You won't get too far at all by sending your ideas to a company or publisher. Like book publishers, they'll send your letters straight back to you, unopened. They can't afford to open them - if they make a game or write a book that's evenly remotely similar to the idea you sent them, regardless or whether or not they used your ideas, they open themselves up to all sorts of lawsuits. If you write to Random House with your novel idea they'll reply with 'Thanks, but no thanks' and your manuscript will be untouched.
If you really want to make a name for yourself, start up a mod team. Find the game engine best suited for your game idea and work on it yourself. You'll need 2D artists, 3D artists, coders and web-design people. You'll need to make sure you've got a design document laid out and that everyone on your team follows your ideas. Give them some leeway, of course, but if your game is to be taken seriously it will have similar art styles, cohesion, etc. If one of your 2D artists works only in cartoon styles, and a 3D artist is only good at robotic or mechanical characters, and your web-design guy is a huge fan of organic and gorey-looking art then you'll get nowhere.
Counter-Strike started out as a mod made by a bunch of guys with lots of free time and lots of knowledge, and look how far they got! I don't mean to burst your bubble but submitting your ideas won't get you a game. Experience and plenty of work to show will help get your foot in the door. Every man and his dog has an idea for a game, but whether there are people willing to realize it is a totally different matter.
If you want your game to come into fruition, I suggest you figure out what skills you have and what you're lacking, and find people to fill those gaps. Make it clear from the beginning what your aim is, pick a popular engine and try your best to make your dream come true. Bear in mind that hardly anyone will play your mod, but if you're looking for industry professionals to take notice, it doesn't matter how many people are playing your mod, it matters how professionally it is put together.
I suggest you take a look around
http://www.polycount.com and perhaps browse the message boards there, and you might get some ideas
