In the presentation file it lists how the concepts are supposed to be grouped together but if you look at the actual table not every value for each tag is present. For example, a row could have three values of the us-gaap:RevenueFromContractWithCustomer tag but in the xml file there could be more than 50 values belonging to that tag. How does it know to only group certain values together?
I tried looking at the contextRef's but those didn't really pertain to row info. I couldn't find anything in the elements' attributes that grouped certain values together either.
This is because of the use of dimensions. The three values that appear in a "basic" fact table will be those of the facts with no user-defined dimensions. The 47+ other values correspond to facts with extra dimensions.
The way to see if there are extra dimensions is to look up the context with its ID in the syntax, and to see if it includes dimension info (in a segment or scenario element).
However, this should best be done by an XBRL processor, otherwise any attempts to write one's own code to process the syntax would be basically rebuilding an XBRL processor from scratch.