Many people consider Buddhism as idealism, because everything in this world is a reflection of our mind. It is not true, although most of other religions in the west are idealism but not Buddhism. On the other hand, Buddhism is neither materialism. Although we may find Buddhism may be partial materialism or idealism, but it is neither in general. Materialism and Idealism belongs to a certain category of western philosophy, but it can not include all the human knowledge.
Buddhism believe the world is neither consist of material or immaterial, it is an illusion created by our mind.
[Excerpt from Luminous Wisdom Book Series 1: The Illusory World]