The Idea guy sounds good ...
I would make sure you understand the term correctly before using it around here...
"The idea guy" is kind of a snotty term used by some game developers for people who do not seem to do any kind of work, but are trying to make others do the work for them. Think of the guy who has this awesome idea for a new game, and tries to assemble a team that should make his vision a reality. When asked by potential team members on what his role on the team is, or what he can do, he answers "I have the ideas"... which for most expierienced game developers is an instant no-go.
It means the guy will do nothing but command you around to do his bidding. Most probably while being overprotective of his "awesome idea".
Now, Frob tried to say that Game Designers are NOT just "The idea guy"... they are expected to do way more than just have a vision and make others realize this vision.
You should feel quite comfortable with Excel, and should be good at math because these are some of the most used tools of Game Developers. They are, after all, also responsible for crafting and perfecting the rules of the game, balancing them, and working with the gamelogic programmers to have them properly implemented.
And then often Game designers are also responsible for additional tasks like project management and stuff like that like Frob has laid out.
I guess if you want a job at the helm of producing a game without having to get "your hands dirty with game development stuff", you could look at the producer role, which is to my knowledge more of a project lead / management position that is used in larger game development projects.
Don't know, but I guess trying to get into a Producer role might be just as hard as getting into a Game Designer role, as there aren't that many of those positions compared to programmers or artists.