United Parcel Service, Inc. Quarterly report [Sections 13 or 15(d)]

EMPLOYEE BENEFIT PLANS - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2026	Dec. 31, 2025
Defined Benefit Plan Disclosure [Line Items]
Multiemployer plans, payment term	36 years
Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Multi-employer plans, withdrawal obligation, fair value	$ 654	$ 662
Defined Benefit Pension Plan \| Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent
Defined Benefit Plan Disclosure [Line Items]
Multiemployer plans, withdrawal obligation, present value	9	9
Defined Benefit Pension Plan \| Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Defined Benefit Plan Disclosure [Line Items]
Multiemployer plans, withdrawal obligation, present value	790	$ 795
U.S \| Defined Benefit Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Amount contributed to company- sponsored benefit plans	434
Estimated future employer contributions to defined benefit plan, current fiscal year	693
U.S \| U.S. Postretirement Medical Benefits
Defined Benefit Plan Disclosure [Line Items]
Amount contributed to company- sponsored benefit plans	147
Estimated future employer contributions to defined benefit plan, current fiscal year	$ 40