air of detachment

Translations
атмосфера отстраненности
He spoke with an air of detachment, as if the issue did not concern him.
Он говорил с атмосферой отстраненности, как будто этот вопрос его не касался.
Definitions
A demeanor or attitude characterized by a lack of emotional involvement or concern, often suggesting indifference or aloofness.