| 特定都市鉄道整備準備金の増減額(△は減少) | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 特定都市鉄道整備準備金の増減額(△は減少)、営業活動によるキャッシュ・フロー、鉄道事業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Increase (decrease) in special reserve for expansion of railway transport capacity | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Increase (decrease) in special reserve for expansion of railway transport capacity-OpeCF-RWY | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |