For the 7160 SEC XBRL financial filings I have been analyzing, all 10-Ks, I did an analysis of the line items of different sections of the balance sheet.
First off, let me say that this analysis is not perfect just yet. For one, I am only able to get to the 91% of filers who provided calculation relations for their Assets and Liabilities and Equity roll ups. (i.e. 9% did not provide XBRL calculation relations for the roll ups and I am not reading those because I am using the calculation relations to find the children.)
Second, I realized that a better assessment would come from separating the filers who have classified balance sheets from those who do NOT have classified balance sheets.
Given the above, this is what I see:
You can get the raw data from this Excel spreadsheet if you desire.
Consider the column "Current Assets". There were an average of about 5 line items for the category current assets in the set of filings analyzed. The extension rate for current assets was 4.2%, slightly less than the average extension rate for the overall balance sheet which is 5.3%.
Here are the most commonly occurring current asset line items:
In the Excel workbook above there is a spreadsheet which contains a list of every extension added to current assets for all the filers. I took that list, I did a search on the term "inventor" (to catch inventory and inventories). I then removed the US GAAP XBRL taxonomy concepts. What was left were these extensions:
Really. The concept "us-gaap:InventoryNet" is not good enough?
Go grab the Excel spreadsheet, slice and dice it, if you find something interesting please let me know.
Something to note. So obviously because I am grabbing this information about the line items per balance sheet section, I can clearly identify the components of that section. This is whether the concept is an extension or not. While I cannot tell you WHAT the extension is without reading the concept documentation; I can get the line item.
As I write this it occurred to me that another interesting bit of information is the number of extensions per balance sheet section. I sort of have that information. If, for example, there are an average of 5 current assets line items and the extension rate is 4.2%; then the average filer has .21 extension concepts. Plus, given the obvious misuse of extensions for the concept inventories above, the extension rate can likely be reduced.
Anyway, have fun looking at the data if you are so inclined.