Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019
Income Statement [Abstract]
REVENUE	$ 17,487	$ 17,010	$ 51,859	$ 51,886
OPERATING EXPENSES:
Salaries and employee benefits	6,382	6,069	18,704	18,589
Purchased transportation	4,558	4,253	12,914	12,566
Rentals and landing fees	964	874	2,808	2,533
Depreciation and amortization	908	851	2,688	2,487
Fuel	879	907	2,639	2,945
Maintenance and repairs	684	658	2,226	2,144
Asset impairment charges			66
Business realignment costs		4		4
Other	2,701	2,483	7,872	7,468
OPERATING EXPENSES	17,076	16,099	49,917	48,736
OPERATING INCOME	411	911	1,942	3,150
OTHER INCOME (EXPENSE):
Interest, net	(155)	(135)	(443)	(393)
Other retirement plans income	168	158	504	474
Other, net	(4)	(3)	(15)	(22)
OTHER INCOME (EXPENSE)	9	20	46	59
INCOME BEFORE INCOME TAXES	420	931	1,988	3,209
PROVISION FOR INCOME TAXES	105	192	368	700
NET INCOME	$ 315	$ 739	$ 1,620	$ 2,509
EARNINGS PER COMMON SHARE:
Basic	$ 1.21	$ 2.83	$ 6.21	$ 9.55
Diluted	1.20	2.80	6.17	9.41
DIVIDENDS DECLARED PER COMMON SHARE	$ 0.65	$ 0.65	$ 2.60	$ 2.60