Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 29, 2020	Feb. 28, 2021	Feb. 29, 2020
Income Statement [Abstract]
REVENUE	$ 21,510	$ 17,487	$ 61,394	$ 51,859
OPERATING EXPENSES:
Salaries and employee benefits	8,010	6,382	22,305	18,704
Purchased transportation	5,660	4,558	16,044	12,914
Rentals and landing fees	1,131	964	3,073	2,808
Depreciation and amortization	956	908	2,818	2,688
Fuel	756	879	1,946	2,639
Maintenance and repairs	822	684	2,443	2,226
Business realignment costs	10		10
Asset impairment charges				66
Other	3,160	2,701	8,695	7,872
OPERATING EXPENSES	20,505	17,076	57,334	49,917
OPERATING INCOME	1,005	411	4,060	1,942
OTHER (EXPENSE) INCOME:
Interest, net	(187)	(155)	(555)	(443)
Other retirement plans income	202	168	553	504
Other, net	29	(4)	3	(15)
OTHER (EXPENSE) INCOME	44	9	1	46
INCOME BEFORE INCOME TAXES	1,049	420	4,061	1,988
PROVISION FOR INCOME TAXES	157	105	698	368
NET INCOME	$ 892	$ 315	$ 3,363	$ 1,620
EARNINGS PER COMMON SHARE:
Basic	$ 3.36	$ 1.21	$ 12.75	$ 6.21
Diluted	3.30	1.20	12.55	6.17
DIVIDENDS DECLARED PER COMMON SHARE	$ 0.65	$ 0.65	$ 2.60	$ 2.60