Try here -
http://www.ancestry.com/learn/facts/Fact.aspx?fid=10&ln=DetwilerThe weiler part may mean "hamlet". The wyl in Detwyl is probably equivalent to German weill, which could mean "well, spring" (I think), or be from the Latin villa, meaning "farm". I would guess that Det is part of an Old Germanic personal name, such as an earlier version of modern Dietrich, or Detlef.