Noah Thompson won season 20 of American Idol on Sunday during a star-studded three-hour finale on ABC.The 19-year-old country singer from Louisa, Kentucky won after his co-worker Arthur signed him up and recorded his virtual audition.HunterGirl, 23, who was an early favorite after earning a Platinum Ticket during her audition, finished in second place. Season champion: Noah Thompson won season 20 of American Idol on Sunday during a star-studded three-hour finale on ABCLeah Marlene, 20, of Normal, Illinois, finished in third place.The three finalists each performed a cover of a Bruce Springsteen song in honor of the American rocker as well as an original song.