POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - TARGET AND ACTUAL ASSET ALLOCATION (Details)	Jun. 30, 2020	Jun. 30, 2019
Pension Plan
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	100.00%	100.00%
Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	100.00%	100.00%
Cash and Cash Equivalents | Pension Plan
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	1.00%	1.00%
Cash and Cash Equivalents | Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	3.00%	3.00%
Debt Securities | Pension Plan
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	67.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	66.00%	63.00%
Debt Securities | Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	2.00%	2.00%
Equity Securities | Pension Plan
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	33.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	33.00%	36.00%
Equity Securities | Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	95.00%
Actual Asset Allocation
Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage	95.00%	95.00%