Retirement Plans - Schedule of MTM Adjustments (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2021
Actuarial Gain Loss By Component Pre Tax [Abstract]
Actual versus expected return on assets	$ 2,492	$ 5,109	$ (1,712)
Discount rate change	(3,395)	(4,486)	(397)
Demographic experience:
Current year actuarial loss	142	504	302
Change in future assumptions	110	314	685
Termination of TNT Express Netherlands pension plan		224
Pension plan amendments, including curtailment gains	1	(87)	(54)
Total MTM (gain) loss	$ (650)	$ 1,578	$ (1,176)