| 営業費用 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 営業費用、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 |
| 営業費用合計 | ja | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |
| Operating expenses - related operations | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Operating expenses-related operations-highway business-HWY | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Total operating expenses - related operations | en | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |