Thursday, 23 January 2014

Fixing errors in XBRL Instance documents

(Should be read in conjunction with the post – XBRL Data Errors)

In my last post, I talked about the different XBRL errors that you could possibly encounter. And we at Fundamental X are going to fix errors in the first two categrories (XBRL formatting errors & stupid mistakes) whenever we come across them.

This approach suits us as the data we currently output to Excel via XBRL to XL and Sector3 is generated on the fly from the original instance documents filed with the SEC. And we figure there are a lot of people out there who prefer to deal with the original documents rather than data that’s been mangled through a database.

XBRL formatting errors are rare. Stupid mistakes made in the creation of the XBRL filing are not (Invalid Axis Member Combination, one of the XBRL US classifications of this type of mistake, currently sits at the top of the error leader board) so I’m going to focus on these.

The following two examples should give you a flavour of the nature of these errors and how we will fix them.

Texas Capital Bancshares 2012 10-K

If you look at the Document and Entity Information in the interactive data on the SEC site, you immediately see the problem:


The "Document Period End Date" and the axis date don't match. That's because the date for this filing hasn't been updated in the XBRL from what is more than likely a previous XBRL filing (you can double check that the date is indeed incorrect by referencing the html 10-K), Therefore the dates for the most important contexts in the entire filing are wrong. At this point our processing software throws a wobbly and we fix the error in the instance document. Seeing it is an elementary error in the XBRL, it seems judicious to fix it in the source rather than further down the processing and storage road.

Of course this kind of error should be bought to the attention of the SEC and the company concerned. The filing will not be corrected but I think an additional amended 10-K/A would be filed instead. But markets wait for no man.......

So what do we do? Well here is what the error looked like in the XBRL:


So we changed the date in the context (and all other relevant contexts) and corrected the context name to reflect the change. At this point all references to this context also needed to be changed. It's important to note that we didn't re-create the XBRL filing as we want to retain the integrity of the existing filing, so we merely amended it. All changes are noted at the top of the file involved and all file changes are summarised in the xsd file as shown below:


The amended files are then used in preference to those on the SEC site when generating XBRL to XL products.

I feel this post is getting a little tedious so the second example will have to wait till the next post. You can download the amended XBRL instance document for Texas Capital Bancshares in it's entirety from here.

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