1. Look at the tables feeding the parameter values, make sure there is a ID,description column. This would enable me to pass the ID's across to the detail for the parameter values.
2. The second option is to use the native SSRS drilldown to sub report option. The drawback of this approach is that the detail report would layover the top of the summary report. The user would have to click on the Back arrow in the browser to go to the summary report.