POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - COMPONENTS OF NET PERIODIC BENEFIT COST (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2020		Jun. 30, 2019		Jun. 30, 2018
Pension Plan
AMOUNTS RECOGNIZED IN NET PERIODIC BENEFIT COST
Defined Benefit Plan, Service Cost	$ 247	[1]	$ 259	[1]	$ 280
Defined Benefit Plan, Interest Cost	276	[1]	339	[1]	348
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(740)		(732)		(751)
Defined Benefit Plan, Amortization of Gain (Loss)	340		225		295
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	25		26		28
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	7		9		0
Defined Benefit Plan, Other Cost (Credit)	11		13		8
Defined Benefit Plan Gross Periodic Benefit Cost	166		139		208
Employee Stock Ownership Plan (ESOP), Dividends on ESOP Preferred Stock	0		0		0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	166		139		208
CHANGE IN PLAN ASSETS AND BENEFIT OBLIGATIONS RECOGNIZED IN AOCI
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	1,027		1,580
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	3		9
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(340)		(225)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	(25)		(26)
Other Comprehensive Income Defined Benefit Plan Settlement And Curtailment Cost Before Tax	(7)		(9)
Other Comprehensive Income, Defined Benefit Plan, Currency Translation and Other, Before Tax	(74)		(84)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	584		1,245
Defined Benefit Plans, Amount Recognized In Periodic Benefit Cost And Accumulated Other Comprehensive Income	750		1,384
Other Retiree Benefits
AMOUNTS RECOGNIZED IN NET PERIODIC BENEFIT COST
Defined Benefit Plan, Service Cost	100	[2]	101	[2]	112
Defined Benefit Plan, Interest Cost	160	[2]	187	[2]	177
Defined Benefit Plan, Expected Return (Loss) on Plan Assets	(473)		(447)		(451)
Defined Benefit Plan, Amortization of Gain (Loss)	68		66		69
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(48)		(48)		(41)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment	0		0		0
Defined Benefit Plan, Other Cost (Credit)	2		8		7
Defined Benefit Plan Gross Periodic Benefit Cost	(191)		(133)		(127)
Employee Stock Ownership Plan (ESOP), Dividends on ESOP Preferred Stock	(19)		(28)		(37)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	(210)		(161)		$ (164)
CHANGE IN PLAN ASSETS AND BENEFIT OBLIGATIONS RECOGNIZED IN AOCI
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	(207)		(1,434)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax	(136)		0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	(68)		(66)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	48		48
Other Comprehensive Income Defined Benefit Plan Settlement And Curtailment Cost Before Tax	0		0
Other Comprehensive Income, Defined Benefit Plan, Currency Translation and Other, Before Tax	(26)		14
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	(389)		(1,438)
Defined Benefit Plans, Amount Recognized In Periodic Benefit Cost And Accumulated Other Comprehensive Income	$ (599)		$ (1,599)

[1] Primarily non-U.S.-based defined benefit retirement plans.

[2] Primarily U.S.-based other postretirement benefit plans.