Pretty young lady sitting next to me in the meeting a few minutes ago:
You can't flush out a concept.
You flesh out a concept.
See the metaphor? A concept is like a quick stick-figure sketch of an idea, and when you flesh it out, you add musculature, texture and other details to realize it.
You can flush something out, but that's quail-hunting. Or plumbing, I suppose.
There. Sorry to interrupt your self-involved blathering. Please -- carry on.