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Share-based payments - Additional Information (Detail)
£ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
award
shares
Dec. 31, 2017
GBP (£)
award
£ / shares
shares
Dec. 31, 2016
USD ($)
award
shares
Dec. 31, 2016
GBP (£)
award
shares
Dec. 31, 2015
USD ($)
award
shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ $ 21   $ 17   $ 19
Weighted average share price at exercise date | £   £ 38.047   £ 25.111  
Administrative expenses [member] | Exceptional items [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Share based payment cost | $ $ 2   $ 0   $ 0
Maximum [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   £ 47.19      
Minimum [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   36.554      
Closing [Member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
IHG share price | £ / shares   £ 47.19      
Annual Performance Plan [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees 234,918 234,918 335,775 335,775 265,285
Annual Performance Plan one-off awards | shares 79,471 79,471 103,071 103,071 58,338
Long Term Incentive Plan [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees 805,045 805,045 1,355,721 1,355,721 1,803,308
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 524,587 524,587 467,203 467,203  
LTIP Performance-related awards [member]          
Disclosure of terms and conditions of share-based payment arrangement [Line Items]          
Number of shares awarded to employees 280,458 280,458 888,518 888,518 1,803,308