How to isolate Accounts that don't have an open Activity?

How to isolate Accounts that don't have an open Activity?

Is there a way to run a report on all Accounts that do not have an Open Activity? Since a Completed Task is designated a status of Completed, I can't just filter for Status is Empty, and not clear to me what other fields I could use to isolate any Account wherein I have not assigned an Activity.

My guess is that I am missing something...