"Total liability for 2013 was down from total liability for 2012, which was $338 billion. The decrease was mainly due to increases in discount rates.... Of the 501 companies that [have retiree medical liability], 67% had no assets backing the liability.... Volatility of the discount rate makes the obligation variable and unpredictable.... Tax reform legislation could wipe out billions in deferred taxes overnight.... Longer life expectancies could increase the projected obligation.... Boards and shareholders view dedicating balance sheet capacity to a nonstrategic benefit as an inefficient use of capital."