Do you create outlines for your books, or make it up as you go?

I have discovered there are two basic types of writers: those who outline, and those who fly by the seats of their pants. I’m an outliner. I can’t move forward until I know where I’m going. I usually write the first chapter, just to get a feel for the story and the characters. But then I stop and write a very detailed, scene by scene outline. I generally stick fairly close to the outline as I write. Occasionally bits here and there are added or deleted, but for the most part I keep on the path I’ve built in the outline without much variation.