Hello PilgrimOffice,
Thanks for sharing your question regarding using Google Documents with the onscreen keyboard on your Surface Pro 3. I'll do what I can to help you with this question.
First, I should ask, just to verify: you are using Google Chrome, correct? You stated that you are editing Google documents, but you don't specify whether you are using Chrome while doing so. Assuming that you are using Google Chrome, it is a touch-optimized program, and as such, when you tap on a writing field, the onscreen keyboard will pop up. What you can do to avoid this is use a mouse or the touchpad on the Surface Pro 3 cover to select the positions in the document that you would like to edit.
Let us know if we understood your issue correctly. Also, please post again if you have any other questions or issues.
Best Wishes,
Zack_T