| 高速道路事業営業費用、営業外費用及び特別損失等明細表 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 高速道路事業営業費用、営業外費用及び特別損失等明細表 [テキストブロック] | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Detailed schedule of operating expenses, non-operating expenses, extraordinary losses, etc. for highway business | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Detailed schedule of operating expenses, non-operating expenses, extraordinary losses, etc. for highway business [text block] | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |