NEW YORK--(BUSINESS WIRE)--Fitch Ratings has affirmed the long-term Issuer Default Rating (IDR) of Otter Tail Corporation (OTTR) at 'BBB-' and the long-term IDR of its regulated electric utility subsidiary, Otter Tail Power Company (OTP) at 'BBB'. The Rating Outlook for OTTR and OTP is Stable. A complete list of ratings is provided at the end of this release. Due to the risks inherent in the diversified business portfolio, Fitch rates OTTR one notch below its regulated subsidiary OTP. OTTR's cu