Doug Mahugh had a post last week showing how you could leverage the custom schema support in OpenXML to create a report based on XBRL data. http://blogs.msdn.com/dmahugh/archive/2007/03/09/xbrl-and-open-xml.aspx#comments
Here's a screenshot of the document he created (where each value is bound to XBRL data):
As I've said in the past, the custom schema support really gives you a lot of power when you want to work with your data, rather than just the data defined in the standard (formatting, layout, etc.). If you're thinking about building a solution, note that the support for custom XML is different in each application (Word, PPT, Excel), so you'll want to look at that as part of your investigation.