Basically, your "footer" (if it is what we normally think of as a footer) is actually just a section that has properties including .Height. Your gap at the bottom of the detail section (between detail and footer) is probably because the detail section's .Height is higher than it needs to be for your desired format.
If you can find the control that is physically the lowest one in the detail section, find that control's .Top and .Height properties and make the detail section's .Height equal to control.Top + control.Height + 1. You should also set your control borders to minimum size as well.