Wikipedia:Splitting

If an article becomes too large, or a section of an article has a length that is out of proportion to the rest of the article, it may be appropriate for some or all of the article to be split into new articles. In some cases, refactoring an article into child or sister articles can allow subtopics to be discussed more fully elsewhere without dominating a general overview article to which they are non-central (but only if the new articles are themselves sufficiently notable to be included in the encyclopedia).