What is the metaphorical meaning of “hover between red and black”? I know the literal meaning of every word, but what’s the whole meaning? This picture is cut out from 00:09:59 of S02E06 of “The House of Cards”.
In finance, ledger entries are written in black when a balance is positive and in red when a balance is negative. Common idioms based on this practice are to say businesses are operating "in the black," meaning they are profitable, or "in the red," meaning they are not profitable. So this means there's no point in doing business if you can't maintain a steady profit.