David Foster has a lot to celebrate.
On Sunday, the 16-time Grammy Award-winning producer and songwriter rang in his one-year wedding anniversary with "American Idol" alum Katharine McPhee, which they marked with takeout from their favorite restaurant in Los Angeles.
"I did manage to buy her a present and a card, and I booked the fire pit at the condo complex we live in," Foster says. "It ended up being too cold outside, so we ate inside. But it was a nice day."
And on Wednesday, a new documentary about his life and illustrious career is streaming on Netflix. "David Foster: Off the Record" tells the stories of many of the classic songs Foster has shepherded in the past four decades, including Whitney Houston's "I Will Always Love You," Celine Dion's "Because You Loved Me," Barbra Streisand's "Somewhere" and Chicago's "You're the Inspiration."
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It also offers a peek behind the curtain at his famous past marriages – to actress Linda Thompson and reality star Yolanda Hadid, among them – and five adult daughters, four of whom are older than McPhee, 36, his fifth wife.
Foster, 70, recently called USA TODAY for a wide-ranging conversation about music, family and marriage.
Question: You say in the documentary that “I Will Always Love You” is one of, if not the proudest, moments of your career. What was it about working with Whitney Houston that made that song so special?
David Foster: The second I heard it, I knew exactly how to make it perfect for Whitney. The whole arrangement and arc of what I did production-wise just unfolded in my head in real time. I ran to the piano, got some musicians, did a demo, played it for Whitney, and she just loved it.
I don't profess to say "The Bodyguard" was her best album ever, because she made so many great records. But I'm pretty sure I caught her when she was peaking vocally. She was like a racehorse in the studio. I'm sure she was always like that, but I caught her when her voice had just matured to the essence of who she is and was. And that song just resonated with everybody.
Q: While recording "All By Myself," did you really tell Celine Dion that you'd bring Whitney into the studio to hold the high note if she couldn't?
Foster: It was awful humor. Because she's French-Canadian, there was a little bit of a language barrier and some of the humor didn't translate completely. And she didn't find it funny. She was like, "What?!" Because Whitney was really in one of the other studios (nearby).
Q: What's a song you heard recently that you wish you'd written?
Foster: I love the (Lady Gaga and Ariana Grande) song "Rain On Me." It's so '70s disco, and it's just great. They got away with that and put a fresh spin on it.
Q: Which artists right now do you think have real staying power?
Foster: (Justin) Bieber. I don't think he's reached his full potential yet – he's a real talent. Shawn Mendes. I remember hearing his name at Disney five years ago and they're going like, "This kid's going to be big," and I was like, "I'm not sure." (Mendes auditioned for the Disney Channel as a younger teen.) Then as I watched him grow musically, it was phenomenal. And all the guys from One Direction have done great.
Q: You get candid in the documentary about your “grass is always greener” attitude in past marriages, and your successes and shortcomings as a dad. Was that painful to revisit?
Foster: It was uncomfortable. I did squirm a little watching the interviews with my daughters. We're all great, we have a great relationship, but it was tough for them for me to be gone a lot (growing up).
Q: Your daughters seem to have strong, supportive relationships with Katharine. Was that pretty immediate, or did they ever express any discomfort about the age difference to you?
Foster: No, they've known Katharine like I have. I've known her for 15 years and they've known her that long as well. It was a comfortable transition, and it's a credit to both my wife and daughters that they've just rolled with it and they do great together. It's been years now with no animosity and no problems, and I have no reason to believe that'll change at all.
Q: You say your relationship with Katharine is "a strange pairing, but it works for us." Why do you think it works?
Foster: Well, we have that musical connection. Look, we have haters on social media and there's not a person around that's not going to make some comment about the age difference. But there are so many things that can bring a marriage down: It can be financial, it can be children, it can be geography, it can be infidelity. And one of them is age difference, but that's our only problem. Everything else is in line, so it's not going to bring us down.
Q: At the end of the film, you say how death is the one unavoidable thing but the one we're all the least prepared for. What do you hope your legacy is?
Foster: If people are going to say anything about me at all, I'd like them just to say, "He did his best." I don't know if that shows in the documentary or not, but I really think that I did my best given the tools I had, both emotionally and musically.
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This article originally appeared on USA TODAY: David Foster, Katharine McPhee's 35-year age gap won't 'bring us down'