| 固定資産圧縮特別勘定積立金 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 固定資産圧縮特別勘定積立金 [メンバー] | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Reserve for special account for tax purpose reduction entry of non-current assets | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Reserve for special account for tax purpose reduction entry of non-current assets [member] | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |