How to protect your unpublished ideas?
Obviously your idea is not 'protected' as someone else might have the same idea and/or a subset of that, and make a publication/patent out of it before you do; and you can't claim that the person stole it through your brain waves! 

Write down the introduction and background to that idea you have, and prove that it is your contribution through case studies and evaluations, and submit it to be published in a conference as a poster or a paper.