This Forbes article, XBRL Would Be Wonderful If It Always Worked, is right. For the information to be useful, it has to be 100% correct. Or close. My fundamental accounting concept analysis shows an accuracy rate of 97.6%. The analysis also shows every SEC XBRL financial filing which contributes to an anomaly being detected. The filers could fix their filings to get this information correct, then the 100% would be realized.
Or, the SEC could institute a set of less than probably 50 automated tests which are executed with the other testing which is done to determine whether the filing will be accepted by the SEC. That would push the accuracy rate for that specific area to 100%.
Sure, more automated tests would be necessary, but these fundamental accounting concepts would be a good start!