I admit I'm a pantser. I write by the seat of my pants. Or as someone once said, "I write into the mist." I know my characters and what their goals, motivation, and conflict are, but I don't know how they will get from A to Z. I agree with Gayle Wilson. What's the point of telling a story if you've already told it in all that plotting?
So, what's your method? Do you plot? Do you know every detail before you write your book?