Let them know that you re confused about the lack of communication and why you ve been left out of the loop. Protecting your ideas within a company is a difficult thing to do since technically, your ideas are the company s property . You do however have every right to stand up and offer input.
I would say you shouldnt have told them about it if you didnt expect them to run with it. If it is that good of an idea you should have gone out on your own.