I am not a developer of any kind, but I do have ideas, as well as opinions - that I like to share, especially on the forums. The case is, your idea would need to be very well thought through, before you even made an announcement as to hire, say, a technical director, who should later on be responsible for the crew, also with whom you ought to consult how feasible your plan is, making such a person automatically a sort of co-founder - or at least giving him the right to make such claim. If you do not have the technical skill to verify that people whom you pay are capable of doing what they promise to be able to do, your technical director also should do as your HR manager, interviewing candidates with having the say over financial gratifications included.
More likely yourself, you would become the chief of the art department, deciding for the graphics and soundscape fitting your project. With the latter, I guess it is easier to verify oneself whether the candidate has some artistic skill or not and whether it is to your liking. You may not be savvy in arts, but you certainly know what you like or dislike, also how your game ultimately should look like. For the money, indeed, as someone pointed out, you better be a well of cash, if you want to keep people on a leash of payroll, so to say, which would allow you to have an ultimate word on what goes around with your game. Also, mind this would be your game in the final credits, the same way as a movie belongs to the movie director, even though the director does rarely star as an actor, edit or shoot the scenes.
Otherwise than that, you can throw loose ideas here and there, but basing on my own experience, nobody is really going to buy them, because first, it is slippery - you could later on make claims or even attempt to sue the company - otherwise than that, idea depends on who actually has the idea. Me and you, we may have the same idea, but when things come down to things, it may happen you will not recognize your idea as carried out by myself, also the other way around. This is furthermore the risk of "ordering" the making of a game, in case you wanted to just remotely hire a company - like ordering a pizza - without hands-on control or personal contribution and leadership. You may actually not recognize it, you may even dislike it. Someone else would have to take charge of the concept and shape it onto own likeness. Some core concepts may be misunderstood or twisted. What then? You still would have to pay for it, because the work is done, as written in the hypothetical contract.
You know how the saying goes, if you want it done right, do it yourself or at least lead by the example. Which is why some ideas are bound to remain ideas.