Unfortunately, if your idea cannot be patented, it is difficult if not impossible to protect an idea. Copyright protects the expression of an idea and trademark protects a word, name, symbol or device that is used to distinguish the source of goods or services from those of others. You can ask the business to sign a nondisclosure agreement (NDA) but the NDA will likely exclude from protection anything that the business already knew. Also, businesses often will not sign NDAs because they don't want to risk being sued for stealing your idea. Probably the best way to protect your idea is to register the copyright in your expression of the idea before you disclose it. That way, if the business "substantially copies" your idea, you may have a copyright claim. Other than that, your best bet is to convince the company that you have a way of carrying out your marketing idea more efficiently and profitably than they can.