Create code to convert iXBRL html files to csv.

UK company accounts are free to be downloaded from http://download.companieshouse.gov.uk/en_accountsdata.html

The download as HTML but are iXBRL (inline eXtensible Business Reporting Language) format (HTML file). When opened the HTML docs appear to be many styles and formats, it is my understanding that this links to a common source that I hope can be extracted.

Information on the file types are here https://resources.companieshouse.gov.uk/infoAndGuide/faq/accountsDataProduct.shtml
This is where is states that 97% of the files will be in iXBRL (inline eXtensible Business Reporting Language) format (HTML file).

Requirements:

1.Written in Python or PHP
2. Convert multiple iXBRL files into one csv file.
3. Robust to adapt to multiple HTML formats
4. Commented code