Can't agree more. If you really want to hand off, you have to find a different EMPLOYER and not a different department/supervisor. Otherwise, every project you've ever lead will be yours forever. Sure, someone may be "responsible" for the day to day stuff and it can be upgraded half a dozen times, but if it falls over and the current guy/gal can't figure it out, you'll be getting the call.
Documentation is great, but it only gets you so far as it's nigh impossible to document everything you did and why, much less what to do when X happens do Y for every case. The other reality w/ documentation is that for it to be useful, someone has to READ it. Good luck with that, RTFM became part of the gestalt for a reason.
Suck it up, follow a previous poster's advice by CC'ing your new supervisor so he/she atleast can see how much time suck is going on and just be helpful as you can to the next guy. After all, it's us vs the users! ;)