| Increase (decrease) in provision for compensation for guaranteed trust principal | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Increase (decrease) in provision for compensation for guaranteed trust principal - OpeCF - BNK | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 信託元本補填引当金の増減(△) | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 信託元本補填引当金の増減(△)、営業活動によるキャッシュ・フロー、銀行業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |