Arelle now has two code branches, the original, using the W3C conforming minidom xml library and its API interfaces, and a new one, using the lxml library, which is much faster and uses a lot less memory.  The lxml branch is still in testing, please send bugs to support@arelle.org.  Both branches are on GitHub, and the lxml branch source code is only available there (linked from download page).

Thanks to the Arelle contributors who dug deep into xml library speed and memory investigations to find the way for those of us who are impatient!!!