CHICAGO--(BUSINESS WIRE)--Fitch Ratings has affirmed Archer Daniels Midland Co.'s (ADM) Issuer Default Rating (IDR) at 'A'. The ratings apply to approximately $5.7 billion of total outstanding debt. The Rating Outlook is Stable. See a full list of ratings at the end of this release. KEY RATING DRIVERS --EBITDA margin increased significantly to 4.8% in 2014 from 3.4% in 2013 concomitant with a 27% increase in EBITDA as ADM successfully executed upon its operating strategy. Fitch sees EBITDA marg