Retirement Plans - Schedule of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Pension Plans [Member] | U.S. Plans [Member]
Net Periodic Benefit Cost
Service cost	$ 208	$ 213
Other retirement plans expense (income):
Interest cost	256	240
Expected return on plan assets	(478)	(446)
Amortization of prior service credit and other	(2)	(2)
Other retirement plans (income) expense	(224)	(208)
Net periodic benefit cost	(16)	5
Pension Plans [Member] | International Pension Plans [Member]
Net Periodic Benefit Cost
Service cost	15	23
Other retirement plans expense (income):
Interest cost	12	10
Expected return on plan assets	(14)	(12)
Amortization of prior service credit and other		(1)
Other retirement plans (income) expense	(2)	(3)
Net periodic benefit cost	13	20
Postretirement Healthcare Plans [Member]
Net Periodic Benefit Cost
Service cost	12	11
Other retirement plans expense (income):
Interest cost	10	10
Other retirement plans (income) expense	10	10
Net periodic benefit cost	$ 22	$ 21