Consider the audience for your documentation. Many of us think that our business reps/super users need long, verbose documentation so that we all understand the problems at hand. It is also a CYA measure. But most business reps/super users prefer brief, to the point documentation, highlights of a meeting, including decisions made, action items, etc. Giving them a lengthy document will just result in a rubber stamp "ok".
In Lean Software Development, documentation is inventory. Inventory can go stale or get old. Keep the inventory to a minimum.
As Scott Ambler says "travel light": "traveling light means you create just enough models and documentation to get by. Every artifact that you create and decide to keep will need to be maintained over time". Ambler, Scott. 2002. Agile Modeling: Effective Practices for eXtreme Programming and the Unified Process. Wiley and Sons: New York, NY. p.29.
Also, as I have learned recently, create a glossary for common terminology so that you are all on the same page. This is especially important in a product that integrates with another team.