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Share-based payments - Additional Information (Detail)
£ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2018
USD ($)
award
shares
Dec. 31, 2018
GBP (£)
award
£ / shares
shares
Dec. 31, 2017
USD ($)
award
shares
Dec. 31, 2017
GBP (£)
award
shares
Dec. 31, 2016
USD ($)
award
shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ $ 27   $ 21   $ 17
Weighted average share price at exercise date | £   £ 45.838   £ 38.047  
System Fund [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ 11   6   6
Administrative expenses [member] | Exceptional items [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ $ 1   $ 2   $ 0
Maximum [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   £ 49.66      
Minimum [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   39.48      
Closing [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   £ 42.37      
Annual Performance Plan [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees 176,000 176,000 235,000 235,000 336,000
Annual Performance Plan one-off awards | shares 48,771 48,771 79,471 79,471 103,071
Long Term Incentive Plan [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees 784,119 784,119 805,045 805,045 1,355,721
Vesting period of share awards 3 years 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 527,000 527,000 525,000 525,000 467,000
LTIP Performance-related awards [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees 257,000 257,000 280,000 280,000 889,000