Oh Really Meaning

(colloquial, sarcastic) Said in response to an obvious statement.

Example: Used other than as an idiom: see oh,‎ really.
2007, Terrye Robins, Revenge in Paradise, page 131,
  "In less than two hours Simon is picking me up, and we're going to Maui for the weekend."
  â€œOh, really.” The line was silent for a moment. “And just what are his intentions in this romantic getaway?”
2009, Elizabeth Marie Galloway-Evans, Embracing the Gift of Parenthood, page 85,
  Well, one day when she got tired of my seemingly spaced-out replies she let me have it. She responded with, "Oh Mommy, I had a horrible day. First I lost my lunch pail and the teacher wouldn't let me go to the office for help. Then I got upset and jumped off the building." My response was “Oh really, darling, that is wonderful.” She started raising her voice and said “See, I knew you were not listening to me. You don't really want to know how my day was, so why do you even ask me?” That was it. I felt terrible.
2004, Martin Pegler, Out of Nowhere: A history of the military sniper, 2012, unnumbered page,
  'It's a sniper' shouted the bush.
  â€˜Oh really! Did you hear that boys, it's a fucking sniper. What am I? Am I talking in Czechoslovakian or what? I know it's a fuckin' sniper.’