With any field in the Pivot a double click will drill down to the records in the query that make up the sum. This enables instant evaluation of the data with the complete record in the query.
So, in our example if we double click on any of the grand total fields we will see all the individual invoice lines.
Just double click a 'Grand Total'
A modal popup appears with a grid showing the sub set of data:
This popup has all the features of column sorting, filtering, grouping export to PDF & Excel. So you could group by 'idxOurRef' to see the whole invoice and total it
Granular control over all the data and the ability to see it any which way you need to and out put the results quickly.