The word that come to my mind immediately is "content" or "contented." Webster's New World Dictionary simply defines the word: "1.satisfied 2.willing; assenting"
Upon further reflection, I tend to think optimism and idealism are confused terms, especially by pessimists. I would say,
When asking for a promotion, an idealist will expect to receive the promotion. An optimist will hope for a promotion, but won't be disappointed without it.
Because optimism is at the core of my being, this is how I would view the situation. Because the optimist is generally going to have an optimistic view, even of not getting the promotion. (Though I doubt many would realistically be "not disappointed" if they're asking for the promotion, even an optimist). But because there is this common misconception of optimist, I believe content or contented would suffice. Besides, content has such a pleasing ring to it, doesn't it?
Note: Webter's New World Dictionary defines as follows:
idealism: 1. behavior or thought based on a conception of things as one thinks they should be 2. a striving for one's ideals
optimism: 1.the belief that good ultimately prevails over evil 2. the tendency to take the most hopeful view of matters