POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - RECONCILIATION OF BENEFIT PLANS RECOGNIZED IN THE BALANCE SHEET (Details) - USD ($) $ in Millions	Jun. 30, 2016	Jun. 30, 2015
Pension Plan
CLASSIFICATION OF NET AMOUNT RECOGNIZED
Defined Benefit Plan, Assets for Plan Benefits, Noncurrent	$ 180	$ 276
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities	(33)	(39)
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(6,761)	(5,247)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(6,614)	(5,010)
AMOUNTS RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (AOCI)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	6,088	4,488
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	270	300
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	6,358	4,788
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	(21)	(20)
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	(1,808)	(1,414)
Defined Benefit Plan, Amounts Recognized in Balance Sheet	(1,829)	(1,434)
AMOUNTS RECOGNIZED IN ACCUMULATED OTHER COMPREHENSIVE INCOME (AOCI)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax	2,247	1,731
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax	(334)	(346)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	$ 1,913	$ 1,385