| 減価償却累計額及び減損損失累計額 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 減価償却累計額及び減損損失累計額、工具、器具及び備品、高速道路事業固定資産、高速道路事業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Accumulated depreciation and impairment loss | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Accumulated depreciation and impairment loss-tools, furniture and fixtures-highway business-NCA-HWY | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |