As the author, you might have every last detail of your character and your setting in your mind. (Or perhaps even drawn out.) However, not every single one of those details needs to make it to the page.
But why? Shouldn't the story be as real as possible?
YES. And that's exactly why: because unless your character is Sherlock Holmes or Shawn Spencer, your character is not Sherlock Holmes or Shawn Spencer. Your character is probably a mere mortal. Which is why, sometimes, generality is key.
Humans think in generalities, and relate stories in generalities, which is why when specifics are introduced, we know they're important. If someone were to tell a story about one of someone's dozen cookies being stolen in an indoor market, they'd probably describe the indoor market as large and bustling, rather than 10,000 cubic feet with seventy-three independent conversations happening between a ratio of three females for every male present, as well as seven babies crying and... If you did that, the next part about how the cookies were arranged (which would differ after some were stolen) would be less important, and might go over the reader's head.
Besides, large and bustling gives about the same mental image, does it not? We humans share a language for a reason--words have meaning. We are readers for a reason--we have imaginations. Together the two can do wonders, so feel free to let the reader take the reins once in a while.