Description of Business Segments and Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, € in Millions	3 Months Ended																12 Months Ended
	May 31, 2020 USD ($) air-craft $ / shares shares		Feb. 29, 2020 $ / shares	[1],[2]	Nov. 30, 2019 USD ($) air-craft $ / shares		Aug. 31, 2019 $ / shares	[1],[2]	May 31, 2019 USD ($) $ / shares		Feb. 28, 2019 USD ($) $ / shares		Nov. 30, 2018 $ / shares	[2],[3]	Aug. 31, 2018 $ / shares	[2],[3]	May 31, 2020 USD ($) air-craft $ / shares shares	May 31, 2019 USD ($) Employee $ / shares shares	May 31, 2018 USD ($) $ / shares shares	May 31, 2020 EUR (€) air-craft shares	May 27, 2020 $ / shares	Jan. 26, 2016 shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross contract assets related to in-transit shipments	$ 563,000,000								$ 533,000,000								$ 563,000,000	$ 533,000,000
Contract assets net of deferred unearned revenue	456,000,000								364,000,000								456,000,000	364,000,000
Contract liabilities related to advance payments from customers	$ 10,000,000								11,000,000								$ 10,000,000	11,000,000
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																	$ 427,000,000	468,000,000	$ 442,000,000
Depreciable life range for majority of aircraft costs																	15 to 30 years
Depreciation expense, excluding gains and losses on sales of property and equipment																	$ 3,615,000,000	3,353,000,000	3,095,000,000
Interest costs capitalized																	$ 54,000,000	64,000,000	61,000,000
Number of aircraft to be permanently retired from service | air-craft					10
Number of aircraft engines to be permanently retired from service | air-craft					12
Noncash impairment charges					$ 66,000,000
Noncash impairment charges net of tax					$ 50,000,000
Noncash impairment charges net of tax per diluted share | $ / shares					$ 0.19
Number of aircraft temporarily idled | air-craft					7
Number of Idle Aircraft | air-craft	14																14			14
Number of months aircraft remained idle																	an average of five months
Gain on sale of TNT express business																		$ 8,000,000	$ 85,000,000
Denominated debt as a net investment hedge | €																				€ 392
Stock repurchase program number of shares authorized to be repurchased | shares																						25,000,000
Number of shares repurchased | shares																	20,000.00	6,600,000	4,300,000
Treasury stock acquired, average cost per share | $ / shares																	$ 156.90	$ 222.94	$ 237.45
Payments for repurchase of common stock																	$ 3,000,000	$ 1,480,000,000	$ 1,017,000,000
Stock repurchase program, remaining number of shares authorized to be repurchased | shares	5,100,000																5,100,000			5,100,000
Dividends payable, date declared																	Jun. 15, 2020
Dividends payable amount per share | $ / shares	$ 0.65																$ 0.65				$ 0.65
Dividends payable, date to be paid																	Jul. 13, 2020
Dividends payable, date of record																	Jun. 29, 2020
Number of employees left or voluntarily leaving | Employee																		1,500
Business realignment costs									$ 316,000,000		$ 4,000,000							$ 320,000,000
Diluted | $ / shares	$ (1.28)	[1],[2]	$ 1.20		$ 2.13	[1],[2]	$ 2.84		$ (7.56)	[2],[3]	$ 2.80	[2],[3]	$ 3.51		$ 3.10		$ 4.90	$ 2.03	$ 16.79
Business Realignment Activities [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Business realignment costs paid at departure																	$ 50,000,000	$ 220,000,000
Amended and Restated Five-Year Credit Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity	$ 2,000,000,000.0																2,000,000,000.0
Amended and Restated 364-Day Credit Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity	$ 1,500,000,000																$ 1,500,000,000
Line of Credit Facility, Term	364 days
Amendments to Credit Agreements [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Dividends payable amount per share | $ / shares	$ 0.65																$ 0.65
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																			$ 85,000,000

[1] The fourth quarter, third quarter, second quarter and first quarter of 2020 include $63 million, $72 million, $64 million and $71 million, respectively, of TNT Express integration expenses. The fourth quarter includes $369 million of goodwill and other asset impairment charges associated with the FedEx Office and FedEx Logistics operating segments and a net loss of $794 million related to the annual MTM retirement plans accounting adjustment. The second quarter of 2020 includes asset impairment charges of $66 million related to the permanent retirement of 10 Airbus A310-300 aircraft and 12 related engines at FedEx Express.

[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 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.