| Increase (decrease) in advances received on service contracts in progress | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Increase (decrease) in advances received on service contracts in progress - OpeCF | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 未成業務受入金の増減額(△は減少) | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 未成業務受入金の増減額(△は減少)、営業活動によるキャッシュ・フロー | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |