A Details section does not have all rows data available to it, it has one at a time, hence your difficulty.
You need to concatenate them into a string in order to display them in thaqt fashion:
Details Formula:
whileprintingrecords;
stringvar MyNames:=Mynames+{table.name}+","
Report footer formula:
whileprintingrecords;
stringvar MyNames;
left(Mynames,len(Mynames)-1)
So the names will display AFTER the details, so just suppress the details section by right clicking it and select Suppress.
If you have groups, and want the names at the group level, you'll display at the group footer level, and add a formula in the group header to reset the Mynames variable, as in:
Group Header formula:
whileprintingrecords;
stringvar MyNames:="";
-k