I think the idea has clearly no value when you create a company. This is what makes most people afraid of launching their own business, they wait for the idea of the century and never have it !
My point is that execution matters much more than the idea itself. Very few people actually execute an idea and execute it well and fast.
This is why when I start a company, I am never afraid of sharing it with everybody. Few people will do the same as you, just bet you will be faster. Sharing it with everybody gets you new ideas and very often constructive criticism, so share it.
I think creating a business is about filling empty space. There is empty space everywhere. How many times today you felt a service or a product was perfectible ? How many times you needed something that no company actually provides ? This is empty space. Just consider how big is the demand for this empty space and you have got your idea.
I would not complete rule out the importance of the idea. It is important, though not critical. What is perhaps crucial is the space in which one wants to operate – what is the final goal / destination, along with execution that is almost flawless.