How would I go about making sure my idea for a national system doesn't get stolen?

...I came up with an idea that could be something huge, it could potentially serve our entire country (nationally).... How would I go about making sure to get credit for my idea? I've thought of a new system (for something I don't want to disclose yet)... and I don't believe anyone's ever thought of it... Anyway, I want to create it without having to worry about someone else coming along and taking my idea from underneath me. Is there anything I can do? Furthermore, how would I begin creating a system (or business) such as this?