How much detail is too much detail for a story?
The cliched answer is still the correct one: When the amount of detail pulls you out of the story, it's too much.
Only you and a reader can know that sweet spot it, and it's going to change with each story. In fact, both you and the reader may have differing criteria for the "how much is too much" question.
But I don't think so much it's the "amount" of detail as it is the "choice" of details you reveal. Those that forward the plot and build on character tend to work better than those that merely drone on about the shape of the rocks. Use world-building details carefully. I'll repeat that. Even if you're writing epic fantasy, be very careful when using world-building details unless they also help advance the plot or reveal character.
I know there's a history of epic tales that focused (some might say overfocused today) on the details of the geography of the mountains, the castles, and even the Gothic mansions, but those were written for audiences who hadn't been over-inundated with image-based media. Modern readers are so used to pre-established visuals that best-selling fiction tends to use short-hand that gets the details out quickly and them move directly into dialog and action.