| Profit (loss) on core business | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Profit (loss) on core business - GAS | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Profit on core business | en | http://www.xbrl.org/2003/role/positiveLabel | http://www.xbrl.org/2003/role/link |
| Loss on core business | en | http://www.xbrl.org/2003/role/negativeLabel | http://www.xbrl.org/2003/role/link |
| 事業利益又は事業損失(△) | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 事業利益又は事業損失(△)、ガス事業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 事業利益 | ja | http://www.xbrl.org/2003/role/positiveLabel | http://www.xbrl.org/2003/role/link |
| 事業損失(△) | ja | http://www.xbrl.org/2003/role/negativeLabel | http://www.xbrl.org/2003/role/link |