| Number of increase (decrease) of non-vested options. | en-US | http://www.xbrl.org/2003/role/documentation | http://www.xbrl.org/2003/role/link |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Number of Shares, Period Increase (Decrease) | en-US | http://www.xbrl.org/2003/role/label | http://www.xbrl.org/2003/role/link |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Number of Shares, Period Increase (Decrease), Total | en-US | http://www.xbrl.org/2003/role/totalLabel | http://www.xbrl.org/2003/role/link |