ACCUMULATED OTHER COMPREHENSIVE INCOME - STATEMENT OF AOCI (Details) - USD ($) $ in Millions		12 Months Ended
		Jun. 30, 2019		Jun. 30, 2018		Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (14,749)		$ (14,632)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(89)	[1]	(372)	[2]
Adoption of New Accounting Standard_Reclass from AOCI to Retained Earnings	[3]	(326)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		229	[4]	253	[5]
Other Comprehensive Income (Loss), Net of Tax		140		(119)		$ 1,275
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest		1		(2)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(14,936)		(14,749)		(14,632)
Accumulated Net Investment Gain (Loss) Attributable to Parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(173)		(25)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		167	[1]	(141)	[2]
Adoption of New Accounting Standard_Reclass from AOCI to Retained Earnings	[3]	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		17	[4]	(7)	[5]
Other Comprehensive Income (Loss), Net of Tax		184		(148)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest				0
Accumulated Other Comprehensive Income (Loss), Net of Tax		11		(173)		(25)
Pension Plan
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(4,058)		(4,397)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(43)	[1]	74	[2]
Adoption of New Accounting Standard_Reclass from AOCI to Retained Earnings	[3]	(308)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		212	[4]	260	[5]
Other Comprehensive Income (Loss), Net of Tax		169		334
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest		1		(5)
Accumulated Other Comprehensive Income (Loss), Net of Tax		(4,198)		(4,058)		(4,397)
Foreign Currency Gain (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated Other Comprehensive Income (Loss), Net of Tax		(10,518)		(10,210)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax		(213)	[1]	(305)	[2]
Adoption of New Accounting Standard_Reclass from AOCI to Retained Earnings	[3]	(18)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax		0	[4]	0	[5]
Other Comprehensive Income (Loss), Net of Tax		(213)		(305)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest		0		3
Accumulated Other Comprehensive Income (Loss), Net of Tax		$ (10,749)		$ (10,518)		$ (10,210)

[1] Net of tax (benefit) / expense of $0, $(44) and $78 for gains/losses on investment securities, pension and other retiree benefit items and foreign currency translation, respectively, for the period ended June 30, 2019.

[2] Net of tax (benefit) / expense of $0, $(23) and $(279) for gains/losses on investment securities, pension and other retiree benefit items and foreign currency translation, respectively, for the period ended June 30, 2018.

[3] Adjustment made to early adopt ASU 2018-02: "Reclassification of Certain Effects from Accumulated Other Comprehensive Income," as discussed in Note 1.

[4] Net of tax (benefit) / expense of $0, $66, $0 for gains/losses on investment securities, pension and other retiree benefit items and foreign currency translation, respectively, for the period ended June 30, 2019.

[5] Net of tax (benefit) / expense of $0, $91 and $0 for gains/losses on investment securities, pension and other retiree benefit items and foreign currency translation, respectively, for the period ended June 30, 2018.