Nobody ever said Mariah Carey would come cheap.
"Her deal is rumored to be just under $18 million for one year with an option to renew," the source says.
The multi-million dollar figure would make her the highest paid judge on any reality show, beating both her fellow pop stars Britney Spears' reported $15 million X Factor salary, and Christina Aguilera's reported $10 million salary for a third season of The Voice.
But clearly, the American Idol team sees her as worth the investment and more.
"We are proud to have one of the world's greatest-ever female singers join our show," American Idol creator and executive producer Simon Fuller said in a statement. "Mariah defines the word 'Idol' and will inspire every singer that has the honor of performing in front of her."
Yesterday, Carey also tweeted her own excitement at joining the hit show.
"It's gonna be so much fun working on @AmericanIdol. As a singer-songwriter, I'm excited to help find and nurture new talent. LYM! --MC," she tweeted.