| 営業収益 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 営業収益、関連事業営業損益、高速道路事業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 営業収益合計 | ja | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |
| Operating revenue - related operations | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Operating revenue-related operations-highway business-HWY | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Total operating revenue - related operations | en | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |