Though I am a Christian and do believe that the God of the Bible created the universe, ID makes no such assumption that a god created the world. As I understand the theory it could literally be anything - aliens from outer space or a time traveling band of intergalactic space hippies. I am being facetious, but you get the point.
If you poke an IDer enough, eventually they will (probably 99+%) say God is the designer. The aliens or space hippies are a red herring. Somewhere less than 15 billion years ago life arose somewhere, and probably many millions of somewheres. At each of those origin events there is only one question: Did that life arise by natural chemical mechanisms (i.e. Abiogenesis), or was it zapped into its designed existence by a god? These are the only two choices as I see it. The designer of ID is a god, or there is no God involved in the origin of life, and subsequently evolution.
If there are other possibilities, I'd like to hear them.