W. R. Berkley Corporation is an insurance holding company. The Company operates through two segments of the property casualty insurance business. Its Insurance segment underwrites predominantly commercial insurance business, including excess and surplus lines, admitted lines and specialty personal lines throughout the United States, as well as insurance business in Asia, Australia, Canada, Continental Europe, Mexico, Scandinavia, South America and the United Kingdom. Its Insurance segment consists of business units, including Acadia Insurance, Admiral Insurance, Berkley Accident and Health, Berkley Agribusiness and others. Its Reinsurance segment provides facultative and treaty reinsurance in the United States, as well as in the Asia Pacific region, Australia, Continental Europe, South Africa and the United Kingdom. The Reinsurance & Monoline Excess segment consists of business units, including Berkley Re America, Berkley Re Asia Pacific, Berkley Re Solutions, and others.