I guess the "ideal" could be the grand architectural plans for Berlin, like it was this return to classic architecture, Hitler wanted to build cities like Rome and Ancient Greece, that would stand for thousands of years and show how powerful Germany was...
The furhrer cities were all based on that sort of ideal and i think Speer really did beleive in it. But yeah self-interest definately comes into it, all the political intrigues and such...
The Cathedral of Light could also be an example of his idealism, the sort of religious, grand, overwhelming power of the Nazi regime probly effected him
anyways, horrible question!
GeorgieGirl