LEASES - Total Lease Costs and Other Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)
Finance lease cost:
Amortization of right-of-use assets	$ 3	$ 9
Interest on lease liabilities	0	0
Operating lease cost	150	383
Short-term lease cost	5	20
Variable lease cost	41	133
Total	$ 199	545
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases		350
Financing cash flows from finance leases		10
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 216
Weighted-average remaining lease term – finance leases	2 years	2 years
Weighted-average remaining lease term – operating leases	11 years	11 years
Weighted-average discount rate – finance leases	2.70%	2.70%
Weighted-average discount rate – operating leases	2.50%	2.50%