POSTRETIREMENT BENEFITS AND EMPLOYEE STOCK OWNERSHIP PLAN - TARGET AND ACTUAL ASSET ALLOCATION (Details)	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Pension Plan
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	100.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%	100.00%
Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	100.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	100.00%	100.00%
Cash and Cash Equivalents | Pension Plan
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	2.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	2.00%	2.00%
Cash and Cash Equivalents | Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	2.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	1.00%	2.00%
Debt Securities | Pension Plan
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	57.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	53.00%	55.00%
Debt Securities | Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	3.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	4.00%	4.00%
Equity Securities | Pension Plan
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	41.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	45.00%	43.00%
Equity Securities | Other Retiree Benefits
Target Asset Allocation
Defined Benefit Plan, Target Plan Asset Allocations	95.00%
Actual Asset Allocation
Defined Benefit Plan, Actual Plan Asset Allocations	95.00%	94.00%