Idea theft is a big concern when you are a creative but can make you an island if you let it. I have met a lot of really good creative people who worry about this to such a degree that their work does not evolve in the way it should. It is true there are 'Sharks' out there ready to prey on inexperienced creatives new ideas but I say the only way to truly protect your self from this is to keep coming up with new ideas.
All the time you spend protecting your one good idea could be spent coming up with 3 more even better ones.
The internet has effectively made us all creative 'watch dogs' and there is less place to hide for those 'Sharks' to hide when they try and take a bite out of someone else's idea.
Through history all the best ideas and concepts have come through cross pollination. Don't make yourself an island. Find some fellow creatives you can work with and who knows where your ideas may take you!