Just as an FYI, it's pretty standard practice in the industry to destroy submitted game ideas unread.  This avoids any potential problems if the studio happens to make a game similar to a submitted idea.

If you want your game made by an existing developer you would likely need to work your way up within the industry.

As for planning your idea, you're probably looking for a "design document".

Tom Sloper wrote a bit about them HERE. Ernest Adams wrote a bit about them HERE.

Hope that helps!

You may have misunderstood - they will destroy the submission without reading it. There is no opportunity in this case to get them interested.

It's just like any other business plan. If you can't do it yourself you'll have to secure funding from investors.

8-bit, it's useless to pitch a game concept to a developer (and Blizzard isn't a developer anyway). Developers don't have the money to develop games. You have to pitch to a publisher. I described the process in FAQ 21. Ask who to submit to, obtain and sign disclosure/submission agreement, before sending idea in. Many will tell you they simply don't accept outside submissions at all. If you pitch to a developer, then a developer would have to submit it to a publisher, but their incentive to do so is greatly reduced because it's your idea, not theirs, and if they get the job, then they have to work with you and/or share the money with you. 

Submitting concepts is a business proposition, so I'm moving this to the Business forum.

It is a running joke / meme with computer programmers / developers that they get hammered with a bunch of ideas regularly from other people that they want to see the developer do.  

Developers don't typically work that way.  If you want a developer to do a game for you, you're going to have to pay the developer to do that work.  Otherwise there is no incentive for a developer to develop your idea for you.  Its a massive time sink with little to no value for the developer.