| Interest income on interest rate swaps | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Interest income on interest rate swaps - OI - BNK | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Interest income on interest rate swaps | en | http://disclosure.edinet-fsa.go.jp/jppfs/bnk/role/label | http://www.xbrl.org/2003/role/link |
| 金利スワップ受入利息 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 金利スワップ受入利息、経常収益、銀行業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| (うち金利スワップ受入利息) | ja | http://disclosure.edinet-fsa.go.jp/jppfs/bnk/role/label | http://www.xbrl.org/2003/role/link |