| Net decrease (increase) in due from banks (excluding due from Bank of Japan) | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Net decrease (increase) in due from banks (excluding due from Bank of Japan) - OpeCF - BNK | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 預け金(日銀預け金を除く)の純増(△)減 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 預け金(日銀預け金を除く)の純増(△)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 |