| Foreign defined benefit plans [member] | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Concept not required due to addition of the 'Geographical areas' axis to IAS 19 taxonomy tables | 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 |
| This member stands for foreign defined benefit plans. [Refer: Defined benefit plans [member]] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |