| 事業経費 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 事業経費、建設保証業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 事業経費合計 | ja | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |
| Operating expenses - general | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Operating expenses-general-CNA | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Total operating expenses - general | en | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |