POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - RECONCILIATION OF BENEFIT PLANS RECOGNIZED IN THE BALANCE SHEET (Details) - USD ($) $ in Millions	Jun. 30, 2017	Jun. 30, 2016
Pension Plan
CLASSIFICATION OF NET AMOUNT RECOGNIZED
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	$ 196	$ 180
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(40)	(33)
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(5,487)	(6,761)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(5,331)	(6,614)
AMOUNTS RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (AOCI)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	4,548	6,088
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	245	270
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	4,793	6,358
Other Retiree Benefits
CLASSIFICATION OF NET AMOUNT RECOGNIZED
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	0	0
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(23)	(21)
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(1,333)	(1,808)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(1,356)	(1,829)
AMOUNTS RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (AOCI)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	1,819	2,247
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	(293)	(334)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	$ 1,526	$ 1,913