Document fields can display table column totals. To set a document field to the value of a column total open the Document Fields Window then select the field you want to set and make sure it is a number. In the Lookup Value field at the bottom of the screen select "Table Total..." from the dropdown and the following window will appear. Select an item in the column totals list and click OK.

Tables

This is a list of all the tables in the style.

Column Totals

This is a list of the column totals in the selected table.