Creating User Segments with Not Logic

It would be helpful to define a user segment with exclusion logic rather than only inclusion logic. I have an article that should be visible to anyone signed in who is NOT in one of four specific organizations. I can create a segment containing all other current organizations. That would work for now... but as we add organizations, I would have to manually update my "all other" segment. I would like to be able to create a segment of "Users NOT in segments A,B,C, or D."