Hide appointment details in resource calendars

I've set up Outlook resource calendars for direct booking by creating an Exchange mailbox for each resource, then used Outlook to log directly into the resource mailbox and set the Resource Scheduling options in Tools | Options | Calendar Options. Then I granted the 'Author' role on the Calendar folder to everyone I wanted to be able to book the resource.
Currently everyone can see the details of the appointments scheduled in the Resource calendars. I would like to hide the details from their view.  Is there a way to do this on the system level?  I believe if the meeting organizer marks the appointment as "private" before sending the meeting it will hide the details, but I wasn't sure if it works for resource calendars since the users already have "author" level permissions.