The Devil in the Details

Good morning, gentle readers!  Have a good weekend? Back at the old grind? Buck up! I'm sure you're all going to have a wonderful day!  And if not, I'm sure there's a cheap liquor store on your way home. ^_^
The other night I finished D.M. Cornish's Foundling, the first book in his Monster Blood Tattoo trilogy.  Foundling was an entertaining read with engaging characters, but the thing that really made this book shine for me, was Mr. Cornish's worldbuilding.  The story is set in a fantastic world of caustic oceans, threatening monsters and surgically altered warriors.  There is a tone to this book, anchored in the Germanic-sounding words Mr. Cornish uses as place names and descriptors.  It is a wonderful book.
At the end of Foundling, is a glossary of terms used, apparently, throughout the entire series. This glossary is over 100 pages which suggests to me that Mr. Cornish may have got a little lost in the process of building his world.
I'm afraid, gentle readers, that this is a problem for a lot of writers.  We get so drawn into the act of creating a believable world that we get lost in the details.  Sometimes, we sacrifice time to deliver ten pages of background on the history of a town or a prominant historical figure that doesn't really have anything to do with the story.
It's like 'color commentary' during a football game.  A little goes a long way, but too much distracts from the enjoyment of the game.
As writers, we have to find the happy medium.  Describing a fantasy world you've spent untold hours developing may be personally enjoyable, but most people won't care that the River Volstag is named after an ancient general who explored the region.  Not unless it's germain to your story.
Even if General Volstag's ghost rises from the water every full moon to terrorize the river, we don't need to know his entire biography.
Think of it like this: there's a devil in the details, just waiting to lure you in and overload your story with unnecessary description. 
Resist him.