RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - SCHEDULE OF DERIVATIVE INSTRUMENTS (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jun. 30, 2019
Derivative [Line Items]
Notional Amount	$ 17,029	$ 17,309
Derivative Asset	389	239
Derivative Liability	(65)	(45)
Derivatives in Fair Value Hedging Relationships | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	7,524	7,721
Derivative Asset	266	177
Derivative Liability	0	(1)
Derivatives in Net Investment Hedging Relationships | Foreign Exchange Contract
Derivative [Line Items]
Notional Amount	3,309	3,157
Derivative Asset	104	35
Derivative Liability	(16)	(24)
Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	10,833	10,878
Derivative Asset	370	212
Derivative Liability	(16)	(25)
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Notional Amount	6,196	6,431
Derivative Asset	19	27
Derivative Liability	$ (49)	$ (20)