Nigel Lythgoe is off American Idol.

The 59-year-old Brit, who has executive produced the hit reality show for all seven seasons, has just taken himself off the program and will not return.

No replacement for him has been named.

Lythgoe apparently felt it was time for someone else to step in. Friends say he's said privately he is "not passionate about it anymore."

American Idol ratings slipped last season, and the show was getting a little boring, sources close to the executive producer said.

Nigel Lythgoe is also said to be working on another joint venture with Simon Fuller, creator American Idol and owner of 19 Records.

Fuller and Lythgoe worked together on Britain's immensely popular Pop Idol, which spawned the U.S. series we know and love.

Lythgoe wants to spend his time on So You Think You Can Dance, the smash summer series now in its fourth season, which he created, produces and serves as a regular judge on.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.