| Useful lives or amortisation rates, intangible assets other than goodwill | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Concept not required as a result of 2018 annual improvements | en | http://www.xbrl.org/2009/role/deprecatedLabel | http://www.xbrl.org/2003/role/link |
| 2019-01-01 | en | http://www.xbrl.org/2009/role/deprecatedDateLabel | http://www.xbrl.org/2003/role/link |
| The useful lives or amortisation rates used for intangible assets other than goodwill. [Refer: Intangible assets other than goodwill] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |