W. R. Berkley Corporation, an insurance holding company, operates as a commercial lines writer in the United States and internationally. It operates through two segments, Insurance and Reinsurance & Monoline Excess. The Insurance segment underwrites commercial insurance business, including premises operations, commercial automobile, property, products liability, and professional liability lines. It also provides workers' compensation, property casualty, general liability, professional liability, and excess and umbrella coverage insurance products; accident and health insurance and reinsurance products; insurance for commercial risks; specialty environmental products for contractors, consultants, and property owners; and liquor liability and inland marine coverage for small to medium-sized insureds. In addition, this segment offers directors and officers, and surety risk products, as well as products for life sciences and travel industries; coverage for excess liability, construction wr