It's not an idea until you write it down. You have to capture it. As someone who has self-identified as a writer for a long time, I sure haven't written things down enough.
Not that I haven't worked on diverse projects writing editorial and copy for all sorts of applications, I have. But there's also so much that has been sparked and gone undone because of a failure to write it down.
We can't turn ideas into things unless we activate them.