Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2021	Aug. 31, 2020
Income Statement [Abstract]
REVENUE	$ 22,003	$ 19,321
OPERATING EXPENSES:
Salaries and employee benefits	7,776	6,852
Purchased transportation	5,659	4,977
Rentals and landing fees	1,133	936
Depreciation and amortization	971	926
Fuel	1,009	565
Maintenance and repairs	869	806
Business realignment costs	67
Other	3,121	2,669
OPERATING EXPENSES	20,605	17,731
OPERATING INCOME	1,398	1,590
OTHER (EXPENSE) INCOME:
Interest, net	(160)	(184)
Other retirement plans income	216	201
Other, net	3	(1)
OTHER INCOME (EXPENSE)	59	16
INCOME BEFORE INCOME TAXES	1,457	1,606
PROVISION FOR INCOME TAXES	345	361
NET INCOME	$ 1,112	$ 1,245
EARNINGS PER COMMON SHARE:
Basic	$ 4.17	$ 4.75
Diluted	4.09	4.72
DIVIDENDS DECLARED PER COMMON SHARE	$ 1.50	$ 1.30