LEASES LEASES - OPERATING LEASE ASSETS (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 1,696	$ 0
Aircraft [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	1,012
CPA Aircraft [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	622
Airport Facilities [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	19
Corporate real estate [Member]
Lessee, Lease, Description [Line Items]
Operating Lease, Right-of-Use Asset	$ 43