You do need to be careful. The old rule for patents followed a "first to invent" policy; in 2013, the law changed to a "first to file" policy. What this means is that even though you came up with the idea first, if someone else comes up with the same idea independently and files for a patent before you, they get initial rights to the patent. Of course, an inventor must have actually come up with the idea themselves to get the patent; someone cannot steal your idea and get a patent.
Even if someone else gets the initial rights to the patent, you can overcome those rights by showing that you came up with the idea first. To overcome the rights of the first filer, you would need to institute litigation (this is called an "interference proceeding"). In legal terms, the "first to file" policy shifts the burden to you to instigate litigation to prove you came up with the idea first. Make sure to fully document your invention (initial idea, further discoveries, and process you are taking to reduce the invention topractice) in a notebook with dates… this will be evidence if there was ever a question as to when the invention was established.
Before you go down the patent route, you should definitely have Non-disclosure agreements for anyone you share your idea with (I can draft this for you). This is a very important first step to protect your idea.
Getting a patent is an expensive and time consuming process, so you need to know what you are getting yourself into. That being said, pursuing a patent early for a viable idea is much cheaper than trying to prove you came up with the idea first in an interference proceeding.