LEASES - Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2019
Lessee, Lease, Description [Line Items]
Operating lease cost (1)	$ 17	$ 20	$ 37
Variable operating lease cost	2		5
Sublease income	(4)		(8)
Short-term lease expense	$ 1		$ 2
As Previously Reported
Lessee, Lease, Description [Line Items]
Operating lease cost (1)		$ 53