LEASES - Components of Operating Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Leases [Abstract]
Operating lease cost	$ 42	$ 123
Short-term lease cost	2	8
Variable lease cost	2	6
Sublease income	(1)	(3)
Total	$ 45	$ 134