I am both.<<I am type C. The one that gets an idea and just wings it to the point of ending a chapter and thinking "Hey this chapter was originally going to be a lighthearted filler type thing but it turned out that six people died, three of which were reborn, and the main character is now married to a goat. Nice, let's keep going."
The Ultimate Character Questionnaire. A character questionnaire can be a great way to inspire a bit (or a lot) more detail about your characters. This list has been compiled from various sources around the net and in books and also our own brains