| 海運業費用 | ja | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| 海運業費用、海運業 | ja | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| 海運業費用合計 | ja | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |
| Shipping business expenses | en | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Shipping business expenses-WAT | en | http://www.xbrl.org/2003/role/verboseLabel | http://www.xbrl.org/2003/role/link |
| Total shipping business expenses | en | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |