Commitments - Schedule of Aircraft Purchase Commitments (Details)	12 Months Ended
May 31, 2021 air-craft
Schedule of Aircraft Commitments [Line Items]
2022	35
2023	33
2024	26
2025	20
2026	6
Total	120
Cessna SkyCourier 408 [Member]
Schedule of Aircraft Commitments [Line Items]
2022	9
2023	12
2024	12
2025	12
2026	5
Total	50
ATR 72-600F [Member]
Schedule of Aircraft Commitments [Line Items]
2022	9
2023	6
2024	6
2025	6
2026	1
Total	28
B767F [Member]
Schedule of Aircraft Commitments [Line Items]
2022	13
2023	13
2024	4
Total	30
B777F [Member]
Schedule of Aircraft Commitments [Line Items]
2022	4
2023	2
2024	4
2025	2
Total	12

The total number of aircraft committed to be purchased.

No definition available.

Name:	fdx_AircraftPurchaseObligation
Namespace Prefix:	fdx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of aircraft committed to be purchased with a delivery date in the fifth fiscal year.

No definition available.

Name:	fdx_AircraftPurchaseObligationWithDeliveryDueInFifthFiscalYear
Namespace Prefix:	fdx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Aircraft purchase obligation with delivery due in first fiscal year.

No definition available.

Name:	fdx_AircraftPurchaseObligationWithDeliveryDueInFirstFiscalYear
Namespace Prefix:	fdx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of aircraft committed to be purchased with a delivery date in the fourth fiscal year.

No definition available.

Name:	fdx_AircraftPurchaseObligationWithDeliveryDueInFourthFiscalYear
Namespace Prefix:	fdx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of aircraft committed to be purchased with a delivery date in the second fiscal year.

No definition available.

Name:	fdx_AircraftPurchaseObligationWithDeliveryDueInSecondFiscalYear
Namespace Prefix:	fdx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of aircraft committed to be purchased with a delivery date in the third fiscal year.

No definition available.

Name:	fdx_AircraftPurchaseObligationWithDeliveryDueInThirdFiscalYear
Namespace Prefix:	fdx_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Schedule of Aircraft Commitments [Line Items]

No definition available.

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Namespace Prefix:	fdx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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Namespace Prefix:
Data Type:	na
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Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=fdx_ATR72600FreighterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=fdx_Boeing767FreighterMember
Namespace Prefix:
Data Type:	na
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