Protecting concepts

How does one protect a concept for a television show, or a film? If I pitch an idea for a new gameshow to a studio or a broadcaster, what’s to stop them from showing me the door, then developing the same concept under a different title, or the same title for that matter?

Ah, that’s the tricky part. They won’t let you pitch it to them, because chances are the idea will suck, but will have one little good part that they’ll later come up with on their own, which will allow you to sue them for stealing your idea.