RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - DERIVATIVE NOTIONAL AMOUNTS AND FAIR VALUE (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Derivative [Line Items]
Notional Amount	$ 13,430	$ 13,793
Derivative Asset	188	196
Derivative Liability	(116)	(184)
Foreign Exchange Contract
Derivative [Line Items]
Notional Amount	7,025	7,358
Derivative Asset	49	30
Derivative Liability	29	56
Derivatives in Fair Value Hedging Relationships | Interest Rate Contracts
Derivative [Line Items]
Notional Amount	4,550	4,587
Derivative Asset	118	125
Derivative Liability	28	53
Derivatives in Net Investment Hedging Relationships
Derivative [Line Items]
Notional Amount	1,855	1,848
Derivative Asset	21	41
Derivative Liability	59	75
Designated as Hedging Instrument
Derivative [Line Items]
Notional Amount	6,405	6,435
Derivative Asset	139	166
Derivative Liability	$ 87	$ 128