ABC News' Amy Robach reports:

Jennifer Lopez surprised the world last week when she confirmed she will not return next season as a judge on " American Idol."

The singer, entrepreneur, dancer, fashion designer and mother of twin toddlers told Ryan Seacrest in a call to his radio show on Friday that her busy schedule and her desire to return to her other projects were the reasons she decided to call it quits.

Now Lopez, 42, has revealed for the first time another factor that sealed her decision, the exit of fellow "Idol" judge Steven Tyler.

"We had magic," Lopez said in a sit-down interview with ABC News' Amy Robach on Sunday. "I don't know, with him gone, it might be a different formula."

Tyler, 64, announced his departure last Thursday, saying he was leaving to return to his "first love," Aerosmith. He and Lopez joined "Idol" as judges for the 2011 season, joining Randy Jackson who has been part of the original judges' table since the show first began in 2002.

With rumors that even Jackson, 56, is now looking to move to more of a mentoring role with the show, the speculation is rampant over which bold-faced names may be tapped to rejuvenate the once-hot reality competition show whose ratings have been sagging.

Lopez, who reportedly earned at least 15 million dollars for her most recent season as an "Idol" judge, weighed in with her own ideas.

"I think like Bono or Bon Jovi or Mick Jagger," she told ABC News. "You know me, I think big."

With "Idol" behind her, Lopez is now preparing to return to her performing roots with a North American tour with singer Enrique Iglesias.

After their tour ends, however, don't look for Iglesias to replace Lopez on "Idol."

"I wouldn't be a good judge," the Latin singer told ABC News. "It's a lot of pressure, just thinking about, 'Oh my god, I just ruined this person's career.'"

"Idol" fans should also not look for Lopez to be completely gone from future seasons of the show. The singer left the door open to some type of collaboration with "Idol," even after confirming her decision to leave.

"I love them and they love me and it's hard when I feel like I should move on," she said. "I don't know that it's even done yet. I don't know. I feel like I'm moving on."

Lopez says no matter where she goes next in her own career she'll always take the memories and lessons of "American Idol" with her.

"It got me back in touch with who I was, watching the contestants and singers," she said. "That's why it's hard to walk away."