Condensed Consolidated Statements of Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2019	Feb. 28, 2018	Feb. 28, 2019	Feb. 28, 2018
Income Statement [Abstract]
REVENUES	$ 17,010	$ 16,526	$ 51,886	$ 48,136
OPERATING EXPENSES:
Salaries and employee benefits	6,069	6,124	18,589	17,677
Purchased transportation	$ 4,253	$ 3,935	$ 12,566	$ 11,220
Type of cost, good or service [extensible list]	us-gaap:ShippingAndHandlingMember	us-gaap:ShippingAndHandlingMember	us-gaap:ShippingAndHandlingMember	us-gaap:ShippingAndHandlingMember
Rentals and landing fees	$ 874	$ 873	$ 2,533	$ 2,526
Depreciation and amortization	851	786	2,487	2,293
Fuel	907	914	2,945	2,435
Maintenance and repairs	658	628	2,144	1,968
Business realignment costs	4	0	4	0
Other	2,483	2,408	7,468	7,073
OPERATING EXPENSES	16,099	15,668	48,736	45,192
OPERATING INCOME	911	858	3,150	2,944
OTHER INCOME (EXPENSE):
Interest, net	(135)	(125)	(393)	(363)
Other retirement plans income	158	143	474	436
Other, net	(3)	(2)	(22)	(22)
OTHER INCOME (EXPENSE)	20	16	59	51
INCOME BEFORE INCOME TAXES	931	874	3,209	2,995
PROVISION FOR INCOME TAXES	192	(1,200)	700	(450)
NET INCOME	$ 739	$ 2,074	$ 2,509	$ 3,445
EARNINGS PER COMMON SHARE:
Basic	$ 2.83	$ 7.74	$ 9.55	$ 12.85
Diluted	2.80	7.59	9.41	12.63
DIVIDENDS DECLARED PER COMMON SHARE	$ 0.65	$ 0.50	$ 2.60	$ 2.00