OS X :: Can't Delete The Documents Folder

I've just recently set it up on my Mac that all of my documents that would normally be in the Documents folder are now on my iDisk, in another folder named Documents. I've created a local copy of my iDisk so that my stuff is always in sync. However, just to make it easier on myself, what I would like to do is delete the (now empty) Documents folder in my Home folder, and replace it with an alias for the local iDisk documents folder. That way, I can still go into the Home folder as usual, but the Documents folder there will just point me directly to the local iDisk location. However, OS X isn't letting me do that - I can't delete the Documents folder to replace it.