Restructuring Charges - Narrative (Details) $ in Millions	9 Months Ended	18 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)
American Rescue Plan Act of 2021, Benefit Coverage Continuation
Restructuring Cost and Reserve [Line Items]
Liability for COBRA	$ 35	$ 35
Property-Level Programs
Restructuring Cost and Reserve [Line Items]
Restructuring charges		258
U.S. & Canada | Above-Property and Property-Level Programs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	7	$ 262
Reimbursed expenses | Property-Level Programs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8
Restructuring and merger-related charges | Property-Level Programs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 1