The purpose of this act is to allow any federal savings bank, federal mutual savings bank or federal savings and loan association, located in Idaho to convert its charter to that of an Idaho bank, an Idaho stock savings bank or an Idaho mutual savings bank. Banks and credit unions chartered either under this title or federal law are also allowed to convert to savings banks as provided herein. Once converted, an Idaho stock savings bank or mutual savings bank shall operate and be supervised pursuant to this act. A savings bank operating under this act may convert to a federal charter as a federal savings bank or federal savings and loan association if authorized by federal law. A savings bank under this act may also convert to a bank charter or to a credit union charter. Wherever the term "savings and loan association" is used in the Idaho Code, it shall include savings banks chartered under this act or associations doing business in this state pursuant to section 26-1815, Idaho Code.