Anybody
familiar with XBRL has heard of extensions. But not many are aware that extensions
go far beyond these custom tags. In fact, filers create an entire EXTENSION
TAXONOMY as a bridge from their internal taxonomy to the US-GAAP standard
taxonomy. Literally anything in this extension taxonomy can be customized: tags,
labels, signs, units, hypercubes, dimensions, members, captions. Obviously,
this is a recipe for chaos.
But there’s one requirement of this taxonomy that allows the data to be usable – the CALCULATION ARC.
This simply describes the relationship between two primary elements, like ‘Inventories’
is a summation component of ‘Current Assets’ with a weight of 1. The
calculation arc gives the extended taxonomy meaning. With it, users (and more
importantly, users’ software) can complete the translation to the standard
taxonomy by mapping custom tags, correcting signs and validating facts. Without it, standardization and
efficient data ingestion are extremely difficult.
Here’s the requirement
from the Edgar Filer Manual – Version 2:
6.15.2.
If the original HTML/ASCII document shows two or more line items along with
their net or total during or at the end of the Required Context period, and the
instance contains corresponding numeric facts, then the DTS of the instance
must have an effective calculation relationship from the total element to each
of the contributing line items.
The problem is that
22,132 calculation arcs are missing YTD. That's 2.1% of the 1,013,308 primary
line items tagged in 13,333 commercial XBRL filings. Many others are
mis-specified. The reasons?
- some filers
simply don’t bother
- most software vendors
don't require calculation arcs
- the SEC chooses
to look the other way.
Clients of certain
software vendors are more likely to omit calculation arcs, like Novaworks.
Here’s a montage of some recent Novawork’s client filings that are
largely devoid of the required calculation arcs. (items in red are missing
arcs, any colored item is a problem)
