RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - SCHEDULE OF DERIVATIVE INSTRUMENTS (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jun. 30, 2018
Derivative [Line Items]
Notional Amount	$ 13,911	$ 13,793
Derivative Asset	196	196
Derivative Liability	(38)	(184)
Derivatives in Fair Value Hedging Relationships | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	4,515	4,587
Derivative Asset	127	125
Derivative Liability	(16)	(53)
Derivatives in Net Investment Hedging Relationships
Derivative [Line Items]
Notional Amount	3,034	1,848
Derivative Asset	27	41
Derivative Liability	(8)	(75)
Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	7,549	6,435
Derivative Asset	154	166
Derivative Liability	(24)	(128)
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Notional Amount	6,362	7,358
Derivative Asset	42	30
Derivative Liability	$ (14)	$ (56)