R&B superstar Mariah Carey is joining the panel of judges for Fox TV's "American Idol" show, it was confirmed on Monday, according to a press release from the network's programming executives.  While neither Carey nor representatives for the show revealed what she will be paid, rumors have estimated her salary at between $12 million and $17 million.  Carey has been considered a frontrunner to become an "Idol" judge ever since Jennifer Lopez and Steven Tyler revealed their departures a couple of weeks ago.  No word on who else will join the show for its upcoming 12th season.