LEASES - Assets and Liabilities of Lessee (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019
Operating leases
Operating lease right-of-use assets	$ 608	$ 595	$ 513
Accounts payable and accrued liabilities	101
Operating lease liabilities	510	$ 496	$ 417
Total operating lease liabilities	611
Finance leases
Property, plant and equipment, at cost	63
Accumulated depreciation	(19)
Property, plant and equipment, net	44
Current maturities of long-term debt and finance lease obligations	0
Long-term debt and finance lease obligations	54
Total finance lease liabilities	$ 54