| 国債等債券売却損 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 国債等債券売却損、経常費用、銀行業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| (うち国債等債券売却損) | ja | http://disclosure.edinet-fsa.go.jp/jppfs/bnk/role/label | http://www.xbrl.org/2003/role/link |
| Loss on sale of bonds | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Loss on sale of bonds - OE - BNK | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Loss on sale of bonds | en | http://disclosure.edinet-fsa.go.jp/jppfs/bnk/role/label | http://www.xbrl.org/2003/role/link |