The percentage of voting interest sold in the disposal of a subsidiary.

No definition available.

Name:	gtmay_PercentageOfVotingEquityInterestsSold
Namespace Prefix:	gtmay_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

General information, Corporate Events (Details)	Dec. 31, 2018	Dec. 21, 2017
Corporate events [Abstract]
Percentage of shares transferred	100.00%
TMM DM [Member]
Corporate events [Abstract]
Percentage of shares transferred		85.00%