If you have a Driver's Licence, I'm not sure about other ID's, it has a little barcode strip on the back that they can scan and look you up in the system automatically. At least, that worked for me last year. I didn't need to bring any paperwork with me because of that. Although, it is always a very smart idea to have a proof of purchase receipt on you, in case something's wrong and they don't see you in the system.