Banking and credit card company Discover Financial Services (NYSE:DFS) reported first-quarter financial results after market close Wednesday. Here are the key highlights. What Happened: Discover Financial reported first-quarter revenue of $4.21 billion, net of interest expense, which was up 13% year-over-year. The total beat a Street estimate of $4.07 billion, according to data from Benzinga Pro. The company reported earnings per share of $1.10, which were down on a year-over-year basis. Total Loans in the first quarter were $126.6 billion, which was up 12% year-over-year. Credit card loans stood at $99.5 billion at the end of the first quarter, which was up 11% year-over-year. "Our first quarter results showed good loan growth, net interest margin expansion, and stabilizing delinquencies, while expenses ...