POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - PENSION PLANS WITH ACCUMULATED AND PROJECTED BENEFIT OBLIGATIONS IN EXCESS OF PLAN ASSETS (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019
Accumulated Benefit Obligation Exceeds the Fair Value of Plan Assets
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	$ 12,095	$ 11,604
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation	11,196	10,711
Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets	5,994	6,026
Projected Benefit Obligation Exceeds the Fair Value of Plan Assets
Defined Benefit Plan, Pension Plans With Projected Benefit Obligations In Excess Of Plan Assets, Aggregate Projected Benefit Obligation	17,635	16,304
Defined Benefit Plan, Pension Plans With Projected Benefit Obligations In Excess Of Plan Assets, Aggregate Accumulated Benefit Obligation	16,377	15,096
Defined Benefit Plan, Pension Plans With Projected Benefit Obligations In Excess Of Plan Assets, Aggregate Fair Value Of Plan Assets	$ 11,347	$ 10,630