The SEC’s Division of Risk, Strategy, and Financial Innovation has updated its guidance for XBRL filings, based on its observations through the send quarter of 2011, to remind filers of some mmon errors that seem to persist.

Overall, mpanies are providing high-quality submissions and appear to be devoting significant resources to assuring their XBRL submissions are aurate and mplete, acrding to the staff. That’s the good news. The bad news, however, is that mpanies seem to be making the same mistakes that the staff has already highlighted and tried to rrect.

The two big areas of ncern are problems with negative values and an inappropriate focus on the physical rendering of the submission. The staff says some preparers still haven’t fully grasped that the taxonomy definitions include ncepts of positive and negative values, so the numbers that are entered already reflect positive and negative values.

When filers add a negative to a number that is already defined in the taxonomy as negative, the reported figure is wrong. The staff guidance includes a detailed explanation of how debits and credits work in the XBRL world, hopefully putting to rest nfusion over positive and negative values.

“Although numbers shown in the HTML attachments of an EDGAR submission may be presented as negative, they should almost always be entered as positive numbers in the XBRL instance attachment,” the guidance says. “The most mmon error filers make is to inrrectly enter an amount with a negative value. Most XBRL tagged numbers are positive even if the value is presented with brackets on the printed financial statements.”

The staff guidance also says filers are too fixated on the physical appearance of their XBRL financial statements, especially newer filers who are still learning how XBRL works. The staff still finds a disturbing number of instances where filers have created extensions solely to achieve a particular alignment of rows and lumns to make their XBRL submissions look just like their HTML financial statements. That’s not necessary, the staff points out, or even appropriate.

“Filers should ncentrate on the quality of the tagging rather than trying to match the rendering of the XBRL exactly to the HTML filing,” the guidance says. “Furthermore, filers should not create custom elements or use inrrect dates in their ntexts just to achieve specific rendering results.”

The rendering might be helpful for spot checking to look for whether tag selections are mplete and proper, although it’s not even the best tool for that process, the guidance says. The staff suggests mpanies check with their service providers or software vendors to determine the best way to check for proper and mplete tag selections.

On the upside, the guidance makes it clear that mpanies are doing a better job of searching the taxonomy and finding appropriate tags to describe items in their financial statements rather than jumping to extensions when they don’t readily find a perfect fit.