For what you want, I think Watson's "Mastering" series is probably the only real option. That gives a general survey of openings without spending too much time on any one opening, and while putting the focus on explanation rather than concrete theory.
It's very general, though.
You'd be further ahead if you were looking for info on specific openings. There are a number of opening guides that offer specific repertoire advice, together with intermediate-level explanation and guidance. But to advise, we'd need to know which openings you're interested in.
I am looking to buy a book on openings. Preferably one which to an extent explains the ideas and typical plans in each opening. Is there any such book?
I hear good things about "Fundamental Chess Openings". Is it any good? Or those volumes by Watson. Any input is appreciated.