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Assets and liabilities sold and held for sale - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Assets and liabilities classified as held for sale [line items]      
Gain on Disposal of Assets and Liabilities Classified as Held For Sale $ 16 $ 21 $ 14
Proceeds From Disposal Of Noncurrent Assets 1    
EMEAA [member]      
Assets and liabilities classified as held for sale [line items]      
Gain on Disposal of Assets and Liabilities Classified as Held For Sale (3)    
Holiday Inn Melbourne Airport [member] | EMEAA [member]      
Assets and liabilities classified as held for sale [line items]      
Gain on Disposal of Assets and Liabilities Classified as Held For Sale 3    
Proceeds From Disposal Of Noncurrent Assets $ 2