Billy Joel is opening up about a tough moment with longtime friend and tourmate Elton John. In the second part of the new two-part HBO Documentary, “Billy Joel: And So It Goes,” the “New York State of Mind” singer shared how John’s public comments that he needed rehab strained their friendship.

Billy Joel acknowledged “bad blood” between himself and Elton John in the second installment of his two-part HBO documentary “Billy Joel: And So It Goes,” released Friday. Joel explained the pair’s fallout occurred after John publicly insisted he needed to go to rehab.

Billy Joel says there was once "bad blood" between him and Elton John. In the second part of a new two-part HBO documentary Billy Joel: And So It Goes, the "Piano Man" singer opens up about how the "Your Song" musician's public declaration that he needed rehab caused tension between them.

Billy Joel's two-parted documentary, And So It Goes, co-executive producer Steve Cohen opened up about Tom Hanks' approach towards the film.The HBO project follows Joel’s

And So It Goes' interviews all four of his wives and candidly examines singer's struggles with money, alcohol and critics

Forgiveness is complicated. And so is self-examination. But Billy Joel, who has an inherent likability, and his loved ones seem to be well-practiced in the art of both.

Here's everything to know about Billy Joel's family, including his parents and siblings. Billy was welcomed by his parents, Rosalind and Howard, on May 9, 1949, in the Bronx, N.Y., per The Kennedy Center. He was then raised in Long Island, N.Y.