Detlef

I agree with paganqueen that the meaning of the name Detlef is "son of the people". The Germanic word "laiba" means "son".
The other person who stated that the name Detlef is quite unpopular in Germany should realise that this has come about only in recent years, when someone had the brilliant idea of using the name as a label for homosexual males. In former times the name was quite respectable.

My uncle who bears this name (he spells it "Detlev") said it means something like "son of the people" or "servant of the people".