Retirement Plans - Schedule of Components of Pension Plans (Details) - Pension Plans [Member] - USD ($) $ in Millions	May 31, 2021	May 31, 2020	May 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation ("PBO")	$ 34,034	$ 32,441
Fair Value of Plan Assets	31,918	28,691
Funded Status	(2,116)	(3,750)
Qualified [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation ("PBO")	31,225	30,004
Fair Value of Plan Assets	29,785	26,978
Funded Status	(1,440)	(3,026)
Nonqualified [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation ("PBO")	198	195
Funded Status	(198)	(195)
International Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Projected Benefit Obligation ("PBO")	2,611	2,242	$ 2,301
Fair Value of Plan Assets	2,133	1,713	$ 1,578
Funded Status	$ (478)	$ (529)