ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - CHANGES IN AOCI AND RECLASSIFICATION OUT OF AOCI (Details) - USD ($) $ in Millions		3 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020
Accumulated Other Comprehensive Income/(Loss)		$ (15,881)		$ (16,165)
OCI before Reclassifications	[1]	206
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]	83
Other Comprehensive Income (Loss), Net of Tax		289	$ (366)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest		5
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]	(195)
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)		5		(1)
OCI before Reclassifications	[1]	6
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]	0
Other Comprehensive Income (Loss), Net of Tax		6
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]	(42)
Accumulated Other Comprehensive Income/(Loss)		(4,419)		(4,350)
OCI before Reclassifications	[1]	(152)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]	83
Other Comprehensive Income (Loss), Net of Tax		(69)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest		0
Reclassification from AOCI, Current Period, Tax	[2]	24
Accumulated Foreign Currency Adjustment Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income/(Loss)		(11,467)		$ (11,814)
OCI before Reclassifications	[1]	352
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	[2]	0
Other Comprehensive Income (Loss), Net of Tax		352
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest		$ 5

[1] Net of tax expense/(benefit) of $0, $(42) and $(195) for gains/losses on investment securities, postretirement benefit items and foreign currency translation, respectively.

[2] Net of tax expense/(benefit) of $0, $24 and $0 for gains/losses on investment securities, postretirement benefit items and foreign currency translation, respectively.