Keith Urban is the man in the mid­dle. The new “Amer­i­can Idol” judge had to play peace­maker between Nicki Minaj and Mariah Carey. Video leaked to TMZ shows Minaj and Carey in a heated and pro­fane argu­ment. Urban says he feels like the United Nations. He made the com­ment on the red car­pet Wednes­day at the New York Film Fes­ti­val gala hon­or­ing his wife, Nicole Kid­man. “Idol” debuts in January.