ACCUMULATED OTHER COMPREHENSIVE INCOME - STATEMENT OF AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2023		Jun. 30, 2022		Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (12,189)		$ (13,744)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(57)	[1]	1,350	[2]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	19	[3]	197	[4]
Other Comprehensive Income (Loss), Net of Tax	(38)		1,547		$ 2,425
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	(7)		(8)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(12,220)		(12,189)		(13,744)
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Including Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	20		15
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(7)	[1]	4	[2]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	[3]	1	[4]
Other Comprehensive Income (Loss), Net of Tax	(7)		5
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	0		0
Accumulated Other Comprehensive Income (Loss), Net of Tax	13		20		15
Other Comprehensive Income (Loss) before Reclassifications, Tax	(2)		1
Reclassification from AOCI, Current Period, Tax	0		0
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	27		(2,963)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	21	[1]	2,797	[2]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	19	[3]	195	[4]
Other Comprehensive Income (Loss), Net of Tax	40		2,992
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	0		2
Accumulated Other Comprehensive Income (Loss), Net of Tax	67		27		(2,963)
Other Comprehensive Income (Loss) before Reclassifications, Tax	1		953
Reclassification from AOCI, Current Period, Tax	8		69
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(12,236)		(10,796)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(71)	[1]	(1,451)	[2]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	[3]	1	[4]
Other Comprehensive Income (Loss), Net of Tax	(71)		(1,450)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	(7)		(10)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(12,300)		(12,236)		$ (10,796)
Accumulated Other Comprehensive Income (Loss), Derivative Qualifying as Hedge, Excluded Component, Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Other Comprehensive Income (Loss) before Reclassifications, Tax	(197)		515
Reclassification from AOCI, Current Period, Tax	$ 0		$ 0

[1] Net of tax (benefit)/expense of $(2), $1 and $(197) for gains/losses on investment securities, postretirement benefit plans and foreign currency translation, respectively, for the period ended June 30, 2023. Income tax effects within foreign currency translation include impacts from items such as net investment hedge transactions.

[2] Net of tax (benefit)/expense of $1, $953 and $515 for gains/losses on investment securities, postretirement benefit plans and foreign currency translation, respectively, for the period ended June 30, 2022. Income tax effects within foreign currency translation include impacts from items such as net investment hedge transactions.

[3] Net of tax (benefit)/expense of $0, $8 and $0 for gains/losses on investment securities, postretirement benefit plans and foreign currency translation, respectively, for the period ended June 30, 2023.

[4] Net of tax (benefit)/expense of $0, $69 and $0 for gains/losses on investment securities, postretirement benefit plans and foreign currency translation, respectively, for the period ended June 30, 2022.