Yes.
it is not possible under current U.S. law to copyright or protect an idea. (You also cannot copyright a title.) So, how much precaution should you take to keep your ideas secret?
Very little. I guarantee that others have similar ideas; you see it happen all the time in the business. Chalk it up to cultural zeitgeist. While I don’t advocate advertising your idea far and yon, or putting flashing lights around it on your blog, the chances that an agent, editor, critique partner, or stranger will:
(a) steal your idea
(b) execute your idea better than you
(c) AND be able to sell it
… are next to zero. It is not worth worrying about. Share your work with trusted advisers, send it to agents/editors for consideration, and talk about aspects of it on your blog. No problem. Unless you are known in the industry for coming up with million-dollar high concepts, it’s not likely you’ll experience idea theft.
Also, I love Jeanne Bowerman‘s take on this fear: Sure, someone can steal your idea, but they can’t possibly execute it or interpret it in the same way you can. No one can be you. That is your best protection of all.