| Accruals and deferred income classified as current | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Concept not required as a result of 2020 general improvements | en | http://www.xbrl.org/2009/role/deprecatedLabel | http://www.xbrl.org/2003/role/link |
| 2021-01-01 | en | http://www.xbrl.org/2009/role/deprecatedDateLabel | http://www.xbrl.org/2003/role/link |
| The amount of accruals and deferred income classified as current. [Refer: Accruals and deferred income] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |