| Methods used to determine construction contract revenue recognised | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Concept not required due to removal of IAS 11 | en | http://www.xbrl.org/2009/role/deprecatedLabel | http://www.xbrl.org/2003/role/link |
| 2018-01-01 | en | http://www.xbrl.org/2009/role/deprecatedDateLabel | http://www.xbrl.org/2003/role/link |
| The description of the methods used by the entity to determine the construction contract revenue recognised in the period. [Refer: Revenue from construction contracts] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |