How to find unmanaged clients on the network

We have unmanaged clients on our network that I need to convert to managed clients.  What's the best way to search for and find those unmanaged clients?  It doesn't make sense that they had this feature available in SEPM 11, but took it away.  I've looked under Home>Security Status>View Details>Unknown Device Failures and nothing is listed.  I also set up a notification, but this is a university, and I don't really want to know when anyone brings an unknown device onto the campus.  I just want to find the SEP installs that are unmanaged and convert them to managed.