Can you create a Drill Down Level for Sub-Totals?

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I have a report similar to the attached image where I have created drill down levels for some grouped records. This works great. I would like to be able to click the subtotal amount and drill down into a level with all of the records in the subtotal listed. 

In the attached image, I have the drill down working successfully for the records in green, but want to know how to drill down into the records in red.