Restructuring Charges - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 305
North America
Restructuring Cost and Reserve [Line Items]
Restructuring charges	215
Global Above-Property Positions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	109
Property-Level and Owned and Leased Properties
Restructuring Cost and Reserve [Line Items]
Restructuring charges	196
Restructuring and merger-related charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges	46
Restructuring and merger-related charges | Global Above-Property Positions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	37
Restructuring and merger-related charges | Property-Level and Owned and Leased Properties
Restructuring Cost and Reserve [Line Items]
Restructuring charges	9
Reimbursed expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	259
Reimbursed expenses | Global Above-Property Positions
Restructuring Cost and Reserve [Line Items]
Restructuring charges	72
Reimbursed expenses | Property-Level and Owned and Leased Properties
Restructuring Cost and Reserve [Line Items]
Restructuring charges	187
Minimum | Global Above-Property Positions
Restructuring Cost and Reserve [Line Items]
Total expected charges	115
Maximum | Global Above-Property Positions
Restructuring Cost and Reserve [Line Items]
Total expected charges	$ 125