You cannot copyright an idea until there is some actual expression of the
idea. In addition, your idea may not be something that can receive copyright protection, which is limited to certain categories such as: literary works, musical works, dramatic works, pantomimes and choreographic works, pictorial, graphic, and sculptural works, motion
pictures and other audiovisual works, sound recordings, and architectural
works. Whether or not your idea may receive copyright protection, it can still be protected before it is implemented. The usual way to do this is to prepare a document known as a “Non-Disclosure/Non-Competition Agreement”, which should be signed by anyone having access to the idea during the development phase. You should consult an attorney familiar with these transactions to prepare the proper documentation.  Once you're up and running, your attorney can help you protect your intellectual property so that "theft" by another company can be a very costly mistake on their part.