No, but you do need it fleshed out to a degree of believability. And that depends on who you're talking to...how easily they can pick the idea up and run with it. A programmer is likely to do this better than a banker: they can probably take the concept and mentally build it out, whereas the banker probably can't.

Now comes the money part. Again, this depends on who you're talking to. How money-savvy are they? A programmer might love the idea and instantly know how to flesh it out. That might generate enough excitement to make the sale happen right there.

For the money-savvy, something's missing though...a whole lotta something. Where's the target market? How do you intend to reach them (ads, traffic, signup)? What business model would you follow (paid third party ads, paid membership, freemium, etc.)? If all you have is the basic *technical* idea but no market analysis, the money-savvy will probably leave it alone.

Given that you didn't provide more detail, you probably think someone is going to steal your idea. Most people are too busy to steal your idea. I've written about this here: http://www.salestactics.org/sharing-new-business-ideas-trust-and-ndas/

As you haven't given more info, it's tough for me to tell--at least in my opinion--whether your idea has legs or not. I guess you could PM it to me if you want. Otherwise, I could help you figure out that marketing side to sell it to the money-savvy type of person.