Well, I think talking to your boss about the details would be a complete waste of time. He knows what this guy is like and that he didn't promote him (probably for those same reasons) so all you would tell him would be nothing new. I would just say that it was "trying" at times but you handled it and if he wants details, then go for it and give him the details. I suspect he knows exactly what he'll hear. If this idiot's (co-worker) behavior was something new, then it would be an entirely different situation.

That's my opinion but it doesn't make me right.