Why does the entity element include a segment element in XBRL contexts?
Sometimes the entity identifier is not sufficient to fully describe the entity being described by the facts associated with the context. For example, some reports are generated for individual lines of business rather than for a whole institution. When the entity identification scheme does not cover the lines of business, additional entity identification markup is required. This markup is always placed in the “segment” element. The specific markup used in the “segment” elements is up to the creator of the instance documents containing the multi-dimensional tables. The particular markup used can be adopted by convention. Preferably, however, it is described and can be validated, using an XML Schema definition of the markup for the various dimensions.
