| Net defined benefit liability (asset) | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Net defined benefit liability (asset) at beginning of period | en | http://www.xbrl.org/2003/role/periodStartLabel | http://www.xbrl.org/2003/role/link |
| Net defined benefit liability (asset) at end of period | en | http://www.xbrl.org/2003/role/periodEndLabel | http://www.xbrl.org/2003/role/link |
| The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]] | en | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |