have (one's) head in the clouds
To be impractical, aloof, or fanciful, often to the point of being very unhelpful or counterproductive. He has his head in the clouds while the rest of us are trying to figure out how to fix this! My daughter always has her head in the clouds as she walks home from school.
head in the clouds, have one's
Be absentminded or impractical, as in She must have had her head in the clouds when she made the reservations, because they never heard of us , or He'll never be able to run the business-he's always got his head in the clouds. This idiom uses in the clouds in the sense of "fanciful" or "unreal," a usage dating from the mid-1600s.