Thursday 23 January 2014

XBRL data errors

I’m going to talk here about actual errors rather than data issues (a whole different topic worthy of a ream of posts by itself). So we are talking here about stuff that is just plain wrong (rather than data that just might need some proper treatment).

XBRL US, to their credit, monitor this all very carefully and clinically. They have divided errors up into 32 types (If we've got a 16,000 plus data set, better make sure we have a similarly impressive number of error types to go with it!).

I guess though I would classify all these errors into four categories:

Errors in the XBRL formatting – you should never see these as the filing would fail the compliance tests on submission although according to the XBRL US stats they do exist - "Filing is Invalid XBRL" in the link above.

Stupid mistakes – often made because the filer quite understandably uses the last filing as a template e.g. period date is wrong.

Erroneous values – seeing the figures are more often than not pasted or automatically transposed from the html filing (this believe it or not is how most XBRL filings are created!!), the absolute values shouldn’t be wrong but the sign or scaling factor could be.

Incorrect or questionable tagging – could either be down to the wrong US GAAP tag being used or the inappropriate use of an extension.

There are various financial data providers out there who can and will fix this type of error in their databases but if like me you prefer to deal with the original documents then what to do?

Well we’ve decided to fix some of these errors in the instance documents themselves. The next post will explain exactly what we are talking about here, by way of a couple of examples.

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