How to protect my idea?

Basically I have a business idea but I cannot execute it by myself. I need a resourceful company like Canon or Samsung with the technological experience and resources. In essence all I have is an idea but I believe such companies can make money from what I have to share with them. My concern is that I may pitch the idea to a big company and not gain anything in the end from the idea as I will have little else to offer. The idea includes photography and possibly internet funstionality but its not another facebook. How do I go about this?? HELP