Related party disclosures - Summary of Total Compensation of Key Management Personnel (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compensation of key management personnel [abstract]
Short-term employment benefits	$ 21.3	$ 19.2	$ 19.5
Contributions to defined contribution pension plans	0.6	0.8	0.7
Equity compensation benefits	10.2	7.4	6.2
Termination benefits	1.9
Total compensation of key management personnel	$ 34.0	$ 27.4	$ 26.4

The amount of compensation to key management personnel. [Refer: Key management personnel of entity or parent [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2017-01-01
-Paragraph 17
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2017-03-01&anchor=para_17&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_KeyManagementPersonnelCompensation
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of compensation to key management personnel in the form of post-employment benefits. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2017-01-01
-Paragraph 17
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2017-03-01&anchor=para_17_b&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_KeyManagementPersonnelCompensationPostemploymentBenefits
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of compensation to key management personnel in the form of share-based payments. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2017-01-01
-Paragraph 17
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2017-03-01&anchor=para_17_e&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_KeyManagementPersonnelCompensationSharebasedPayment
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of compensation to key management personnel in the form of short-term employee benefits. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2017-01-01
-Paragraph 17
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2017-03-01&anchor=para_17_a&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_KeyManagementPersonnelCompensationShorttermEmployeeBenefits
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of compensation to key management personnel in the form of termination benefits. [Refer: Termination benefits expense; Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
-IssueDate 2017-01-01
-Paragraph 17
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=24&date=2017-03-01&anchor=para_17_d&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_KeyManagementPersonnelCompensationTerminationBenefits
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Compensation of key management personnel abstract.

+ References

No definition available.

+ Details

Name:	ihg_CompensationOfKeyManagementPersonnelAbstract
Namespace Prefix:	ihg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration