Carey, Minaj and Urban replace Jennifer Lopez and Steven Tyler, who departed at the end of last season. Host Ryan Seacrest remains. The return of Jackson, who is Carey's manager, ended speculation that he might leave the judge's panel to become an advisor on the show.
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His exit would have cost "Idol" its last original judge. "Idol" debuted in 2002 with Jackson, Paula Abdul and Simon Cowell, but Cowell left to create "X Factor," and Abdul served as one of its judges last season.
"Idol," which lost its status as TV's top-rated show last season after eight years of wearing the crown, faces an increasingly crowded field of musical competition shows, all of which have borrowed from its format to varying degrees.
"Idol" spent last season in a tight ratings fight with NBC's "The Voice," and this week "The Voice" and "X Factor" faced off head-to-head for the first time. They tied in the ratings overall, though "The Voice" won in the hour they aired opposite one another.
"Idol" hopes Carey will provide star power while Jackson offers a familiar face and Minaj draws a younger, hip-hop audience. It hopes Urban will draw a country audience, as Blake Shelton does to "The Voice."