You can have anyone you actually discuss the details of your idea with sign a Non-Disclosure agreement to protect your idea and this before beginning discussions.

It is standard operating procedure for us to sign a legal document that guarantees our potential customers that we will not steal their ideas while we discuss whether or not we will be the company to work for them. (I'm in food manufacturing). I imagine it would easily work the same or similarly in other industries.

Tina Brooks, VP Marketing
Brooks Pepperfire Foods Inc.
http://www.peppermaster.com