LEASES - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Leases not yet commenced, amount	$ 11
Weighted average remaining operating lease term	6 years
Operating lease liability	$ 411	$ 439
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	12 years