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, 2019	May 31, 2018	May 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 24,898	$ 23,566
U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 23,320	$ 22,057	$ 24,933
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		$ 570	$ 714
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		$ 1,578	$ 1,509	1,379
Portion of Fair Value of Plan Assets		$ 1,374	$ 1,320
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		$ 57	$ 24
Actual %		4.00%	2.00%
U.S. Large Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 2,546	$ 2,449
Actual %	[2]	11.00%	11.00%
International Equity Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 3,306	$ 3,506
Actual %	[2]	14.00%	16.00%
International Equity Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 72	$ 146
Actual %	[2]	5.00%	11.00%
Global Equity Funds [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 1,451	$ 1,772
Actual %	[2]	6.00%	8.00%
Global Equity Funds [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 206	$ 228
Actual %	[2]	15.00%	17.00%
U.S. SMID Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 731	$ 780
Actual %		3.00%	4.00%
Corporate Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		$ 6,794	$ 5,834
Actual %		29.00%	26.00%
Corporate Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 322	$ 306
Actual %	[2]	24.00%	23.00%
Government Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 5,384	$ 4,872
Actual %	[2]	23.00%	22.00%
Government Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 438	$ 452
Actual %	[2]	32.00%	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]	$ 622	$ 626
Actual %	[2]	3.00%	3.00%
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]	$ 167	$ 168
Actual %	[2]	12.00%	13.00%
Alternative investments [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	$ 1,963	$ 1,573
Actual %	[2]	9.00%	7.00%
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%	10.00%
Alternative investments [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets			$ 19
Actual %			2.00%
Other [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Liabilities		$ (47)	$ (69)
Other [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	$ 112
Actual %	[2]	8.00%
Portion of Fair Value of Plan Liabilities			$ (23)
Actual %			(2.00%)
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		$ 4,310	$ 4,258
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		50	19
Fair Value Inputs Level 1 [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets		357	104
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		57	2
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]	875	840
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]	2,700	2,681
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		730	780
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]	290	108
Fair Value Inputs Level 1 [Member] | Other [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Liabilities		(45)	(62)
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]	10
Portion of Fair Value of Plan Liabilities			(6)
Fair Value Inputs Level 2 [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		11,230	10,164
Fair Value Inputs Level 2 [Member] | U.S. Plans [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		520	695
Fair Value Inputs Level 2 [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets		17	418
Fair Value Inputs Level 2 [Member] | International Plans [Member] | Cash And Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets			22
Fair Value Inputs Level 2 [Member] | International Equity Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]		172
Fair Value Inputs Level 2 [Member] | International Equity Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]		70
Fair Value Inputs Level 2 [Member] | U.S. SMID Cap Equity [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		1
Fair Value Inputs Level 2 [Member] | Corporate Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		6,794	5,834
Fair Value Inputs Level 2 [Member] | Corporate Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]		68
Fair Value Inputs Level 2 [Member] | Government Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	3,742	3,345
Fair Value Inputs Level 2 [Member] | Government Fixed Income Securities [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]		256
Fair Value Inputs Level 2 [Member] | Mortgage Backed And Other Fixed Income Securities [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets	[2]	175	125
Fair Value Inputs Level 2 [Member] | Alternative investments [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets			19
Fair Value Inputs Level 2 [Member] | Other [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Liabilities		(2)	(7)
Fair Value Inputs Level 2 [Member] | Other [Member] | International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Portion of Fair Value of Plan Assets	[2]	17
Portion of Fair Value of Plan Liabilities			(17)
Fair Value Inputs Level 3 [Member] | U.S. Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair Value of Plan Assets		302	209	$ 129
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]	$ 302	$ 209

[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.