Not sure of any documentaries. But someone, I believe one of his grandsons wrote a book about him. I've seen it at my local Barnes & Noble but cannot vouch for how good it is.

http://www.amazon.com/Godfather-Garden-Rivergate-Regionals-Collection/dp/0813560616

This life of ours, this is a wonderful life. If you can get through life like this, hey, thats great. But it's very, very unpredictable. There are so many ways you can screw it up.-Paul Castellano (he would know)

"I'm not talking about Italians, I'm talking about criminals."-Joe Valachi