LOS ANGELES (Reuters) - Grammy-winning pop star Mariah Carey will join Fox television's "American Idol" singing contest as a judge next season as the highly rated show fights to regain its slumping audiences. Kevin Reilly, president of entertainment for Fox Broadcasting, told television critics on Monday in Los Angeles that popular singer Carey will be one of the replacements for departing judges Steven Tyler and Jennifer Lopez. Tyler, the front man for rock band Aerosmith, announced his exit earlier this month to focus on his revived music career. ...