Sub Transfer_Summary_Detail()
  Dim c As Range, j As Integer
  Dim Source As Worksheet, Target As Worksheet

  Set Source = ActiveWorkbook.Worksheets("Summary")  ' Change worksheet designations as needed
  Set Target = ActiveWorkbook.Worksheets("Sheet1")
  
  j = 4     ' Start copying to 4th row in target sheet
  For Each c In Source.Range("P4:P4000")   ' Do 4000 rows
    If c.Value <> 0 Then
      Source.Rows(c.Row).Copy Target.Range("A" & j)
      j = j + 1
    End If
  Next c
End Sub