ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - CHANGES IN AOCI AND RECLASSIFICATION OUT OF AOCI (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Jun. 30, 2020
Accumulated Other Comprehensive Income/(Loss)		$ (15,489)		$ (15,489)		$ (16,165)
OCI before Reclassifications	[1]			431
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]			251
Other Comprehensive Income (Loss), Net of Tax		(399)	$ (985)	682	$ (997)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest				6
Accumulated Other Comprehensive Income (Loss), Derivative Qualifying as Hedge, Excluded Component, Including Portion Attributable to Noncontrolling Interest [Member]
Other Comprehensive Income (Loss) before Reclassifications, Tax	[1]			(206)
Reclassification from AOCI, Current Period, Tax	[2]			0
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Including Noncontrolling Interest [Member]
Other Comprehensive Income (Loss) before Reclassifications, Tax	[1]			0
Accumulated Other Comprehensive Income/(Loss)		18		18		(1)
OCI before Reclassifications	[1]			17
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]			2
Other Comprehensive Income (Loss), Net of Tax				19
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest				0
Reclassification from AOCI, Current Period, Tax	[2]			0
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Including Portion Attributable to Noncontrolling Interest
Other Comprehensive Income (Loss) before Reclassifications, Tax	[1]			(65)
Accumulated Other Comprehensive Income/(Loss)		(4,325)		(4,325)		(4,350)
OCI before Reclassifications	[1]			(225)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]			249
Other Comprehensive Income (Loss), Net of Tax				24
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest				(1)
Reclassification from AOCI, Current Period, Tax	[2]			77
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income/(Loss)		$ (11,182)		(11,182)		$ (11,814)
OCI before Reclassifications	[1]			639
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]			0
Other Comprehensive Income (Loss), Net of Tax				639
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest				$ 7

[1] Net of tax expense/(benefit) of $0, $(65) and $(206) for gains/losses on investment securities, postretirement benefit items and foreign currency translation, respectively.

[2] Net of tax expense/(benefit) of $0, $77 and $0 for gains/losses on investment securities, postretirement benefit items and foreign currency translation, respectively.