| 退職給付及び役員退職慰労引当金の増減額(△は減少) | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 退職給付及び役員退職慰労引当金の増減額(△は減少)、営業活動によるキャッシュ・フロー | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Increase (decrease) in provision for retirement benefits and retirement benefits for directors (and other officers) | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Increase (decrease) in provision for retirement benefits and retirement benefits for directors (and other officers) - OpeCF | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |