Yes, there is a way to protect certain cells and allow the user to show and hide detail depending on their preference. Here's how you can do it:

1. Select the cells that you want to protect.
2. Right-click on the selected cells and choose "Format Cells" from the context menu.
3. In the "Format Cells" dialog box, go to the "Protection" tab.
4. Uncheck the "Locked" checkbox and click OK.
5. Now, protect the worksheet by going to "Tools" "Protection" "Protect Sheet".
6. In the "Protect Sheet" dialog box, check the "Use AutoFilter" and "Use PivotTable reports" checkboxes.
7. Click OK to protect the worksheet.

Now, you can use the "Group" and "Outline" options to show or hide the detail in the protected worksheet. To do this, follow these steps:

1. Select the rows or columns that you want to group or outline.
2. Go to "Data" "Group and Outline" "Group" or "Outline".
3. The grouped or outlined sections will be collapsed by default.
4. To expand a section, click on the "+" sign next to it.
5. To collapse a section, click on the "-" sign next to it.

Note that the "Group" and "Outline" options will only work on the unprotected cells in the protected worksheet. If you try to use these options on the protected cells, you will get the error message "You cannot use this command on a protected sheet".