Expand or collapse data details in Excel Services
If the workbook that you have contains a PivotTable report, you can expand or collapse to any level of data detail. For example, if you see data at a country/region level, you can expand to a state level, and down to a city level.
Note Although the expand and collapse buttons are usually turned on by default, the workbook author may have turned off the expand and collapse buttons.
On a field, click the expand or collapse button.