5.00%
International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 2,133	$ 1,713	1,578
Portion of Fair Value of Plan Assets		$ 1,882	$ 1,497
Actual %		100.00%	100.00%
International Plans [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets		$ 10	$ 9
Actual %		1.00%	1.00%
U.S. Large Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 4,038	$ 3,070
Actual %	[2]	14.00%	11.00%
International Equity Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 4,664	$ 3,314
Actual %	[2]	16.00%	12.00%
International Equity Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 123	$ 72
Actual %	[2]	7.00%	5.00%
Global Equity Funds [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 1,668	$ 1,350
Actual %	[2]	6.00%	5.00%
Global Equity Funds [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 335	$ 218
Actual %	[2]	18.00%	15.00%
U.S. SMID Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 967	$ 673
Actual %		3.00%	3.00%
Corporate Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 8,714	$ 7,983
Actual %		29.00%	30.00%
Corporate Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 434	$ 342
Actual %	[2]	23.00%	23.00%
Government Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 5,190	$ 6,928
Actual %	[2]	17.00%	26.00%
Government Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 574	$ 510
Actual %	[2]	30.00%	34.00%
Mortgage Backed And Other Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 1,065	$ 634
Actual %	[2]	3.00%	2.00%
Mortgage Backed And Other Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 217	$ 188
Actual %	[2]	12.00%	12.00%
Alternative investments [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 2,855	$ 2,264
Actual %	[2]	10.00%	8.00%
Alternative investments [Member] | U.S. Plans [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1],[2]	0.00%	0.00%
Alternative investments [Member] | U.S. Plans [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1],[2]	15.00%	15.00%
Other [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 10	$ 53
Other [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 189	$ 158
Actual %	[2]	9.00%	10.00%
Total Equities [Member] | U.S. Plans [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1]	30.00%	30.00%
Total Equities [Member] | U.S. Plans [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1]	50.00%	50.00%
Total Fixed Income Securities [Member] | U.S. Plans [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1]	50.00%	50.00%
Total Fixed Income Securities [Member] | U.S. Plans [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Target %	[1]	70.00%	70.00%
Fair Value Inputs Level 1 [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 6,342	$ 4,918
Fair Value Inputs Level 1 [Member] | U.S. Plans [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		36	278
Fair Value Inputs Level 1 [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets		379	340
Fair Value Inputs Level 1 [Member] | International Plans [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets		10	9
Fair Value Inputs Level 1 [Member] | U.S. Large Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	1,644	1,172
Fair Value Inputs Level 1 [Member] | International Equity Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	3,792	2,738
Fair Value Inputs Level 1 [Member] | U.S. SMID Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		884	673
Fair Value Inputs Level 1 [Member] | Government Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	350
Fair Value Inputs Level 1 [Member] | Mortgage Backed And Other Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]		318
Fair Value Inputs Level 1 [Member] | Other [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets			57
Fair Value of Plan Liabilities		(14)
Fair Value Inputs Level 1 [Member] | Other [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	19	13
Fair Value, Inputs, Level 2 | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		12,817	13,233
Fair Value, Inputs, Level 2 | U.S. Plans [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		578	431
Fair Value, Inputs, Level 2 | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets		36	63
Fair Value, Inputs, Level 2 | International Equity Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	2
Fair Value, Inputs, Level 2 | U.S. SMID Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		5
Fair Value, Inputs, Level 2 | Corporate Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		8,714	7,983
Fair Value, Inputs, Level 2 | Government Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	3,296	4,652
Fair Value, Inputs, Level 2 | Mortgage Backed And Other Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	226	170
Fair Value, Inputs, Level 2 | Other [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Liabilities		(4)	(3)
Fair Value, Inputs, Level 2 | Other [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	36	63
Fair Value Inputs Level 3 [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		537	416	$ 302
Fair Value Inputs Level 3 [Member] | Alternative investments [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 537	$ 416

[1] Target ranges have not been provided for international plan assets as they are managed at an individual country level.

[2] Certain investments that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy but are included in the total.