From Television Heaven:

"What Silverman envisioned was a cross between a popular 1940's radio programme 'I Love A Mystery' which was about three detectives, and a 1959 sitcom 'The Many Loves of Dobie Gillis', about a scatterbrained teenager and his friends."¹

Silverman is credited with creating the name of the show's title character. As the story goes, Silverman got Scooby's name from the scat singing at the end of Frank Sinatra's song Strangers in the Night. Silverman thought he heard Sinatra sing, "Scooby Dooby Doo." However, as that song's recording reveals (https://vimeo.com/62569524), Sinatra actually sings, "Dooby dooby doo."²

It should be noted that Silverman had not envisioned a dog being the star of the cartoon that he wanted to be created. His idea was for the cartoon to feature mystery-solving teenagers.

Information Sources:

¹Scooby Doo Where Are You? Television Heaven. Retrieved from https://web.archive.org/web/20130128110448/http://www.televisionheaven.co.uk/scooby.htm

²20 Frank Sinatra Facts. This Day in Music. Retrieved from http://www.thisdayinmusic.com/pages/frank_sinatra