The SEC is complaining about extensions. Just looking at the total number of extension elements only tells part of the story. For example, the company who created the most extension report elements, Realty Income Corp, had 4,399 extensions, but 4,123 of them where [Member]s. Those [Member]s seem perfectly reasonable to me. (You can go to their filing here, look at the second to the last schedule in the Notes Detail)
So, one really needs to understand which category of report element is being extended. This visualization which I created shows that detail.
Isn't Tableau useful? I think so. Slice, dice, sort, search, filter to your hearts content. Find anything interesting be sure to let me know.