Before you discuss any details with anyone, especially a company, document your ideas and include a date timestamp.
Many years ago, when I worked at a university research center doing research with a consortium of companies, everyone was required to document everything in composition or engineering notebooks and to date each page.
Today, you could send an email to yourself and save it and a printout with all the header information. This would enough to establish when you came up with the idea.
When discussing your ideas with anyone, make it clear that you have documented them.