OTHER CONTINGENCIES AND GUARANTEES (Details) - USD ($) $ in Millions	6 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2017
Loss Contingencies [Line Items]
Liability for aggregate future remediation costs	$ 27	$ 27
Letter of credit	10
Letter of credit, amount outstanding	0
Alameda County, California Matter
Loss Contingencies [Line Items]
Liability for aggregate future remediation costs	$ 14	14	$ 14
Remediation period	30 years
Maximum undiscounted costs	$ 28
Dickinson County, Michigan Matter
Loss Contingencies [Line Items]
Liability for aggregate future remediation costs	$ 11	$ 11
Remediation period	30 years
Percentage of liability for aggregate remediation and associated costs, other than legal fees	24.30%