How do you write documentation?

I'm curious how those of you building tools for other developers write documentation.

Do you include everything about the API in excruciating detail?
Do you just stick to the basics and keep it high level?
Do you include code examples?
Do you write in a more technical style or keep it light and fun?

I've been trying to strike the right balance of easy to glance over and understand, but also informative and detailed when necessary.