It really depends on what your idea is and if it can even be protected. You best bet would be to speak to an IP (intellectual property) expert. I am sure their first consult will be complimentary - there may even be IP experts here on Savvy.
Entrepreneur.com puts it well....
"It's natural to fear that your idea might be stolen. But you can't turn your vision into reality without the help of others. Sooner or later, you're going to want to ask an industry expert to evaluate your product or service. You're going to need to collaborate with a manufacturer or distributor. But patents cost thousands of dollars and take years to be issued. You can't afford to wait that long to start bringing your product to market."
Consider other options as well like NDA (non disclosure agreements), high security in your work environment (physical protection of your idea), Non compete clauses with your employees etc.
As always in these matters it is best to speak to an experty.