If you're specifically referring to logoff events, these are not scanned by default, though you could potentially detect them by
scanning non-error events and building a report based on the tblntlog (event log) database tables. Only logon (not logoff) events are scanned by default.
Computer shutdowns, reboots and other uptime events *are* scanned by default. To query this information, you can build a report based on the tblUptime database table.