Description of Business and Summary of Significant Accounting Policies (Details) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	May. 31, 2015 USD ($) $ / shares shares		Feb. 28, 2015 USD ($) $ / shares		Nov. 30, 2014 USD ($) $ / shares		Aug. 31, 2014 USD ($) $ / shares		May. 31, 2014 USD ($) $ / shares		Feb. 28, 2014 USD ($) $ / shares		Nov. 30, 2013 USD ($) $ / shares		Aug. 31, 2013 USD ($) $ / shares		May. 31, 2015 USD ($) $ / shares shares	May. 31, 2014 USD ($) $ / shares shares	May. 31, 2013 USD ($) $ / shares shares	May. 31, 2012 USD ($)
Advertising [Abstract]
Advertising and promotion expenses																	$ 403	$ 407	$ 424
Business Realignment Costs [Abstract]
Business Realignment Costs																			560
Business Realignment Costs, Net Of Tax																			$ 353
Business Realignment Costs, Diluted EPS Impact | $ / shares																			$ 1.11
Business Realignment Costs Paid																		$ 300	$ 180
Number of Employees Accepted Voluntary Buyout																		3,600
Percent Employees Departed May 31, 2013																			40.00%
Percent Employees Departed Throughout 2014																		35.00%
Percent Employees Departed on May 31, 2014																		25.00%
Capitalized Interest [Abstract]
Interest Costs Capitalized																	$ 37	$ 29	$ 45
Dividends Declared [Abstract]
Dividends Payable, Date Declared																	Jun. 08, 2015
Dividends Payable Amount Per Share | $ / shares	$ 0.25																$ 0.25
Dividends Payable, Date Paid																	Jul. 02, 2015
Dividends Payable, Date Of Record																	Jun. 18, 2015
Impairment of Long Lived Assets [Abstract]
Asset impairments Diluted EPS impact | $ / shares																	$ 0.61		$ 0.20
Asset impairments, net of tax																	$ 175		$ 63
Number of Impaired Airbus A310-200 Aircraft																			2
Number of Impaired Airbus A310-300 Aircraft	4																4		3
Number of Impaired Airbus A300-600 Aircraft	3																3
Number of Impaired Boeing MD10-10 Aircraft	1																1		5
Number of Impaired Boeing MD11 Aircraft	7																7
Number of Impaired Airbus A300-600 Aircraft Engines	3																3
Number of Impaired Boeing MD10-10 Aircraft Engines	3																3		15
Number of Impaired Boeing MD11 Aircraft Engines	12																12
Number of Impaired Airbus 310-200 Aircraft Engines																			4
Number of Impaired Airbus A310-300 Aircraft Engines	3																3		2
Number of Idle Aircraft	1																1
Aircraft Idle Term																	2 months
Asset impairments																	$ 276
Asset impairment non-cash																	246		$ 100
Pension And Postretirement Healthcare Plans Equity Impact [Abstract]
MTM Accounting Cumulative Effect on Retained Earnings																				$ 8,900
OPERATING EXPENSES:
Salaries and employee benefits																	17,110	16,171	16,055
Retirement plans mark-to-market adjustment																	2,190	15	(1,368)
Operating income	$ (1,321)	[1]	$ 1,038	[1]	$ 1,088	[1]	$ 1,062	[1]	$ 1,264	[1]	$ 737	[1]	$ 923	[1]	$ 891	[1]	1,867	3,815	4,434
Income Before Income Taxes																	1,627	3,658	4,338
Provision for Income Taxes																	577	1,334	1,622
Net income	$ (895)	[1]	$ 628	[1]	$ 663	[1]	$ 653	[1]	$ 780	[1]	$ 437	[1]	$ 559	[1]	$ 548	[1]	$ 1,050	$ 2,324	$ 2,716
Basic earnings per common share | $ / shares	$ (3.16)	[2]	$ 2.21	[2]	$ 2.34	[2]	$ 2.29	[2]	$ 2.66	[2]	$ 1.44	[2]	$ 1.77	[2]	$ 1.73	[2]	$ 3.70	$ 7.56	$ 8.61
Diluted earnings per common share | $ / shares	$ (3.16)	[2]	$ 2.18	[2]	$ 2.31	[2]	$ 2.26	[2]	$ 2.62	[2]	$ 1.42	[2]	$ 1.75	[2]	$ 1.72	[2]	$ 3.65	$ 7.48	$ 8.55
Consolidated Statements of Comprehensive Income
Net income	$ (895)	[1]	$ 628	[1]	$ 663	[1]	$ 653	[1]	$ 780	[1]	$ 437	[1]	$ 559	[1]	$ 548	[1]	$ 1,050	$ 2,324	$ 2,716
Amortization of prior service credit and other, net of tax																		76	63
CONSOLIDATED BALANCE SHEETS
Retained earnings	16,900								16,229								16,900	16,229
Accumulated other comprehensive income	172								506								172	506	607
Operating Activities:
Net income	(895)	[1]	$ 628	[1]	$ 663	[1]	$ 653	[1]	780	[1]	$ 437	[1]	$ 559	[1]	$ 548	[1]	1,050	2,324	2,716
Deferred income taxes and other noncash items																	(572)	339	734
Retirement plans MTM adjustment																	2,190	15	(1,368)
Property And Equipment [Line Items]
Net property and equipment	$ 20,875								19,550								20,875	19,550
Depreciation expense, excluding gains and losses on sales of property and equipment																	$ 2,600	2,600	$ 2,300
Depreciable Life Range For Majority Of Aircraft Costs																	15 to 30
Number of Aircraft With Shortened Depreciable Lives	23																23		76	54
Number of Aircraft Engines With Shortened Depreciable Lives	57																57
Incremental Depreciation Expense																		74	$ 69
Balance Sheet reclassification of vehicles									1,100									1,100
Balance Sheet reclassification of facilities and other									72									$ 72
Treasury Shares [Abstract]
Treasury Stock Acquired, Average Cost Per Share | $ / shares																	$ 154.03	$ 131.83
Purchase of treasury stock																	$ 1,254	$ 4,857	$ 246
Stock Repurchase Program, Number Of Shares Authorized To Be Repurchased | shares	15,000,000																15,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased | shares	12,200,000																12,200,000
Treasury Stock Shares Acquired | shares																	8,100,000	36,800,000	2,700,000
Wide Body Aircraft And Related Equipment [Member]
Property And Equipment [Line Items]
Depreciable lives range																	15 to 30 years
Net property and equipment	$ 7,548								7,223								$ 7,548	$ 7,223
Narrow Body And Feeder Aircraft And Related Equipment [Member]
Property And Equipment [Line Items]
Depreciable lives range																	5 to 18 years
Net property and equipment	2,943								2,639								$ 2,943	2,639
Package Handling And Ground Support Equipment [Member]
Property And Equipment [Line Items]
Depreciable lives range																	3 to 30 years
Net property and equipment	2,410								2,024								$ 2,410	2,024
Vehicles [Member]
Property And Equipment [Line Items]
Depreciable lives range																	3 to 15 years
Net property and equipment	2,717								2,615								$ 2,717	2,615
Computer And Electronic Equipment [Member]
Property And Equipment [Line Items]
Depreciable lives range																	2 to 10 years
Net property and equipment	866								923								$ 866	923
Facilities And Other Property [Member]
Property And Equipment [Line Items]
Depreciable lives range																	2 to 40 years
Net property and equipment	$ 4,391								4,126								$ 4,391	4,126
Previously Reported [Member]
OPERATING EXPENSES:
Salaries and employee benefits																		16,555	$ 16,570
Operating income																		3,446	2,551
Income Before Income Taxes																		3,289	2,455
Provision for Income Taxes																		1,192	894
Net income																		$ 2,097	$ 1,561
Basic earnings per common share | $ / shares																		$ 6.82	$ 4.95
Diluted earnings per common share | $ / shares																		$ 6.75	$ 4.91
Consolidated Statements of Comprehensive Income
Net income																		$ 2,097	$ 1,561
Amortization of prior service credit and other, net of tax																		151	1,092
CONSOLIDATED BALANCE SHEETS
Retained earnings									20,429									20,429	18,519
Accumulated other comprehensive income									(3,694)									(3,694)	(3,820)
Operating Activities:
Net income																		2,097	1,561
Deferred income taxes and other noncash items																		581	521
Adjusted [Member]
OPERATING EXPENSES:
Salaries and employee benefits																		16,171	16,055
Retirement plans mark-to-market adjustment																		15	(1,368)
Operating income																		3,815	4,434
Income Before Income Taxes																		3,658	4,338
Provision for Income Taxes																		1,334	1,622
Net income																		$ 2,324	$ 2,716
Basic earnings per common share | $ / shares																		$ 7.56	$ 8.61
Diluted earnings per common share | $ / shares																		$ 7.48	$ 8.55
Consolidated Statements of Comprehensive Income
Net income																		$ 2,324	$ 2,716
Amortization of prior service credit and other, net of tax																		(76)	(63)
CONSOLIDATED BALANCE SHEETS
Retained earnings									16,229									16,229	14,092
Accumulated other comprehensive income									506									506	607
Operating Activities:
Net income																		2,324	2,716
Deferred income taxes and other noncash items																		339	734
Retirement plans MTM adjustment																		15	(1,368)
Effect of Change [Member]
OPERATING EXPENSES:
Salaries and employee benefits																		(384)	(515)
Retirement plans mark-to-market adjustment																		15	(1,368)
Operating income																		369	1,883
Income Before Income Taxes																		369	1,883
Provision for Income Taxes																		142	728
Net income																		$ 227	$ 1,155
Basic earnings per common share | $ / shares																		$ 0.74	$ 3.66
Diluted earnings per common share | $ / shares																		$ 0.73	$ 3.64
Consolidated Statements of Comprehensive Income
Net income																		$ 227	$ 1,155
Amortization of prior service credit and other, net of tax																		(227)	(1,155)
CONSOLIDATED BALANCE SHEETS
Retained earnings									(4,200)									(4,200)	(4,427)
Accumulated other comprehensive income									$ 4,200									4,200	4,427
Operating Activities:
Net income																		227	1,155
Deferred income taxes and other noncash items																		(242)	213
Retirement plans MTM adjustment																		$ 15	$ (1,368)

[1] The fourth quarter of 2015 includes a $2.2 billion retirement plans mark-to-market loss, $276 million of impairment and related charges resulting from the decision to permanently retire and adjust the retirement schedule of certain aircraft and related engines at FedEx Express and a $197 million reserve increase due to the settlement of a legal matter at FedEx Ground. In addition, the first, second and third quarters of 2015 and all quarters of 2014 have been recast to conform to the current year presentation reflecting the retirement plans accounting changes discussed further in Note 1 and Note 13 and that were included in our June 12, 2015, Form 8-K filing with the Securities and Exchange Commission.

[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.