Retirement Plans - Schedule of Retirement Plan Costs (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Nov. 30, 2019	Nov. 30, 2018	Nov. 30, 2019	Nov. 30, 2018
Pension And Other Postretirement Benefit Expense [Abstract]
Defined benefit pension plans, net	$ 37	$ 29	$ 74	$ 57
Defined contribution plans	136	133	278	277
Postretirement healthcare plans	21	18	43	37
Retirement plans costs	$ 194	$ 180	$ 395	$ 371

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