( a ) includes $ 367 million of both amortized cost and fair value of securities classified as corporate stocks and other at december 31 , 2012 . comparably , at december 31 , 2011 , the amortized cost and fair value of corporate stocks and other was $ 368 million . the remainder of securities available for sale were debt securities . the carrying amount of investment securities totaled $ 61.4 billion at december 31 , 2012 , which was made up of $ 51