thanks for this one, Bill Finger is one of the best writers they ever had. i've been reading the really early work for the past couple years or so i've read them all digital of course from (1939) to where i am at now (1953) fall (1953) in fact and he's a very underrated writer i think. so i am thrilled that DC is now giving him the credit he deserves by putting his name along Bob Kane's as co creator.
Bob Kane did come up with the idea of batman but Bill thought up the outfit the gadgets, the origin story as well... he also co-created the joker and i think catwoman to... he also introduced Science into batman to make it more realistic as well. he also co-created Robin as well. among other things like i think two face was one of his creations i forget to be honest.
look him up or better yet watch this documentary about the guy.