XBRL-based structured digital financial reporting - Blog: Digital Financial Reporting (using XBRL)

An analysis provided by Calcbench shows three types of common errors in SEC XBRL financial filings:

Sign switches (about 50% of filings), which is reporting the incorrect polarity of a number such as reporting a negative number which should have been positive
Scale errors (about 8% to 12% of filings), which is reporting 5 when the number 5000 should have been reported
DEI errors (about 3% of filings), such as incorrect infomation for the fiscal period, fiscal year, or document balance sheet date

For more information on errors, you can see my analysis of a basic set of minimum criteria here necessary to make safe, reliable, repeatable, predicatable use of SEC XBRL financial filings. Details which explain each of those minimum criteria can be found here.