RISK MANAGEMENT ACTIVITIES AND FAIR VALUE MEASUREMENTS - ASSETS MEASURED AT FAIR VALUE ON A RECURRING BASIS (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jun. 30, 2018
Fair Value Asset	$ 8,584	$ 9,422
U.S. Government Securities
Fair Value Asset	5,177	5,544
Corporate Bond Securities
Fair Value Asset	3,244	3,737
Other Investments
Fair Value Asset	$ 163	$ 141

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant