Description of Business and Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Millions		3 Months Ended																12 Months Ended
	Apr. 30, 2018 USD ($)	May 31, 2019 USD ($) air-craft $ / shares shares		Feb. 28, 2019 USD ($) $ / shares		Nov. 30, 2018 $ / shares	[1],[2]	Aug. 31, 2018 $ / shares	[1],[2]	May 31, 2018 USD ($) $ / shares		Feb. 28, 2018 $ / shares	[2],[3]	Nov. 30, 2017 $ / shares	[2],[3]	Aug. 31, 2017 $ / shares	[2],[3]	May 31, 2019 USD ($) air-craft Employee $ / shares shares	May 31, 2018 USD ($) $ / shares shares	May 31, 2017 USD ($) $ / shares shares	Jan. 26, 2016 shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross contract assets related to in-transit packages		$ 533								$ 542								$ 533	$ 542
Contract assets net of deferred unearned revenue		364								363								364	363
Contract liabilities related to advance payments from customers		$ 11								$ 13								$ 11	13
Payment terms of customer contracts																		Under the typical payment terms of our customer contracts, the customer pays at periodic intervals (e.g., every 15 days, 30 days, 45 days, etc.) for shipments included on invoices received. It is not customary business practice to extend payment terms past 90 days, and as such, we do not have a practice of including a significant financing component within our revenue contracts with customers.
Advertising and promotion expenses																		$ 468	442	$ 458
Depreciable life range for majority of aircraft costs																		15 to 30 years
Depreciation expense, excluding gains and losses on sales of property and equipment																		$ 3,353	3,095	2,995
Interest costs capitalized																		$ 64	61	$ 41
Number of Idle Aircraft | air-craft		7																7
Number of months aircraft remained idle																		an average of 23 months
Gain on sale of TNT express business																		$ 8	$ 85
Stock repurchase program number of shares authorized to be repurchased | shares																					25,000,000
Number of shares repurchased | shares																		6,600,000	4,300,000	3,000,000
Treasury stock acquired, average cost per share | $ / shares																		$ 222.94	$ 237.45	$ 172.13
Payments for repurchase of common stock																		$ 1,480	$ 1,017	$ 509
Stock repurchase program, remaining number of shares authorized to be repurchased | shares		5,100,000																5,100,000
Dividends payable, date declared																		Jun. 10, 2019
Dividends payable amount per share | $ / shares		$ 0.65																$ 0.65
Dividends payable, date to be paid																		Jul. 08, 2019
Dividends payable, date of record																		Jun. 24, 2019
Number of employees left or voluntarily leaving | Employee																		1,500
Business realignment costs		$ 316		$ 4														$ 320
Diluted | $ / shares		$ (7.56)	[1],[2]	$ 2.80	[1],[2]	$ 3.51		$ 3.10		$ 4.15	[2],[3]	$ 7.59		$ 2.84		$ 2.19		$ 2.03	$ 16.79	$ 11.07
Business Realignment Activities [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Business realignment costs																		$ 320
Business realignment costs, net of tax																		$ 243
Diluted | $ / shares																		$ 0.91
Business realignment costs paid at departure																		$ 220
Minimum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Intangible assets amortization periods																		3 years
Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Intangible assets amortization periods																		15 years
FedEx Express Segment [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gain on sale of TNT express business	$ 85

[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 sum of the quarterly earnings per share may not equal annual amounts due to differences in the weighted-average number of shares outstanding during the respective periods.

[3] 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.