Mariah Carey was just settling into life as a pop superstar when her producers came to her in 1994 with an idea: How about a Christmas record?

Initially, Carey was not enthused.

"I felt like it was a little bit too early in my career to be doing a Christmas album. And then — I decided to do it," Carey said in an interview with Billboard.

The album, Merry Christmas, and its monster single "All I Want For Christmas Is You," have been holiday staples ever since — and continue to provide a growing platform for Carey's flourishing side-career as queen of the holidays.

"The crazy thing about it is, every year it tends to increase in popularity," she said of the tune, which is the most downloaded holiday song of all time with 3.2 million hits, besting classics such as "Feliz Navidad" and "Jingle Bell Rock." The song, which Carey wrote with producer Walter Afanasieff, peaked at No. 11 on the Billboard Hot 100 last year, 22 years after its release.

Accordingly, Carey continues to expand her holiday offerings. This year, in addition to her annual run of Christmas concerts, she has a line of holiday cookies and other treats, and she's debuting a holiday movie, Mariah Carey's All I Want For Christmas Is You.

Carey produced and narrates the animated feature, available on Blu-ray, DVD, digital and on-demand Tuesday (Nov. 14), which costars Henry Winkler and Lacey Chabert. The movie features Young Mariah in search of the perfect holiday puppy, and is based on her 2015 children's book of the same name.

"I'm very thankful that people seem to still have an attachment to it," she said of the song, which has spawned its own mini-empire. "It makes me feel good when people tell me that it's part of their lives."

Back when she was writing it, it didn't occur to her that she might be creating an annuity — or something that could someday put her on hallowed holiday ground with great songwriters of the last century such as Irving Berlin.

"Oh my gosh, no no, never, no. I feel like this is something small compared to the rest of my catalogue. This song just continues to surprise me."

Also new for her this season, Carey will take her holiday concerts overseas for the first time with dates in London, Manchester and Paris.

"It's the first time we're taking the show from the Beacon Theater," she said of her annual run of concerts in the New York venue. "It's an intimate evening."

The five-time Grammy winner is involved with yet another film this holiday season. She has written and sings a new Christmas ballad, "The Star," the title track to an animated film in theaters Friday.

She will also soon be back in the studio for a new (non-Christmas) album due in 2018. After more than 25 years in the business, what's the secret to her longevity?

"Great music is the most important thing," she says, "in my opinion."