SEC XBRL Context Dates

Question

In SEC XBRL financial filings, why do the date ranges for duration contexts not match the context's quarter?

e.g. The markup for the context "D2012Q3" may look like:

<xbrli:context id="D2012Q3">
    <xbrli:entity>
        <xbrli:identifier scheme="http://www.sec.gov/CIK">0000826083</xbrli:identifier>
    </xbrli:entity>
    <xbrli:period>
        <xbrli:startDate>2011-07-30</xbrli:startDate>
        <xbrli:endDate>2011-10-28</xbrli:endDate>
    </xbrli:period>
</xbrli:context>

As you can see, the context is for the 3rd quarter of 2012, but only covers the date range from 2011-7-30 to 2011-10-28, which is 11 months before the 3rd quarter of 2012. Why is this?

And this pattern isn't even consistent, because other contexts, even for the same company, may look like:

<xbrli:context id="D2011Q4YTD">
    <xbrli:entity>
        <xbrli:identifier scheme="http://www.sec.gov/CIK">0000826083</xbrli:identifier>
    </xbrli:entity>
    <xbrli:period>
        <xbrli:startDate>2010-01-30</xbrli:startDate>
        <xbrli:endDate>2011-01-28</xbrli:endDate>
    </xbrli:period>
</xbrli:context>

Here, Q4 of 2011 has date ranges covering an entire year. Presumably, the YTD indicates an aggregation over several quarters, but I still don't understand where they're the date ranges from or what they signify.

Answer 1

This has to do with Fiscal Year End. In your particular case for CIK = 826083, which is Dell Inc, Fiscal Year End is 0129, which means January 29th. D2012Q3 means is is in FY = 2012, End of the year is 012912, because it's the report for Q3, you count 3 months behind and the end of Q3 is 102811.

Same for the second example you gave, as it is the same company. D2011Q4YTD means FY = 2011 so ends 012811 which is the one stated in the XBRL extract that you gave us.

Hope this helps.

P.S. You should check www.finviews.com, we have already done all the work. We can provide all the XBRL reports directly into Excel, and when a company files its reports (10Q, 10K) with the SEC, it takes us less than 2 minutes to have all the data in Excel as the company published, so you can do your financial modelling afterwards.

Answer 2

The standard is outlined here.

The id field needs only to be relatively unique based on some factors.

The reason why dates are inconsistent from year to year is because those are the dates the books are opened and closed.

Those dates are governed by regulation and the internal intricacies of a company in question which are both many.