Retirement Plans - Schedule of Retirement Plan Costs (Details) - USD ($) $ in Millions	3 Months Ended
Aug. 31, 2024	Aug. 31, 2023
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Defined benefit pension plans	$ 70	$ 91
Defined contribution plans	287	240
Postretirement healthcare plans	22	23
Retirement plans costs	$ 379	$ 354

The total amount of net periodic benefit cost for defined benefit postretirement healthcare plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain or loss, prior service cost or credit, transition asset or obligation, and gain or loss due to settlements or curtailments.

No definition available.

Name:	fdx_PostretirementHealthcarePlansNetPeriodicBenefitCost
Namespace Prefix:	fdx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration