LEASES MATURITIES OF LEASE LIABILITIES (Details) $ in Millions	Mar. 31, 2019 USD ($)
Aircraft [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	$ 191
Lessee, Operating Lease, Liability, Payments, Due Year Two	228
Lessee, Operating Lease, Liability, Payments, Due Year Three	189
Lessee, Operating Lease, Liability, Payments, Due Year Four	164
Lessee, Operating Lease, Liability, Payments, Due Year Five	110
Lessee, Operating Lease, Liability, Payments, Due after Year Five	287
Lessee, Operating Lease, Liability, Payments, Due	1,169
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(150)
Operating Lease, Liability	1,019
CPA Aircraft [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	60
Lessee, Operating Lease, Liability, Payments, Due Year Two	79
Lessee, Operating Lease, Liability, Payments, Due Year Three	79
Lessee, Operating Lease, Liability, Payments, Due Year Four	79
Lessee, Operating Lease, Liability, Payments, Due Year Five	79
Lessee, Operating Lease, Liability, Payments, Due after Year Five	408
Lessee, Operating Lease, Liability, Payments, Due	784
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(148)
Operating Lease, Liability	636
Airport Facilities [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	2
Lessee, Operating Lease, Liability, Payments, Due Year Two	3
Lessee, Operating Lease, Liability, Payments, Due Year Three	3
Lessee, Operating Lease, Liability, Payments, Due Year Four	2
Lessee, Operating Lease, Liability, Payments, Due Year Five	2
Lessee, Operating Lease, Liability, Payments, Due after Year Five	12
Lessee, Operating Lease, Liability, Payments, Due	24
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(5)
Operating Lease, Liability	19
Corporate real estate [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year	6
Lessee, Operating Lease, Liability, Payments, Due Year Two	7
Lessee, Operating Lease, Liability, Payments, Due Year Three	6
Lessee, Operating Lease, Liability, Payments, Due Year Four	3
Lessee, Operating Lease, Liability, Payments, Due Year Five	2
Lessee, Operating Lease, Liability, Payments, Due after Year Five	73
Lessee, Operating Lease, Liability, Payments, Due	97
Lessee, Operating Lease, Liability, Undiscounted Excess Amount	(53)
Operating Lease, Liability	$ 44