| r0.1 | label_boi_a2/Included companies | boi_met:mi1 | xbrli:monetaryItemType | instant | N/A | N/A | boi_IP:x23 | N/A | boi_RP:x24 |
| r0.2 | label_boi_a2/consolidated companies | boi_met:mi1 | xbrli:monetaryItemType | instant | N/A | N/A | boi_IP:x26 | N/A | boi_RP:x24 |
| r0.3 | label_boi_a2/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | N/A | N/A | boi_IP:x31 | N/A | boi_RP:x24 |
| r0.4 | label_boi_a2/Reputation costs | boi_met:mi376 | xbrli:monetaryItemType | instant | N/A | N/A | boi_IP:x31 | N/A | boi_RP:x24 |
| r0.5 | label_boi_a2/Accumulated amortisation Reputation | boi_met:mi346 | xbrli:monetaryItemType | instant | N/A | N/A | boi_IP:x31 | N/A | boi_RP:x24 |
| r1.1 | Balance/Included companies | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_IP:x23 | boi_MC:x837 | boi_RP:x24 |
| r1.2 | Balance/consolidated companies | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_IP:x26 | boi_MC:x837 | boi_RP:x24 |
| r1.3 | Balance/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| r1.4 | Balance/Reputation costs | boi_met:mi376 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| r1.5 | Balance/Accumulated amortisation Reputation | boi_met:mi346 | xbrli:monetaryItemType | instant | boi_BC:x1 | N/A | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| 14.1 | Consolidated/Included companies | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_IP:x23 | boi_MC:x837 | boi_RP:x24 |
| 14.2 | Consolidated/consolidated companies | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_IP:x26 | boi_MC:x837 | boi_RP:x24 |
| 14.3 | Consolidated/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| 14.4 | Consolidated/Reputation costs | boi_met:mi376 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| 14.5 | Consolidated/Accumulated amortisation Reputation | boi_met:mi346 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x2 | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| 37.1 | Solo/Included companies | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_IP:x23 | boi_MC:x837 | boi_RP:x24 |
| 37.2 | Solo/consolidated companies | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_IP:x26 | boi_MC:x837 | boi_RP:x24 |
| 37.3 | Solo/Total | boi_met:mi1 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| 37.4 | Solo/Reputation costs | boi_met:mi376 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |
| 37.5 | Solo/Accumulated amortisation Reputation | boi_met:mi346 | xbrli:monetaryItemType | instant | boi_BC:x1 | boi_CS:x1 | boi_IP:x31 | boi_MC:x837 | boi_RP:x24 |