When working on a large code base across many projects, you have files which are different code styles. As the code is version controlled, it is not desirable to reformat all the code. Ideally, idea could auto detect the code style for a file and match the style. OR in the worst case, it just remember the style on a file by file basis. (ugly) Style differences include 2 space indentation, 4 space indentation, tab indentation.