Mariah Carey IS "That Chick"

In the two decades since she burst onto the scene, Mariah Carey has produced more chart-topping singles than Elvis.

With more than 200 million albums sold, she is now the best selling female artist of all time. In a tucked away corner of her palatial New York City penthouse are Grammys, Vibe awards, World Music awards -- accolades from an unparalleled career.

The singer, who is expected to release a new album in the coming months, sat down for an exclusive interview with ABC's Barbara Walters to talk about her music, being a mother to twins and what's in store for her future.

Watch Barbara's exclusive interview on "Nightline" tonight at 11:35 p.m. ET

We're used to seeing Carey on stage, belting out her music with a voice of staggering power and range. But starting next week, she will be judging the singers, instead of being the singer, as a new judge of "American Idol."

And her star power doesn't come cheap. Although she wouldn't confirm it, Carey is reportedly being paid $18 million a season.

"I think we're in the ballpark, [but] I can't even talk about those things," she told Walters.

But it's not only Carey's salary that is drawing attention these days. It's her relationship with fellow "Idol" judge, Nicki Minaj.

In October, TMZ released a video of a heated argument between the two divas during an audition in North Carolina. After the cameras were off, Carey claims others heard Minaj take it even further and say, "If I had a gun, I would shoot that bitch," as Walters reported on her daytime talk show, "The View."

"It felt like an unsafe work environment," Carey said. "Anytime anybody's reeling threats at somebody, you know, it's not appropriate. I'm a professional. I'm not used to that type of environment."

"I just felt it was the appropriate thing to do," she said. "Sitting there on the road with two babies, I'm not going to take any chances."As a result, Carey said she hired more security.

Minaj has denied saying anything about a gun, calling the statement a "fabrication." When ABC News asked her for comment for this story, her representative said "she's said what she's saying on this topic."

"For all the drama, I hope it helps the show," Carey said. "I think it's a classic, classy show and it didn't need this."

The public battle with Minaj is not the only challenge Carey faced recently. Nick Cannon, her husband of five years and the host of the rival competitive singing show, "America's Got Talent," suddenly fell ill and was hospitalized for kidney failure last year.

"It was very serious, but he's got some great doctors who really got in there and helped him out and at this point he is doing great," she said. "He's better than ever."

His struggle with that life-threatening illness inspired her recently released song, "Triumphant."

"I was just trying to encourage people to never give up and to get through and to persevere," Carey said. "And that's what the meaning of 'Triumphant' was to me."

The couple have something else to rejoice over: Their 20-month-old twins, a girl named Monroe and a little boy named Morrocan.

"I call her Miss Monroe, and that kind of dictated her personality," Carey said of her daughter. "She's a total diva. She's into jewelry. She's fascinated by jewelry."

Her son's nickname, she said, is "Rock."

"He's my pal," Carey said. "He'll just watch movies with me. We've watched 'Shrek' I don't know how many times. We watch movies all the time together, relax. He's more chill."

The power couple recently celebrated the twins' first birthday in true diva style with a family trip to Paris, where they renewed their vows on the Eiffel Tower. In fact, they renew their vows every year.

"[Nick] is just as festive as I am," Carey said. "I'm very, very festive, and he kind of almost trumps me there."

Despite the glamorous trips, Carey is trying to stay close to home, for now, to spend quality time with the kids. She said she and Minaj have made up, and she is looking forward to the return of "American Idol" for its 12th season next week.

"For me, ultimately, this is about the kids, the contestants," Carey said. "I've been blessed to live my dream more than half my life, so I want help give that back to someone else."