POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - TOTAL BENEFIT PAYMENTS EXPECTED TO BE PAID (Details) $ in Millions	Jun. 30, 2020 USD ($)
Pension Plan
EXPECTED BENEFIT PAYMENTS
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 559
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	534
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	556
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	573
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	608
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	3,258
Other Retiree Benefits
EXPECTED BENEFIT PAYMENTS
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	196
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	205
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	214
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	221
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	225
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 1,199