[wpietri]

If you have that much depth of knowledge, then I think the idea is going to have similar depth. In which case you come up with a short summary that doesn't give away any of the key insights.

But even if you're generous with information, the idea probably isn't at that much risk. The idea would have to end up in the hands of somebody who not only could out-execute you, but also has the time and interest to do so, is smart enough to recognize the value of your idea, and isn't already attached to some idea of their own.

[ScottBurson]

I think that last sentence deserves emphasis. There's a lot of "NIH syndrome" ("Not Invented Here") around -- and the deeper someone's domain knowledge, the more likely they are to suffer from it.