INTANGIBLE ASSETS AND GOODWILL - Carrying Amount of Goodwill (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 9,207
Foreign currency translation	(168)
Ending balance	9,039
North American Full-Service
Goodwill [Roll Forward]
Beginning balance	3,585
Foreign currency translation	(19)
Ending balance	3,566
North American Limited-Service
Goodwill [Roll Forward]
Beginning balance	1,769
Foreign currency translation	(14)
Ending balance	1,755
Asia Pacific
Goodwill [Roll Forward]
Beginning balance	1,928
Foreign currency translation	(66)
Ending balance	1,862
Other International
Goodwill [Roll Forward]
Beginning balance	1,925
Foreign currency translation	(69)
Ending balance	$ 1,856