.0 at maturity for a total cost of $ 258.6 , which included the principal amount of the notes , accrued interest to the redemption date , and a prepayment penalty of $ 1.4 . to redeem these notes we used the proceeds from the sale and issuance in july 2005 of $ 250.0 floating rate senior unsecured notes due 2008 . floating rate senior unsecured notes in december 2006 , we exchanged all of our $ 250.0 floating rate notes due 2008 for $ 250.0 aggregate principal amount floating rate notes due 2010