Prepayments (Details) - MXN ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Prepayments [Abstract]
Prepaid expenses	$ 4,775	$ 7,258
Prepaid insurance premiums	4,328	1,672
Fleet insurance	2,424	6,350
Prepayments	$ 11,527	$ 15,280

The amount recognized as a current asset for fleet insurance payments made prior to the period when the economic benefit will be realized.

No definition available.

+ Details

Name:	gtmay_CurrentPrepaidFleetInsurance
Namespace Prefix:	gtmay_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount recognized as a current asset for insurance premium payments made prior to the period when the economic benefit will be realized.

+ References

No definition available.

+ Details

Name:	gtmay_CurrentPrepaidInsurancePremiums
Namespace Prefix:	gtmay_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	gtmay_PrepaymentsAbstract
Namespace Prefix:	gtmay_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount recognised as a current asset for expenditures made prior to the period when the economic benefit will be realised.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_CurrentPrepaidExpenses
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of current prepayments. [Refer: Prepayments]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 78
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78_b&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_CurrentPrepayments
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant