POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - TOTAL BENEFIT PAYMENTS EXPECTED TO BE PAID (Details) $ in Millions	Jun. 30, 2019 USD ($)
Pension Plan
EXPECTED BENEFIT PAYMENTS
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	$ 518
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	536
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	549
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	574
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	583
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	3,220
Other Retiree Benefits
EXPECTED BENEFIT PAYMENTS
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months	191
Defined Benefit Plan, Expected Future Benefit Payment, Year Two	203
Defined Benefit Plan, Expected Future Benefit Payment, Year Three	214
Defined Benefit Plan, Expected Future Benefit Payment, Year Four	224
Defined Benefit Plan, Expected Future Benefit Payment, Year Five	233
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter	$ 1,283