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Share-based payments - Additional Information (Detail)
$ in Millions
12 Months Ended
Dec. 31, 2019
USD ($)
award
shares
Dec. 31, 2019
£ / shares
Dec. 31, 2018
USD ($)
award
shares
Dec. 31, 2018
£ / shares
Dec. 31, 2017
USD ($)
award
shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ $ 28   $ 27   $ 21
Weighted average share price at exercise date | £ / shares   £ 45.848   £ 45.838  
Share based payment cash-settled | $ 2   0   0
System Fund [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ 12   11   6
Administrative expenses [member] | Exceptional items [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ $ 1   $ 1   $ 2
Maximum [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   57.38      
Minimum [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   40.92      
Closing [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   £ 52.08      
Annual Performance Plan [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees | award 217,000   176,000   235,000
Annual Performance Plan one-off awards | shares 86,126   48,771   79,471
Long Term Incentive Plan [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees | award 826,313   784,119   805,045
Vesting period of share awards 3 years        
LTIP Restricted stock units [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees | award 540,000   527,000   525,000
LTIP Performance-related awards [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees | award 287,000   257,000   280,000