Condensed Consolidating Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended																12 Months Ended
	May 31, 2019		Feb. 28, 2019		Nov. 30, 2018		Aug. 31, 2018	[1]	May 31, 2018		Feb. 28, 2018	[2]	Nov. 30, 2017	[2]	Aug. 31, 2017	[2]	May 31, 2019		May 31, 2018		May 31, 2017
Condensed Statement Of Income Captions [Line Items]
REVENUES	$ 17,807	[1]	$ 17,010	[1]	$ 17,824	[1]	$ 17,052		$ 17,314	[2]	$ 16,526		$ 16,313		$ 15,297		$ 69,693	[3]	$ 65,450	[3],[4]	$ 60,319	[3],[4]
OPERATING EXPENSES:
Salaries and employee benefits																	24,776		23,795		21,989
Purchased transportation																	$ 16,654		$ 15,101		$ 13,630
Type of cost, good or service [extensible list]																	us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember
Rentals and landing fees																	$ 3,360		$ 3,361		$ 3,240
Depreciation and amortization																	3,353		3,095		2,995
Fuel																	3,889		3,374		2,773
Maintenance and repairs																	2,834		2,622		2,374
Goodwill and other asset impairment charges									380										380
Business realignment costs	316		4														320
Other																	10,041		9,450		8,752
OPERATING EXPENSES																	65,227		61,178		55,753
OPERATING INCOME	1,316	[1]	911	[1]	1,168	[1]	1,071		1,328	[2]	858		1,115		971		4,466	[5]	4,272	[6]	4,566	[7]
OTHER (EXPENSE) INCOME:
Interest, net																	(529)		(510)		(479)
Other retirement plans (expense) income																	(3,251)		598		471
Other, net																	(31)		(7)		21
INCOME BEFORE INCOME TAXES																	655		4,353		4,579
Provision for income taxes (benefit)			90		60												115		(219)		1,582
NET INCOME	$ (1,969)	[1],[8]	$ 739	[1],[8]	$ 935	[1],[8]	$ 835	[8]	$ 1,127	[2],[9]	$ 2,074	[9]	$ 775	[9]	$ 596	[9]	540		4,572		2,997
COMPREHENSIVE INCOME (LOSS)																	253		4,409		2,751
Consolidation Eliminations [Member]
Condensed Statement Of Income Captions [Line Items]
REVENUES																	(381)		(407)		(302)
OPERATING EXPENSES:
Purchased transportation																	$ (184)		$ (224)		$ (125)
Type of cost, good or service [extensible list]																	us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember
Rentals and landing fees																	$ (7)		$ (7)		$ (6)
Maintenance and repairs																	(2)
Other																	(188)		(176)		(171)
OPERATING EXPENSES																	(381)		(407)		(302)
OTHER (EXPENSE) INCOME:
Equity in earnings of subsidiaries																	(714)		(4,634)		(3,065)
INCOME BEFORE INCOME TAXES																	(714)		(4,634)		(3,065)
NET INCOME																	(714)		(4,634)		(3,065)
COMPREHENSIVE INCOME (LOSS)																	(714)		(4,634)		(3,065)
Parent Company [Member] | Reportable Legal Entities [Member]
OPERATING EXPENSES:
Salaries and employee benefits																	$ 138		$ 149		$ 123
Type of cost, good or service [extensible list]																	us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember
Rentals and landing fees																	$ 6		$ 5		$ 5
Depreciation and amortization																	1		1		1
Maintenance and repairs																	1		1		1
Business realignment costs																	320
Intercompany charges, net																	(765)		(437)		(434)
Other																	299		281		304
OTHER (EXPENSE) INCOME:
Equity in earnings of subsidiaries																	540		4,572		2,997
Interest, net																	(586)		(541)		(507)
Intercompany charges, net																	606		544		508
Other, net																	(20)		(3)		(1)
INCOME BEFORE INCOME TAXES																	540		4,572		2,997
NET INCOME																	540		4,572		2,997
COMPREHENSIVE INCOME (LOSS)																	453		4,489		2,922
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
REVENUES																	50,431		48,601		44,823
OPERATING EXPENSES:
Salaries and employee benefits																	19,055		18,380		17,137
Purchased transportation																	$ 10,344		$ 9,134		$ 8,260
Type of cost, good or service [extensible list]																	us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember
Rentals and landing fees																	$ 2,582		$ 2,587		$ 2,517
Depreciation and amortization																	2,877		2,644		2,538
Fuel																	3,587		3,077		2,476
Maintenance and repairs																	2,475		2,294		2,086
Intercompany charges, net																	(861)		(125)		179
Other																	6,674		6,227		5,734
OPERATING EXPENSES																	46,733		44,218		40,927
OPERATING INCOME																	3,698		4,383		3,896
OTHER (EXPENSE) INCOME:
Equity in earnings of subsidiaries																	174		62		68
Interest, net																	54		46		27
Other retirement plans (expense) income																	(2,675)		547		516
Intercompany charges, net																	(442)		(296)		(299)
Other, net																	53		(120)		(134)
INCOME BEFORE INCOME TAXES																	862		4,622		4,074
Provision for income taxes (benefit)																	77		309		1,439
NET INCOME																	785		4,313		2,635
COMPREHENSIVE INCOME (LOSS)																	838		4,263		2,580
Non-guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Statement Of Income Captions [Line Items]
REVENUES																	19,643		17,256		15,798
OPERATING EXPENSES:
Salaries and employee benefits																	5,583		5,266		4,729
Purchased transportation																	$ 6,494		$ 6,191		$ 5,495
Type of cost, good or service [extensible list]																	us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember		us-gaap:ShippingAndHandlingMember
Rentals and landing fees																	$ 779		$ 776		$ 724
Depreciation and amortization																	475		450		456
Fuel																	302		297		297
Maintenance and repairs																	360		327		287
Goodwill and other asset impairment charges																			380
Intercompany charges, net																	1,626		562		255
Other																	3,256		3,118		2,885
OPERATING EXPENSES																	18,875		17,367		15,128
OPERATING INCOME																	768		(111)		670
OTHER (EXPENSE) INCOME:
Interest, net																	3		(15)		1
Other retirement plans (expense) income																	(576)		51		(45)
Intercompany charges, net																	(164)		(248)		(209)
Other, net																	(64)		116		156
INCOME BEFORE INCOME TAXES																	(33)		(207)		573
Provision for income taxes (benefit)																	38		(528)		143
NET INCOME																	(71)		321		430
COMPREHENSIVE INCOME (LOSS)																	$ (324)		$ 291		$ 314

[1] The fourth quarter, third quarter, second quarter and first quarter of 2019 include $84 million, $69 million, $114 million and $121 million, respectively, of TNT Express integration expenses (including any restructuring charges). The fourth quarter and third quarter of 2019 include business realignment costs of $316 million and $4 million, respectively. The fourth quarter includes a net loss of $3.9 billion related to the annual MTM retirement plans accounting adjustment. The second quarter of 2019 includes costs incurred in connection with the settlement of a legal matter involving FedEx Ground of $46 million.

[2] The fourth quarter, third quarter, second quarter and first quarter of 2018 include $136 million, $106 million, $122 million and $112 million, respectively, of TNT Express integration expenses (including any restructuring charges). The fourth quarter of 2018 includes goodwill and other asset impairment charges related to FedEx Supply Chain of $380 million and a net gain of $10 million related to the annual MTM retirement plans accounting adjustment. The fourth quarter and first quarter of 2018 include charges for legal reserves related to certain CBP matters involving FedEx Logistics of $1 million and $7 million, respectively.

[3] International revenue includes shipments that either originate in or are destined to locations outside the United States, which could include U.S. payors. Noncurrent assets include property and equipment, goodwill and other long-term assets. Our flight equipment is registered in the U.S. and is included as U.S. assets; however, many of our aircraft operate internationally.

[4] Prior year amounts have been revised to conform to the current year presentation.

[5] Includes TNT Express integration expenses and restructuring charges of $388 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes business realignment costs of $320 million and costs incurred in connection with the settlement of a legal matter involving FedEx Ground of $46 million.

[6] Includes TNT Express integration expenses and restructuring charges of $477 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes goodwill and other asset impairment charges of $380 million.

[7] Includes TNT Express integration expenses and restructuring charges of $327 million. These expenses are included in “Corporate, other and eliminations” and the FedEx Express segment. Also includes $39 million of charges for legal reserves related to certain U.S. Customs and Border Protection (“CBP”) matters involving FedEx Logistics and $22 million of charges in connection with the settlement of and certain expected losses relating to independent contractor litigation matters at FedEx Ground.

[8] The income tax benefit for the fourth quarter of 2019 was unfavorably impacted by $200 million due to the lower statutory tax rate under the TCJA on fiscal 2019 earnings and the annual retirement plans accounting MTM adjustment. The third quarter, second quarter and first quarter of 2019 include $60 million, $150 million and $135 million, respectively, of tax benefits primarily from the lower statutory tax rate under the TCJA on fiscal 2019 earnings. The third quarter of 2019 includes a tax benefit of $90 million from the reduction of a valuation allowance on certain tax loss carryforwards and a tax expense of $50 million related to a lower tax rate in the Netherlands applied to our deferred tax balances. The second quarter of 2019 includes a tax benefit of approximately $60 million from accelerated deductions claimed on our 2018 U.S. income tax return. In addition, we recognized a tax expense of $4 million in the second quarter of 2019 as a revision of the provisional benefit associated with the remeasurement of our net U.S. deferred tax liability upon completion of the accounting for the tax effects of the TCJA.

[9] The fourth quarter of 2018 includes a $255 million net tax benefit from corporate structuring transactions as part of the ongoing integration of FedEx Express and TNT Express. The fourth quarter, third quarter, and second quarter of 2018 include $133 million, $12 million, and $80 million, respectively, of tax benefits from foreign tax credits associated with distributions to the U.S. from foreign operations. The fourth quarter and third quarter of 2018 include $100 million and $165 million, respectively, of tax benefits related to a lower statutory income tax rate on fiscal 2018 earnings. In addition, the third quarter of 2018 includes the following TCJA-related items: a provisional benefit of $1.15 billion related to the remeasurement of our net U.S. deferred tax liability and a one-time benefit of $204 million from a $1.5 billion contribution to our U.S. Pension Plans.