Index: django/contrib/admin/views/doc.py
===================================================================
--- django/contrib/admin/views/doc.py	(revision 1012)
+++ django/contrib/admin/views/doc.py	(working copy)
@@ -290,7 +290,7 @@
     # ForeignKey is a special case. Use the field type of the relation.
     if field.__class__.__name__ == 'ForeignKey':
         field = field.rel.get_related_field()
-    return DATA_TYPE_MAPPING[field.__class__.__name__] % field.__dict__
+    return DATA_TYPE_MAPPING[field.get_internal_type()] % field.__dict__
 
 def extract_views_from_urlpatterns(urlpatterns, base=''):
     """