| 任意積立金 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 任意積立金 [メンバー] | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 任意積立金計 | ja | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |
| Voluntary retained earnings | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Voluntary retained earnings [member] | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Total voluntary retained earnings | en | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |