. the vesting date fair value of restricted stock awards which vested during 2007 , 2006 and 2005 was $ 29 million , $ 32 million and $ 13 million . as of december 31 , 2007 , there was $ 37 million of unrecognized compensation cost related to restricted stock awards which is expected to be recognized over a weighted average period of 1.4 year . 25