RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - SCHEDULE OF DERIVATIVE INSTRUMENTS (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jun. 30, 2019
Derivative [Line Items]
Notional Amount	$ 16,182	$ 17,309
Derivative Asset	190	239
Derivative Liability	(47)	(45)
Derivatives in Fair Value Hedging Relationships | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	7,097	7,721
Derivative Asset	128	177
Derivative Liability	(5)	(1)
Derivatives in Net Investment Hedging Relationships | Foreign Exchange Contract
Derivative [Line Items]
Notional Amount	3,291	3,157
Derivative Asset	13	35
Derivative Liability	(25)	(24)
Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	10,388	10,878
Derivative Asset	141	212
Derivative Liability	(30)	(25)
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Notional Amount	5,794	6,431
Derivative Asset	49	27
Derivative Liability	$ (17)	$ (20)