| Amortization of debenture issuance costs | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Amortization of debenture issuance costs - OE - BNK | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Amortization of debenture issuance costs | en | http://disclosure.edinet-fsa.go.jp/jppfs/bnk/role/label | http://www.xbrl.org/2003/role/link |
| 債券発行費用償却 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 債券発行費用償却、経常費用、銀行業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| (うち債券発行費用償却) | ja | http://disclosure.edinet-fsa.go.jp/jppfs/bnk/role/label | http://www.xbrl.org/2003/role/link |