Deleting Rows Macro :: Rows That Don't Contain Word ...

I got a code to delete all rows in the sheet which contain the word "DETAILS" but I now want to delete all the rows that do not contain the word "DETAILS"

My code if needed is:


Sub Find_details()
Dim rng As Range
Dim what As String
what = "DETAILS"
Do
Set rng = ActiveSheet.UsedRange.Find(what)
If rng Is Nothing Then
Exit Do
Else
Rows(rng.Row).Delete
End If
Loop
End Sub