Is there a Perl library for handling XBRL information

I don't think so. I know of no existing Perl solution for this. Of course it is XML and any validating parser (with full support for XML Schema) can be used. However, XML Schema validation is only a part of the story, you do need additional software. I recommend taking a look at XBRL tools. In general www.xml.com is also a place to check.

Cheers

Harry

PS Beware of the XBRL learning curve it's not really simple.