@Matt_2.0
graphicdesign.stackexchange.com/questions/11122/… || If you have older version, you can go to
Layout > Margins and columns... and check
Layout adjustment. After that change you document size. ( This is very tiny tiny layer adjustment compared to Liquid layout in cs6. Layer adjustment can be a life saver, though.. ) About Layout adjustment:
adobe.ly/1ct8IwT