RDF Data Access Providers (Drivers)
Enable the XBRL Cartridge
 
You need to ensure the Virtuoso RDF Mappers VAD package is installed.
If you have not built this yourself from your open source build it is 
also available for download from:
http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/ VOSDownload#Other%20Virtuoso%20Packages
It can be installed from the "System Admin" -> "Packages" tab of the 
Virtuoso Conductor.
Details on the Virtuoso Sponger and usage examples can be found at:
          http://virtuoso.openlinksw.com/dataspace/dav/wiki/Main/VirtSponger