| 特別法上の引当金 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 特別法上の引当金 [タイトル項目] | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 引当金 | ja | http://disclosure.edinet-fsa.go.jp/jppfs/gas/role/label | http://www.xbrl.org/2003/role/link |
| Reserves under special laws | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Reserves under special laws-2 [abstract] | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Provisions | en | http://disclosure.edinet-fsa.go.jp/jppfs/gas/role/label | http://www.xbrl.org/2003/role/link |