What Format do you use when writing a story for a movie?

I know how to write the proper format for a screenplay, but sometimes screenplays need to be adapted from the written story first. For example, Christopher Nolan wrote the story for The Dark Knight, then his brother Johnathan Nolan adapted the screenplay from it. So what format do you use for the story? Do you do it like how a novel is written? Now I know writers intend to go straight to the screenplay first sometimes, but I like to make sure everything is how it should be before finally making the screenplay. And what would be the best font to use? The same as the screenplays? Courier?