over the moon

(idiom) very happy
Example Sentences:

A: Did your husband have fun at the Car Show?
B: Yeah! He was over the moon! I’ve never seen him smile so much!

Robert felt like he was over the moon when he passed the important exam.

From the Blogs:

“Twilight” Fans To Be Over the moon For Death Cab For Cutie Really Soon

Media:

Similar idioms:

1. walking on air
2. like a kid in a candy store
3. once in a blue moon