BUSINESS SEGMENTS - Capital Expenditures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Capital expenditures	$ 653	$ 556	$ 240
Total segment | North American Full-Service
Segment Reporting Information [Line Items]
Capital expenditures	270	290	21
Total segment | North American Limited-Service
Segment Reporting Information [Line Items]
Capital expenditures	17	15	10
Total segment | Asia Pacific
Segment Reporting Information [Line Items]
Capital expenditures	2	6	12
Total segment | Other International
Segment Reporting Information [Line Items]
Capital expenditures	164	40	42
Unallocated corporate
Segment Reporting Information [Line Items]
Capital expenditures	$ 200	$ 205	$ 155